,illustration3 ,dunes at ,ipswich       
,light1 ,massachusetts4 ,note the effect
 of bushes in arresting the movement of 
the wind-blown sand4                    
,,outlines ,,of ,,the                   
,,earth',s ,,history                    
,a ,,popular ,,study                    
,,in ,,physiography                     
,,by                        ,,nathaniel 
,,southgate ,,shaler                    
,,professor ,,of ,,geology ,,in         
,,harvard ,,university                  
,,dean ,,of ,,lawrence ,,scientific     
,,school                                
,,illustrated ,,with ,,index            
,,new ,,york ,,and ,,london             
,d4 ,,appleton ,,and ,,company          
#ahih1 #aiaj                            
,,preface4   ,the object of this book is
 to provide the beginner in the study of
 the earth's history with a general     
account of those actions which can be   
readily understood and which will afford
 him clear understandings as to the     
nature of the processes which have made 

this and other celestial spheres4 ,it   
has been the writer's purpose to select 
those series of facts which serve to    
show the continuous operations of       
energy1 so that the reader might be     
helped to a truer conception of the     
nature of this sphere than he can obtain
 from ordinary text-books4  ,in the     
usual method of presenting the elements 
of the earth's history the facts are set
 forth in a manner which leads the      
student to conceive that history as in a
 way completed4 ,the natural            
prepossession to the effect that the    
visible universe represents something   
done1 rather than something endlessly   
doing1 is thus re-enforced1 with the    
result that one may fail to gain the    
largest and most educative impression   
which physical science can afford him in
 the sense of the swift and unending    
procession of events4  ,it is well known
 to all who are acquainted with the     
history of geology that the static      
conception of the earth--the idea that  

its existing condition is the finished  
product of forces no longer in          
action--led to prejudices which have    
long retarded1 and indeed still retard1 
the progress of that science4 ,this fact
 indicates that at the outset of a      
student's work in this field he should  
be guarded against such misconceptions4 
,the only way to attain the end is by   
bringing to the understanding of the    
beginner a clear idea of successions of 
events which are caused by the forces   
operating in and on this sphere4 ,of all
 the chapters of this great story1 that 
which relates to the history of the work
 done by the heat of the sun is the most
 interesting and awakening4 ,therefore  
an effort has been made to present the  
great successive steps by which the     
solar energy acts in the processes of   
the air and the waters4  ,the interest  
of the beginner in geology is sure to be
 aroused when he comes to see how very  
far the history of the earth has        
influenced the fate of men4 ,therefore  

the aim has been1 where possible1 to    
show the ways in which geological       
processes and results are related to    
ourselves2 how1 in a word1 this earth   
has been the well-appointed nursery of  
our kind4  ,all those who are engaged in
 teaching elementary science learn the  
need of limiting the story they have to 
tell to those truths which can be easily
 understood by beginners4 ,it is        
sometimes best1 as in stating such      
difficult matters as those concerning   
the tides1 to give explanations which   
are far from complete1 and which1 as to 
their mode of presentation1 would be    
open to criticism were it not for the   
fact that any more elaborate statements 
would most likely be incomprehensible to
 the novice1 thus defeating the         
teacher's aim4  ,it will be observed    
that no account is here given of the    
geological ages or of the successions of
 organic life4 ,chapters on these       
subjects were prepared1 but were omitted
 for the reason that they made the story

 too long1 and also because they carried
 the reader into a field of much greater
 difficulty than that which is found in 
the physical history of the earth4      
,n4,s4,s4 ,march1 #ahih4                
,,contents4       ,,chapter             
,,page         ,i4--,,introduction ,,to 
,,the ,,study ,,of ,,nature             
#a       ,,ii4--,,ways ,,and ,,means    
,,of ,,studying ,,nature                
#i      ,,iii4--,,the ,,stellar ,,realm 
#ca       ,,iv4--,,the ,,earth          
#ha        ,v4--,,the ,,atmosphere      
#ig       ,,vi4--,,glaciers             
#bjg      ,,vii4--,,the ,,work ,,of     
,,underground ,,water                   
#bej     ,,viii4--,,the ,,soil          
#cac       ,,ix4--,,the ,,rocks ,,and   
,,their ,,order                         
#cdi                      ,,list ,,of   
,,full-,,page ,,illustrations4          
,,facing ,,page      ,dunes at ,ipswich 
,light1 ,massachusetts                  
,frontispiece     ,seal ,rocks near ,san
 ,francisco1 ,california                

#cc     ,lava stream1 in ,hawaiian      
,islands1 flowing into the sea      #gb 
,waterfall near ,gadsden1 ,alabama      
#ij     ,south shore1 ,martha's         
,vineyard1 ,massachusetts               
#aba     ,pocket ,creek1 ,cape ,ann1    
,massachusetts                      #afc
     ,muir ,glacier1 ,alaska            
#bjg     ,front of ,muir ,glacier       
#bdj     ,mount tna1 seen from near     
,catania                         #bja   
,mountain gorge1 ,himalayas1 ,india     
#ccj                         ,,outlines 
,,of ,,the ,,earth',s ,,history4        
,,chapter ,i4                 ,,an      
,,introduction ,,to ,,the ,,study ,,of  
,,nature4   ,the object of this book is 
to give the student who is about to     
enter on the study of natural science   
some general idea as to the conditions  
of the natural realm4 ,as this field of 
inquiry is vast1 it will be possible    
only to give the merest outline of its  
subject-matter1 noting those features   
alone which are of surpassing interest1 

which are demanded for a large          
understanding of man's place in this    
world1 or which pertain to his duties in
 life4  ,in entering on any field of    
inquiry1 it is most desirable that the  
student should obtain some idea as to   
the ways in which men have been led to  
the knowledge which they possess        
concerning the world about them4        
,therefore it will be well briefly to   
sketch the steps by which natural       
science has come to be what it is4 ,by  
so doing we shall perceive how much we  
owe to the students of other            
generations2 and by noting the          
difficulties which they encountered1 and
 how they avoided them1 we shall more   
easily find our own way to knowledge4   
,the primitive savages1 who were the    
ancestors of all men1 however civilized 
they may be1 were students of ,nature4  
,the remnants of these lowly people who 
were left in different parts of the     
world show us that man was not long in  
existence before he began to devise some

 explanation concerning the course of   
events in the outer world4 ,seeing the  
sun rise and set1 the changes of the    
moon1 the alternation of the seasons1   
the incessant movement of the streams   
and sea1 and the other more or less     
orderly successions of events1 our      
primitive forefathers were driven to    
invent some explanation of them4 ,this1 
independently1 and in many different    
times and places1 they did in a simple  
and natural way by supposing that the   
world was controlled by a host of       
intelligent beings1 each of which had   
some part in ordering material things4  
,sometimes these invisible powers were  
believed to be the spirits of great     
chieftains1 who were active when on     
earth1 and who after death continued to 
exercise their power in the larger      
realms of ,nature4 ,again1 and perhaps  
more commonly1 these movements of       
,nature were supposed to be due to the  
action of great though invisible beasts1
 much like those which the savage found 

about him4 ,thus among our ,north       
,american ,indians the winds are        
explained by the supposition that the   
air is fanned by the wings of a great   
unseen bird1 whose duty it is to set the
 atmosphere into motion4 ,that no one   
has ever seen the bird doing the work1  
or that the task is too great for any   
conceivable bird1 is to the simple1     
uncultivated man no objection to this   
view4 ,it is long1 indeed1 before       
education brings men to the point where 
they can criticise their first          
explanations of ,nature4  ,as men in    
their advance come to see how much      
nobler are their own natures than those 
of the lower animals1 they gradually put
 aside the explanation of events by the 
actions of beasts1 and account for the  
order of the world by the supposition   
that each and every important detail is 
controlled by some immortal creature    
essentially like a man1 though much more
 powerful than those of their own kind4 
,this stage of understanding is perhaps 

best shown by the mythology of the      
,greeks1 where there was a great god    
over all1 very powerful but not         
omnipotent2 and beneath him1 in endless 
successions of command1 subordinate     
powers1 each with a less range of duties
 and capacities than those of higher    
estate1 until at the bottom of the      
system there were minor deities and     
demigods charged with the management of 
the trees1 the flowers1 and the         
springs--creatures differing little from
 man1 except that they were immortal1   
and generally invisible1 though they1   
like all the other deities1 might at    
their will display themselves to the    
human beings over whom they watched1 and
 whose path in life they guided4  ,among
 only one people do we find that the    
process of advance led beyond this early
 and simple method of accounting for the
 processes of ,nature1 bringing men to  
an understanding such as we now possess4
 ,this great task was accomplished by   
the ,greeks alone4 ,about twenty-five   

hundred years ago the philosophers of   
,greece began to perceive that the early
 notion as to the guidance of the world 
by creatures essentially like men could 
not be accepted1 and must be replaced by
 some other view which would more       
effectively account for the facts4 ,this
 end they attained by steps which can   
not well be related here1 but which led 
them to suppose separate powers behind  
each of the natural series--powers      
having no relation to the qualities of  
mankind1 but ever acting to a definite  
end4 ,thus ,plato1 who represents most  
clearly this advance in the             
interpretation of facts1 imagined that  
each particular kind of plant or animal 
had its shape inevitably determined by  
something which he termed an idea1 a    
shape-giving power which existed before 
the object was created1 and which would 
remain after it had been destroyed1 ever
 ready again to bring matter to the     
particular form4 ,from this stage of    
understanding it was but a short step to

 the modern view of natural law4 ,this  
last important advance was made by the  
great philosopher ,aristotle1 who1      
though he died about twenty-two hundred 
years ago1 deserves to be accounted the 
first and in many ways the greatest of  
the ancient men of science who were     
informed with the modern spirit4  ,with 
,aristotle1 as with all his intellectual
 successors1 the operations of ,nature  
were conceived as to be accounted for by
 the action of forces which we commonly 
designate as natural laws1 of which     
perhaps the most familiar and universal 
is that of gravitation1 which impels all
 bodies to move toward each other with a
 degree of intensity which is measured  
by their weight and the distance by     
which they are separated4  ,for many    
centuries students used the term law in 
somewhat the same way as the more       
philosophical believers in polytheism   
spoke of their gods1 or as ,plato of the
 ideas which he conceived to control    
,nature4 ,we see by this instance how   

hard it is to get rid of old ways of    
thinking4 ,even when the new have been  
adopted we very often find that         
something of the ancient and discarded  
notions cling in our phrases4 ,the more 
advanced of our modern philosophers are 
clear in their mind that all we know as 
to the order of ,nature is that1 given  
certain conditions1 certain consequences
 inevitably follow4  ,although the      
limitations which modern men of science 
perceive to be put upon their labours   
may seem at first sight calculated to   
confine our understanding within a      
narrow field of things which can be     
seen1 or in some way distinctly proved  
to exist1 the effect of this limitation 
has been to make science what it is--a  
realm of things known as distinct from  
things which may be imagined4 ,all the  
difference between ancient science and  
modern consists in the fact that in     
modern science inquirers demand a       
businesslike method in the              
interpretation of ,nature4 ,among the   

,greeks the philosopher who taught      
explanations of any feature in the      
material world which interested him was 
content if he could imagine some way    
which would account for the facts4 ,it  
is the modern custom now to term the    
supposition of an explanation a working 
hypothesis1 and only to give it the name
 of theory after a very careful search  
has shown that all the facts which can  
be gathered are in accordance with the  
view4 ,thus when ,newton made his great 
suggestion concerning the law of        
gravitation1 which was to the effect    
that all bodies attracted each other in 
proportion to their masses1 and         
inversely as the square of their        
distance from each other1 he did not    
rest content1 as the old ,greeks would  
have done1 with the probable truth of   
the explanation1 but carefully explored 
the movements of the planets and        
satellites of the solar system to see if
 the facts accorded with the hypothesis4
 ,even the perfect correspondence which 

he found did not entirely content       
inquirers1 and in this century very     
important experiments have been made    
which have served to show that a ball   
suspended in front of a precipice will  
be attracted toward the steep1 and that 
even a mass of lead some tons in weight 
will attract toward itself a small body 
suspended in the manner of a pendulum4  
,it is this incessant revision of the   
facts1 in order to see if they accord   
with the assumed rule or law1 which has 
given modern science the sound footing  
that it lacked in earlier days1 and     
which has permitted our learning to go  
on step by step in a safe way up the    
heights to which it has climbed4 ,all   
explanations of ,nature begin with the  
work of the imagination4 ,in common     
phrase1 they all are guesses which have 
at first but little value1 and only     
attain importance in proportion as they 
are verified by long-continued          
criticism1 which has for its object to  
see whether the facts accord with the   

theory4 ,it is in this effort to secure 
proof that modern science has gathered  
the enormous store of well-ascertained  
facts which constitutes its true wealth1
 and which distinguishes it from the    
earlier imaginative and to a great      
extent unproved views4  ,in the original
 state of learning1 natural science was 
confounded with political and social    
tradition1 with the precepts of duty    
which constitute the law of the people1 
as well as with their religion1 the     
whole being in the possession of the    
priests or wise men4 ,so long as natural
 action was supposed to be in the       
immediate control of numerous gods and  
demigods1 so long1 in a word1 as the    
explanation of ,nature was what we term 
polytheistic1 this association of       
science with other forms of learning was
 not only natural but inevitable4       
,gradually1 however1 as the conception  
of natural law replaced the earlier idea
 as to the intervention of a spirit1    
science departed from other forms of    

lore and came to possess a field to     
itself4 ,at first it was one body of    
learning4 ,the naturalists of           
,aristotle's time1 and from his day down
 to near our own1 generally concerned   
themselves with the whole field of      
,nature4 ,for a time it was possible for
 any one able and laborious man to know 
all which had been ascertained          
concerning astronomy1 chemistry1        
geology1 as well as the facts relating  
to living beings4 ,the more1 however1 as
 observation accumulated1 and the store 
of facts increased1 it became difficult 
for any one man to know the whole4      
,hence it has come about that in our own
 time natural learning is divided into  
many distinct provinces1 each of which  
demands a lifetime of labour from those 
who would know what has already been    
done in the field1 and what it is now   
important to do in the way of new       
inquiries4  ,the large divisions which  
naturalists have usually made of their  
tasks rest in the main on the natural   

partitions which we may readily observe 
in the phenomenal world4 ,first of all  
comes astronomy1 including the phenomena
 exhibited in the heavens1 beyond the   
limits of the earth's atmosphere4       
,second1 geology1 which takes account of
 all those actions which in process of  
time have been developed in our own     
sphere4 ,third1 physics1 which is       
concerned with the laws of energy1 or   
those conditions which affect the motion
 of bodies1 and the changes which are   
impressed upon them by the different    
natural forces4 ,fourth1 chemistry1     
which seeks to interpret the principles 
which determine the combination of atoms
 and the molecules which are built of   
them under the influence of the chemical
 affinities4 ,fifth1 biology1 or the    
laws of life1 a study which pertains to 
the forms and structures of animals and 
plants1 and their wonderful successions 
in the history of the world4 ,sixth1    
mathematics1 or the science of space and
 number1 that deals with the principles 

which underlie the order of ,nature as  
expressed at once in the human          
understanding and in the material       
universe4 ,by its use men were made able
 to calculate1 as in arithmetic1 the    
problems which concern their ordinary   
business1 as well as to compute the     
movements of the celestial bodies1 and a
 host of actions which take place on the
 earth that would be inexplicable except
 by the aid of this science4 ,last of   
all among the primary sciences we may   
name that of psychology1 which takes    
account of mental operations among man  
and his lower kindred1 the animals4  ,in
 addition to the seven sciences above   
mentioned1 which rest in a great measure
 on the natural divisions of phenomena1 
there are many1 indeed1 indefinitely    
numerous1 subdivisions which have been  
made to suit the convenience of         
students4 ,thus astronomy is often      
separated into physical and mathematical
 divisions1 which take account either of
 the physical phenomena exhibited by the

 heavenly bodies or of their motions4   
,in geology there are half a dozen      
divisions relating to particular        
branches of that subject4 ,in the realm 
of organic life1 in chemistry1 and in   
physics there are many parts of these   
sciences which have received particular 
names4  ,it must not be supposed that   
these sciences have the independence of 
each other which their separate names   
would imply4 ,in fact1 the student of   
each1 however1 far he may succeed in    
separating his field from that of the   
other naturalists1 as we may fitly term 
all students of ,nature1 is compelled   
from time to time to call in the aid of 
his brethren who cultivate other        
branches of learning4 ,the modern       
astronomer needs to know much of        
chemistry1 or else he can not understand
 many of his observations on the sun4   
,the geologists have to share their work
 with the student of animal and         
vegetable life1 with the physicists2    
they must1 moreover1 know something of  

the celestial spheres in order to       
interpret the history of the earth4 ,in 
fact1 day by day1 with the advance of   
learning1 we come more clearly to       
perceive that all the processes of      
,nature are in a way related to each    
other1 and that in proportion as we     
understand any part of the great        
mechanism1 we are forced in a manner to 
comprehend the whole4 ,in other words1  
we are coming to understand that these  
divisions of the field of science depend
 upon the limitations of our knowledge1 
and not upon the order of ,nature       
itself4 ,for the purposes of education  
it is important that every one should   
know something of the great truths which
 each science has disclosed4 ,no mortal 
man can compass the whole realm of this 
knowledge1 but every one can gain some  
idea of the larger truths which may help
 him to understand the beauty and       
grandeur of the sphere in which he      
dwells1 which will enable him the better
 to meet the ordinary duties of life1   

that in almost all cases are related to 
the facts of the world about us4 ,it has
 been of late the custom to term this   
body of general knowledge which takes   
account of the more evident facts and   
important series of terrestrial actions 
physiography1 or1 as the term implies1 a
 description of ,nature1 with the       
understanding that the knowledge chosen 
for the account is that which most      
intimately concerns the student who     
seeks information that is at once       
general and important4 ,therefore1 in   
this book the effort is made first to   
give an account as to the ways and means
 which have led to our understanding of 
scientific problems1 the methods by     
which each person may make himself an   
inquirer1 and the outline of the        
knowledge that has been gathered since  
men first began to observe and criticise
 the revelations the universe may afford
 them4                                  
,,chapter ,,ii4                         
,,ways ,,and ,,means ,,of ,,studying    

,,nature4   ,it is desirable that the   
student of ,nature keep well in mind the
 means whereby he is able to perceive   
what goes on in the world about him4 ,he
 should understand something as to the  
nature of his senses1 and the extent to 
which these capacities enable him to    
discern the operations of ,nature4 ,man1
 in common with his lower kindred1 is1  
by the mechanism of the body1 provided  
with five somewhat different ways by    
which he may learn something of the     
things about him4 ,the simplest of these
 capacities is that of touch1 a faculty 
that is common to the general surface of
 the body1 and which informs us when the
 surface is affected by contact with    
some external object4 ,it also enables  
us to discern differences of            
temperature4 ,next is the sense of      
taste1 which is limited to the mouth and
 the parts about it4 ,this sense is in a
 way related to that of touch1 for the  
reason that it depends on the contact of
 our body with material things4 ,third  

is the sense of smell1 so closely       
related to that of taste that it is     
difficult to draw the line between the  
two4 ,yet through the apparatus of the  
nose we can perceive the microscopically
 small parts of matter borne to us      
through the air1 which could not be     
appreciated by the nerves of the mouth4 
,fourth in order of scope comes the     
hearing1 which gives us an account of   
those waves of matter that we understand
 as sound4 ,this power is much more far 
ranging than those before noted2 in some
 cases1 as in that of the volcanic      
explosions from the island of ,krakatoa1
 in the eruption of #ahhc1 the          
convulsions were audible at the distance
 of more than a thousand miles away4    
,the greater cannon of modern days may  
be heard at the distance of more than a 
hundred miles1 so that while the sense  
of touch1 taste1 and smell demand       
contact with the bodies which we        
appreciate1 hearing gives us information
 concerning objects at a considerable   

distance4 ,last and highest of the      
senses1 vastly the most important in all
 that relates to our understanding of   
,nature1 is sight1 or the capacity which
 enables us to appreciate the movement  
of those very small waves of ether which
 constitute light4 ,the eminent         
peculiarity of sight is that it may give
 us information concerning things which 
are inconceivably far away2 it enables  
us to discern the light of suns probably
 millions of times as remote from us as 
is the centre of our own solar system4  
,although much of the pleasure which the
 world affords us comes through the     
other senses1 the basis of almost all   
our accurate knowledge is reported by   
sight4 ,it is true that what we have    
observed with our eyes may be set forth 
in words1 and thus find its way to the  
understanding through the ears2 also    
that in many instances the sense of     
touch conveys information which extends 
our perceptions in many important ways2 
but science rests practically on sight1 

and on the insight that comes from the  
training of the mind which the eyes make
 possible4  ,the early inquirers had no 
resources except those their bodies     
afforded2 but man is a tool-making      
creature1 and in very early days he     
began to invent instruments which helped
 him in inquiry4 ,the earliest          
deliberate study was of the stars4      
,science began with astronomy1 and the  
first instruments which men contrived   
for the purpose of investigation were   
astronomical4 ,in the beginning of this 
search the stars were studied in order  
to measure the length of the year1 and  
also for the reason that they were      
supposed in some way to control the fate
 of men4 ,so far as we know1 the first  
pieces of apparatus for this purpose    
were invented in ,egypt1 perhaps about  
four thousand years before the          
,christian era4 ,these instruments were 
of a simple nature1 for the magnifying  
glass was not yet contrived1 and so the 
telescope was impossible4 ,they         

consisted of arrangements of straight   
edges and divided circles1 so that the  
observers1 by sighting along the        
instruments1 could in a rough way       
determine the changes in distance       
between certain stars1 or the height of 
the sun above the horizon at the various
 seasons of the year4 ,it is likely that
 each of the great pyramids of ,egypt   
was at first used as an observatory1    
where the priests1 who had some         
knowledge of astronomy1 found a station 
for the apparatus by which they made the
 observations that served as a basis for
 casting the horoscope of the king4  ,in
 the progress of science and of the     
mechanical invention attending its      
growth1 a great number of inventions    
have been contrived which vastly        
increase our vision and add             
inconceivably to the precision it may   
attain4 ,in fact1 something like as much
 skill and labour has been given to the 
development of those inventions which   
add to our learning as to those which   

serve an immediate economic end4 ,by far
 the greatest of these scientific       
inventions are those which depend upon  
the lens4 ,by combining shaped bits of  
glass so as to control the direction in 
which the light waves move through them1
 naturalists have been able to create   
the telescope1 which in effect may bring
 distant objects some thousand times    
nearer to view than they are to the     
naked eye2 and the microscope1 which so 
enlarges minute objects as to make them 
visible1 as they were not before4 ,the  
result has been enormously to increase  
our power of vision when applied to     
distant or to small objects4 ,in fact1  
for purposes of learning1 it is safe to 
say that those tools have altogether    
changed man's relation to the visible   
universe4 ,the naked eye can see at best
 in the part of the heavens visible from
 any one point not more than thirty     
thousand stars4 ,with the telescope     
somewhere near a hundred million are    
brought within the limits of vision4    

,without the help of the microscope an  
object a thousandth of an inch in       
diameter appears as a mere point1 the   
existence of which we can determine only
 under favourable circumstances4 ,with  
that instrument the object may reveal an
 extended and complicated structure     
which it may require a vast labour for  
the observer fully to explore4  ,next in
 importance to the aid of vision above  
noted come the scientific tools which   
are used in weighing and measuring4     
,these balances and gauges have attained
 such precision that intervals so small 
as to be quite invisible1 and weights as
 slight as a ten-thousandth of a grain1 
can be accurately measured4 ,from these 
instruments have come all those precise 
examinations on which the accuracy of   
modern science intimately depends4 ,all 
these instruments of precision are the  
inventions of modern days4 ,the simplest
 telescopes were made only about two    
hundred and fifty years ago1 and the    
earlier compound microscopes at a yet   

later date4 ,accurate balances and other
 forms of gauges of space1 as well as   
good means of dividing time1 such as our
 accurate astronomical clocks and       
chronometers1 are only about a century  
old4 ,the instruments have made science 
accurate1 and have immensely extended   
its powers in nearly all the fields of  
inquiry4  ,although the most striking   
modern discoveries are in the field     
which was opened to us by the lens in   
its manifold applications1 it is in the 
chemist's laboratory that we find that  
branch of science1 long cultivated1 but 
rapidly advanced only within the last   
two centuries1 which has done the most  
for the needs of man4 ,the ancients     
guessed that the substances which make  
up the visible world were more          
complicated in their organization than  
they appear to our vision4 ,they even   
suggested the great truth that matter of
 all kinds is made up of inconceivably  
small indivisible bits which they and we
 term atoms4 ,it is likely that in the  

classic days of ,greece men began to    
make simple experiments of a chemical   
nature4 ,a century or two after the time
 of ,mohammed1 the ,arabians of his     
faith1 a people who had acquired ,greek 
science from the libraries which their  
conquests gave them1 conducted extensive
 experiments1 and named a good many     
familiar chemical products1 such as     
alcohol1 which still bears its ,arabic  
name4  ,these chemical studies were     
continued in ,europe by the alchemists1 
a name also of ,arabic origin1 a set of 
inquirers who were to a great extent    
drawn away from scientific studies by   
vain though unending efforts to change  
the baser metals into gold and silver1  
as well as to find a compound which     
would make men immortal in the body4 ,by
 the invention of the accurate balance1 
and by patient weighing of the matters  
which they submitted to experiment1 by  
the invention of hypotheses or guesses  
at truth1 which were carefully tested by
 experiment1 the majestic science of    

modern chemistry has come forth from the
 confused and mystical studies of the   
alchemists4 ,we have learned to know    
that there are seventy or more primitive
 or apparently unchangeable elements    
which make up the mass of this world1   
and probably constitute all the         
celestial spheres1 and that these       
elements in the form of their separate  
atoms may group themselves in almost    
inconceivably varied combinations4 ,in  
the inanimate realm these associations1 
composed of the atoms of the different  
substances1 forming what are termed     
molecules1 are generally composed of but
 few units4 ,thus carbonic-acid gas1 as 
it is commonly called1 is made up of an 
aggregation of molecules1 each composed 
of one atom of carbon and two of oxygen2
 water1 of two atoms of hydrogen and one
 of oxygen2 ordinary iron oxide1 of two 
atoms of iron and three of oxygen4 ,in  
the realm of organic life1 however1     
these combinations become vastly more   
complicated1 and with each of them the  

properties of the substance thus        
produced differ from all others4 ,a     
distinguished chemist has estimated that
 in one group of chemical compounds1    
that of carbon1 it would be possible to 
make such an array of substances that it
 would require a library of many        
thousand ordinary volumes to contain    
their names alone4  ,it is              
characteristic of chemical science that 
it takes account of actions which are   
almost entirely invisible4 ,no          
contrivances have been or are likely to 
be invented which will show the observer
 what takes place when the atoms of any 
substance depart from their previous    
combination and enter on new            
arrangements4 ,we only know that under  
certain conditions the old atomic       
associations break up1 and new ones are 
formed4 ,but though the processes are   
hidden1 the results are manifest in the 
changes which are brought about upon the
 masses of material which are subjected 
to the altering conditions4 ,gradually  

the chemists of our day are learning to 
build up in their laboratories more and 
more complicated compounds2 already they
 have succeeded in producing many of the
 materials which of old could only be   
obtained by extracting them from plants4
 ,thus a number of the perfumes of      
flowers1 and many of the dye-stuffs     
which a century ago were extracted from 
vegetables1 and were then supposed to be
 only obtainable in that way1 are now   
readily manufactured4 ,in time it seems 
likely that important articles of food1 
for which we now depend upon the seeds  
of plants1 may be directly built up from
 the mineral kingdom4 ,thus the result  
of chemical inquiry has been not only to
 show us much of the vast realm of      
actions which go on in the earth1 but to
 give us control of many of these       
movements so that we may turn them to   
the needs of man4  ,animals and plants  
were at an early day very naturally the 
subjects of inquiry4 ,the ancients      
perceived that there were differences of

 kind among these creatures1 and even in
 ,aristotle's time the sciences of      
zology and botany had attained the point
 where there were considerable treatises
 on those subjects4 ,it was not1        
however1 until a little more than a     
century ago that men began accurately to
 describe and classify these species of 
the organic world4 ,since the time of   
,linnus the growth of our knowledge has 
gone forward with amazing swiftness4    
,within a century we have come to know  
perhaps a hundred times as much         
concerning these creatures as was       
learned in all the earlier ages4 ,this  
knowledge is divisible into two main    
branches3 in one the inquirers have     
taken account of the different species1 
genera1 families1 orders1 and classes of
 living forms with such effect that they
 have shown the existence at the present
 time of many hundred thousand distinct 
species1 the vast assemblage being      
arranged in a classification which shows
 something as to the relationship which 

the forms bear to each other1 and       
furthermore that the kinds now living   
have not been long in existence1 but    
that at each stage in the history of the
 earth another assemblage of species    
peopled the waters and the lands4  ,at  
first naturalists concerned themselves  
only with the external forms of living  
creatures2 but they soon came to        
perceive that the way in which these    
organisms worked1 their physiology1 in a
 word1 afforded matters for extended    
inquiry4 ,these researches have         
developed the science of physiology1 or 
the laws of bodily action1 on many      
accounts the most modern and extensive  
of our new acquisitions of natural      
learning4 ,through these studies we have
 come to know something of the laws or  
principles by which life is handed on   
from generation to generation1 and by   
which the gradations of structure have  
been advanced from the simple creatures 
which appear like bits of animated jelly
 to the body and mind of man4  ,the     

greatest contribution which modern      
naturalists have made to knowledge      
concerns the origin of organic species4 
,the students of a century ago believed 
that all these different kinds had been 
suddenly created either through natural 
law or by the immediate will of ,god4   
,we now know that from the beginning of 
organic life in the remote past to the  
present day one kind of animal or plant 
has been in a natural and essentially   
gradual way converted into the species  
which was to be its successor1 so that  
all the vast and complicated assemblage 
of kinds which now exists has been      
derived by a process of change from the 
forms which in earlier ages dwelt upon  
this planet4 ,the exact manner in which 
these alterations were produced is not  
yet determined1 but in large part it has
 evidently been brought about by the    
method indicated by ,mr4 ,darwin1       
through the survival of the fittest     
individuals in the struggle for         
existence4  ,until men came to have a   

clear conception as to the spherical    
form of the earth1 it was impossible for
 them to begin any intelligent inquiries
 concerning its structure or history4   
,the ,greeks knew the earth to be a     
sphere1 but this knowledge was lost     
among the early ,christian people1 and  
it was not until about four hundred     
years ago that men again came to see    
that they dwelt upon a globe4 ,on the   
basis of this understanding the science 
of geology1 which had in a way been     
founded by the ,greeks1 was revived4 ,as
 this science depends upon the knowledge
 which we have gained of astronomy1     
physics1 chemistry1 and biology1 all of 
which branches of learning have to be   
used in explaining the history of the   
earth1 the advance which has been made  
has been relatively slow4 ,geology as a 
whole is the least perfectly organized  
of all the divisions of learning4 ,a    
special difficulty peculiar to this     
science has also served to hinder its   
development4 ,all the other branches of 

learning deal mainly1 if not altogether1
 with the conditions of ,nature as they 
now exist4 ,in this alone is it         
necessary at every step to take account 
of actions which have been performed in 
the remote past4  ,it is an easy matter 
for the students of to-day to imagine   
that the earth has long endured2 but to 
our forefathers1 who were educated in   
the view that it had been brought from  
nothingness into existence about seven  
thousand years ago1 it was most         
difficult and for a time impossible to  
believe in its real antiquity4          
,endeavouring1 as they naturally did1 to
 account for all the wonderful          
revolutions1 the history of which is    
written in the pages of the great stone 
book1 the early geologists supposed this
 planet to have been the seat of        
frequent and violent changes1 each of   
which revolutionized its shape and      
destroyed its living tenants4 ,it was   
only very gradually that they became    
convinced that a hundred million years  

or more have elapsed since the dawn of  
life on the earth1 and that in this vast
 period the march of events has been    
steadfast1 the changes taking place at  
about the same rate in which they are   
now going on4 ,as yet this conception as
 to the history of our sphere has not   
become the general property of the      
people1 but the fact of it is recognised
 by all those who have attentively      
studied the matter4 ,it is now as well  
ascertained as any of the other truths  
which science has disclosed to us4  ,it 
is instructive to note the historic     
outlines of scientific development4 ,the
 most conspicuous truth which this      
history discloses is that all science   
has had its origin and almost all its   
development among the peoples belonging 
to the ,aryan race4 ,this body of folk  
appears to have taken on its race       
characteristics1 acquired its original  
language1 its modes of action1 and the  
foundations of its religion in that part
 of northern ,europe which is about the 

,baltic ,sea4 ,thence the body of this  
people appear to have wandered toward   
central ,asia1 where after ages of      
pastoral life in the high table lands   
and mountains of their country it sent  
forth branches to ,india1 ,asia ,minor  
and ,greece1 to ,persia1 and to western 
,europe4 ,it seems ever to have been a  
characteristic of these ,aryan peoples  
that they had an extreme love for       
,nature2 moreover1 they clearly         
perceived the need of accounting for the
 things that happened in the world about
 them4 ,in general they inclined to what
 is called the pantheistic explanation  
of the universe4 ,they believed a       
supreme ,god in many different forms to 
be embodied in all the things they saw4 
,even their own minds and bodies they   
conceived as manifestations of this     
supreme power4 ,among the ,aryans who   
came to dwell in ,europe and along the  
eastern ,mediterranean this method of   
explaining ,nature was in time changed  
to one in which humanlike gods were     

supposed to control the visible and     
invisible worlds4 ,in that marvellous   
centre of culture which was developed   
among the ,greeks this conception of    
humanlike deities was in time replaced  
by that of natural law1 and in their    
best days the ,greeks were men of       
science essentially like those of       
to-day1 except that they had not learned
 by experience how important it was to  
criticise their theories by patiently   
comparing them with the facts which they
 sought to explain4 ,the last of the    
important ,greek men of science1        
,strabo1 who was alive when ,christ was 
born1 has left us writings which in     
quality are essentially like many of the
 able works of to-day4 ,but for the     
interruption in the development of      
,greek learning1 natural science would  
probably have been fifteen hundred years
 ahead of its present stage4 ,this      
interruption came in two ways4 ,in one1 
through the conquest of ,greece and the 
destruction of its intellectual life by 

the ,romans1 a people who were          
singularly incapable of appreciating    
natural science1 and who had no other   
interest in it except now and then a    
vacant and unprofitable curiosity as to 
the processes of the natural world4 ,a  
second destructive influence came       
through the fact that ,christianity1 in 
its energetic protest against the sins  
of the pagan civilization1 absolutely   
neglected and in a way despised all     
forms of science4  ,the early           
indifference of ,christians to natural  
learning is partly to be explained by   
the fact that their religion was        
developed among the ,hebrews1 a people  
remarkable for their lack of interest in
 the scientific aspects of ,nature4 ,to 
them it was a sufficient explanation    
that one omnipotent ,god ruled all      
things at his will1 the heavens and the 
earth alike being held in the hollow of 
his hand4  ,finding the centre of its   
development among the ,romans1          
,christianity came mainly into the      

control of a people who1 as we have     
before remarked1 had no scientific      
interest in the natural world4 ,this    
condition prolonged the separation of   
our faith from science for fifteen      
hundred years after its beginning4 ,in  
this time the records of ,greek         
scientific learning mostly disappeared4 
,the writings of ,aristotle were        
preserved in part for the reason that   
the ,church adopted many of his views   
concerning questions in moral philosophy
 and in politics4 ,the rest of ,greek   
learning was1 so far as ,europe was     
concerned1 quite neglected4  ,a large   
part of ,greek science which has come   
down to us owes its preservation to a   
very singular incident in the history of
 learning4 ,in the ninth century1 after 
the ,arabs had been converted to        
,mohammedanism1 and on the basis of that
 faith had swiftly organized a great and
 cultivated empire1 the scholars of that
 folk became deeply interested in the   
remnants of ,greek learning which had   

survived in the monastic and other      
libraries about the eastern             
,mediterranean4 ,so greatly did they    
prize these records1 which were         
contemned by the ,christians1 that it   
was their frequent custom to weigh the  
old manuscripts in payment against the  
coin of their realm4 ,in astronomy1     
mathematics1 chemistry1 and geology the 
,arabian students1 building on the      
ancient foundations1 made notable and   
for a time most important advances4 ,in 
the tenth century of our era they seemed
 fairly in the way to do for science    
what western ,europe began five         
centuries later to accomplish4 ,in the  
fourteenth century the centre of        
,mohammedan strength was transferred    
from the ,arabians to the ,turks1 from a
 people naturally given to learning to a
 folk of another race1 who despised all 
such culture4 ,thenceforth in place of  
the men who had treasured and deciphered
 with infinite pains all the records of 
earlier learning1 the followers of      

,mohammed zealously destroyed all the   
records of the olden days4 ,some of     
these records1 however1 survived among  
the ,arabs of ,spain1 and others were   
preserved by the ,christian scholars who
 dwelt in ,byzantium1 or                
,constantinople1 and were brought into  
western ,europe when that city was      
captured by the ,turks in the fifteenth 
century4  ,already the advance of the   
fine arts in ,italy and the general     
tendency toward the study of ,nature1   
such as painting and sculpture indicate1
 had made a beginning1 or rather a      
proper field for a beginning1 of        
scientific inquiry4 ,the result was a   
new interest in ,greek learning in all  
its branches1 and a very rapid awakening
 of the scientific spirit4 ,at first the
 ,roman ,church made no opposition to   
this new interest which developed among 
its followers1 but in the course of a   
few years1 animated with the fear that  
science would lead men to doubt many of 
the dogmas of the ,church1 it undertook 

sternly to repress the work of all      
inquirers4  ,the conflict between those 
of the ,roman faith and the men of      
science continued for above two hundred 
years4 ,in general1 the part which the  
,church took was one of remonstrance1   
but in a few cases the spirit of        
fanaticism led to the persecution of the
 men who did not obey its mandates and  
disavow all belief in the new opinions  
which were deemed contrary to the       
teachings of ,scripture4 ,the last      
instance of such oppression occurred in 
,france in the year #agef1 when the     
great ,buffon was required to recant    
certain opinions concerning the         
antiquity of the earth which he had     
published in his work on ,natural       
,history4 ,this he promptly did1 and in 
almost servile language withdrew all the
 opinions to which the fathers had      
objected4 ,a like conflict between the  
followers of science and the clerical   
authorities occurred in ,protestant     
countries4 ,although in no case were the

 men of science physically tortured or  
executed for their opinions1 they were  
nevertheless subjected to great         
religious and social pressure3 they were
 almost as effectively disciplined as   
were those who fell under the ban of the
 ,roman ,church4  ,some historians have 
criticised the action of the clerical   
authorities toward science as if the    
evil which was done had been performed  
in our own day4 ,it should be           
remembered1 however1 that in the earlier
 centuries the churches regarded        
themselves as bound to protect all men  
from the dangers of heresy4 ,for        
centuries in the early history of       
,christianity the defenders of the faith
 had been engaged in a life-and-death   
struggle with paganism1 the followers of
 which held all that was known of       
,nature4 ,quite naturally the priestly  
class feared that the revival of        
scientific inquiry would bring with it  
the evils from which the world had      
suffered in pagan times4 ,there is no   

doubt that these persecutions of science
 were done under what seemed the        
obligations of duty4 ,they may properly 
be explained particularly by men of     
science as one of the symptoms of       
development in the day in which they    
were done4 ,it is well for those who    
harshly criticise the relations of the  
,church to science to remember that in  
our own country1 about two centuries    
ago1 among the most enlightened and     
religious people of the time1 ,quakers  
were grievously persecuted1 and witches 
hanged1 all in the most dutiful and     
,god-fearing way4 ,in considering these 
relations of science to our faith1 the  
matter should be dealt with in a        
philosophical way1 and with a sense of  
the differences between our own and     
earlier ages4  ,to the student of the   
relations between ,christianity and     
science it must appear doubtful whether 
the criticism or the other consequences 
which the men of science had to meet    
from the ,church was harmful to their   

work4 ,the early naturalists1 like the  
,greeks whom they followed1 were greatly
 given to speculations concerning the   
processes of ,nature1 which1 though     
interesting1 were unprofitable4 ,they   
also showed a curious tendency to mingle
 their scientific speculations with     
ancient and base superstitions4 ,they   
were often given to the absurdity       
commonly known as the black art1 or     
witchcraft1 and held to the preposterous
 notions of the astrologists4 ,even the 
immortal astronomer ,kepler1 who lived  
in the sixteenth century1 was a         
professional astrologer1 and still held 
to the notion that the stars determined 
the destiny of men4 ,many other of the  
famous inquirers in those years which   
ushered in modern science believed in   
witchcraft4 ,thus for a time natural    
learning was in a way associated with   
ancient and pernicious beliefs which the
 ,church was seeking to overthrow4 ,one 
result of the clerical opposition to the
 advancement of science was that its    

votaries were driven to prove every step
 which led to their conclusions4 ,they  
were forced to abandon the loose        
speculation of their intellectual       
guides1 the ,greeks1 and to betake      
themselves to observation4 ,thus a part 
of the laborious fact-gathering habit on
 which the modern advance of science has
 absolutely depended was due to the care
 which men had to exercise in face of   
the religious authorities4  ,in our own 
time1 in the latter part of the         
nineteenth century1 the conflict between
 the religious authority and the men of 
science has practically ceased4 ,even   
the ,roman ,church permits almost       
everywhere an untrammelled teaching of  
the established learning to which it was
 at one time opposed4 ,men have come to 
see that all truth is accordant1 and    
that religion has nothing to fear from  
the faithful and devoted study of       
,nature4  ,the advance of science in    
general in modern times has been greatly
 due to the development of mechanical   

inventions4 ,among the ancients1 the    
tools which served in the arts were few 
in number1 and these of exceeding       
simplicity4 ,so far as we can ascertain1
 in the five hundred years during which 
the ,greeks were in their intellectual  
vigour1 not more than half a dozen new  
machines were invented1 and these were  
exceedingly simple4 ,the fact seems to  
be that a talent for mechanical         
invention is mainly limited to the      
peoples of ,france1 ,germany1 and of the
 ,english-speaking folk4 ,the first     
advances in these contrivances were made
 in those countries1 and all our        
considerable gains have come from their 
people4 ,thus1 while the spirit of      
science in general is clearly limited to
 the ,aryan folk1 that particular part  
of the motive which leads to the        
invention of tools is restricted to     
western and northern ,europe1 to the    
people to whom we give the name of      
,teutonic4  ,mechanical inventions have 
aided the development of our sciences in

 several ways4 ,they have furnished     
inquirers with instruments of precision2
 they have helped to develop accuracy of
 observation2 best of all1 they have    
served ever to bring before the         
attention of men a spectacle of the     
conditions in ,nature which we term     
cause and effect4 ,the influence of     
these inventions on the development of  
learning has been particularly great    
where the machines1 such as our wind and
 water mills1 and our steam engine1 make
 use of the forces of ,nature1          
subjugating them to the needs of man4   
,such instruments give an unending      
illustration as to the presence in      
,nature of energy4 ,they have helped men
 to understand that the machinery of the
 universe is propelled by the unending  
application of power4 ,it was1 in fact1 
through such machines that men of       
science first came to understand that   
energy1 manifested in the natural       
forces1 is something that eternally     
endures2 that we may change its form in 

our arts as its form is changed in the  
operations of ,nature1 but the power    
endures forever4  ,it is interesting to 
note that the first observation which   
led to this most important scientific   
conclusion that energy is indestructible
 however much it may change its form1   
was made by an ,american1 ,benjamin     
,thompson1 who left this country at the 
time of the ,revolution1 and after a    
curious life became the executive       
officer1 and in effect king1 of         
,bavaria4 ,while engaged in             
superintending the manufacture of       
cannon1 he observed that in boring out  
the barrel of the gun an amount of heat 
was produced which evaporated a certain 
amount of water4 ,he therefore concluded
 that the energy required to do the     
boring of the metal passed into the     
state of heat1 and thus only changed its
 state1 in no wise disappearing from the
 earth4 ,other students pursuing the    
same line of inquiry have clearly       
demonstrated what is called the law of  

the conservation of energy1 which more  
than anything has helped us to          
understand the large operations of      
,nature4 ,through these studies we have 
come to see that1 while the universe is 
a place of ceaseless change1 the        
quantities of energy and of matter      
remain unaltered4  ,the foregoing brief 
sketch1 which sets forth some of the    
important conditions which have affected
 the development of science1 may in a   
way serve to show the student how he can
 himself become an interpreter of       
,nature4 ,the evidence indicates that   
the people of our race have been in a   
way chosen among all the varieties of   
mankind to lead in this great task of   
comprehending the visible universe4 ,the
 facts1 moreover1 show that discovery   
usually begins with the interest which  
men feel in the world immediately about 
them1 or which is presented to their    
senses in a daily spectacle4 ,thus      
,benjamin ,franklin1 in the midst of a  
busy life1 became deeply interested in  

the phenomena of lightning1 and by a    
very simple experiment proved that this 
wonder of the air was due to electrical 
action such as we may arouse by rubbing 
a stick of sealing-wax or a piece of    
amber with a cloth4 ,all discoveries1 in
 a word1 have had their necessary       
beginnings in an interest in the facts  
which daily experience discloses4 ,this 
desire to know something more than the  
first sight exhibits concerning the     
actions in the world about us is native 
in every human soul--at least1 in all   
those who are born with the heritage of 
our race4 ,it is commonly strong in     
childhood2 if cultivated by use1 it will
 grow throughout a lifetime1 and1 like  
other faculties1 becomes the stronger   
and more effective by the exertions     
which it inspires4 ,it is therefore most
 important that every one should obey   
this instinctive command to inquiry1 and
 organize his life and work so that he  
may not lose but gain more and more as  
time goes on of this noble capacity to  

interrogate and understand the world    
about him4  ,it is best that all study  
of ,nature should begin not in          
laboratories1 nor with the things which 
are remote from us1 but in the field of 
,nature which is immediately about us4  
,the student1 even if he dwell in the   
unfavourable conditions of a great city1
 is surrounded by the world which has   
yielded immeasurable riches in the way  
of learning1 which he can appropriate by
 a little study4 ,he can readily come to
 know something of the movements of the 
air2 the buildings will give him access 
to a great many different kinds of      
stone2 the smallest park1 a little      
garden1 or even a few potted plants and 
captive animals1 may tell him much      
concerning the forms and actions of     
living beings4 ,by studying in this way 
he can come to know something of the    
differences between things and their    
relations to each other4 ,he will thus  
have a standard by which he can measure 
and make familiar the body of learning  

concerning ,nature which he may find in 
books4 ,from printed pages alone1       
however well they be written1 he can    
never hope to catch the spirit that     
animates the real inquirer1 the true    
lover of ,nature4  ,on many accounts the
 most attractive way of beginning to    
form the habit of the naturalist is by  
the study of living animals and plants4 
,to all of us life adds interest1 and   
growth has a charm4 ,therefore it is    
well for the student to start on the way
 of inquiry by watching the actions of  
birds and insects or by rearing plants4 
,it is fortunate if he can do both these
 agreeable things4 ,when the habit of   
taking an account of that most important
 part of the world which is immediately 
about him has been developed in the     
student1 he may profitably proceed to   
acquire the knowledge of the invisible  
universe which has been gathered by the 
host of inquirers of his race4 ,however 
far he journeys1 he should return to the
 home world that lies immediately and   

familiarly about him1 for there alone   
can he acquire and preserve that        
personal acquaintance with things which 
is at once the inspiration and the test 
of all knowledge4  ,along with this     
study of the familiar objects about us  
the student may well combine some       
reading which may serve to show him how 
others have been successful in thus     
dealing with ,nature at first hand4 ,for
 this purpose there are1 unfortunately1 
but few works which are well calculated 
to serve the needs of the beginner4     
,perhaps the best naturalist book1      
though its form is somewhat ancient1 is 
,white's ,natural ,history of ,selborne4
 ,hugh ,miller's works1 particularly his
 ,old ,red ,sandstone and ,my ,schools  
and ,schoolmasters1 show well how a man 
may become a naturalist under           
difficulties4 ,sir ,john ,lubbock's     
studies on ,wasps1 and ,darwin's work on
 ,animals and ,plants under             
,domestication are also admirable to    
show how observation should be made4    

,dr4 ,asa ,gray's little treatise on    
,how ,plants ,grow will also be useful  
to the beginner who wishes to approach  
botany from its most attractive         
side--that of the development of the    
creature from the seed to seed4  ,there 
is another kind of training which every 
beginner in the art of observing ,nature
 should obtain1 and which many          
naturalists of repute would do well to  
give themselves--namely1 an education in
 what we may call the art of distance   
and geographical forms4 ,with the       
primitive savage the capacity to        
remember and to picture to the eye the  
shape of a country which he knows is    
native and instinctive4 ,accustomed to  
range the woods1 and to trust to his    
recollection to guide him through the   
wilderness to his home1 the primitive   
man develops an important art which     
among civilized people is generally     
dormant4 ,in fact1 in our well-trodden  
ways people may go for many generations 
without ever being called upon to use   

this natural sense of geography4 ,the   
easiest way to cultivate the geographic 
sense is by practising the art of making
 sketch maps4 ,this the student1 however
 untrained1 can readily do by taking    
first his own dwelling house1 on which  
he should practise until he can readily 
from memory make a tolerably correct and
 proportional plan of all its rooms4    
,then on a smaller scale he should begin
 to make also from recollection a map   
showing the distribution of the roads1  
streams1 and hills with which his daily 
life makes him familiar4 ,from time to  
time this work from memory should be    
compared with the facts4 ,at first the  
record will be found to be very poor1   
but with a few months of occasional     
endeavour the observer will find that   
his mind takes account of geographic    
features in a way it did not before1    
and1 moreover1 that his mind becomes    
enriched with impressions of the country
 which are clear and distinct1 in place 
of the shadowy recollections which he at

 first possessed4  ,when the student has
 attained the point where1 after walking
 or riding over a country1 he can       
readily recall its physical features of 
the simpler sort1 he will find it       
profitable to undertake the method of   
mapping with contour lines--that is1 by 
pencilling in indications to show the   
exact shape of the elevations and       
depressions4 ,the principle of contour  
lines is that each of them represents   
where water would come against the slope
 if the area were sunk step by step     
below the sea level--in other words1    
each contour line marks the intersection
 of a horizontal plane with the         
elevation of the country4 ,practice on  
this somewhat difficult task will soon  
give the student some idea as to the    
complication of the surface of a region1
 and afford him the basis for a better  
understanding of what geography means   
than all the reading he can do will     
effect4 ,it is most desirable that      
training such as has been described     

should be a part of our ordinary school 
education4  ,very few people have clear 
ideas of distances4 ,even the men whose 
trade requires some such knowledge are  
often without that which a little       
training could give them4 ,without some 
capacity in this direction1 the student 
is always at a disadvantage in his      
contact with ,nature4 ,he can not make a
 record of what he sees as long as the  
element of horizontal and vertical      
distance is not clearly in mind4 ,to    
attain this end the student should begin
 by pacing some length of road where the
 distances are well known4 ,in this way 
he will learn the length of his step1   
which with a grown man generally ranges 
between two and a half and three feet4  
,learning the average length of his     
stride by frequent counting1 it is easy 
to repeat the trial until one can almost
 unconsciously keep the count as he     
walks4 ,properly to secure the training 
of this sort the observer should first  
attentively look across the distance    

which is to be determined4 ,he should   
notice how houses1 fences1 people1 and  
trees appear at that distance4 ,he will 
quickly perceive that each hundred feet 
of additional interval somewhat changes 
their aspect4 ,in training soldiers to  
measure with the eye the distances which
 they have to know in order effectively 
to use the modern weapons of war1 a     
common device is to take a squad of men1
 or sometimes a company1 under the      
command of an officer1 who halts one man
 at each hundred yards until the        
detachment is strung out with that      
interval as far as the eye can see them4
 ,the men then walk to and fro so that  
the troops who are watching them may    
note the effects of increased distance  
on their appearance1 whether standing or
 in motion4 ,at three thousand yards a  
man appears as a mere dot1 which is not 
readily distinguishable4 ,schoolboys may
 find this experiment amusing and       
instructive4  ,after the student has    
gained1 as he readily may1 some sense of

 the divisions of distance within the   
range of ordinary vision1 he should try 
to form some notion of greater          
intervals1 as of ten1 a hundred1 and    
perhaps a thousand miles4 ,the task     
becomes more difficult as the length of 
the line increases1 but most persons can
 with a little address manage to bring  
before their eyes a tolerably clear     
image of a hundred miles of distance by 
looking from some elevation which       
commands a great landscape4 ,it is      
doubtful1 however1 whether the          
best-trained man can get any clear      
notion of a thousand miles--that is1 can
 present it to himself in imagination as
 he may readily do with shorter         
intervals4  ,the most difficult part of 
the general education which the student 
has to give himself is begun when he    
undertakes to picture long intervals of 
time4 ,space we have opportunities to   
measure1 and we come in a way to        
appreciate it1 but the longest lived of 
men experiences at most a century of    

life1 and this is too small a measure to
 give any notion as to the duration of  
such great events as are involved in the
 history of the earth1 where the periods
 are to be reckoned by the millions of  
years4 ,the only way in which we can get
 any aid in picturing to ourselves great
 lapses of time is by expressing them in
 units of distance4 ,let a student walk 
away on a straight road for the distance
 of a mile2 let him call each step a    
year2 when he has won the first         
milestone1 he may consider that he has  
gone backward in time to the period of  
,christ's birth4 ,two miles more will   
take him to the station which will      
represent the age when the oldest       
pyramids were built4 ,he is still1      
however1 in the later days of man's     
history on this planet4 ,to attain on   
the scale the time when man began1 he   
might well have to walk fifty miles     
away1 while a journey which would thus  
by successive steps describe the years  
of the earth's history since life       

appeared upon its surface would probably
 require him to circle the earth at     
least four times4 ,we may accept it as  
impossible for any one to deal with such
 vast durations save with figures which 
are never really comprehended4 ,it is   
well1 however1 to enlarge our view as to
 the age of the earth by such efforts as
 have just been indicated4  ,when we go 
beyond the earth into the realm of the  
stars all efforts toward understanding  
the ranges of space or the durations of 
time are quite beyond the efforts of    
man4 ,even the distance of about two    
hundred and forty thousand miles which  
separates us from the moon can not be   
grasped by even the greater minds4 ,no  
human intelligence1 however cultivated1 
can conceive the distance of about      
ninety-five million miles which         
separates us from the sun4 ,in the      
celestial realm we can only deal with   
relations of space and time in a general
 and comparative way4 ,we can state the 
distances if we please in millions of   

miles1 or we can reckon the ampler      
spaces by using the interval which      
separates the earth from the sun as we  
do a foot rule in our ordinary work1 but
 the depths of the starry spaces can    
only be sounded by the winged           
imagination4  ,although the student has 
been advised to begin his studies of    
,nature on the field whereon he dwells1 
making that study the basis of his most 
valuable communications with ,nature1 it
 is desirable that he should at the same
 time gain some idea as to the range and
 scope of our knowledge concerning the  
visible universe4 ,as an aid toward this
 end the following chapters of this book
 will give a very brief survey of some  
of the most important truths concerning 
the heavens and the earth which have    
rewarded the studies of scientific men4 
,of remoter things1 such as the bodies  
in the stellar spaces1 the account will 
be brief1 for that which is known and   
important to the general student can be 
briefly told4 ,so1 too1 of the earlier  

ages of the earth's history1 although a 
vast deal is known1 the greater part of 
the knowledge is of interest and value  
mainly to geologists who cultivate that 
field4 ,that which is most striking and 
most important to the mass of mankind is
 to be found in the existing state of   
our earth1 the conditions which make it 
a fit abode for our kind1 and replete   
with lessons which he may study with his
 own eyes without having to travel the  
difficult paths of the higher sciences4 
,although physiography necessarily takes
 some account of the things which have  
been1 even in the remote past1 and this 
for the reason that everything in this  
day of the world depends on the events  
of earlier days1 the accent of its      
teaching is on the immediate1 visible1  
as we may say1 living world1 which is a 
part of the life of all its inhabitants4
                                        
,,chapter ,,iii4                        
,,the ,,stellar ,,realm4   ,even before 
men came to take any careful account of 

the ,nature immediately about them they 
began to conjecture and in a way to     
inquire concerning the stars and the    
other heavenly bodies4 ,it is difficult 
for us to imagine how hard it was for   
students to gain any adequate idea of   
what those lights in the sky really are4
 ,at first men imagined the celestial   
bodies to be1 as they seemed1 small     
objects not very far away4 ,among the   
,greeks the view grew up that the       
heavens were formed of crystal spheres  
in which the lights were placed1 much as
 lanterns may be hung upon a ceiling4   
,these spheres were conceived to be one 
above the other2 the planets were on the
 lower of them1 and the fixed stars on  
the higher1 the several crystal roofs   
revolving about the earth4 ,so long as  
the earth was supposed to be a flat and 
limitless expanse1 forming the centre of
 the universe1 it was impossible for the
 students of the heavens to attain any  
more rational view as to their plan4    
,the fact that the earth was globular in

 form was understood by the ,greek men  
of science4 ,they may1 indeed1 have     
derived the opinion from the ,egyptian  
philosophers4 ,the discovery rested upon
 the readily observed fact that on a    
given day the shadow of objects of a    
certain height was longer in high       
latitude than in low4 ,within the       
tropics1 when the sun was vertical1     
there would be no shadow1 while as far  
north as ,athens it would be of         
considerable length4 ,the conclusion    
that the earth was a sphere appears to  
have been the first large discovery made
 by our race4 ,it was1 indeed1 one of   
the most important intellectual         
acquisitions of man4  ,understanding the
 globular form of the earth1 the next   
and most natural step was to learn that 
the earth was not the centre of the     
planetary system1 much less of the      
universe1 but that that centre was the  
sun1 around which the earth and the     
other planets revolved4 ,the ,greeks    
appear to have had some idea that this  

was the case1 and their spirit of       
inquiry would probably have led them to 
the whole truth but for the overthrow of
 their thought by the ,roman conquest   
and the spread of ,christianity4 ,it was
 therefore not until after the revival  
of learning that astronomers won their  
way to our modern understanding         
concerning the relation of the planets  
to the sun4 ,with ,galileo this opinion 
was affirmed4 ,although for a time the  
,church1 resting its opposition on the  
interpretation of certain passages of   
,scripture1 resisted this view1 and even
 punished the men who held it1 it       
steadfastly made its way1 and for more  
than two centuries has been the         
foundation of all the great discoveries 
in the stellar realm4 ,yet long after   
the fact that the sun was the centre of 
the solar system was well established no
 one understood why the planets should  
move in their ceaseless1 orderly        
procession around the central mass4 ,to 
,newton we owe the studies on the law of

 gravitation which brought us to our    
present large conception as to the      
origin of this order4 ,starting with the
 view that bodies attracted each other  
in proportion to their weight1 and in   
diminishing proportion as they are      
removed from each other1 ,newton        
proceeded by most laborious studies to  
criticise this view1 and in the end     
definitely proved it by finding that the
 motions of the moon about the earth1 as
 well as the paths of the planets1      
exactly agreed with the supposition4    
,the last great path-breaking discovery 
which has helped us in our understanding
 of the stars was made by ,fraunhofer   
and other physicists1 who showed us that
 substances when in a heated1 gaseous1  
or vaporous state produced1 in a way    
which it is not easy to explain in a    
work such as this1 certain dark lines in
 the spectrum1 or streak of divided     
light which we may make by means of a   
glass prism1 or1 as in the rainbow1 by  
drops of water4 ,carefully studying     

these very numerous lines1 those        
naturalists found that they could with  
singular accuracy determine what        
substances there were in the flame which
 gave the light4 ,so accurate is this   
determination that it has been made to  
serve in certain arts where there is no 
better means of ascertaining the        
conditions of a flaming substance except
 by the lines which its light exhibits  
under this kind of analysis4 ,thus1 in  
the manufacture of iron by what is      
called the ,bessemer process1 it has    
been found very convenient to judge as  
to the state of the molten metal by such
 an analysis of the flame which comes   
forth from it4  ,illustration3 ,seal    
,rocks near ,san ,francisco1            
,california1 showing slight effect of   
waves where there is no beach4  ,no     
sooner was the spectroscope invented    
than astronomers hastened by its aid to 
explore the chemical constitution of the
 sun4 ,these studies have made it plain 
that the light of our solar centre comes

 forth from an atmosphere composed of   
highly heated substances1 all of which  
are known among the materials forming   
the earth4 ,although for various reasons
 we have not been able to recognise in  
the sun all the elements which are found
 in our sphere1 it is certain that in   
general the two bodies are alike in     
composition4 ,an extension of the same  
method of inquiry to the fixed stars was
 gradually though with difficulty       
attained1 and we now know that many of  
the elements common to the sun and earth
 exist in those distant spheres4 ,still 
further1 this method of inquiry has     
shown us1 in a way which it is not worth
 while here to describe1 that among     
these remoter suns there are many       
aggregations of matter which are not    
consolidated as are the spheres of our  
own solar system1 but remain in the     
gaseous state1 receiving the name of    
nebul4  ,along with the growth of       
observational astronomy which has taken 
place since the discoveries of ,galileo1

 there has been developed a view        
concerning the physical history of the  
stellar world1 known as the nebular     
hypothesis1 which1 though not yet fully 
proved1 is believed by most astronomers 
and physicists to give us a tolerably   
correct notion as to the way in which   
the heavenly spheres were formed from an
 earlier condition of matter4 ,this     
majestic conception was first advanced1 
in modern times at least1 by the ,german
 philosopher ,immanuel ,kant4 ,it was   
developed by the ,french astronomer     
,laplace1 and is often known by his     
name4 ,the essence of this view rests   
upon the fact previously noted that in  
the realm of the fixed stars there are  
many faintly shining aggregations of    
matter which are evidently not solid    
after the manner of the bodies in our   
solar system1 but are in the state where
 their substances are in the condition  
of dustlike particles1 as are the bits  
of carbon in flame or the elements which
 compose the atmosphere4 ,the view held 

by ,laplace was to the effect that not  
only our own solar system1 but the      
centres of all the other similar        
systems1 the fixed stars1 were          
originally in this gaseous state1 the   
material being disseminated throughout  
all parts of the heavenly realm1 or at  
least in that portion of the universe of
 which we are permitted to know         
something4 ,in this ancient state of    
matter we have to suppose that the      
particles of it were more separated from
 each other than are the atoms of the   
atmospheric gases in the most perfect   
vacuum which we can produce with the    
air-pump4 ,still we have to suppose that
 each of these particles attract the    
other in the gravitative way1 as in the 
present state of the universe they      
inevitably do4  ,under the influence of 
the gravitative attraction the materials
 of this realm of vapour inevitably     
tended to fall in toward the centre4 ,if
 the process had been perfectly simple1 
the result would have been the formation

 of one vast mass1 including all the    
matter which was in the original body4  
,in some way1 no one has yet been able  
to make a reasonable suggestion of just 
how1 there were developed in the process
 of concentration a great many separate 
centres of aggregation1 each of which   
became the beginning of a solar system4 
,the student may form some idea of how  
readily local centres may be produced in
 materials disseminated in the vaporous 
state by watching how fog or the thin1  
even misty clouds of the sunrise often  
gather into the separate shapes which   
make what we term a mackerel sky4 ,it is
 difficult to imagine what makes centres
 of attraction1 but we readily perceive 
by this instance how they might have    
occurred4  ,when the materials of each  
solar system were thus set apart from   
the original mass of star dust or       
vapour1 they began an independent       
development which led step by step1 in  
the case of our own solar system at     
least1 and presumably also in the case  

of the other suns1 the fixed stars1 to  
the formation of planets and their moons
 or satellites1 all moving around the   
central sun4 ,at this stage of the      
explanation the nebular hypothesis is   
more difficult to conceive than in the  
parts of it which have already been     
described1 for we have now to understand
 how the planets and satellites had     
their matter separated from each other  
and from the solar centre1 and why they 
came to revolve around that central     
body4 ,these problems are best          
understood by noting some familiar      
instances connected with the movement of
 fluids and gases toward a centre4      
,first let us take the case of a basin  
in which the water is allowed to flow   
out through a hole in its centre4 ,when 
we lift the stopper the fluid for a     
moment falls straight down through the  
opening4 ,very quickly1 however1 all the
 particles of the water start to move   
toward the centre1 and almost at once   
the mass begins to whirl round with such

 speed that1 although it is working     
toward the middle1 it is by its movement
 pushed away from the centre and forms a
 conical depression4 ,as often as we try
 the experiment1 the effect is always   
the same4 ,we thus see that there is    
some principle which makes particles of 
fluid that tend toward a centre fail    
directly to attain it1 but win their way
 thereto in a devious1 spinning         
movement4  ,although the fact is not so 
readily made visible to the eye1 the    
same principle is illustrated in        
whirling storms1 in which1 as we shall  
hereafter note with more detail1 the air
 next the surface of the earth is moving
 in toward a kind of chimney by which it
 escapes to the upper regions of the    
atmosphere4 ,a study of cyclones and    
tornadoes1 or even of the little        
air-whirls which in hot weather lift the
 dust of our streets1 shows that the    
particles of the atmosphere in rushing  
in toward the centre of upward movement 
take on the same whirling motion as do  

the molecules of water in the basin--in 
fact1 the two actions are perfectly     
comparable in all essential regards1    
except that the fluid is moving         
downward1 while the air flows upward4   
,briefly stated1 the reason for the     
movement of fluid and gas in the        
whirling way is as follows3 ,if every   
particle on its way to the centre moved 
on a perfectly straight line toward the 
point of escape1 the flow would be      
directly converging1 and the paths      
followed would resemble the spokes of a 
wheel4 ,but when by chance one of the   
particles sways ever so little to one   
side of the direct way1 a slight lateral
 motion would necessarily be            
established4 ,this movement would be due
 to the fact that the particle which    
pursued the curved line would press     
against the particles on the out-curved 
side of its path--or1 in other words1   
shove them a little in that             
direction--to the extent that they      
departed from the direct line they would

 in turn communicate the shoving to the 
next beyond4 ,when two particles are    
thus shoving on one side of their paths1
 the action which makes for revolution  
is doubled1 and1 as we readily see1 the 
whole mass may in this way become       
quickly affected1 the particles driven  
out of their path1 moving in a curve    
toward the centre4 ,we also see that the
 action is accumulative3 the more curved
 the path of each particle1 the more    
effectively it shoves2 and so1 in the   
case of the basin1 we see the whirling  
rapidly developed before our eyes4  ,in 
falling in toward the centre the        
particles of star dust or vapour would  
no more have been able one and all to   
pursue a perfectly straight line than   
the particles of water in the basin4 ,if
 a man should spend his lifetime in     
filling and emptying such a vessel1 it  
is safe to say that he would never fail 
to observe the whirling movement4 ,as   
the particles of matter in the nebular  
mass which was to become a solar system 

are inconceivably greater than those of 
water in the basin1 or those of air in  
the atmospheric whirl1 the chance of the
 whirling taking place in the heavenly  
bodies is so great that we may assume   
that it would inevitably occur4  ,as the
 vapours in the olden day tended in     
toward the centre of our solar system1  
and the mass revolved1 there is reason  
to believe that ringlike separations    
took place in it4 ,whirling in the      
manner indicated1 the mass of vapour or 
dust would flatten into a disk or a body
 of circular shape1 with much the       
greater diameter in the plane of its    
whirling4 ,as the process of            
concentration went on1 this disk is     
supposed to have divided into ringlike  
masses1 some approach to which we can   
discern in the existing nebul1 which    
here and there among the farther fixed  
stars appear to be undergoing such      
stages of development toward solar      
systems4 ,it is reasonably supposed that
 after these rings had been developed   

they would break to pieces1 the matter  
in them gathering into a sphere1 which  
in time was to become a planet4 ,the    
outermost of these rings led to the     
formation of the planet farthest from   
the sun1 and was probably the first to  
separate from the parent mass4 ,then in 
succession rings were formed inwardly1  
each leading in turn to the creation of 
another planet1 the sun itself being the
 remnant1 by far the greater part of the
 whole mass of matter1 which did not    
separate in the manner described1 but   
concentrated on its centre4 ,each of    
these planetary aggregations of vapour  
tended to develop1 as it whirled upon   
its centre1 rings of its own1 which in  
turn formed1 by breaking and            
concentrating1 the satellites or moons  
which attend the earth1 as they do all  
the planets which lie farther away from 
the sun than our sphere4  ,illustration3
 ,fig4 #a4--,saturn1 ,jan4 #bf1 #ahhi   
7,antoniadi74  ,as if to prove that the 
planets and moons of the solar system   

were formed somewhat in the manner in   
which we have described it1 one of these
 spheres1 ,saturn1 retains a ring1 or   
rather a band which appears to be       
divided obscurely into several rings    
which lie between its group of          
satellites and the main sphere4 ,how    
this ring has been preserved when all   
the others have disappeared1 and what is
 the exact constitution of the mass1 is 
not yet well ascertained4 ,it seems     
clear1 however1 that it can not be      
composed of solid matter4 ,it is either 
in the form of dust or of small spheres1
 which are free to move on each other2  
otherwise1 as computation shows1 the    
strains due to the attraction which     
,saturn itself and its moons exercise   
upon it would serve to break it in      
pieces4 ,although this ring theory of   
the formation of the planets and        
satellites is not completely proved1 the
 occurrence of such a structure as that 
which girdles ,saturn affords           
presumptive evidence that it is true4   

,taken in connection with what we know  
of the nebul1 the proof of ,laplace's   
nebular hypothesis may fairly be        
regarded as complete4  ,it should be    
said that some of the fixed stars are   
not isolated suns like our own1 but are 
composed of two great spheres revolving 
about one another2 hence they are termed
 double stars4 ,the motions of these    
bodies are very peculiar1 and their     
conditions show us that it is not well  
to suppose that the solar system in     
which we dwell is the only type of order
 which prevails in the celestial        
families2 there may1 indeed1 be other   
variations as yet undetected4 ,still1   
these differences throw no doubt on the 
essential truth of the theory as to the 
process of development of the celestial 
systems4 ,though there is much room for 
debate as to the details of the work    
there1 the general truth of the theory  
is accepted by nearly all the students  
of the problem4  ,a peculiar advantage  
of the nebular hypothesis is that it    

serves to account for the energy which  
appears as light and heat in the sun and
 the fixed stars1 as well as that which 
still abides in the mass of our earth1  
and doubtless also in the other large   
planets4 ,when the matter of which these
 spheres were composed was disseminated 
through the realms of space1 it is      
supposed to have had no positive        
temperature1 and to have been dark1     
realizing the conception which appears  
in the first chapter of ,genesis1       
without form1 and void4 ,with each stage
 of the falling in toward the solar     
centres what is called the energy of    
position of this original matter became 
converted into light and heat4 ,to      
understand how this took place1 the     
reader should consider certain simple   
yet noble generalizations of physics4   
,we readily recognise the fact that when
 a hammer falls often on an anvil it    
heats itself and the metal on which it  
strikes4 ,those who have been able to   
observe the descent of meteoric stones  

from the heavens have remarked that when
 they came to the earth they were1 on   
their surfaces at least1 exceedingly    
hot4 ,any one may observe shining       
meteors now and then flashing in the    
sky4 ,these are known commonly to be    
very small bits of matter1 probably not 
larger than grains of sand1 which1      
rushing into our atmosphere1 are so     
heated by the friction which they       
encounter that they burn to a gas or    
vapour before they attain the earth4 ,as
 we know that these particles come from 
the starry spaces1 where the temperature
 is somewhere near #ejj below #j ,fahr41
 it is evident that the light and heat  
are not brought with them into the      
atmosphere2 it can only be explained by 
the fact that when they enter the air   
they are moving at an average speed of  
about twenty miles a second1 and that   
the energy which this motion represents 
is by the resistance which the body     
encounters converted into heat4 ,this   
fact will help us to understand how1 as 

the original star dust fell in toward   
the centre of attraction1 it was able to
 convert what we have termed the energy 
of position into temperature4 ,we see   
clearly that every such particle of dust
 or larger bit of matter which falls    
upon the earth brings about the         
development of heat1 even though it does
 not actually strike upon the solid mass
 of our sphere4 ,the conception of what 
took place in the consolidation of the  
originally disseminated materials of the
 sun and planets can be somewhat helped 
by a simple experiment4 ,if we fit a    
piston closely into a cylinder1 and then
 suddenly drive it down with a heavy    
blow1 the compressed air is so heated   
that it may be made to communicate fire4
 ,if the piston should be slowly moved1 
the same amount of heat would be        
generated1 or1 as we may better say1    
liberated by the compression1 though the
 effect would not be so striking4 ,a    
host of experiments show that when a    
given mass of matter is brought to      

occupy a less space the effect is in    
practically all cases to increase the   
temperature4 ,the energy which kept the 
particles apart is1 when they are driven
 together1 converted into heat4 ,these  
two classes of actions are somewhat     
different in their nature2 in the case  
of the meteors1 or the equivalent star  
dust1 the coming together of the        
particles is due to gravitation4 ,in the
 experiment with the cylinder above     
described1 the compression is due to    
mechanical energy1 a force of another   
nature4  ,there is reason for believing 
that all our planets1 as well as the sun
 itself1 and also the myriad other orbs 
of space1 have all passed through the   
stages of a transition in which a       
continually concentrating vapour1 drawn 
together by gravitation1 became         
progressively hotter and more dense     
until it assumed the condition of a     
fluid4 ,this fluid gradually parted with
 its heat to the cold spaces of the     
heavens1 and became more and more       

concentrated and of a lower temperature 
until in the end1 as in the case of our 
earth and of other planets1 it ceased to
 glow on the outside1 though it remained
 intensely heated in the inner parts4   
,it is easy to see that the rate of this
 cooling would be in some proportion to 
the size of the sphere4 ,thus the earth1
 which is relatively small1 has become  
relatively cold1 while the sun itself1  
because of its vastly greater mass1     
still retains an exceedingly high       
temperature4 ,the reason for this can   
readily be conceived by making a        
comparison of the rate of cooling which 
occurs in many of our ordinary          
experiences4 ,thus a vial of hot water  
will quickly come down to the           
temperature of the air1 while a large   
jug filled with the fluid at the same   
temperature will retain its heat many   
times as long4 ,the reason for this     
rests upon the simple principle that the
 contents of a sphere increase with its 
enlargement more rapidly than the       

surface through which the cooling takes 
place4  ,the modern studies on the      
physical history of the sun and other   
celestial bodies show that their        
original store of heat is constantly    
flowing away into the empty realms of   
space4 ,the rate at which this form of  
energy goes away from the sun is vast   
beyond the powers of the imagination to 
conceive2 thus1 in the case of our      
earth1 which viewed from the sun would  
appear no more than a small star1 the   
amount of heat which falls upon it from 
the great centre is enough each day to  
melt1 if it all could be put to such    
work1 about eight thousand cubic miles  
of ice4 ,yet the earth receives only    
#a_/b1agj1jjj1jjj part of the solar     
radiation4 ,the greater part of this    
solar heat--in fact1 we may say nearly  
all of it--slips by the few and         
relatively small planets and disappears 
in the great void4  ,the destiny of all 
the celestial spheres seems in time to  
be that they shall become cooled down to

 a temperature far below anything which 
is now experienced on this earth4 ,even 
the sun1 though its heat will doubtless 
endure for millions of years to come1   
must in time1 so far as we can see1     
become dark and cold4 ,so far as we     
know1 we can perceive no certain method 
by which the life of the slowly decaying
 suns can be restored4 ,it has1 however1
 been suggested that in many cases a    
planetary system which has attained the 
lifeless and lightless stage may by     
collision with some other association of
 spheres be by the blow restored to its 
previous state of vapour1 the joint mass
 of the colliding systems once again to 
resume the process of concentration     
through which it had gone before4 ,now  
and then stars have been seen to flash  
suddenly into great brilliancy in a way 
which suggests that possibly their heat 
had been refreshed by a collision with  
some great mass which had fallen into   
them from the celestial spaces4 ,there  
is room for much speculation in this    

field1 but no certainty appears to be   
attainable4  ,the ancients believed that
 light and heat were emanations which   
were given off from the bodies that     
yielded them substantially as odours are
 given forth by many substances4 ,since 
the days of ,newton inquiry has forced  
us to the conviction that these effects 
of temperature are produced by          
vibrations having the general character 
of waves1 which are sent through the    
spaces with great celerity4 ,when a ray 
of light departs from the sun or other  
luminous body1 it does not convey any   
part of the mass2 it transmits only     
motion4 ,a conception of the action can 
perhaps best be formed by suspending a  
number of balls of ivory1 stone1 or     
other hard substance each by a cord1 the
 series so arranged that they touch each
 other4 ,then striking a blow against   
one end of the line1 we observe that the
 ball at the farther end of the line is 
set in motion1 swinging a little away   
from the place it occupied before4 ,the 

movement of the intermediate balls may  
be so slight as to escape attention4 ,we
 thus perceive that energy can be       
transmitted from one to another of these
 little spheres4 ,close observation     
shows us that under the impulse which   
the blow gives each separate body is    
made to sway within itself much in the  
manner of a bell when it is rung1 and   
that the movement is transmitted to the 
object with which it is in contact4 ,in 
passing from the sun to the earth1 the  
light and heat traverse a space which we
 know to be substantially destitute of  
any such materials as make up the mass  
of the earth or the sun4 ,judged by the 
standards which we can apply1 this space
 must be essentially empty4 ,yet because
 motions go through it1 we have to      
believe that it is occupied by something
 which has certain of the properties of 
matter4 ,it has1 indeed1 one of the most
 important properties of all substances1
 in that it can vibrate4 ,this          
practically unknown thing is called     

ether4  ,the first important            
observational work done by the ancients 
led them to perceive that there was a   
very characteristic difference between  
the planets and the fixed stars4 ,they  
noted the fact that the planets wandered
 in a ceaseless way across the heavens1 
while the fixed stars showed little     
trace of changing position in relation  
to one another4 ,for a long time it was 
believed that these1 as well as the     
remoter fixed stars1 revolved about the 
earth4 ,this error1 though great1 is    
perfectly comprehensible1 for the       
evident appearance of the movement is   
substantially what would be brought     
about if they really coursed around our 
sphere4 ,it was only when the true      
nature of the earth and its relations to
 the sun were understood that men could 
correct this first view4 ,it was not1   
indeed1 until relatively modern times   
that the solar system came to be        
perceived as something independent and  
widely detached from the fixed stars    

system2 that the spaces which separate  
the members of our own solar family1    
inconceivably great as they are1 are but
 trifling as compared with the intervals
 which part us from the nearer fixed    
stars4 ,at this stage of our knowledge  
men came to the noble suggestion that   
each of the fixed stars was itself a    
sun1 each of the myriad probably        
attended by planetary bodies such as    
exist about our own luminary4  ,it will 
be well for the student to take an      
imaginary journey from the sun forth    
into space1 along the plane in which    
extends that vast aggregation of stars  
which we term the ,milky ,way4 ,let him 
suppose that his journey could be made  
with something like the speed of light1 
or1 say1 at the rate of about two       
hundred thousand miles a second4 ,it is 
fit that the imagination1 which is free 
to go through all things1 should essay  
such excursions4 ,on the fancied        
outgoing1 the observer would pass the   
interval between the sun and the earth  

in about eight minutes4 ,it would       
require some hours before he attained to
 the outer limit of the solar system4   
,on his direct way he would pass the    
orbits of the several planets4 ,some    
would have their courses on one side or 
the other of his path2 we should say    
above or below1 but for the fact that we
 leave these terms behind in the        
celestial realm4 ,on the margin of the  
solar system the sun would appear       
shrunken to the state where it was      
hardly greater than the more brilliant  
of the other fixed stars4 ,the onward   
path would then lead through a void     
which it would require years to         
traverse4 ,gradually the sun which      
happened to lie most directly in his    
path would grow larger2 with nearer     
approach1 it would disclose its planets4
 ,supposing that the way led through    
this solar system1 there would doubtless
 be revealed planets and satellites in  
their order somewhat resembling those of
 our own solar family1 yet there would  

doubtless be many surprises in the view4
 ,arriving near the first sun to be     
visited1 though the heavens would have  
changed their shape1 all the existing   
constellations having altered with the  
change in the point of view1 there would
 still be one familiar element in that  
the new-found planets would be near by1 
and the nearest fixed stars far away in 
the firmament4  ,with the speed of light
 a stellar voyage could be taken along  
the path of the ,milky ,way1 which would
 endure for thousands of years4 ,through
 all the course the journeyer would     
perceive the same vast girdle of stars1 
faint because they were far away1 which 
gives the dim light of our galaxy4 ,at  
no point is it probable that he would   
find the separate suns much more        
aggregated or greatly farther apart than
 they are in that part of the ,milky    
,way which our sun now occupies4        
,looking forth on either side of the    
galactic plane1 there would be the same 
scattering of stars which we now behold 

when we gaze at right angles to the way 
we are supposing the spirit to traverse4
  ,as the form of the ,milky ,way is    
irregular1 the mass1 indeed1 having     
certain curious divisions and branches1 
it well might be that the supposed path 
would occasionally pass on one or the   
other side of the vast star layer4 ,in  
such positions the eye would look forth 
into an empty firmament1 except that    
there might be in the far away1 tens of 
thousands of years perhaps at the rate  
that light travels away from the        
observer1 other galaxies or ,milky ,ways
 essentially like that which he was     
traversing4 ,at some point the journeyer
 would attain the margin of our star    
stratum1 whence again he would look     
forth into the unpeopled heavens1 though
 even there he might discern other      
remote star groups separated from his   
own by great void intervals4            
99       99       99       99       99  
,the revelations of the telescope show  
us certain features in the constitution 

and movements of the fixed stars which  
now demand our attention4 ,in the first 
place1 it is plain that not all of these
 bodies are in the same physical        
condition4 ,though the greater part of  
these distant luminous masses are       
evidently in the state of aggregation   
displayed by our own sun1 many of them  
retain more or less of that vaporous1 it
 may be dustlike1 character which we    
suppose to have been the ancient state  
of all the matter in the universe4 ,some
 of these masses appear as faint1 almost
 indistinguishable clouds1 which even to
 the greatest telescope and the         
best-trained vision show no distinct    
features of structure4 ,in other cases  
the nebulous appearance is hardly more  
than a mist about a tolerably distinct  
central star4 ,yet again1 and most      
beautifully in the great nebula of the  
constellation of ,orion1 the cloudy     
mass1 though hardly visible to the naked
 eye1 shows a division into many        
separate parts1 the whole appearing as  

if in process of concentration about    
many distinct centres4  ,the nebulas are
 reasonably believed by many astronomers
 to be examples of the ancient condition
 of the physical universe1 masses of    
matter which for some reason as yet     
unknown have not progressed in their    
consolidation to the point where they   
have taken on the characteristics of    
suns and their attendant planets4  ,many
 of the fixed stars1 the incomplete list
 of which now amounts to several        
hundred1 are curiously variable in the  
amount of light which they send out to  
the earth4 ,sometimes these variations  
are apparently irregular1 but in the    
greater number of cases they have fixed 
periods1 the star waxing and waning at  
intervals varying from a few months to a
 few years4 ,although some of the sudden
 flashings forth of stars from apparent 
small size to near the greatest         
brilliancy may be due to catastrophes   
such as might be brought about by the   
sudden falling in of masses of matter   

upon the luminous spheres1 it is more   
likely that the changes which we observe
 are due to the fact that two suns      
revolving around a common centre are in 
different stages of extinction4 ,it may 
well be that one of these orbs1         
presumably the smaller1 has so far lost 
temperature that it has ceased to glow4 
,if in its revolution it regularly comes
 between the earth and its luminous     
companion1 the effect would be to give  
about such a change in the amount of    
light as we observe4  ,the supposition  
that a bright sun and a relatively dark 
sun might revolve around a common centre
 of gravity may at first sight seem     
improbable4 ,the fact is1 however1 that 
imperfect as our observations on the    
stars really are1 we know many instances
 in which this kind of revolution of one
 star about another takes place4 ,in    
some cases these stars are of the same  
brilliancy1 but in others one of the    
lights is much brighter than the other4 
,from this condition to the state where 

one of the stars is so nearly dark as to
 be invisible1 the transition is but    
slight4 ,in a word1 the evidence goes to
 show that while we see only the        
luminous orbs of space1 the dark bodies 
which people the heavens are perhaps as 
numerous as those which send us light1  
and therefore appear as stars4  ,besides
 the greater spheres of space1 there is 
a vast host of lesser bodies1 the       
meteorites and comets1 which appear to  
be in part members of our solar system1 
and perhaps of other similar systems1   
and in part wanderers in the vast realm 
which intervenes between the solar      
systems4 ,of these we will first        
consider the meteors1 of which we know  
by far the most2 though even of them1 as
 we shall see1 our knowledge is limited4
  ,from time to time on any starry      
night1 and particularly in certain      
periods of the year1 we may behold1 at  
the distance of fifty or more miles     
above the surface of the earth1 what are
 commonly called shooting stars4 ,the   

most of these flashing meteors are      
evidently very small1 probably not      
larger than tiny sand grains1 possibly  
no greater than the fragments which     
would be termed dust4 ,they enter the   
air at a speed of about thirty miles a  
second4 ,they are so small that they    
burn to vapour in the very great heat   
arising from their friction on the air1 
and do not attain the surface of the    
earth4 ,these are so numerous that1 on  
the average1 some hundreds of thousands 
probably strike the earth's atmosphere  
each day4 ,from time to time larger     
bodies fall--bodies which are of        
sufficient bulk not to be burned up in  
the air1 but which descend to the       
ground4 ,these may be from the smallest 
size which may be observed to masses of 
many hundred pounds in weight4 ,these   
are far less numerous than the dust     
meteorites2 it is probable1 however1    
that several hundred fragments each year
 attain the earth's surface4 ,they come 
from various directions of space1 and   

there is as yet no means of determining 
whether they were formed in some manner 
within our planetary system or whether  
they wander to us from remoter realms4  
,we know that they are in part composed 
of metallic iron commingled with nickel 
and carbon 7sometimes as very small     
diamonds7 in a way rarely if ever found 
on the surface of our sphere1 and having
 a structure substantially unknown in   
its deposits4 ,in part they are composed
 of materials which somewhat resemble   
certain lavas4 ,it is possible that     
these fragments of iron and stone which 
constitute the meteorites have been     
thrown into the planetary spaces by the 
volcanic eruption of our own and other  
planets4 ,if hurled forth with a        
sufficient energy1 the fragments would  
escape from the control of the          
attraction of the sphere whence they    
came1 and would become independent      
wanderers in space1 moving around the   
sun in varied orbits until they were    
again drawn in by some of the greater   

planets4  ,as they come to us these     
meteorites often break up in the        
atmosphere1 the bits being scattered    
sometimes over a wide area of country4  
,thus1 in the case of the ,cocke ,county
 meteorite of ,tennessee1 one of the    
iron species1 the fragments1 perhaps    
thousands in number1 which came from the
 explosion of the body were scattered   
over an area of some thousand square    
miles4 ,when they reach the surface in  
their natural form1 these meteors always
 have a curious wasted and indented     
appearance1 which makes it seem likely  
that they have been subject to frequent 
collisions in their journeys after they 
were formed by some violent rending     
action4  ,in some apparent kinship with 
the meteorites may be classed the       
comets4 ,the peculiarity of these bodies
 is that they appear in most cases to be
 more or less completely vaporous4      
,rushing down from the depths of the    
heavens1 these bodies commonly appear as
 faintly shining1 cloudlike masses4 ,as 

they move in toward the sun long trails 
of vapour stream back from the somewhat 
consolidated head4 ,swinging around that
 centre1 they journey again into the    
outer realm4 ,as they retreat1 their    
tail-like streamers appear to gather    
again upon their centres1 and when they 
fade from view they are again           
consolidated4 ,in some cases it has been
 suspected that a part at least of the  
cometary mass was solid4 ,the evidence  
goes to show1 however1 that the matter  
is in a dustlike or vaporous condition1 
and that the weight of these bodies is  
relatively very small4  ,illustration3  
,fig4 #b4--,the ,great ,comet of #ahaa1 
one of the many varied forms of these   
bodies4  ,owing to their strange        
appearance1 comets were to the ancients 
omens of calamity4 ,sometimes they were 
conceived as flaming swords2 their      
forms1 indeed1 lend themselves to this  
imagining4 ,they were thought to presage
 war1 famine1 and the death of kings4   
,again1 in more modern times1 when they 

were not regarded as portents of        
calamity1 it was feared that these      
wanderers moving vagariously through our
 solar system might by chance come in   
contact with the earth with disastrous  
results4 ,such collisions are not       
impossible1 for the reason that the     
planets would tend to draw these errant 
bodies toward them if they came near    
their spheres2 yet the chance of such   
collisions happening to the earth is so 
small that they may be disregarded4     
,,motions ,,of ,,the ,,spheres4         
,although little is known of the motions
 which occur among the celestial bodies 
beyond the sphere of our solar family1  
that which has been ascertained is of   
great importance1 and serves to make it 
likely that all the suns in space are   
upon swift journeys which in their speed
 equal1 if they do not exceed1 the rate 
of motion among the planetary spheres1  
which may1 in general1 be reckoned at   
about twenty miles a second4 ,our whole 
solar system is journeying away from    

certain stars1 and in the direction of  
others which are situated in the        
opposite part of the heavens4 ,the proof
 of this fact is found in the           
observations which show that on one side
 of us the stars are apparently coming  
closer together1 while on the other side
 they are going farther apart4 ,the     
phenomenon1 in a word1 is one of        
perspective1 and may be made real to the
 understanding by noting what takes     
place when we travel down a street along
 which there are lights4 ,we readily    
note that these lights appear to close  
in behind us1 and widen their intervals 
in the direction in which we journey4   
,by such evidence astronomers have      
become convinced that our sphere1 along 
with the sun which controls it1 is each 
second a score of miles away from the   
point where it was before4  ,there is   
yet other and most curious evidence     
which serves to show that certain of the
 stars are journeying toward our part of
 the heavens at great speed1 while      

others are moving away from us by their 
own proper motion4 ,these indications   
are derived from the study of the lines 
in the light which the spectrum reveals 
to us when critically examined4 ,the    
position of these cross lines is1 as we 
know1 affected by the motion of the body
 whence the light comes1 and by close   
analysis of the facts it has been pretty
 well determined that the distortion in 
their positions is due to very swift    
motions of the several stars4 ,it is not
 yet certain whether these movements of 
our sun and of other solar bodies are in
 straight lines or in great circles4    
,it should be noted that1 although the  
evidence from the spectroscope serves to
 show that the matter in the stars is   
akin to that of our own earth1 there is 
reason to believe that those great      
spheres differ much from each other in  
magnitude4  ,we have now set forth some 
of the important facts exhibited by the 
stellar universe4 ,the body of details  
concerning that realm is vast1 and the  

conclusions drawn from it important2    
only a part1 however1 of the matter with
 which it deals is of a nature to be    
apprehended by the student who does not 
approach it in a somewhat professional  
way4 ,we shall therefore now turn to a  
description of the portion of the starry
 world which is found in the limits of  
our solar system4 ,there the influences 
of the several spheres upon our planet  
are matters of vital importance2 they in
 a way affect1 if they do not control1  
all the operations which go on upon the 
surface of the earth4                   
,,the ,,solar ,,system4  ,we have seen  
that the matter in the visible universe 
everywhere tends to gather into vast    
associations which appear to us as      
stars1 and that these orbs are engaged  
in ceaseless motion in journeys through 
space4 ,in only one of these            
aggregations--that which makes our own  
solar system--are the bodies            
sufficiently near to our eyes for us1   
even with the resources of our          

telescopes and other instruments1 to    
divine something of the details which   
they exhibit4 ,in studying what we may  
concerning the family of the sun1 the   
planets1 and their satellites1 we may   
reasonably be assured that we are       
tracing a history which with many       
differences is in general repeated in   
the development of each star in the     
firmament4 ,therefore the inquiry is one
 of vast range and import4  ,following1 
as we may reasonably do1 the nebular    
hypothesis--a view which1 though not    
wholly proved1 is eminently probable--we
 may regard our solar system as having  
begun when the matter of which it is    
composed1 then in a finely divided1     
cloudy state1 was separated from the    
similar material which went to make the 
neighbouring fixed stars4 ,the period   
when our solar system began its         
individual life was remote beyond the   
possibility of conception4 ,naturalists 
are pretty well agreed that living      
beings began to exist upon the earth at 

least a hundred million years ago2 but  
the beginnings of our solar system must 
be placed at a date very many times as  
remote from the present day4#a          
,footnote #a3 ,some astronomers1        
particularly the distinguished          
,professor ,newcomb1 hold that the sun  
can not have been supplying heat as at  
present for more than about ten million 
years1 and that all geological time must
 be thus limited4 ,the geologist        
believes that this reckoning is far too 
short4  ,according to the nebular       
theory1 the original vapour of the solar
 system began to fall in toward its     
centre and to whirl about that point at 
a time long before the mass had shrunk  
to the present limits of the solar      
system as defined by the path of the    
outermost planets4 ,at successive stages
 of the concentration1 rings after the  
manner of those of ,saturn separated    
from the disklike mass1 each breaking up
 and consolidating into a body of       
nebulous matter which followed in the   

same path1 generally forming rings which
 became by the same process the moons or
 satellites of the sphere4 ,in this way 
the sun produced eight planets which are
 known1 and possibly others of small    
size on the outer verge of the system   
which have eluded discovery4 ,according 
to this view1 the planetary masses were 
born in succession1 the farthest away   
being the oldest4 ,it is1 however1 held 
by an able authority that the mass of   
the solar system would first form a     
rather flat disk1 the several rings     
forming and breaking into planets at    
about the same time4 ,the conditions in 
,saturn1 where the inner ring remains   
parted1 favours the view just stated4   
,before making a brief statement of the 
several planets1 the asteroids1 and the 
satellites1 it will be well to consider 
in a general way the motions of these   
bodies about their centres and about the
 sun4 ,the most characteristic and      
invariable of these movements is that by
 which each of the planetary spheres1 as

 well as the satellites1 describes an   
orbit around the gravitative centre     
which has the most influence upon       
it--the sun4 ,to conceive the nature of 
this movement1 it will be well to       
imagine a single planet revolving around
 the sun1 each of these bodies being    
perfect spheres1 and the two the only   
members of the solar system4 ,in this   
condition the attraction of the two     
bodies would cause them to circle around
 a common centre of gravity1 which1 if  
the planet were not larger or the sun   
smaller than is the case in our solar   
system1 would lie within the mass of the
 sun4 ,in proportion as the two bodies  
might approach each other in size1 the  
centre of gravity would come the nearer 
to the middle point in a line connecting
 the two spheres4 ,in this condition of 
a sun with a single planet1 whatever    
were the relative size of sun and       
planet1 the orbits which they traverse  
would be circular4 ,in this state of    
affairs it should be noted that each of 

the two bodies would have its plane of  
rotation permanently in the same        
position4 ,even if the spheres were more
 or less flattened about the poles of   
their axes1 as is the case with all the 
planets which we have been able         
carefully to measure1 as well as with   
the sun1 provided the axes of rotation  
were precisely parallel to each other1  
the mutual attraction of the masses     
would cause no disturbance of the       
spheres4 ,the same would be the case if 
the polar axis of one sphere stood      
precisely at right angles to that of the
 other4 ,if1 however1 the spheres were  
somewhat flattened at the poles1 and the
 axes inclined to each other1 then the  
pull of one mass on the other would     
cause the polar axes to keep up a       
constant movement which is called       
nutation1 or nodding4  ,the reason why  
this nodding movement of the polar axes 
would occur when these lines were       
inclined to each other is not difficult 
to see if we remember that the          

attraction of masses upon each other is 
inversely as the square of the distance2
 each sphere1 pulling on the equatorial 
bulging of the other1 pulls most        
effectively on the part of it which is  
nearest1 and tends to draw it down      
toward its centre4 ,the result is that  
the axes of the attracted spheres are   
given a wobbling movement1 such as we   
may note in the spinning top1 though in 
the toy the cause of the motion is not  
that which we are considering4  ,if1    
now1 in that excellent field for the    
experiment we are essaying1 the mind's  
eye1 we add a second planet outside of  
the single sphere which we have so far  
supposed to journey about the sun1 or   
rather about the common centre of       
gravity1 we perceive at once that we    
have introduced an element which leads  
to a complication of much importance4   
,the new sphere would1 of course1 pull  
upon the others in the measure of its   
gravitative value--i4e41 its weight4    
,the centre of gravity of the system    

would now be determined not by two      
distinct bodies1 but by three4 ,if we   
conceive the second planet to journey   
around the sun at such a rate that a    
straight line always connected the      
centres of the three orbs1 then the only
 effect on their gravitative centre     
would be to draw the first-mentioned    
planet a little farther away from the   
centre of the sun2 but in our own solar 
system1 and probably in all others1 this
 supposition is inadmissible1 because   
the planets have longer journeys to go  
and also move slower1 the farther they  
are from the sun4 ,thus ,mercury        
completes the circle of its year in     
eighty-eight of our days1 while the     
outermost planet requires sixty thousand
 days 7more than one hundred and        
sixty-four years7 for the same task4    
,the result is not only that the centre 
of gravity of the system is somewhat    
displaced--itself a matter of no great  
account--but also that the orbit of the 
original planet ceases to be circled and

 becomes elliptical1 and this for the   
evident reason that the sphere will be  
drawn somewhat away from the sun when   
the second planet happens to lie in the 
part of its orbit immediately outside of
 its position1 in which case the pull is
 away from the solar centre2 while1 on  
the other hand1 when the new planet was 
on the other side of the sun1 its pull  
would serve to intensify the attraction 
which drew the first sphere toward the  
centre of gravity4 ,as the pulling      
action of the three bodies upon each    
other1 as well as upon their equatorial 
protuberances1 would vary with every    
change in their relative position1      
however slight1 the variations in the   
form of their orbits1 even if the       
spheres were but three in number1 would 
be very important4 ,the consequences of 
these perturbations will appear in the  
sequel4  ,in our solar system1 though   
there are but eight great planets1 the  
group of asteroids1 and perhaps a score 
of satellites1 the variety of orbital   

and axial movement which is developed   
taxes the computing genius of the ablest
 astronomer4 ,the path which our earth  
follows around the sun1 though it may in
 general and for convenience be         
described as a variable ellipse1 is1 in 
fact1 a line of such complication that  
if we should essay a diagram of it on   
the scale of this page it would not be  
possible to represent any considerable  
part of its deviations4 ,these1 in fact1
 would elude depiction1 even if the     
draughtsman had a sheet for his drawing 
as large as the orbit itself1 for every 
particle of matter in space1 even if it 
be lodged beyond the limits of the      
farthest stars revealed to us by the    
telescope1 exercises a certain          
attraction1 which1 however small1 is    
effective on the mass of the earth4     
,science has to render its conclusions  
in general terms1 and we can safely take
 them as such2 but in this1 as in other 
instances1 it is well to qualify our    
acceptance of the statements by the     

memory that all things are infinitely   
more complicated than we can possibly   
conceive or represent them to be4  ,we  
have next to consider the rotations of  
the planetary spheres upon their axes1  
together with the similar movement1 or  
lack of it1 in the case of their        
satellites4 ,this rotation1 according to
 the nebular hypothesis1 may be         
explained by the movements which would  
set up in the share of matter which was 
at first a ring of the solar nebula1 and
 which afterward gathered into the      
planetary aggregation4 ,the way of it   
may be briefly set forth as follows3    
,such a ring doubtless had a diameter of
 some million miles2 we readily perceive
 that the particles of matter in the    
outer part of the belt would have a     
swifter movement around the sun than    
those on the inside4 ,when by some      
disturbance1 as possibly by the passage 
of a great meteoric body of a           
considerable gravitative power1 this    
ring was broken in two1 the particles   

composing it on either side would1      
because of their mutual attraction1 tend
 to draw away from the breach1 widening 
that gap until the matter of the broken 
ring was aggregated into a sphere of the
 star dust or vapour4 ,when the nebulous
 matter originally in the ring became   
aggregated into a spherical form1 it    
would1 on account of the different rates
 at which the particles were moving when
 they came together1 be the surer to    
fall in toward the centre1 not in       
straight lines1 but in curves--in other 
words1 the mass would necessarily take  
on a movement of rotation essentially   
like that which we have described in    
setting forth the nebular hypothesis4   
,in the stages of concentration the     
planetary nebul might well repeat those 
through which the greater solar mass    
proceeded4 ,if the volume of the        
material were great1 subordinate rings  
would be formed1 which when they broke  
and concentrated would constitute       
secondary planets or satellites1 such as

 our moon4 ,for some reason as yet      
unknown the outer planets--in fact1 all 
those in the solar system except the two
 inner1 ,venus and ,mercury and the     
asteroids--formed such attendants4 ,all 
these satellite-forming rings have      
broken and concentrated except the inner
 of ,saturn1 which remains as an        
intellectual treasure of the solar      
system to show the history of its       
development4  ,to the student who is not
 seeking the fulness of knowledge which 
astronomy has to offer1 but desires only
 to acquaint himself with the more      
critical and important of the heavenly  
phenomena which help to explain the     
earth1 these features of planetary      
movement should prove especially        
interesting for the reason that they    
shape the history of the spheres4 ,as we
 shall hereafter see1 the machinery of  
the earth's surface1 all the life which 
it bears1 its winds and                 
rains--everything1 indeed1 save the     
actions which go on in the depths of the

 sphere--is determined by the heat and  
light which come from the sun4 ,the     
conditions under which this vivifying   
tide is received have their origin in   
the planetary motion4 ,if our earth's   
path around the centre of the system was
 a perfect circle1 and if its polar axis
 lay at right angles to the plane of its
 journey1 the share of light and heat   
which would fall upon any one point on  
the sphere would be perfectly uniform4  
,there would be no variations in the    
length of day or night2 no changes in   
the seasons2 the winds everywhere would 
blow with exceeding steadiness--in fact1
 the present atmospheric confusion would
 be reduced to something like order4    
,from age to age1 except so far as the  
sun itself might vary in the amount of  
energy which it radiated1 or lands rose 
up into the air or sunk down toward the 
sea level1 the climate of each region   
would be perfectly stable4 ,in the      
existing conditions the influences bring
 about unending variety4 ,first of all1 

the inclined position of the polar axis 
causes the sun apparently to move across
 the heavens1 so that it comes in an    
overhead position once or twice in the  
year in quite half the area of the lands
 and seas4 ,this apparent swaying to and
 fro of the sun1 due to the inclination 
of the axis of rotation1 also affects   
the width of the climatal belts on      
either side of the equator1 so that all 
parts of the earth receive a            
considerable share of the sun's         
influence4 ,if the axis of the earth's  
rotation were at right angles to the    
plane of its orbit1 there would be a    
narrow belt of high temperature about   
the equator1 north and south of which   
the heat would grade off until at about 
the parallels of fifty degrees we should
 find a cold so considerable and uniform
 that life would probably fade away2 and
 from those parallels to the poles the  
conditions would be those of permanent  
frost1 and of days which would darken   
into the enduring night or twilight in  

the realm of the far north and south4   
,thus the wide habitability of the earth
 is an effect arising from the          
inclination of its polar axis4          
,illustration3 ,fig4 #c4--;,inclination 
of ,planetary ,orbits 7from ,chambers74 
,as the most valuable impression which  
the student can receive from his study  
of ,nature is that sense of the order   
which has made possible all life1       
including his own1 it will be well for  
him to imagine1 as he may readily do1   
what would be the effect arising from   
changes in relations of earth and sun4  
,bringing the earth's axis in           
imagination into a position at right    
angles to the plane of the orbit1 he    
will see that the effect would be to    
intensify the equatorial heat1 and to   
rob the high latitudes of the share     
which they now have4 ,on moving the axis
 gradually to positions where it        
approaches the plane of the orbit1 he   
will note that each stage of the change 
widens the tropic belt4 ,bringing the   

polar axis down to the plane of the     
orbit1 one hemisphere would receive     
unbroken sunshine1 the other remaining  
in perpetual darkness and cold4 ,in this
 condition1 in place of an equatorial   
line we should have an equatorial point 
at the pole nearest the sun2 thence the 
temperatures would grade away to the    
present equator1 beyond which half the  
earth would be in more refrigerating    
condition than are the poles at the     
present day4 ,in considering the        
movements of our planet1 we shall see   
that no great changes in the position of
 the polar axis can have taken place4   
,on this account the suggested          
alterations of the axis should not be   
taken as other than imaginary changes4  
,it is easy to see that with a circular 
orbit and with an inclined axis winter  
and summer would normally come always at
 the same point in the orbit1 and that  
these seasons would be of perfectly even
 length4 ,but1 as we have before noted1 
the earth's path around the sun is in   

its form greatly affected by the        
attractions which are exercised by the  
neighbouring planets1 principally by    
those great spheres which lie in the    
realm without its orbit1 ,jupiter and   
,saturn4 ,when these attracting bodies1 
as is the case from time to time1 though
 at long intervals1 are brought together
 somewhere near to that part of the     
solar system in which the earth is      
moving around the sun1 they draw our    
planet toward them1 and so make its path
 very elliptical4 ,when1 however1 they  
are so distributed that their pulling   
actions neutralize each other1 the orbit
 returns more nearly to a circular form4
 ,the range in its eccentricity which   
can be brought about by these           
alterations is very great4 ,when the    
path is most nearly circular1 the       
difference in the major and minor axis  
may amount to as little as about five   
hundred thousand miles1 or about one one
 hundred and eighty-sixth of its average
 diameter4 ,when the variation is       

greatest the difference in these        
measurements may be as much as near     
thirteen million miles1 or about one    
seventh of the mean width of the orbit4 
,the first and most evident effect      
arising from these changes of the orbit 
comes from the difference in the amount 
of heat which the earth may receive     
according as it is nearer or farther    
from the sun4 ,as in the case of other  
fires1 the nearer a body is to it the   
larger the share of light and heat which
 it will receive4 ,in an orbit made     
elliptical by the planetary attraction  
the sun necessarily occupies one of the 
foci of the ellipse4 ,the result is1 of 
course1 that the side of the earth which
 is toward the sun1 while it is thus    
brought the nearer to the luminary1     
receives more energy in the form of     
light and heat than come to any part    
which is exposed when the spheres are   
farther away from each other in the     
other part of the orbit4 ,computations  
clearly show that the total amount of   

heat and the attendant light which the  
earth receives in a year is not affected
 by these changes in the form of its    
path4 ,while it is true that it receives
 heat more rapidly in the half of the   
ellipse which is nearest the source of  
the inundation1 it obtains less while it
 is farther away1 and these two         
variations just balance each other4     
,although the alterations in the        
eccentricity of its orbit do not vary   
the annual supply of heat which the     
earth receives1 they are capable of     
changing the character of the seasons1  
and this in the way which we will now   
endeavour to set forth1 though we must  
do it at the cost of considerable       
attention on the part of the reader1 for
 the facts are somewhat complicated4 ,in
 the first place1 we must note that the 
ellipticity of the earth's orbit is not 
developed on fixed lines1 but is        
endlessly varied1 as we can readily     
imagine it would be for the reason that 
its form depends upon the wandering of  

the outer planetary spheres which pull  
the earth about4 ,the longer axis of the
 ellipse is itself in constant motion in
 the direction in which the earth       
travels4 ,this movement is slow1 and at 
an irregular rate4 ,it is easy to see   
that the effect of this action1 which is
 called the revolution of the apsides1  
or1 as the word means1 the movement of  
the poles of the ellipse1 is to bring   
the earth1 when a given hemisphere is   
turned toward the sun1 sometimes in the 
part of the orbit which is nearest the  
source of light and heat1 and sometimes 
farther away4 ,it may thus well come    
about that at one time the summer season
 of a hemisphere arrives when it is     
nearest the sun1 so that the season1    
though hot1 will be very short1 while at
 another time the same season will      
arrive when the earth is farthest from  
the sun1 and receives much less heat1   
which would tend to make a long and     
relatively cool summer4 ,the reason for 
the difference in length of the seasons 

is to be found in the relative swiftness
 of the earth's revolution when it is   
nearest the sun1 and the slowness when  
it is farther away4  ,there is a further
 complication arising from that curious 
phenomenon called the precession of the 
equinoxes1 which has to be taken into   
account before we can sufficiently      
comprehend the effect of the varying    
eccentricity of the orbit on the earth's
 seasons4 ,to understand this feature of
 precession we should first note that it
 means that each year the change from   
the winter to the summer--or1 as we     
phrase it1 the passage of the           
equinoctial line--occurs a little sooner
 than the year before4 ,the cause of    
this is to be found in the attraction   
which the heavenly bodies1 practically  
altogether the moon1 exercises on the   
equatorial protuberance of the earth4   
,we know that the diameter of our sphere
 at the equator is1 on the average1     
something more than twenty-six miles    
greater than it is through the poles4   

,we know1 furthermore1 that the position
 of the moon in relation to the earth is
 such that it causes the attraction on  
one half of this protuberance to be     
greater than it is upon the other4 ,we  
readily perceive that this action will  
cause the polar axis to make a certain  
revolution1 or1 what comes to the same  
thing1 that the plane of the equator    
will constantly be altering its         
position4 ,now1 as the equinoctial      
points in the orbit depend for their    
position upon the attitude of the       
equatorial plane1 we can conceive that  
the effect is a change in position of   
the place in that orbit where summer and
 winter begin4 ,the actual result is to 
bring the seasonal points backward1 step
 by step1 through the orbit in a regular
 measure until in twenty-two thousand   
five hundred years they return to the   
place where they were before4 ,this     
cycle of change was of old called the   
,annus ,magnus1 or great year4  ,if the 
earth's orbit were an ellipse1 the major

 axis of which remained in the same     
position1 we could readily reckon all   
the effects which arise from the        
variations of the great year4 ,but this 
ellipse is ever changing in form1 and in
 the measure of its departure from a    
circle the effects on the seasons       
distributed over a great period of time 
are exceedingly irregular4 ,now and     
then1 at intervals of hundreds of       
thousands or millions of years1 the     
orbit becomes very elliptical2 then     
again for long periods it may in form   
approach a circle4 ,when in the state of
 extreme ellipticity1 the precession of 
the equinoxes will cause the hemispheres
 in turn each to have their winter and  
summer alternately near and far from the
 sun4 ,it is easily seen that when the  
summer season comes to a hemisphere in  
the part of the orbit which is then     
nearest the sun the period will be very 
hot4 ,when the summer came farthest from
 the sun that part of the year would    
have the temperature mitigated by its   

removal to a greater distance from the  
source of heat4 ,a corresponding effect 
would be produced in the winter season4 
,as long as the orbit remained eccentric
 the tendency would be to give          
alternately intense seasons to each     
hemisphere through periods of about     
twelve thousand years1 the other        
hemisphere having at the same time a    
relatively slight variation in the      
summer and winter4  ,at first sight it  
may seem to the reader that these       
studies we have just been making in     
matters concerning the shape of the     
orbit and the attendant circumstances   
which regulate the seasons were of no   
very great consequence2 but1 in the     
opinion of some students of climate1 we 
are to look to these processes for an   
explanation of certain climatal changes 
on the earth1 including the ,glacial    
periods1 accidents which have had the   
utmost importance in the history of man1
 as well as of all the other life of the
 planet4  ,it is now time to give some  

account as to what is known concerning  
the general conditions of the solar     
bodies--the planets and satellites of   
our own celestial group4 ,for our       
purpose we need attend only to the      
general physical state of these orbs so 
far as it is known to us by the studies 
of astronomers4 ,the nearest planet to  
the sun is ,mercury4 ,this little       
sphere1 less than half the diameter of  
our earth1 is so close to the sun that  
even when most favourably placed for    
observation it is visible for but a few 
minutes before sunrise and after sunset4
 ,although it may without much          
difficulty be found by the ordinary eye1
 very few people have ever seen it4 ,to 
the telescope when it is in the full    
moon state it appears as a brilliant    
disk2 it is held by most astronomers    
that the surface which we see is made up
 altogether of clouds1 but this1 as most
 else that has been stated concerning   
this planet1 is doubtful4 ,the sphere is
 so near to the sun that if it were     

possessed of water it would inevitably  
bear an atmosphere full of vapour4      
,under any conceivable conditions of a  
planet placed as ,mercury is1 provided  
it had an atmosphere to retain the heat1
 its temperature would necessarily be   
very high4 ,life as we know it could not
 well exist upon such a sphere4  ,next  
beyond ,mercury is ,venus1 a sphere only
 a little less in diameter than the     
earth4 ,of this sphere we know more than
 we do of ,mercury1 for the reason that 
it is farther from the sun and so       
appears in the darkened sky4 ,most      
astronomers hold that the surface of    
this planet apparently is almost        
completely and continually hidden from  
us by what appears to be a dense cloud  
envelope1 through which from time to    
time certain spots appear of a dark     
colour4 ,these1 it is claimed1 retain   
their place in a permanent way2 it is1  
indeed1 by observing them that the      
rotation period of the planet has1      
according to some observers1 been       

determined4 ,it therefore seems likely  
that these spots are the summits of     
mountains1 which1 like many of our own  
earth1 rise above the cloud level4      
,recent observations on ,venus made by  
,mr4 ,percival ,lowell appear to show   
that the previous determinations of the 
rotation of that planet1 as well as     
regards its cloud wrap1 are in error4   
,according to these observations1 the   
sphere moves about the sun1 always      
keeping the same side turned toward the 
solar centre1 just as the moon does in  
its motion around the earth4 ,moreover1 
,mr4 ,lowell has failed to discover any 
traces of clouds upon the surface of the
 planet4 ,as yet these results have not 
been verified by the work of other      
astronomers2 resting1 however1 as they  
do on studies made with an excellent    
telescope and in the very translucent   
and steady air of the ,flagstaff        
,station1 they are more likely to be    
correct than those obtained by other    
students4 ,if it be true that ,venus    

does not turn upon its axis1 such is    
likely to be the case also with the     
planet ,mercury4  ,next in the series of
 the planets is our own earth4 ,as the  
details of this planet are to occupy us 
during nearly all the remainder of this 
work1 we shall for the present pass it  
by4  ,beyond the earth we pass first to 
the planet ,mars1 a sphere which has    
already revealed to us much concerning  
its peculiarities of form and physical  
state1 and which is likely in the future
 to give more information than we shall 
obtain from any other of our companions 
in space1 except perhaps the moon4 ,mars
 is not only nearer to us than any other
 planet1 but it is so placed that it    
receives the light of the sun under     
favourable conditions for our vision4   
,moreover1 its sky appears to be        
generally almost cloudless1 so that when
 in its orbital course the sphere is    
nearest our earth it is under favourable
 conditions for telescopic observation4 
,at such times there is revealed to the 

astronomer a surface which is covered   
with an amazing number of shadings and  
markings which as yet have been         
incompletely interpreted4 ,the faint    
nature of these indications has led to  
very contradictory statements as to     
their form2 no two maps which have been 
drawn agree except in their             
generalities4 ,there is reason to       
believe that ,mars has an atmosphere2   
this is shown by the fact that in the   
appropriate season the region about     
either pole is covered by a white       
coating1 presumably snow4 ,this covering
 extends rather less far toward the     
planet's equator than does the snow     
sheet on our continents4 ,taking into   
account the colour of the coating1 and  
the fact that it disappears when the    
summer season comes to the hemisphere in
 which it was formed1 we are1 in fact1  
forced to believe that the deposit is   
frozen water1 though it has been        
suggested that it may be frozen carbonic
 acid4 ,taken in connection with what we

 have shortly to note concerning the    
apparent seas of this sphere1 the       
presumption is overwhelmingly to the    
effect that ,mars has seasons not unlike
 our own4  ,the existence of snow on any
 sphere may safely be taken as evidence 
that there is an atmosphere4 ,in the    
case of ,mars1 this supposition is borne
 out by the appearance of its surface4  
,the ruddy light which it sends back to 
us1 and the appearance on the margin of 
the sphere1 which is somewhat dim1      
appears to indicate that its atmosphere 
is dense4 ,in fact1 the existence of an 
atmosphere much denser than that of our 
own earth appears to be demanded by the 
fact that the temperatures are such as  
to permit the coming and going of snow4 
,it is well known that the temperature  
of any point on the earth1 other things 
being equal1 is proportionate to the    
depth of atmosphere above its surface4  
,if ,mars had no more air over its      
surface than has an equal area of the   
earth1 it would remain at a temperature 

so low that such seasonal changes as we 
have observed could not take place4 ,the
 planet receives one third less heat    
than an equal area of the earth1 and its
 likeness to our own temperature1 if    
such exists1 is doubtless brought about 
by the greater density of its           
atmosphere1 that serves to retain the   
heat which comes upon its surface4 ,the 
manner in which this is effected will be
 set forth in the study of the earth's  
atmosphere4  ,illustration3 ,fig4       
#d4--,mars1 ,august #bg1 #ahib 7,guiot71
 the white patch is the supposed ,polar 
,snow ,cap4  ,as is shown by the maps of
 ,mars1 the surface is occupied by      
shadings which seem to indicate the     
existence of water and lands4 ,those    
portions of the area which are taken to 
be land are very much divided by what   
appear to be narrow seas4 ,the general  
geographic conditions differ much from  
those of our own sphere in that the     
parts of the planet about the water     
level are not grouped in great          

continents1 and there are no large      
oceans4 ,the only likeness to the       
conditions of our earth which we can    
perceive is in a general pointing of the
 somewhat triangular masses of what     
appears to be land toward one pole4 ,as 
a whole1 the conditions of the ,martial 
lands and seas as regards their form1 at
 least1 is more like that of ,europe    
than that of any other part of the      
earth's surface4 ,europe in the early   
,tertiary times had a configuration even
 more like that of ,mars than it        
exhibits at present1 for in that period 
the land was very much more divided than
 it now is4  ,if the lands of ,mars are 
framed as are those of our own earth1   
there should be ridges of mountains     
constituting what we may term the       
backbones of the continent4 ,as yet such
 have not been discerned1 which may be  
due to the fact that they have not been 
carefully looked for4 ,the only peculiar
 physical features which have as yet    
been discerned on the lands of ,mars are

 certain long1 straight1 rather narrow  
crevicelike openings1 which have        
received the name of canals4 ,these     
features are very indistinct1 and are   
just on the limit of visibility4 ,as yet
 they have been carefully observed by   
but few students1 so that their features
 are not yet well recorded2 as far as we
 know them1 these fissures have no      
likeness in the existing conditions of  
our earth4 ,it is difficult to          
understand how they are formed or       
preserved on a surface which is         
evidently subjected to rainfalls4  ,it  
will require much more efficient        
telescopes than we now have before it   
will be possible to begin any           
satisfactory study on the geography of  
this marvellous planet4 ,we can not hope
 as yet to obtain any indications as to 
the details of its structure2 we can not
 see closely enough to determine whether
 rivers exist1 or whether there is a    
coating which we may interpret as       
vegetation1 changing its hues in the    

different seasons of the year4 ,an      
advance in our instruments of research  
during the coming century1 if made with 
the same speed as during the last1 will 
perhaps enable us to interpret the      
nature of this neighbour1 and thereby to
 extend the conception of planetary     
histories which we derive from our own  
earth4  ,illustration3 ,fig4            
#e4--;,comparative ,sizes of the        
,planets 7,chambers74  ,beyond ,mars we 
find one of the most singular features  
of our solar system in a group of small 
planetary bodies1 the number of which   
now known amounts to some two hundred1  
and the total may be far greater4 ,these
 bodies are evidently all small2 it is  
doubtful if the largest is three hundred
 and the smaller more than twenty miles 
in diameter4 ,so far as it has been     
determined by the effect of their       
aggregate mass in attracting the other  
spheres1 they would1 if put together1   
make a sphere far less in diameter than 
our earth1 perhaps not more than five   

hundred miles through4 ,the forms of    
these asteroids is as yet unknown2 we   
therefore can not determine whether     
their shapes are spheroidal1 as are     
those of the other planets1 or whether  
they are angular bits like the          
meteorites4 ,we are thus not in a       
position to conjecture whether their    
independence began when the nebulous    
matter of the ring to which they        
belonged was in process of              
consolidation1 or whether1 after the    
aggregation of the sphere was           
accomplished1 and the matter solidified1
 the mass was broken into bits in some  
way which we can not yet conceive4 ,it  
has been conjectured that such a solid  
sphere might have been driven asunder by
 a collision with some wandering        
celestial body2 but all we can conceive 
of such actions leads us to suppose that
 a blow of this nature would tend to    
melt or convert materials subjected to  
it into the state of vapour1 rather than
 to drive them asunder in the manner of 

an explosion4  ,the four planets which  
lie beyond the asteroids give us        
relatively little information concerning
 their physical condition1 though they  
afford a wide field for the philosophic 
imagination4 ,from this point of view   
the reader is advised to consult the    
writings of the late ,r4,a4 ,proctor1   
who has brought to the task of          
interpreting the planetary conditions   
the skill of a well-trained astronomer  
and a remarkable constructive           
imagination4  ,the planet ,jupiter1 by  
far the largest of the children of the  
sun1 appears to be still in a state     
where its internal heat has not so far  
escaped that the surface has cooled down
 in the manner of our earth4 ,what      
appear to be good observations show that
 the equatorial part of its area1 at    
least1 still glows from its own heat4   
,the sphere is cloud-wrapped1 but it is 
doubtful whether the envelope be of     
watery vapour2 it is1 indeed1 quite     
possible that besides such vapour it may

 contain some part of the many          
substances which occupy the atmosphere  
of the sun4 ,if the ,jovian sphere were 
no larger than the earth1 it would1 on  
account of its greater age1 long ago    
have parted with its heat2 but on       
account of its great size it has been   
able1 notwithstanding its antiquity1 to 
retain a measure of temperature which   
has long since passed away from our     
earth4  ,in the case of ,saturn1 the    
cloud bands are somewhat less visible   
than on ,jupiter1 but there is reason to
 suppose in this1 as in the last-named  
planet1 that we do not behold the more  
solid surface of the sphere1 but see    
only a cloud wrap1 which is probably due
 rather to the heat of the sphere itself
 than to that which comes to it from the
 sun4 ,at the distance of ,saturn from  
the centre of the solar system a given  
area of surface receives less than one  
ninetieth of the sun's heat as compared 
with the earth2 therefore we can not    
conceive that any density of the        

atmosphere whatever would suffice to    
hold in enough temperature to produce   
ordinary clouds4 ,moreover1 from time to
 time bright spots appear on the surface
 of the planet1 which must be due to    
some form of eruptions from its         
interior4  ,beyond ,saturn the two      
planets ,uranus and ,neptune1 which     
occupy the outer part of the solar      
system1 are so remote that even our best
 telescopes discern little more than    
their presence1 and the fact that they  
have attendant moons4  ,from the point  
of view of astronomical science1 the    
outermost planet ,neptune1 of peculiar  
interest for the reason that it was1 as 
we may say1 discovered by computation4  
,astronomers had for many years remarked
 the fact that the next inner planetary 
sphere exhibited peculiarities in its   
orbit which could only be accounted for 
on the supposition that it was subjected
 to the attraction of another wandering 
body which had escaped observation4 ,by 
skilful computation the place in the    

heavens in which this disturbing element
 lay was so accurately determined that  
when the telescope was turned to the    
given field a brief study revealed the  
planet4 ,nothing else in the history of 
the science of astronomy1 unless it be  
the computation of eclipses1 so clearly 
and popularly shows the accuracy of the 
methods by which the work of that       
science may be done4  ,as we shall see  
hereafter1 in the chapters which are    
devoted to terrestrial phenomena1 the   
physical condition of the sun determines
 the course of all the more important   
events which take place on the surface  
of the earth4 ,it is therefore fit that 
in this preliminary study of the        
celestial bodies1 which is especially   
designed to make the earth more         
interpretable to us1 we should give a   
somewhat special attention to what is   
known under the title of ,solar         
,physics4  ,the reader has already been 
told that the sun is one of many million
 similar bodies which exist in space1   

and1 furthermore1 that these            
aggregations of matter have been        
developed from an original nebulous     
condition4 ,the facts indicate that the 
natural history of the sun1 as well as  
that of its attendant spheres1 exhibits 
three momentous stages3 ,first1 that of 
vapour2 second1 that of igneous         
fluidity2 third1 that in which the      
sphere is so far congealed that it      
becomes dark4 ,neither of these states  
is sharply separated from the other2 a  
mass may be partly nebulous and partly  
fluid2 even when it has been converted  
into fluid1 or possibly into the solid  
state1 it may still retain on the       
exterior some share of its original     
vaporous condition4 ,in our sun the     
concentration has long since passed     
beyond the limits of the nebulous state2
 the last of the successively developed 
rings has broken1 and has formed itself 
into the smallest of the planets1 which 
by its distance from the sun seems to   
indicate that the process of division by

 rings long ago attained in our solar   
system its end1 the remainder of its    
nebulous material concentrating on its  
centre without sign of any remaining    
tendency to produce these planet-making 
circles4                      ,,the     
,,constitution ,,of ,,the ,,sun4        
,before the use of the telescope in     
astronomical work1 which was begun by   
the illustrious ,galileo in #afjh1      
astronomers were unable to approach the 
problem of the structure of the sun4    
,they could discern no more than can be 
seen by any one who looks at the great  
sphere through a bit of smoked glass1 as
 we know this reveals a disklike body of
 very uniform appearance4 ,the only     
variation in this simple aspect occurs  
at the time of a total eclipse1 when for
 a minute or two the moon hides the     
whole body of the sun4 ,on such         
occasions even the unaided eye can see  
that there is about the sphere a broad1 
rather bright field1 of an aspect like a
 very thin cloud or fog1 which rises in 

streamer like projections at points to a
 quarter of a million miles or more     
above the surface of the sphere4 ,the   
appearance of this shining field1 which 
is called the corona1 reminds one of the
 aurora which glows in the region about 
either pole of the earth4  ,one of the  
first results of the invention of the   
telescope was the revelation of the     
curious dark objects on the sun's disk1 
known by the name of spots from the time
 of their discovery1 or1 at least1 from 
the time when it was clearly perceived  
that they were not planets1 but really  
on the solar body4 ,the interest in the 
constitution of the sphere has increased
 during the last fifty years4 ,this     
interest has rapidly grown until at the 
present time a vast body of learning has
 been gathered for the solution of the  
many problems concerning the centre of  
our system4 ,as yet there is great      
divergence in the views of astronomers  
as to the interpretation of their       
observations1 but certain points of     

great general interest have been        
tolerably well determined4 ,these may be
 briefly set forth by an account of what
 would meet the eye if an observer were 
able to pass from the surface of the    
earth to the central part of the sun4   
,illustration3 ,lava stream1 in         
,hawaiian ,islands1 flowing into the    
sea4 ,note the ropy character of the    
half-frozen rock on the sides of the    
nearest rivulet of the lava4  ,in       
passing from the earth to a point about 
a quarter of a million miles from the   
sun's surface--a distance about that of 
the moon from our sphere--the observer  
would traverse the uniformly empty      
spaces of the heavens1 where1 but for   
the rare chance of a passing meteorite  
or comet1 there would be nothing that we
 term matter4 ,arriving at a point some 
two or three hundred thousand miles from
 the body of the sun1 he would enter the
 realm of the corona2 here he would find
 scattered particles of matter1 the bits
 so far apart that there would perhaps  

be not more than one or two in the cubic
 mile2 yet1 as they would glow intensely
 in the central light1 they would be    
sufficient to give the illumination     
which is visible in an eclipse4 ,these  
particles are most likely driven up from
 the sun by some electrical action1 and 
are constantly in motion1 much as are   
the streamers of the aurora4  ,below the
 corona and sharply separated from it   
the observer finds another body of very 
dense vapour1 which is termed the       
chromosphere1 and which has been        
regarded as the atmosphere of the sun4  
,this layer is probably several thousand
 miles thick4 ,from the manner in which 
it moves1 in the way the air of our own 
planet does in great storms1 it is not  
easy to believe that it is a fluid1 yet 
its sharply defined upper surface leads 
us to suppose that it can not well be a 
mere mass of vapour4 ,the spectroscope  
shows us that this chromosphere contains
 in the state of vapour a number of     
metallic substances1 such as iron and   

magnesium4 ,to an observer who could    
behold this envelope of the sun from the
 distance at which we see the moon1 the 
spectacle would be more magnificent than
 the imagination1 guided by the sight of
 all the relatively trifling fractures  
of our earth1 can possibly conceive4    
,from the surface of the fiery sea vast 
uprushes of heated matter rise to the   
height of two or three hundred thousand 
miles1 and then fall back upon its      
surface4 ,these jets of heated matter   
have the aspect of flames1 but they     
would not be such in fact1 for the      
materials are not burning1 but merely   
kept at a high temperature by the heat  
of the great sphere beneath4 ,they      
spring up with such energy that they at 
times move with a speed of one hundred  
and fifty miles a second1 or at a rate  
which is attained by no other matter in 
the visible universe1 except that       
strange1 wandering star known to        
astronomers as ,grombridge1 #ahcj1 which
 is traversing the firmament with a     

speed of not less than two hundred miles
 a second4  ,below the chromosphere is  
the photosphere1 the lower envelope of  
the sun1 if it be not indeed the body of
 the sphere itself2 from this comes the 
light and heat of the mass4 ,this1 too1 
can not well be a firm-set mass1 for the
 reason that the spots appear to form in
 and move over it4 ,it may be regarded  
as an extremely dense mass of gas1 so   
weighed down by the vast attraction of  
the great sphere below it that it is in 
effect a fluid4 ,the near-at-hand       
observer would doubtless find this      
photosphere1 as it appears in the       
telescope1 to be sharply separated from 
the thinner and more vaporous           
envelopes--the chromosphere and the     
corona--which are1 indeed1 so thin that 
they are invisible even with the        
telescope1 except when the full blaze of
 the sun is cut off in a total eclipse4 
,the fact that the photosphere1 except  
when broken by the so-called spots1 lies
 like a great smooth sea1 with no parts 

which lie above the general line1 shows 
that it has a very different structure  
from the envelope which lies upon it4   
,if they were both vaporous1 there would
 be a gradation between them4  ,on the  
surface of the photosphere1 almost      
altogether within thirty degrees of the 
equator of the sun1 a field             
corresponding approximately to the      
tropical belt of the earth1 there appear
 from time to time the curious          
disturbances which are termed spots4    
,these appear to be uprushes of matter  
in the gaseous state1 the upward        
movement being upon the margins of the  
field and a downward motion taking place
 in the middle of the irregular opening1
 which is darkened in its central part1 
thus giving it1 when seen by an ordinary
 telescope1 the aspect of a black patch 
on the glowing surface4 ,these spots1   
which are from some hundred to some     
thousand miles in diameter1 may endure  
for months before they fade away4 ,it is
 clear that they are most abundant at   

intervals of about eleven years1 the    
last period of abundance being in #ahic4
 ,the next to come may thus be expected 
in #aijd4 ,in the times of least        
spotting more than half the days of a   
year may pass without the surface of the
 photosphere being broken1 while in     
periods of plenty no day in the year is 
likely to fail to show them4            
,illustration3 ,fig4 #f4--,ordinary     
,sun-spot1 ,june #bb1 #ahhe4  ,it is    
doubtful if the closest seeing would    
reveal the cause of the solar spots4    
,the studies of the physicists who have 
devoted the most skill to the matter    
show little more than that they are     
tumults in the photosphere1 attended by 
an uprush of vapours1 in which iron and 
other metals exist2 but whether these   
movements are due to outbreaks from the 
deeper parts of the sun or to some      
action like the whirling storms of the  
earth's atmosphere is uncertain4 ,it is 
also uncertain what effect these        
convulsions of the sun have on the      

amount of the heat and light which is   
poured forth from the orb4 ,the common  
opinion that the sun-spot years are the 
hottest is not yet fully verified4      
,below the photosphere lies the vast    
unknown mass of the unseen solar realm4 
,it was at one time supposed that the   
dark colour of the spots was due to the 
fact that the photosphere was broken    
through in those spaces1 and that we    
looked down through them upon the       
surface of the slightly illuminated     
central part of the sphere4 ,this view  
is untenable1 and in its place we have  
to assume that for the eight hundred and
 sixty thousand miles of its diameter   
the sun is composed of matter such as is
 found in our earth1 but throughout in a
 state of heat which vastly exceeds that
 known on or in our planet4 ,owing to   
its heat1 this matter is possibly not in
 either the solid or the fluid state1   
but in that of very compressed gases1   
which are kept from becoming solid or   
even fluid by the very high temperature 

which exists in them4 ,this view is     
apparently supported by the fact that1  
while the pressure upon its matter is   
twenty-seven times greater in the sun   
than it is in the earth1 the weight of  
the whole mass is less than we should   
expect under these conditions4  ,as for 
the temperature of the sun1 we only know
 that it is hot enough to turn the      
metals into gases in the manner in which
 this is done in a strong electric arc1 
but no satisfactory method of reckoning 
the scale of this heat has been devised4
 ,the probabilities are to the effect   
that the heat is to be counted by the   
tens of thousands of degrees            
,fahrenheit1 and it may amount to       
hundreds of thousands2 it has1 indeed1  
been reckoned as high as a million      
degrees4 ,this vast discharge is not due
 to any kind of burning action--i4e41 to
 the combustion of substances1 as in a  
fire4 ,it must be produced by the       
gradual falling in of the materials1 due
 to the gravitation of the mass toward  

its centre1 each particle converting its
 energy of position into heat1 as does  
the meteorite when it comes into the    
air4  ,it is well to close this very    
imperfect account of the learning which 
relates to the sun with a brief tabular 
statement showing the relative masses of
 the several bodies of the solar system4
 ,it should be understood that by mass  
is meant not the bulk of the object1 but
 the actual amount of matter in it as   
determined by the gravitative attraction
 which it exercises on other celestial  
bodies4 ,in this test the sun is taken  
as the measure1 and its mass is for     
convenience reckoned at #a1jjj1jjj1jjj4 
,,table ,,of ,,relative ,,masses ,,of   
,,sun ,,and ,,planets4#b                
----------------------------------------
--------------------       ,the sun     
#a1jjj1jjj1jjj         ,mercury         
#bjj         ,venus                     
#b1cec         ,earth                   
#c1jfj         ,mars                    
#cci         ,asteroids                 

8         ,saturn                       
#bhe1ehj         ,jupiter               
#ied1cje         ,uranus                
#dd1bej         ,neptune                
#ea1fjj           ,combined mass of the 
four inner planets          #e1ieb      
,combined mass of all the planets       
#a1cda1fhg                              
----------------------------------------
--------------------  ,footnote #b3 ,see
 ,newcomb's ,popular ,astronomy1 p4     
#bcd4 ,harper ,brothers1 ,new ,york4    
,it thus appears that the mass of all   
the planets is about one seven hundredth
 that of the sun4  ,those who wish to   
make a close study of celestial         
geography will do well to procure the   
interesting set of diagrams prepared by 
the late ,james ,freeman ,clarke1 in    
which transparencies placed in a        
convenient lantern show the grouping of 
the important stars in each             
constellation4 ,the advantage of this   
arrangement is that the little maps can 
be consulted at night and in the open   

air in a very convenient manner4 ,after 
the student has learned the position of 
a dozen of the constellations visible in
 the northern hemisphere1 he can rapidly
 advance his knowledge in the admirable 
method invented by ,dr4 ,clarke4        
,having learned the constellations1 the 
student may well proceed to find the    
several planets1 and to trace them in   
their apparent path across the fixed    
stars4 ,it will be well for him here to 
gain if he can the conception that their
 apparent movement is compounded of     
their motion around the sun and that of 
our own sphere2 that it would be very   
different if our earth stood still in   
the heavens4 ,at this stage he may well 
begin to take in mind the evidence which
 the planetary motion supplies that the 
earth really moves round the sun1 and   
not the sun and planets round the earth4
 ,this discovery was one of the great   
feats of the human mind2 it baffled the 
wits of the best men for thousands of   
years4 ,therefore the inquirer who works

 over the evidence is treading one of   
the famous paths by which his race      
climbed the steeps of science4  ,the    
student must not expect to find the     
evidence that the sun is the centre of  
the solar system very easy to interpret2
 and yet any youth of moderate          
curiosity1 and that interest in the     
world about him which is the foundation 
of scientific insight1 can see through  
the matter4 ,he will best begin his     
inquiries by getting a clear notion of  
the fact that the moon goes round the   
earth4 ,this is the simplest case of    
movements of this nature which he can   
see in the solar system4 ,noting that   
the moon occupies a different place at a
 given hour in the twenty-four1 but is  
evidently at all times at about the same
 distance from the earth1 he readily    
perceives that it circles about our     
sphere4 ,this the people knew of old1   
but they made of it an evidence that the
 sun also went around our sphere4 ,here1
 then1 is the critical point4 ,why does 

the sun not behave in the same manner as
 the moon8 ,at this stage of his inquiry
 the student best notes what takes place
 in the motions of the planets between  
the earth and the sun4 ,he observes that
 those so-called inferior planets       
,mercury and ,venus are never very far  
away from the central body2 that they   
appear to rise up from it1 and then to  
go back to it1 and that they have phases
 like the moon4 ,now and then ,venus may
 be observed as a black spot crossing   
the disk of the sun4 ,a little          
consideration will show that on the     
theory that bodies revolve round each   
other in the solar system these         
movements of the inner planets can only 
be explained on the supposition that    
they at least travel around the great   
central fire4 ,now1 taking up the outer 
planets1 we observe that they           
occasionally appear very bright1 and    
that they are then at a place in the    
heavens where we see that they are far  
from the solar centre4 ,gradually they  

move down toward the sunset and         
disappear from view4 ,here1 too1 the    
movement1 though less clearly so1 is    
best reconcilable with the idea that    
these bodies travel in orbits1 such as  
those which are traversed by the inner  
planets4 ,the wonder is that with these 
simple facts before them1 and with ample
 time to think the matter over1 the     
early astronomers did not learn the     
great truth about the solar             
system--namely1 that the sun is the     
centre about which the planets circled4 
,their difficulty lay mainly in the fact
 that they did not conceive the earth as
 a sphere1 and even after they attained 
that conception they believed that our  
globe was vastly larger than the        
planets1 or even than the sun4 ,this    
misconception kept even the thoughtful  
,greeks1 who knew that the earth was    
spherical in form1 from a clear notion  
as to the structure of our system4 ,it  
was not1 indeed1 until mathematical     
astronomy attained a considerable       

advance1 and men began to measure the   
distances in the solar system1 and until
 the ,newtonian theory of gravitation   
was developed1 that the planetary orbits
 and the relation of the various bodies 
in the solar system to each other could 
be perfectly discerned4  ,care has been 
taken in the above statements to give   
the student indices which may assist him
 in working out for himself the evidence
 which may properly lead a person1 even 
without mathematical considerations of a
 formal kind1 to construct a theory as  
to the relation of the planets to the   
sun4 ,it is not likely that he can go   
through all the steps of this argument  
at once1 but it will be most useful to  
him to ponder upon the problem1 and     
gradually win his way to a full         
understanding of it4 ,with that purpose 
in mind1 he should avoid reading what   
astronomers have to say on the matter   
until he is satisfied that he has done  
as much as he can with the matter on his
 own account4 ,he should1 however1 state

 his observations1 and as far as        
possible draw the results in his        
note-book in a diagrammatic form4 ,he   
should endeavour to see if the facts are
 reconcilable with any other supposition
 than that the earth and the other      
planets move around the sun4 ,when he   
has done his task1 he will have passed  
over one of the most difficult roads    
which his predecessors had to traverse  
on their way to an understanding of the 
heavens4 ,even if he fail he will have  
helped himself to some large            
understandings4  ,the student will find 
it useful to make a map of the heavens1 
or rather make several representing     
their condition at different times in   
the year4 ,on this plot he should put   
down only the stars whose places and    
names he has learned1 but he should plot
 the position of the planets at         
different times4 ,in this way1 though at
 first his efforts will be very awkward1
 he will soon come to know the general  
geography of the heavens4  ,although the

 possession or at least the use of a    
small astronomical telescope is a great 
advantage to a student after he has made
 a certain advance in his work1 such an 
instrument is not at all necessary1 or1 
indeed1 desirable at the outset of his  
studies4 ,an ordinary opera-glass1      
however1 will help him in picking out   
the stars in the constellations1 in     
identifying the planets1 and in getting 
a better idea as to the form of the     
moon's surface--a matter which will be  
treated in this work in connection with 
the structure of the earth4             
,,chapter ,,iv4                         
,,the ,,earth4   ,in beginning the study
 of the earth it is important that the  
student should at once form the habit of
 keeping in mind the spherical form of  
the planet4 ,many persons1 while they   
may blindly accept the fact that the    
earth is a sphere1 do not think of it as
 having that form4 ,perhaps the simplest
 way of securing the correct image of   
the shape is to imagine how the earth   

would appear as seen from the moon4 ,in 
its full condition the moon is apt to   
appear as a disk4 ,when it is new1 and  
also when in its waning stages it is    
visible in the daytime1 the spherical   
form is very apparent4 ,imagining       
himself on the surface of the moon1 the 
student can well perceive how the earth 
would appear as a vast body in the      
heavens2 its eight thousand miles of    
diameter1 about four times that of the  
satellite1 would give an area sixteen   
times the size which the moon presents  
to us4 ,on this scale the continents and
 oceans would appear very much more     
plain than do the relatively slight     
irregularities on the lunar surface4    
,with the terrestrial globe in hand1 the
 student can readily construct an image 
which will represent1 at least in       
outline1 the appearance which the sphere
 he inhabits would present when seen    
from a distance of about a quarter of a 
million miles away4 ,the continent of   
,europe-,asia would of itself appear    

larger than all the lunar surface which 
is visible to us4 ,every continent and  
all the greater islands would be clearly
 indicated4 ,the snow covering which in 
the winter of the northern hemisphere   
wraps so much of the land would be seen 
to come and go in the changes of the    
seasons2 even the permanent ice about   
either pole1 and the greater regions of 
glaciers1 such as those of the ,alps and
 the ,himalayas1 would appear as        
brilliant patches of white amid fields  
of darker hue4 ,even the changes in the 
aspect of the vegetation which at one   
season clothes the wide land with a     
green mantle1 and at another assumes the
 dun hue of winter1 would be1 to the    
unaided eye1 very distinct4 ,it is      
probable that all the greater rivers    
would be traceable as lines of light    
across the relatively dark surface of   
the continents4 ,by such exercises of   
the constructive imagination--indeed1 in
 no other way--the student can acquire  
the habit of considering the earth as a 

vast whole4 ,from time to time as he    
studies the earth from near by he should
 endeavour to assemble the phenomena in 
the general way which we have indicated4
  ,the reader has doubtless already     
learned that the earth is a slightly    
flattened sphere1 having an average     
diameter of about eight thousand miles1 
the average section at the equator being
 about twenty-six miles greater than    
that from pole to pole4 ,in a body of   
such large proportions this difference  
in measurement appears not important2 it
 is1 however1 most significant1 for it  
throws light upon the history of the    
earth's mass4 ,computation shows that   
the measure of flattening at the poles  
is just what would occur if the earth   
were or had been at the time when it    
assumed its present form in a fluid     
condition4 ,we readily conceive that a  
soft body revolving in space1 while all 
its particles by gravitation tended to  
the centre1 would in turning around1 as 
our earth does upon its axis1 tend to   

bulge out in those parts which were     
remote from the line upon which the     
turning took place4 ,thus the flattening
 of our sphere at the poles corroborates
 the opinion that its mass was once     
molten--in a word1 that its ancient     
history was such as the nebular theory  
suggests4  ,although we have for        
convenience termed the earth a flattened
 spheroid1 it is only such in a very    
general sense4 ,it has an infinite      
number of minor irregularities which it 
is the province of the geographer to    
trace and that of the geologist to      
account for4 ,in the first place1 its   
surface is occupied by a great array of 
ridges and hollows4 ,the larger of      
these1 the oceans and continents1 first 
deserve our attention4 ,the difference  
in altitude of the earth's surface from 
the height of the continents to the     
deepest part of the sea is probably     
between ten and eleven miles1 thus      
amounting to about two fifths of the    
polar flattening before noted4 ,the     

average difference between the ocean    
floor and the summits of the            
neighbouring continents is probably     
rather less than four miles4 ,it        
happens1 most fortunately for the       
history of the earth1 that the water    
upon its surface fills its great        
concavities on the average to about four
 fifths of their total depth1 leaving   
only about one fifth of the relief      
projecting above the ocean level4 ,we   
have termed this arrangement fortunate1 
for it insures that rainfall visits     
almost all the land areas1 and thereby  
makes those realms fit for the uses of  
life4 ,if the ocean had only half its   
existing area1 the lands would be so    
wide that only their fringes would be   
fertile4 ,if it were one fifth greater  
than it is1 the dry areas would be      
reduced to a few scattered islands4     
,from all points of view the most       
important feature of the earth's surface
 arises from its division into land and 
water areas1 and this for the reason    

that the physical and vital work of our 
sphere is inevitably determined by this 
distribution4 ,the shape of the seas and
 lands is fixed by the positions at     
which the upper level of the great water
 comes against the ridges which fret the
 earth's surface4 ,these elevations are 
so disposed that about two thirds of the
 hard mass is at the present time       
covered with water1 and only one third  
exposed to the atmosphere4 ,this        
proportion is inconstant4 ,owing to the 
endless up-and-down goings of the       
earth's surface1 the place of the shore 
lines varies from year to year1 and in  
the geological ages great revolutions in
 the forms and relative area of water   
and land are brought about4  ,noting the
 greater divisions of land and water as 
they are shown on a globe1 we readily   
perceive that those parts of the        
continental ridges which rise above the 
sea level are mainly accumulated in the 
northern hemisphere--in fact1 far more  
than half the dry realm is in that part 

of the world4 ,we furthermore perceive  
that all the continents more or less    
distinctly point to the southward2 they 
are1 in a word1 triangles1 with their   
bases to the northward1 and their       
apices1 usually rather acute1 directed  
to the southward4 ,this form is very    
well indicated in three of the great    
lands1 ,north and ,south ,america and   
,africa2 it is more indistinctly shown  
in ,asia and in ,australia4 ,as yet we  
do not clearly understand the reason why
 the continents are triangular1 why they
 point toward the south pole1 or why    
they are mainly accumulated in the      
northern hemisphere4 ,as stated in the  
chapter on astronomy1 some trace of the 
triangular form appears in the land     
masses of the planet ,mars4 ,there1 too1
 these triangles appear to point toward 
one pole4  ,besides the greater lands1  
the seas are fretted by a host of       
smaller dry areas1 termed islands4      
,these1 as inquiry has shown1 are of two
 very diverse natures4 ,near the        

continents1 practically never more than 
a thousand miles from their shores1 we  
find isles1 often of great size1 such as
 ,madagascar1 which in their structure  
are essentially like the                
continents--that is1 they are built in  
part or in whole of non-volcanic rocks1 
sandstones1 limestones1 etc4 ,in most   
cases these islands1 to which we may    
apply the term continental1 have at some
 time been connected with the           
neighbouring mainland1 and afterward    
separated from it by a depression of the
 surface which permitted the sea to flow
 over the lowlands4 ,geologists have    
traced many cases where in the past     
elevations which are now parts of a     
continent were once islands next its    
shore4 ,in the deeper seas far removed  
from the margins of the continents the  
islands are made up of volcanic         
ejections of lava1 pumice1 and dust1    
which has been thrown up from craters   
and fallen around their margin or are   
formed of coral and other organic       

remains4  ,next after this general      
statement as to the division of sea and 
land we should note the peculiarities   
which the earth's surface exhibits where
 it is bathed by the air1 and where it  
is covered by the water4 ,beginning with
 the best-known region1 that of the dry 
land1 we observe that the surface is    
normally made up of continuous slopes of
 varying declivity1 which lead down from
 the high points to the sea4 ,here and  
there1 though rarely1 these slopes      
centre in a basin which is occupied by a
 lake or a dead sea4 ,on the deeper     
ocean floors1 so far as we may judge    
with the defective information which the
 plumb line gives us1 there is no such  
continuity in the downward sloping of   
the surface1 the area being cast into   
numerous basins1 each of great extent4  
,when we examine in some detail the     
shape of the land surface1 we readily   
perceive that the continuous down slopes
 are due to the cutting action of       
rivers4 ,in the basin of a stream the   

waters act to wear away the original    
heights1 filling them into the hollows1 
until the whole area has a continuous   
down grade to the point where the waters
 discharge into the ocean or perhaps    
into a lake4 ,on the bottom of the sea1 
except near the margin of the continent1
 where the floor may in recent          
geological times have been elevated into
 the air1 and thus exposed to river     
action1 there is no such agent working  
to produce continuous down grades4      
,looking upon a map of a continent which
 shows the differences in altitude of   
the land1 we readily perceive that the  
area is rather clearly divided into two 
kinds of surface1 mountains and plains1 
each kind being sharply distinguished   
from the other by many important        
peculiarities4 ,mountains are           
characteristically made up of distinct1 
more or less parallel ridges and        
valleys1 which are grouped in very      
elongated belts1 which1 in the case of  
the ,american ,cordilleras1 extend from 

the ,arctic to the ,antarctic ,circle4  
,only in rare instances do we find      
mountains occupying an area which is not
 very distinctly elongated1 and in such 
cases the elevations are usually of no  
great height4 ,plains1 on the other     
hand1 commonly occupy the larger part of
 the continent1 and are distributed     
around the flanks of the mountain       
systems4 ,there is no rule as to their  
shape2 they normally grade away from the
 bases of the mountains toward the sea1 
and are often prolonged below the level 
of the water for a considerable distance
 beyond the shore1 forming what is      
commonly known as the continental shelf 
or belt of shallows along the coast     
line4 ,we will now consider some details
 concerning the form and structure of   
mountains4  ,in almost any mountain     
region a glance over the surface of the 
country will give the reader a clew to  
the principal factor which has          
determined the existence of these       
elevations4 ,wherever the bed rocks are 

revealed he will recognise the fact that
 they have been much disturbed4 ,almost 
everywhere the strata are turned at high
 angles2 often their slopes are steeper 
than those of house roofs1 and not      
infrequently they stand in attitudes    
where they appear vertical4 ,under the  
surface of plains bedded rocks generally
 retain the nearly horizontal position  
in which all such deposits are most     
likely to be found4 ,if the observer    
will attentively study the details of   
position of these tilted rocks of       
mountainous districts1 he will in most  
cases be able to perceive that the beds 
have been flexed or folded in the manner
 indicated by the diagram4 ,sometimes1  
though rarely1 the tops of these        
foldings or arches have been preserved1 
so that the nature of the movement can  
be clearly discerned4 ,more commonly the
 upper parts of the upward-arching      
strata have been cut off by the action  
of the decay-bringing forces--frost1    
flowing water1 or creeping ice in       

glaciers--so that only the downward     
pointing folds which were formed in the 
mountain-making are well preserved1 and 
these are almost invariably hidden      
within the earth4  ,illustration3 ,fig4 
#g4--,section of mountains4 ,rockbridge 
and ,bath counties1 ,va4 7from ,dana74  
,the numbers indicate the several       
formations4  ,by walking across any     
considerable mountain chain1 as1 for    
instance1 that of the ,alleghanies1 it  
is generally possible to trace a number 
of these parallel up-and-down folds of  
the strata1 so that we readily perceive 
that the original beds had been packed  
together into a much less space than    
they at first occupied4 ,in some cases  
we could prove that the shortening of   
the line has amounted to a hundred miles
 or more--in other words1 points on the 
plain lands on either side of the       
mountain range which now exists may have
 been brought a hundred miles or so     
nearer together than they were before   
the elevations were produced4 ,the      

reader can make for himself a convenient
 diagram showing what occurred by       
pressing a number of leaves of this book
 so that the sheets of paper are thrown 
into ridges and furrows4 ,by this       
experiment he also will see that the    
easiest way to account for such foldings
 as we observe in mountains is by the   
supposition that some force residing in 
the earth tends to shove the beds into a
 smaller space than they originally     
occupied4 ,not only are the rocks       
composing the mountains much folded1 but
 they are often broken through after the
 manner of masonry which has been       
subjected to earthquake shocks1 or of   
ice which has been strained by the      
expansion that affects it as it becomes 
warmed before it is melted4 ,in fact1   
many of our small lakes in ,new ,england
 and in other countries of a long winter
 show in a miniature way during times of
 thawing ice folds which much resemble  
mountain arches4  ,at first geologists  
were disposed to attribute all the      

phenomena of mountain-folding to the    
progressive cooling of the earth4       
,although this sphere has already lost a
 large part of the heat with which it   
was in the beginning endowed1 it is     
still very hot in its deeper parts1 as  
is shown by the phenomena of volcanoes4 
,this internal heat1 which to the       
present day at the depth of a hundred   
miles below the surface is probably     
greater than that of molten iron1 is    
constantly flowing away into space2     
probably enough of it goes away on the  
average each day to melt a hundred cubic
 miles or more of ice1 or1 in more      
scientific phrase1 the amount of heat   
rendered latent by melting that volume  
of frozen water4 ,j4,r4 ,meyer1 an      
eminent physicist1 estimated the        
quantity of heat so escaping each day of
 the year to be sufficient to melt two  
hundred and forty cubic miles of ice4   
,the effect of this loss of heat is     
constantly to shrink the volume of the  
earth2 it has1 indeed1 been estimated   

that the sphere on this account         
contracts on the average to the amount  
of some inches each thousand years4 ,for
 the reason that almost all this heat   
goes from the depths of the earth1 the  
cool outer portion losing no            
considerable part of it1 the contraction
 that is brought about affects the      
interior portions of the sphere alone4  
,the inner mass constantly shrinking as 
it loses heat1 the outer1 cold part is  
by its weight forced to settle down1 and
 can only accomplish this result by     
wrinkling4 ,an analogous action may be  
seen where an apple or a potato becomes 
dried2 in this case the hard outer rind 
is forced to wrinkle1 because1 losing no
 water1 it does not diminish in its     
extent1 and can only accommodate itself 
to the interior by a wrinkling process4 
,in one case it is water which escapes1 
in the other heat2 but in both          
contraction of the part which suffers   
the loss leads to the folding of the    
outside of the spheroid4  ,although this

 loss of heat on the part of the earth  
accounts in some measure for the        
development of mountains1 it is not of  
itself sufficient to explain the        
phenomena1 and this for the reason that 
mountains appear in no case to develop  
on the floors of the wide sea4 ,the     
average depth of the ocean is only      
fifteen thousand feet1 while there are  
hundreds1 if not thousands1 of mountain 
crests which exceed that height above   
the sea4 ,therefore if mountains grew on
 the sea floor as they do upon the land1
 there should be thousands of peaks     
rising above the plain of the waters1   
while1 in fact1 all of the islands      
except those near the shores of         
continents are of volcanic origin--that 
is1 are lands of totally different      
nature4  ,whenever a considerable       
mountain chain is formed1 although the  
actual folding of the beds is limited to
 the usually narrow field occupied by   
these disturbances1 the elevation takes 
place over a wide belt of country on one

 or both sides of the range4 ,thus if we
 approach the ,rocky ,mountains from the
 ,mississippi ,valley1 we begin to mount
 up an inclined plane from the time we  
pass westward from the ,mississippi     
,river4 ,the beds of rock as well as the
 surface rises gradually until at the   
foot of the mountain2 though the rocks  
are still without foldings1 they are at 
a height of four or five thousand feet  
above the sea4 ,it seems                
probable--indeed1 we may say almost     
certain--that when the crust is broken1 
as it is in mountain-building1 by       
extensive folds and faults1 the matter  
which lies a few score miles below the  
crust creeps in toward those fractures1 
and so lifts up the country on which    
they lie4 ,when we examine the forms of 
any of our continents1 we find that     
these elevated portions of the earth's  
crust appear to be made up of mountains 
and the table-lands which fringe those  
elevations4 ,there is not1 as some of   
our writers suppose1 two different kinds

 of elevation in our great lands--the   
continents and the mountains which they 
bear--but one process of elevation by   
which the foldings and the massive      
uplifts which constitute the table-lands
 are simultaneously and by one process  
formed4  ,looking upon continents as the
 result of mountain growth1 we may say  
that here and there on the earth's crust
 these dislocations have occurred in    
such association and of such magnitude  
that great areas have been uplifted     
above the plain of the sea4 ,in general1
 we find these groups of elevations so  
arranged that they produce the          
triangular form which is characteristic 
of the great lands4 ,it will be         
observed1 for instance1 that the form of
 ,north ,america is in general          
determined by the position of the       
,appalachian and ,cordilleran systems on
 its eastern and western margins1 though
 there are a number of smaller chains1  
such as the ,laurentians in ,canada and 
the ice-covered mountains of ,greenland1

 which have a measure of influence in   
fixing its shore lines4  ,illustration3 
,waterfall near ,gadsden1 ,alabama4 ,the
 upper shelf of rock is a hard          
sandstone1 the lower beds are soft      
shale4 ,the conditions are those of most
 waterfalls1 such as ,niagara4  ,the    
history of plains1 as well as that of   
mountains1 will have further light      
thrown upon it when in the next chapter 
we come to consider the effect of rain  
water on the land4 ,we may here note the
 fact that the level surfaces which are 
above the seashores are divisible into  
two main groups--those which have been  
recently lifted above the sea level1    
composed of materials laid down in the  
shallows next the shore1 and which have 
not yet shared in mountain-building     
disturbances1 and those which have been 
slightly tilted in the manner before    
indicated in the case of the plains     
which border the ,rocky ,mountains on   
the east4 ,the great southern plain of  
eastern and southern ,united ,states1   

extending from near ,new ,york to       
,mexico1 is a good specimen of the level
 lands common on all the continents     
which have recently emerged from the    
sea4 ,the table-lands on either side of 
the ,mississippi ,valley1 sloping from  
the ,alleghanies and the ,cordilleras1  
represent the more ancient type of plain
 which has already shared in the        
elevation which mountain-building brings
 about4 ,in rarer cases plains of small 
area are formed where mountains formerly
 existed by the complete moving down of 
the original ridges4  ,there is a common
 opinion that the continents are liable 
in the course of the geologic ages to   
very great changes of position2 that    
what is now sea may give place to new   
great lands1 and that those already     
existing may utterly disappear4 ,this   
opinion was indeed generally held by    
geologists not more than thirty years   
ago4 ,further study of the problem has  
shown us that while parts of each       
continent may at any time be depressed  

beneath the sea1 the whole of its       
surface rarely if ever goes below the   
water level4 ,thus1 in the case of      
,north ,america1 we can readily note    
very great changes in its form since the
 land began to rise above the water4    
,but always1 from that ancient day to   
our own1 some portion of the area has   
been above the level of the sea1 thus   
providing an ark of refuge for the land 
life when it was disturbed by           
inundations4 ,the strongest evidence in 
favour of the opinion that the existing 
continents have endured for many million
 years is found in the fact that each of
 the great lands preserves many distinct
 groups of animals and plants which have
 descended from ancient forms dwelling  
upon the same territory4 ,if at any time
 the relatively small continent of      
,australia had gone beneath the sea1 all
 of the curious pouched animals akin to 
the opossum and kangaroo which abound in
 that country--creatures belonging in   
the ancient life of the world--would    

have been overwhelmed4  ,we have already
 noted the fact that the uplifting of   
mountains and of the table-lands about  
them1 which appears to have been the    
basis of continental growth1 has been   
due to strains in the rocks sufficiently
 strong to disturb the beds4 ,at each   
stage of the mountain-building movement 
these compressive strains have had to   
contend with the very great weight of   
the rocks which they had to move4 ,these
 lands are not to be regarded as firm   
set or rigid arches1 but as highly      
elastic structures1 the shapes of which 
may be determined by any actions which  
put on or take off burden4 ,we see a    
proof of this fact from numerous        
observations which geologists are now   
engaged in making4 ,thus during the last
 ice epoch1 when almost all the northern
 part of this continent1 as well as the 
northern part of ,europe1 was covered by
 an ice sheet several thousand feet     
thick1 the lands sank down under their  
load1 and to an extent roughly          

proportional to the depth of the icy    
covering4 ,while the northern regions   
were thus tilted down by the weight     
which was upon them1 the southern       
section of this land1 the region about  
the ,gulf of ,mexico1 was elevated much 
above its present level2 it seems       
likely1 indeed1 that the peninsula of   
,florida rose to the height of several  
hundred feet above its present shore    
line4 ,after the ice passed away the    
movements were reversed1 the northern   
region rising and the southern sinking  
down4 ,these movements are attested by  
the position of the old shore lines     
formed during the later stages of the   
,glacial epoch4 ,thus around ,lake      
,ontario1 as well as the other ,great   
,lakes1 the beaches which mark the      
higher positions of those inland seas   
during the closing stages of the ice    
time1 and which1 of course1 were when   
formed horizontal1 now rise to the      
northward at the rate of from two to    
five feet for each mile of distance4    

,recent studies by ,mr4 ,g4,k4 ,gilbert 
show that this movement is still in     
progress4  ,other evidence going to show
 the extent to which the movements of   
the earth's crust are affected by the   
weight of materials are found in the    
fact that wherever along the shores     
thick deposits of sediments are         
accumulated the tendency of the region  
where they lie is gradually to sink     
downward1 so that strata having an      
aggregate thickness of ten thousand feet
 or more may be accumulated in a sea    
which was always shallow4 ,the ocean    
floor1 in general1 is the part of the   
earth's surface where strata are        
constantly being laid down4 ,in the     
great reservoir of the waters the dbris 
washed from the land1 the dust from     
volcanoes1 and that from the stellar    
spaces1 along with the vast accumulation
 of organic remains1 almost everywhere  
lead to the steadfast accumulation of   
sedimentary deposits4 ,on the other     
hand1 the realms of the surface above   

the ocean level are constantly being    
worn away by the action of the rivers   
and glaciers1 of the waves which beat   
against the shores1 and of the winds    
which blow over desert regions4 ,the    
result is that the lands are wearing    
down at the geologically rapid average  
rate of somewhere about one foot in five
 thousand years4 ,all this heavy matter 
goes to the sea bottoms4 ,probably to   
this cause we owe in part the fact that 
in the wrinklings of the crust due to   
the contraction of the interior the     
lands exhibit a prevailing tendency to  
uprise1 while the ocean floors sink     
down4 ,in this way the continents are   
maintained above the level of the sea   
despite the powerful forces which are   
constantly wearing their substance away1
 while the seas remain deep1 although   
they are continually being burdened with
 imported materials4  ,illustration3    
,fig4 #h4--;,diagram showing the effect 
of the position of the fulcrum point in 
the movement of the land masses4 ,in    

diagrams ,i and ,,ii1 the lines a b     
represent the land before the movement1 
and a' b' its position after the        
movement2 s1 s1 the position of the     
shore line2 p1 p1 the pivotal points2 l1
 s1 the sea line4 ,in diagram ,,iii1 the
 curved line designates a shore2 the    
line a b1 connecting the pivotal points 
p1 p1 is partly under the land and      
partly under the sea4  ,it is easy to   
see that if the sea floors tend to sink 
downward1 while the continental lands   
uprise1 the movements which take place  
may be compared with those which occur  
in a lever about a fulcrum point4 ,in   
this case the sea end of the bar is     
descending and the land end ascending4  
,now1 it is evident that the fulcrum    
point may fall to the seaward or to the 
landward of the shore2 only by chance   
and here and there would it lie exactly 
at the coast line4 ,by reference to the 
diagram 7,fig4 #h71 it will be seen     
that1 while the point of rotation is    
just at the shore1 a considerable       

movement may take place without altering
 the position of the coast line4 ,where 
the point of no movement is inland of   
the coast1 the sea will gain on the     
continent2 where1 however1 the point is 
to seaward1 beneath the water1 the land 
will gain on the ocean4 ,in this way we 
can1 in part at least1 account for the  
endless changes in the attitude of the  
land along the coastal belt without     
having to suppose that the continents   
cease to rise or the sea floors to sink 
downward4 ,it is evident that the bar or
 section of the rocks from the interior 
of the land to the bottoms of the seas  
is not rigid2 it is also probable that  
the matter in the depths of the earth1  
which moves with the motions of this    
bar1 would change the position of the   
fulcrum point from time to time4 ,thus  
it may well come about that our coast   
lines are swaying up and down in        
ceaseless variation4  ,in very recent   
geological times1 probably since the    
beginning of the last ,glacial period1  

the region about the ,dismal ,swamp in  
,virginia has swayed up and down through
 four alternating movements to the      
extent of from fifty to one hundred     
feet4 ,the coast of ,new ,jersey is now 
sinking at the rate of about two feet in
 a hundred years4 ,the coast of ,new    
,england1 though recently elevated to   
the extent of a hundred feet or more1 at
 a yet later time sank down1 so that at 
some score of points between ,new ,york 
and ,eastport1 ,me41 we find the remains
 of forests with the roots of their     
trees still standing below high-tide    
mark in positions where the trees could 
not have grown4 ,along all the marine   
coasts of the world which have been     
carefully studied from this point of    
view there are similar evidences of     
slight or great modern changes in the   
level of the lands4 ,at some points1    
particularly on the coast of ,alaska and
 along the coast of ,peru1 these uplifts
 of the land have amounted to a thousand
 feet or more4 ,in the peninsular       

district of ,scandinavia the swayings1  
sometimes up and sometimes down1 which  
are now going on have considerably      
changed the position of the shore lines 
since the beginning of the historical   
period4  ,there are other causes which  
serve to modify the shapes and sizes of 
the continents which may best be        
considered in the sequel2 for the       
present we may pass from this subject   
with the statement that our great lands 
are relatively permanent features2 their
 forms change from age to age1 but they 
have remained for millions of years     
habitable to the hosts of animals and   
plants which have adapted their life to 
the conditions which these fields afford
 them4                                  
,,chapter ,v4                           
,,the ,,atmosphere4   ,the firm-set     
portion of the earth1 composed of       
materials which became solid when the   
heat so far disappeared from the sphere 
that rocky matter could pass from its   
previous fluid condition to the solid or

 frozen state1 is wrapped about by two  
great envelopes1 the atmosphere and the 
waters4 ,of these we shall first        
consider the lighter and more universal 
air2 in taking account of its           
peculiarities we shall have to make some
 mention of the water with which it is  
greatly involved2 afterward we shall    
consider the structure and functions of 
that fluid4  ,atmospheric envelopes     
appear to be common features about the  
celestial spheres4 ,in the sun there is1
 as we have noted1 a very deep envelope 
of this sort which is in part composed  
of the elements which form our own air2 
but1 owing to the high temperature of   
the sphere1 these are commingled with   
many substances which in our earth--at  
least in its outer parts--have entered  
in the solid state4 ,some of the        
planets1 so far as we can discern their 
conditions1 seem also to have gaseous   
wraps2 this is certainly the case with  
the planet ,mars1 and even the little we
 know of the other like spheres         

justifies the supposition that ,jupiter 
and ,saturn1 at least1 have a like      
constitution4 ,we may regard an         
atmosphere1 in a word1 as representing a
 normal and long-continued state in the 
development of the heavenly orbs4 ,in   
only one of these considerable bodies of
 the solar system1 the moon1 do we find 
tolerably clear evidence that there is  
no atmosphere4  ,the atmosphere of the  
earth is composed mainly of very        
volatile elements1 known as nitrogen and
 argon4 ,this is commingled with oxygen1
 also a volatile element4 ,into this    
mass a number of other substances enter 
in varying but always relatively very   
small proportions4 ,of these the most   
considerable are watery vapour and      
carbon dioxide2 the former of these     
rarely amounts to one per cent of the   
weight of the air1 considering the      
atmosphere as a whole1 and the latter is
 never more than a small fraction of one
 per cent in amount4 ,as a whole1 the   
air envelope of the earth should be     

regarded as a mass of nitrogen and      
argon1 which only rarely1 under the     
influence of conditions which exist in  
the soil1 enters into combinations with 
other elements by which it assumes a    
solid form4 ,the oxygen1 though a       
permanent element in the atmosphere1    
tends constantly to enter into          
combinations which fix it temporarily or
 permanently in the earth1 in which it  
forms1 indeed1 in its combined state    
about one half the weight of all the    
mineral substances we know4 ,the carbon 
dioxide1 or carbonic-acid gas1 as it is 
commonly termed1 is a most important    
substance1 as it affords plants all that
 part of their bodies which disappear on
 burning4 ,it is constantly returned to 
the atmosphere by the decay of organic  
matter1 as well as by volcanic action4  
,in addition to the above-noted         
materials composing the air1 all of     
which are imperatively necessary to the 
wonderful work accomplished by that     
envelope1 we find a host of other       

substances which are accidentally1      
variably1 and always in small quantities
 contained in this realm4 ,thus near the
 seashores1 and indeed for a            
considerable distance into the          
continent1 we find the air contains a   
certain amount of salt so finely divided
 that it floats in the atmosphere4 ,so1 
too1 we find the air1 even on the       
mountain tops amid eternal snows1       
charged with small particles of dust1   
which1 though not evident to the        
unassisted eye1 become at once visible  
when we permit a slender ray of light to
 enter a dark chamber4  ,it is commonly 
asserted that the atmosphere does not   
effectively extend above the height of  
forty-five miles2 we know that it is    
densest on the surface of the earth1 the
 most so in those depressions which lie 
below the level of the sea4 ,this is    
proved to us by the weight which the air
 imposes upon the mercury at the open   
end of a barometric tube4 ,if we could  
deepen these cavities to the extent of a

 thousand miles1 the pressure would     
become so great that if the pit were    
kept free from the heat of the earth the
 gaseous materials would become         
liquefied4 ,upward from the earth's     
surface at the sea level the atoms and  
molecules of the air become farther     
apart until1 at the height of somewhere 
between forty and fifty miles1 the      
quantity of them contained in the ether 
is so small that we can trace little    
effect from them on the rays of light   
which at lower levels are somewhat bent 
by their action4 ,at yet higher levels1 
however1 meteors appear to inflame by   
friction against the particles of air1  
and even at the height of eighty miles  
very faint clouds have at times been    
discerned1 which are possibly composed  
of volcanic dust floating in the very   
rarefied medium1 such as must exist at  
this great elevation4  ,the air not only
 exists in the region where we          
distinctly recognise it2 it also        
occupies the waters and the under earth4

 ,in the waters it occurs as a          
mechanical mixture which is brought     
about as the rain forms and falls in the
 air1 as the streams flow to the sea1   
and as the waves roll over the deep and 
beat against the shores4 ,in the realm  
of the waters1 as well as on the land1  
the air is necessary for the maintenance
 of all animal forms2 but for its       
presence such life would vanish from the
 earth4  ,owing to certain peculiarities
 in its constitution1 the atmosphere of 
our earth1 and that doubtless of myriad 
other spheres1 serves as a medium of    
communication between different regions4
 ,it is1 as we know1 in ceaseless motion
 at rates which may vary from the speed 
in the greatest tempests1 which may move
 at the rate of somewhere a hundred and 
fifty miles an hour1 to the very slow   
movements which occur in caverns1 where 
the transfer is sometimes effected at an
 almost microscopic rate in the space of
 a day4 ,the motion of the atmosphere is
 brought about by the action of heat    

here and there1 and in a trifling way1  
by the heat from the interior of the    
earth escaping through hot springs or   
volcanoes1 but almost altogether by the 
heat of the sun4 ,if we can imagine the 
earth cut off from the solar radiation1 
the air would cease to move4 ,we often  
note how the variable winds fall away in
 the nighttime4 ,those who in seeking   
for the ,north ,pole have spent winters 
in the long-continued dark of that      
region have noted that the winds almost 
cease to blow1 the air being disturbed  
only when a storm originated in the     
sunlit realm forced its way into the    
circumpolar darkness4  ,the sun's heat  
does not directly disturb the           
atmosphere2 if we could take the solid  
sphere of the world away1 leaving the   
air1 the rays would go straight through1
 and there would be no winds produced4  
,this is due to the fact that the air   
permits the direct rays of heat1 such as
 come from the sun1 to pass through it  
with very slight resistance4 ,in an     

arial globe such as we have imagined1   
the rays impinging upon its surface     
would be slightly thrown out of their   
path as they are in passing through a   
lens1 but they would journey on in space
 without in any considerable measure    
warming the mass4 ,coming1 however1 upon
 the solid earth1 the heat rays warm the
 materials on which they are arrested1  
bringing them to a higher temperature   
than the air4 ,then these heated        
materials radiate the energy into the   
air2 it happens1 however1 that this     
radiant heat can not journey back into  
space as easily as it came in2 therefore
 the particles of air next the surface  
acquire a relatively high temperature4  
,thus a thermometer next the ground may 
rise to over a hundred degrees          
,fahrenheit1 while at the same time the 
fleecy clouds which we may observe      
floating at the height of five or six   
miles above the surface are composed of 
frozen water4  ,the effect of the heated
 air which acquires its temperature by  

radiation from the earth's surface is to
 produce the winds4 ,this it brings     
about in a very simple manner1 though   
the details of the process have a       
certain complication4 ,the best         
illustration of the mode in which the   
winds are produced is obtained by       
watching what takes place about an      
ordinary fire at the bottom of a        
chimney4 ,as soon as the fire is lit1 we
 observe that the air about it1 so far  
as it is heated1 tends upward1 drawing  
the smoke with it4 ,if the air in the   
chimney be cold1 it may not draw well at
 first2 but in a few minutes the draught
 is established1 or1 in other words1 the
 heated lower air breaks its way up the 
shaft1 gradually pushing the cooler     
matter out at the top4 ,in still air we 
may observe the column from the flue    
extending about the chimney-top1        
sometimes to the height of a hundred    
feet or more before it is broken to     
pieces4 ,it is well here to note the    
fact that the energy of the draught in a

 chimney is1 with a given heat of fire  
and amount of air which is permitted to 
enter the shaft1 directly proportionate 
to the height2 thus in very tall flues1 
between two and three hundred feet high1
 which are sometimes constructed1 the   
uprush is at the speed of a gale4       
,whenever the air next the surface is so
 far heated that it may overcome the    
inertia of the cooler air above1 it     
forces its way up through it in the     
general manner indicated in the chimney 
flue4 ,when such a place of uprush is   
established1 the hot air next the       
surface flows in all directions toward  
the shaft1 joining the expedition to the
 heights of the atmosphere4 ,owing to   
the conditions of the earth's surface1  
which we shall now proceed to trace1    
these ascents of heated air belong in   
two distinct classes--those which move  
upward through more or less cylindrical 
chimneys in the atmosphere1 shafts which
 are impermanent1 which vary in diameter
 from a few feet to fifty or perhaps a  

hundred miles1 and which move over the  
surface of the earth2 and another which 
consists of a broad1 beltlike shaft in  
the equatorial regions1 which in a way  
girdles the earth1 remains in about the 
same place1 continually endures1 and has
 a width of hundreds of miles4 ,of these
 two classes of uprushes we shall first 
consider the greatest1 which occurs in  
the central portions of the tropical    
realm4  ,under the equator1 owing to the
 fact that the sun for a considerable   
belt of land and sea maintains the earth
 at a high temperature1 there is a      
general updraught which began many      
million years ago1 probably before the  
origin of life1 in the age when our     
atmosphere assumed its present          
conditions4 ,into this region the cooler
 air from the north and south           
necessarily flows1 in part pressed in by
 the weight of the cold air which       
overlies it1 but aided in its motion by 
the fact that the particles which ascend
 leave place for others to occupy4 ,over

 the surfaces of the land within the    
tropical region this draught toward what
 we may term the equatorial chimney is  
perturbed by the irregularities of the  
surface and many local accidents4 ,but  
on the sea1 where the conditions are    
uniform1 the air moving toward the point
 of ascent is marked in the trade winds1
 which blow with a steadfast sweep down 
toward the equator4 ,many slight        
actions1 such as the movement of the hot
 and cold currents of the sea1 the local
 air movements from the lands or from   
detached islands1 somewhat perturb the  
trade winds1 but they remain among the  
most permanent features in this         
changeable world4 ,it is doubtful if    
anything on this sphere except the atoms
 and molecules of matter have varied as 
little as the trade winds in the centre 
of the wide ocean4 ,so steadfast and    
uniform are they that it is said that   
the helm and sails of a ship may be set 
near the west coast of ,south ,america  
and be left unchanged for a voyage which

 will carry the navigator in their belt 
across the width of the ,pacific4       
,rising up from the earth in the        
tropical belt1 the air attains the      
height of several thousand feet2 it then
 begins to curve off toward the north   
and south1 and at the height of         
somewhere about three to five miles     
above the surface is again moving       
horizontally toward either pole2        
attaining a distance on that journey1 it
 gradually settles down to the surface  
of the earth1 and ceases to move toward 
higher latitudes4 ,if the earth did not 
revolve upon its axis the course of     
these winds along the surface toward the
 equator1 and in the upper air back     
toward the poles1 would be made in what 
we may call a square manner--that is1   
the particles of air would move toward  
the point where they begin to rise      
upward in due north and south lines1    
according as they came from the southern
 or northern hemisphere1 and the upper  
currents or counter trades would retrace

 their paths also parallel with the     
meridians or longitude lines4 ,but      
because the earth revolves from west to 
east1 the course of the trade winds is  
oblique to the equator1 those in the    
northern hemisphere blowing from        
northeast to southwest1 those in the    
southern from southeast to northwest4   
,the way in which the motion of the     
earth affects the direction of these    
currents is not difficult to understand4
 ,it is as follows3  ,let us conceive a 
particle of air situated immediately    
over the earth's polar axis4 ,such an   
atom would by the rotation of the sphere
 accomplish no motion except1 indeed1   
that it might turn round on its own     
centre4 ,it would acquire no velocity   
whatever by virtue of the earth's       
movement4 ,then let us imagine the      
particle moving toward the equator with 
the speed of an ordinary wind4 ,at every
 step of its journey toward lower       
latitudes it would come into regions    
having a greater movement than those    

which it had just left4 ,owing to its   
inertia1 it would thus tend continually 
to lag behind the particles of matter   
about it4 ,it would thus fall off to the
 westward1 and1 in place of moving due  
south1 would in the northern hemisphere 
drift to the southwest1 and in the      
southern hemisphere toward the          
northwest4 ,a good illustration of this 
action may be obtained from an ordinary 
turn-table such as is used about railway
 stations to reverse the position of a  
locomotive4 ,if the observer will stand 
in the centre of such a table while it  
is being turned round he will perceive  
that his body is not swayed to the right
 or left4 ,if he will then try to walk  
toward the periphery of the rotating    
disk1 he will readily note that it is   
very difficult1 if not impossible1 to   
walk along the radius of the circle2 he 
naturally falls behind in the movement1 
so that his path is a curved line       
exactly such as is followed by the winds
 which move toward the equator in the   

trades4 ,if now he rests a moment on the
 periphery of the table1 so that his    
body acquires the velocity of the disk  
at that point1 and then endeavours to   
walk toward the centre1 he will find    
that again he can not go directly2 his  
path deviates in the opposite           
direction--in other words1 the body     
continually going to a place having a   
less rate of movement by virtue of the  
rotation of the earth1 on account of its
 momentum is ever moving faster than the
 surface over which it passes4 ,this    
experiment can readily be tried on any  
small rotating disk1 such as a potter's 
wheel1 or by rolling a marble or a shot 
from the centre to the circumference and
 from the circumference to the centre4  
,a little reflection will show the      
inquirer how these illustrations clearly
 account for the oblique though opposite
 sets of the trade winds in the upper   
and lower parts of the air4  ,the       
dominating effect of the tropical heat  
in controlling the movements of the air 

currents extends1 on the ocean surface1 
in general about as far north and south 
as the parallels of forty degrees1      
considerably exceeding the limits of the
 tropics1 those lines where the sun1    
because of the inclination of the       
earth's axis1 at some time of the year  
comes just overhead4 ,between these     
belts of trade winds there is a strip or
 belt under the region where the        
atmosphere is rising from the earth1 in 
which the winds are irregular and have  
little energy4 ,this region of the      
doldrums or frequent calms is one of    
much trouble to sailing ships on their  
voyages from one hemisphere to another4 
,in passing through it their sails are  
filled only by the airs of local storms1
 or winds which make their way into that
 part of the sea from the neighbouring  
continents4 ,beyond the trade-wind belt1
 toward the poles1 the movements of the 
atmosphere are dependent in part on the 
counter trades which descend to the     
surface of the earth in latitudes higher

 than that in which the surface or trade
 winds flow4 ,thus along our ,atlantic  
coast1 and even in the body of the      
continent1 at times when the air is not 
controlled by some local storm1 the     
counter trade blows with considerable   
regularity4  ,the effect of the trade   
and counter-trade movements of the air  
on the distribution of temperature over 
the earth's surface is momentous4 ,in   
part their influence is due to the      
direct heat-carrying power of the       
atmosphere2 in larger measure it is     
brought about by the movement of the    
ocean waters which they induce4         
,atmospheric air1 when deprived of the  
water which it ordinarily contains1 has 
very little heat-containing capacity4   
,practically nearly all the power of    
conveying heat which it possesses is due
 to the vapour of water which it        
contains4 ,by virtue of this moisture   
the winds do a good deal to transfer    
heat from the tropical or superheated   
portion of the earth's surface to the   

circumpolar or underheated realms4 ,at  
first1 the relatively cool air which    
journeys toward the equator along the   
surface of the sea constantly gains in  
heat1 and in that process takes up more 
and more water1 for precisely the same  
reason that causes anything to dry more 
rapidly in air which has been warmed    
next a fire4 ,the result is that before 
it begins to ascend in the tropical     
updraught1 being much moisture-laden1   
the atmosphere stores a good deal of    
heat4 ,as it rises1 rarefies1 and cools1
 the moisture descends in the torrential
 rains which ordinarily fall when the   
sun is nearly vertical in the tropical  
belt4  ,here comes in a very interesting
 principle which is of importance in    
understanding the nature of great       
storms1 either the continuous storm of  
the tropics or the local and irregular  
whirlings which occur in various parts  
of the earth4 ,when the moisture-laden  
air starts on its upward journey from   
the earth it has1 by virtue of the      

watery vapour which it contains1 a store
 of energy which becomes applied to     
promoting the updraught4 ,as it rises1  
the moisture in the air gathers together
 or condenses1 and in so doing parts    
with the heat which caused it to        
evaporate from the ocean surface4 ,for a
 given weight of water1 the amount of   
heat required to effect the evaporation 
is very great2 this we may roughly judge
 by observing what a continuous fire is 
required to send a pint of water into   
the state of steam4 ,this energy1 when  
it is released by the condensation of   
water into rain or snow1 becomes again  
heat1 and tends somewhat1 as does the   
fire in the chimney1 to accelerate the  
upward passage of the air4 ,the result  
is that the water which ascends in the  
equatorial updraught becomes what we may
 term fuel to promote this important    
element in the earth's arial            
circulation4 ,trades and counter trades 
would doubtless exist but for the       
efficiency of this updraught1 which is  

caused by the condensation of watery    
vapour1 but the movement would be much  
less than it is4                        
,,whirling ,,storms4  ,in the region    
near the equator1 or near the line of   
highest temperature1 which for various  
reasons does not exactly follow the     
equator1 there is1 as we have noticed1 a
 somewhat continuous uprushing current  
where the air passes upward through an  
ascending chimney1 which in a way       
girdles the sea-covered part of the     
earth4 ,in this region the movements of 
the air are to a great extent under the 
control of the great continuous         
updraught4 ,as we go to the north and   
south we enter realms where the air at  
the surface of the earth is1 by the heat
 which it acquires from contact with    
that surface1 more or less impelled     
upward2 but there being no permanent    
updraught for its escape1 it from time  
to time breaks through the roof of cold 
air which overlies it and makes a       
temporary channel of passage4 ,going    

polarward from the equator1 we first    
encounter these local and temporary     
upcastings of the air near the margin of
 the tropical belt4 ,in these districts1
 at least over the warmer seas1 during  
the time of the year when it is         
midsummer1 and in the regions where the 
trade winds are not strong enough to    
sweep the warm and moisture-laden air   
down to the equatorial belt1 the upward 
tending strain of the atmosphere next   
the earth often becomes so strong that  
the overlying air is displaced1 forming 
a channel through which the air swiftly 
passes4 ,as the moisture condenses in   
the way before noted1 the energy set    
free serves to accelerate the updraught1
 and a hurricane is begun4 ,at first the
 movement is small and of no great      
speed1 but as the amount of air tending 
upward is likely to be great1 as is also
 the amount of moisture which it        
contains1 the arial chimney is rapidly  
enlarged1 and the speed of the rising   
air increased4 ,the atmosphere next the 

surface of the sea flows in toward the  
channel of escape2 its passage is marked
 by winds which are blowing toward the  
centre4 ,on the periphery of the        
movement the particles move slowly1 but 
as they win their way toward the centre 
they travel with accelerating velocity4 
,on the principle which determines the  
whirling movement of the water escaping 
through a hole in the bottom of a basin1
 the particles of the air do not move on
 straight lines toward the centre1 but  
journey in spiral paths1 at first along 
the surface1 and then ascending4  ,we   
have noted the fact that in a basin of  
water the direction of the whirling is  
what we may term accidental--that is1   
dependent on conditions so slight that  
they elude our observation--but in      
hurricanes a certain fact determines in 
an arbitrary way the direction in which 
the spin shall take place4 ,as soon as  
such a movement of the air attains any  
considerable diameter1 although in its  
beginning it may have spun in a         

direction brought about by local        
accidents1 it will be affected by the   
diverse rates of travel1 by virtue of   
the earth's rotation1 of the air on its 
equatorial and polar sides4 ,on the     
equatorial side this air is moving more 
rapidly than it is on the polar side4   
,by observing the water passing from a  
basin this principle1 with a few        
experiments1 can be made plain4 ,the    
result is to cause these great          
whirlwinds of the hurricanes of higher  
latitudes to whirl round from right to  
left in the northern hemisphere and in  
the reverse way in the southern4 ,the   
general system of the air currents still
 further affects these1 as other        
whirling storms1 by driving their       
centres or chimneys over the surface of 
the earth4 ,the principle on which this 
is done may be readily understood by    
observing how the air shaft above a     
chimney1 through which we may observe   
the smoke to rise during a time of calm1
 is drawn off to one side by the slight 

current which exists even when we feel  
no wind2 it may also be discerned in the
 little dust whirls which form in the   
streets on a summer day when the air is 
not much disturbed4 ,while they spin    
they move on in the direction of the air
 drift4 ,in this way a hurricane        
originating in the ,gulf of ,mexico may 
gradually journey under the influence of
 the counter trades across the          
,antilles1 or over southern ,florida1   
and thence pursue a devious northerly   
course1 generally near the ,atlantic    
coast and in the path of the ,gulf      
,stream1 until it has travelled a       
thousand miles or more toward the ,north
 ,atlantic4 ,the farther it goes        
northward the less effectively it is fed
 with warm and moisture-laden air1 the  
feebler its movement becomes1 until at  
length it is broken up by the variable  
winds which it encounters4  ,a very     
interesting and1 from the point of view 
of the navigator1 important peculiarity 
of these whirls is that at their centre 

there is a calm1 similar in origin and  
nature to the calm under the equator    
between the trade-wind belts4 ,both     
these areas are in the field where the  
air is ascending1 and therefore at the  
surface of the earth does not affect the
 sails of ships1 though if men ever come
 to use flying machines and sail through
 the tropics at a good height above the 
sea it will be sensible enough4 ,the    
difference between the doldrum of the   
equator and that of the hurricane1      
besides their relative areas1 is that   
one is a belt and the other a disk4 ,if 
the seafarer happens to sail on a path  
which leads him through the hurricane   
centre1 he will first discern1 as from  
the untroubled air and sea he approaches
 the periphery of the storm1 the horizon
 toward the disturbance beset by        
troubled clouds1 all moving in one      
direction4 ,entering beneath this pall1 
he finds a steadily increasing wind1    
which in twenty miles of sailing may1   
and in a hundred miles surely will1     

compel him to take in all but his storm 
sails1 and is likely to bring his ship  
into grave peril4 ,the most furious     
winds the mariner knows are those which 
he encounters as he approaches the still
 centre4 ,these trials are made the more
 appalling by the fact that in the      
furious part of the whirl the rain1     
condensing from the ascending air1 falls
 in torrents1 and the electricity       
generated in the condensation gives rise
 to vivid lightning4 ,if the storm-beset
 ship can maintain her way1 in a score  
or two of miles of journey toward the   
centre1 generally very quickly1 it      
passes into the calm disk1 where the    
winds1 blowing upward1 cease to be felt4
 ,in this area the ship is not out of   
danger1 for the waves1 rolling in from  
the disturbed areas on either side1 make
 a torment of cross seas1 where it is   
hard to control the movements of a      
sailing vessel because the impulse of   
the winds is lost4 ,passing through this
 disk of calm1 the ship re-encounters in

 reverse order the furious portion of   
the whirl1 afterward the lessening      
winds1 until it escapes again into the  
airs which are not involved in the great
 torment4  ,in the old days1 before     
,dove's studies of storms had shown the 
laws of hurricane movement1 unhappy     
shipmasters were likely to be caught and
 retained in hurricanes1 and to battle  
with them for weeks until their vessels 
were beaten to pieces4 ,now the ,sailing
 ,directions1 which are the mariner's   
guide1 enable him1 from the direction of
 the winds and the known laws of motion 
of the storm centre1 to sail out of the 
danger1 so that in most cases he may    
escape calamity4 ,it is otherwise with  
the people who dwell upon the land over 
which these atmospheric convulsions     
sweep4 ,fortunately1 where these great  
whirlwinds trespass on the continent1   
they quickly die out1 because of the    
relative lack of moisture which serves  
to stimulate the uprush which creates   
them4 ,thus in their more violent forms 

hurricanes are only felt near the sea1  
and generally on islands and peninsulas4
 ,there the hurricane winds1 by the     
swiftness of their movement1 which often
 attains a speed of a hundred miles or  
more1 apply a great deal of energy to   
all obstacles in their path4 ,the       
pressure thus produced is only less     
destructive than that which is brought  
about by the tornadoes1 which are next  
to be described4  ,there is another     
effect from hurricanes which is even    
more destructive to life than that      
caused by the direct action of the wind4
 ,in these whirlings great differences  
in atmospheric pressure are brought     
about in contiguous areas of sea4 ,the  
result is a sudden elevation in the     
level of one part of the water4 ,these  
disturbances1 where the shore lands are 
low and thickly peopled1 as is the case 
along the western coast of the ,bay of  
,bengal1 may produce inundations which  
are terribly destructive to life and    
property4 ,they are known also in       

southern ,florida and along the islands 
of the ,caribbean1 but in that region   
are not so often damaging to mankind4   
,fortunately1 hurricanes are limited to 
a very small part of the tropical       
district4 ,they occur only in those     
regions1 on the eastern faces of        
tropical lands1 where the general       
westerly set of the winds favours the   
accumulation of great bodies of very    
warm1 moist air next the surface of the 
sea4 ,the western portion of the ,gulf  
of ,mexico and the ,caribbean1 the ,bay 
of ,bengal1 and the southeastern portion
 of ,asia are especially liable to their
 visitations4 ,they sometimes develop1  
though with less fury1 in other parts of
 the tropics4 ,on the western coast of  
,south ,america and ,africa1 where the  
oceans are visited by the dry land      
winds1 and where the waters are cooled  
by currents setting in from high        
latitudes1 they are unknown4  ,only less
 in order of magnitude than the         
hurricanes are the circular storms known

 as cyclones4 ,these occur on the       
continents1 especially where they afford
 broad plains little interrupted by     
mountain ranges4 ,they are particularly 
well exhibited in that part of ,north   
,america north of ,mexico and south of  
,hudson ,bay4 ,like the hurricanes1 they
 appear to be due to the inrush of      
relatively warm air entering an         
updraught which had been formed in the  
overlying1 cooler portions of the       
atmosphere4 ,they are1 however1 much    
less energetic1 and often of greater    
size than the hurricane whirl4 ,the lack
 of energy is probably due to the       
comparative dryness of the air4 ,the    
greater width of the ascending column   
may perhaps be accounted for by the fact
 that1 originating at a considerable    
height above the sea1 they have a less  
thickness of air to break through1 and  
so the upward setting column is readily 
made broad4  ,the cyclones of ,north    
,america appear generally to originate  
in the region of the ,rocky ,mountains1 

though it is probable that in some      
instances1 perhaps in many1 the upward  
set of the air which begins the storm   
originates in the ocean along the       
,pacific coast4 ,they gather energy as  
they descend the great sloping plain    
leading eastward from the ,rocky        
,mountains to the central portion of the
 great continental valley4 ,thence they 
move on across the country to the       
,atlantic coast4 ,not infrequently they 
continue on over the ocean to the       
,european continent4 ,the eastward      
passage of the storm centre is due to   
the prevailing eastward movement of the 
air in its upper part throughout that   
portion of the northern hemisphere4     
,commonly they incline somewhat to the  
northward of east in their journey4 ,in 
all cases the winds appear to blow      
spirally into the common storm centre4  
,there is the same doldrum area or calm 
field in the centre of the storm that we
 note between the trade winds and in the
 middle of a hurricane disk1 though this

 area is less defined than in the other 
instances1 and the forward motion of the
 storm at a considerable speed is in    
most cases characteristic of the        
disturbance4 ,on the front of one of    
these storms in ,north ,america the     
winds commonly begin in the northeast1  
thence they veer by the east to the     
southwest4 ,at this stage in the        
movement the storm centre has passed by1
 the rainfall commonly ceases1 and cold1
 dry winds setting to the northwestward 
set in4 ,this is caused by the fact that
 the ascending air1 having attained a   
height above the earth1 settles down    
behind the storm1 forming an anticyclone
 or mass of dry air1 which presses      
against the retreating side of the great
 whirlwind4  ,in front of the storm the 
warm and generally moist relatively warm
 air1 pressing in toward the point of   
uprise and overlaid by the upper cold   
air1 is brought into a condition where  
it tends to form small subordinate      
shafts up through which it whirls on the

 same principle1 but with far greater   
intensity than the main ascending       
column4 ,the reason for the violence of 
this movement is that the difference in 
temperature of the air next the surface 
and that at the height of a few thousand
 feet is great4 ,as might be expected1  
these local spinnings are most apt to   
occur in the season when the air next   
the earth is relatively warm1 and they  
are aptest to take place in the half of 
the advancing front lying between the   
east and south1 for the reason that     
there the highest temperatures and the  
greatest humidity are likely to coexist4
 ,in that part of the field1 during the 
time when the storm is advancing from   
the ,rocky ,mountains to the ,atlantic1 
a dozen or more of these spinning       
uprushes may be produced1 though few of 
them are likely to be of large size or  
of great intensity4  ,the secondary     
storms of cyclones1 such as are above   
noted1 receive the name of tornadoes4   
,they are frequent and terrible         

visitations of the country from northern
 ,texas1 ,florida1 and ,alabama to about
 the line of the ,great ,lakes2 they are
 rarely developed in the region west of 
central ,kansas1 and only occasionally  
do they exhibit much energy in the      
region east of the plain-lands of the   
,ohio ,valley4 ,although known in other 
lands1 they nowhere1 so far as our      
observations go1 exhibit the paroxysmal 
intensity which they show in the central
 portion of the ,north ,american        
continent4 ,there the air which they    
affect acquires a speed of movement and 
a fury of action unknown in any other   
atmospheric disturbances1 even in those 
of the hurricanes4  ,the observer who   
has a chance to note from an            
advantageous position the development of
 a tornado observes that in a tolerably 
still air1 or at least an air unaffected
 by violent winds--generally in what is 
termed a sultry state of the            
atmosphere--the storm clouds in the     
distance begin to form a kind of        

funnel-shaped dependence1 which         
gradually extends until it appears to   
touch the earth4 ,as the clouds are low1
 this downward-growing column probably  
in no case is observed for the height of
 more than three or four thousand feet4 
,as the funnel descends1 the clouds     
above and about it may be seen to take  
on a whirling movement around the       
centre1 and under favourable            
circumstances an uprush of vapours may  
be noted in the centre of the swaying   
shaft4 ,as the whirl comes nearer1 the  
roar of the disturbance1 which at a     
distance is often compared to the sound 
made by a threshing machine or to that  
of distant musketry1 increases in       
loudness until it becomes overwhelming4 
,when a storm such as this strikes a    
building1 it is not only likely to be   
razed by the force of the wind1 but it  
may be exploded1 as by the action of    
gunpowder fired within its walls1       
through the sudden expansion of the air 
which it contains4 ,in the centre of the

 column1 although it rarely has a       
diameter of more than a few hundred     
feet1 the uprush is so swift that it    
makes a partial vacuum4 ,the air1       
striving to get into the space which it 
is eager to occupy1 is whirling about at
 such a rate that the centrifugal motion
 which it thus acquires restrains its   
entrance4 ,in this way there may be1 as 
the column rapidly moves by1 a          
difference of pressure amounting        
probably to what the mercury of a       
barometer would indicate by four or five
 inches of fall4 ,unless the structure  
is small and its walls strong1 its roof 
and sides are apt to be blown apart by  
this difference of pressure and the     
consequent expansion of the contained   
air4 ,in some cases where wooden        
buildings have withstood this curious   
action the outer clapboards have been   
blown off by the expansion of the small 
amount of air contained in the          
interspaces between that covering and   
the lath and plaster within 7see ,fig4  

#i74  ,illustration3 ,fig4 #i4--,showing
 effect of expansion of air contained in
 a hollow wall during the passage of the
 storm4  ,the blow of the air due to its
 rotative whirling has in several cases 
proved sufficient to throw a heavy      
locomotive from the track of a          
well-constructed railway4 ,in all cases 
where it is intense it will overturn the
 strongest trees4 ,the ascending wind in
 the centre of the column may sometimes 
lift the bodies of men and of animals1  
as well as the branches and trunks of   
trees and the timber of houses1 to the  
height of hundreds of feet above the    
surface4 ,one of the most striking      
exhibitions of the upsucking action in a
 tornado is afforded by the effect which
 it produces when it crosses a small    
sheet of water4 ,in certain cases where1
 in the ,northwestern ,states of this   
country1 the path of the storm lay over 
the pool1 the whole of the water from a 
basin acres in extent has been entirely 
carried away1 leaving the surface1 as   

described by an observer1 apparently dry
 enough to plough4  ,fortunately for the
 interests of man1 as well as those of  
the lower organic life1 the paths of    
these storms1 or at least the portion of
 their track where the violence of the  
air movement makes them very            
destructive1 often does not exceed five 
hundred feet in width1 and is rarely as 
great as half a mile in diameter4 ,in   
most cases the length of the journey of 
an individual tornado does not exceed   
thirty miles4 ,it rarely if ever amounts
 to twice that distance4  ,in every     
regard except their small size and their
 violence these tornadoes closely       
resemble hurricanes4 ,there is the same 
broad disk of air next the surface      
spirally revolving toward the ascending 
centre1 where its motion is rapidly     
changed from a horizontal to a vertical 
direction4 ,the energy of the uprush in 
both cases is increased by the energy   
set free through the condensation of the
 water1 which tends further to heat and 

thus to expand the air4 ,the smaller    
size of the tornado may be accounted for
 by the fact that we have in their      
originating conditions a relatively thin
 layer of warm1 moist air next the earth
 and a relatively very cold layer       
immediately overlying it4 ,thus the     
tension which serves to start the       
movement is intense1 though the masses  
involved are not very great4 ,the short 
life of a tornado may be explained by   
the fact that1 though it apparently     
tends to grow in width and energy1 the  
central spout is small1 and is apt to be
 broken by the movements of the         
atmosphere1 which in the front of a     
cyclone are in all cases irregular4  ,on
 the warmer seas1 but often beyond the  
limits of the tropics1 another class of 
spinning storms1 known as waterspouts1  
may often be observed4 ,in general      
appearance these air whirls resemble    
tornadoes1 except that they are in all  
cases smaller than that group of        
whirlings4 ,as in the tornadoes1 the    

waterspout begins with a funnel1 which  
descends from the sky to the surface of 
the sea4 ,up the tube vapours may be    
seen ascending at great speed1 the whole
 appearing like a gigantic pillar of    
swiftly revolving smoke4 ,when the whirl
 reaches the water1 it is said that the 
fluid leaps up into the tube in the form
 of dense spray1 an assertion which1 in 
view of the fact of the action of a     
tornado on a lake as before described1  
may well be believed4 ,like the         
tornadoes and dust whirls1 the life of a
 waterspout appears to be brief4 ,they  
rarely endure for more than a few       
minutes1 or journey over the sea for    
more than two or three miles before the 
column appears to be broken by some     
swaying of the atmosphere4 ,as these    
peculiar storms are likely to damage    
ships1 the old-fashioned sailors were   
accustomed to fire at them with cannon4 
,it has been claimed that a shot would  
break the tube and end the little       
convulsion4 ,this1 in view of the fact  

that they appear to be easily broken up 
by relatively trifling air currents1 may
 readily be believed4 ,the danger which 
these disturbances bring to ships is    
probably not very serious4  ,the special
 atmospheric conditions which bring     
about the formation of waterspouts are  
not well known2 they doubtless include1 
however1 warm1 moist air next the       
surface of the sea and cold air above4  
,just why these storms never attain     
greater size or endurance is not yet    
known4 ,these disturbances have been    
seen for centuries1 but as yet they have
 not been1 in the scientific sense1     
observed4 ,their picturesqueness        
attracts all beholders2 it is           
interesting to note the fact that       
perhaps the earliest description of     
their phenomena--one which takes account
 in the scientific spirit of all the    
features which they present--was written
 by the poet ,camons in the ,lusiad1 in 
which he strangely mingles fancy and    
observation in his account of the great 

voyage of ,vasco da ,gama4 ,the poet    
even notes that the water which falls   
when the spout is broken is not salt1   
but fresh--a point which clearly proves 
that not much of the water which the    
tube contains is derived from the sea4  
,it is1 in fact1 watery vapour drawn    
from the air next the surface of the    
ocean1 and condensed in its ascent      
through the tube4 ,in this and other    
descriptions of ,nature ,camons shows   
more of the scientific spirit than any  
other poet of his time4 ,he was in this 
regard the first of modern writers to   
combine a spiritual admiration for      
,nature with some sense of its          
scientific meaning4  ,in treating of the
 atmosphere1 meteorologists base their  
studies largely on changes in the weight
 of that medium1 which they determine by
 barometric observations4 ,in fact1 the 
science of the air had its beginning in 
,pascal's admirable observation on the  
changes in the height of a column of    
mercury contained in a bent tube as he  

ascended the volcanic peak known as ,puy
 de ,dome1 in central ,france4 ,as      
before noted1 it is to the disturbances 
in the weight of the air1 brought about 
mainly by variations in temperature1    
that we owe all its currents1 and it is 
upon these winds that the features we   
term climate in largest measure depend4 
,every movement of the winds is not only
 brought about by changes in the        
relative weight of the air at certain   
points1 but the winds themselves1 owing 
to the momentum which the air attains by
 them1 serve to bring about alterations 
in the quantity of air over different   
parts of the earth1 which are marked    
most distinctly by barometric           
variations4 ,these changes are          
exceedingly complicated2 a full account 
of them would demand the space of this  
volume4 ,a few of the facts1 however1   
should be presented here4 ,in the first 
place1 we note that each day there is   
normally a range in the pressure which  
causes the barometer to be at the lowest

 at about four o'clock in the morning   
and four o'clock in the afternoon1 and  
highest at about ten o'clock in those   
divisions of the day4 ,this change is   
supposed to be due to the fact that the 
motes of dust in the atmosphere in the  
night1 becoming cooled1 condense the    
water vapour upon their surfaces1 thus  
diminishing the volume of the air4 ,when
 the sun rises the water evaporated by  
the heat returns from these little      
storehouses into the body of the        
atmosphere4 ,again in the evening the   
condensation sets in2 at the same time  
the air tends to drift in from the      
region to the westward1 where the sun is
 still high1 toward the field where the 
barometer has been thus lowered2 the    
current gradually attains a certain     
volume1 and so brings about the rise of 
the barometer about ten o'clock at      
night4  ,in the winter time1            
particularly on the well-detached       
continent of ,north ,america1 we find a 
prevailing high barometer in the        

interior of the country and a           
corresponding low state of pressure on  
the ,atlantic ,ocean4 ,in the summer    
season these conditions are on the whole
 reversed4  ,under the tropics1 in the  
doldrum belt1 there is a zone of low    
barometer connected to the ascending    
currents which take place along that    
line4 ,this is a continuous             
manifestation of the same action which  
gives a large area of a disklike form in
 the centre or eye of the hurricane and 
in the middle portion of the tornado's  
whirl4 ,in general1 it may be said that 
the weight of the air is greatest in the
 regions from which it is blowing toward
 the points of upward escape1 and least 
in and about those places where the     
superincumbent air is rising through a  
temporary or permanent line of escape4  
,in other words1 ascending air means    
generally a relatively low barometer1   
while descending air is accompanied by  
greater pressure in the field upon which
 it falls4  ,in almost every part of the

 earth which is affected by a particular
 physiography we find that the movements
 of the atmosphere next the surface are 
qualified by the condition which it     
encounters4 ,in fact1 if a person were  
possessed of all the knowledge which    
could be obtained concerning winds1 he  
could probably determine as by a map the
 place where he might chance to find    
himself1 provided he could extend his   
observations over a term of years4 ,in  
other words1 the regimen of the         
winds--at least those of a superficial  
nature--is almost as characteristic of  
the field over which they go as is a map
 of the country4 ,of these special winds
 a number of the more important have    
been noted1 only a few of which we can  
advert to4 ,first among these may well  
come the land and sea breezes which are 
remarked about all islands which are not
 continuously swept by permanent winds4 
,one of the most characteristic         
instances of these alternate winds is   
perhaps that afforded on the island of  

,jamaica4  ,the island of ,jamaica is so
 situated within the basin of the       
,caribbean that it does not feel the    
full influence of the trades4 ,it has a 
range of high mountains through its     
middle part4 ,in the daytime the surface
 of the land1 which has the sun overhead
 twice each year1 and is always exposed 
to nearly vertical radiation1 becomes   
intensely hot1 so that an upcurrent is  
formed4 ,the formation of this current  
is favoured by the mountains1 which     
apply a part of the heat at the height  
of about a mile above the surface of the
 sea4 ,this action is parallel to that  
we notice when1 in order to create a    
draught in the air of a chimney1 we put 
a torch some distance up above the      
fireplace1 thus diminishing the height  
of the column of air which has to be set
 in motion4 ,it is further shown by the 
fact that when miners sought to make an 
upcurrent in a shaft1 in order to lead  
pure air into the workings through other
 openings1 they found after much        

experience that it was better to have   
the fire near the top of the shaft      
rather than at the bottom4  ,the        
ascending current being induced up the  
mountain sides of ,jamaica1 the air is  
forced in from the sea to the relatively
 free space4 ,before noon the current1  
aided in its speed by a certain amount  
of the condensation of the watery vapour
 before described1 attains the          
proportions of a strong wind4 ,as the   
sun begins to sink1 the earth's surface 
pours forth its heat2 the radiation     
being assisted by the extended surfaces 
of the plants1 cooling rapidly takes    
place4 ,meanwhile the sea1 because of   
the great heat-storing power of water1  
is very little cooled1 the ascent of the
 air ceases1 the temporary chimney with 
its updraught is replaced by a downward 
current1 and the winds blow from the    
land until the sun comes again to       
reverse the current4 ,in many cases     
these movements of the daily winds      
flowing into and from islands induce a  

certain precipitation of moisture in the
 form of rain4 ,generally1 however1     
their effect is merely to ameliorate the
 heat by bringing alternately currents  
from the relatively cool sea and from   
the upper atmosphere to lessen the      
otherwise excessive temperature of the  
fields which they traverse4  ,although  
characteristic sea and land winds are   
limited to regions where the sun's heat 
is great1 they are traceable even in    
high latitudes during the periods of    
long-continued calm attended with clear 
skies4 ,thus on the island of ,martha's 
,vineyard1 in ,massachusetts1 the writer
 has noted1 when the atmosphere was in  
such a state1 distinct night and day1 or
 sea and land1 breezes coming in their  
regular alternation4 ,during the night  
when these alternate winds prevail the  
central portion of the island1 at the   
distance of three miles from the sea1 is
 remarkably cold1 the low temperature   
being due to the descending air current4
 ,to the same physical cause may be     

attributed the frequent insets of the   
sea winds toward midday along the       
continental shores of various countries4
 ,thus along the coast of ,new ,england 
in the summer season a clear1 still1 hot
 day is certain to lead to the creation 
of an ingoing tide of air1 which reaches
 some miles into the interior4 ,this    
stream from the sea enters as a thin    
wedge1 it often being possible to note  
next the shore when the movement begins 
a difference of ten degrees of          
temperature between the surface of the  
ground to which the point of the wedge  
has attained1 and a position twenty feet
 higher in the air4 ,this is a beautiful
 example to show at once how the        
relative weight of the atmosphere1 even 
when the differences are slight1 may    
bring about motion1 and also how masses 
of the atmosphere may move by or through
 the rest of the medium in a way which  
we do not readily conceive from our     
observations on the transparent mass4   
,very few people have any idea how      

general is the truth that the air1 even 
in continuous winds1 tends to move in   
more or less individualized masses4     
,this1 however1 is made very evident by 
watching the gusts of a storm or the    
wandering patches of wind which disturb 
the surface of an otherwise smooth sea4 
,illustration3 ,south shore1 ,martha's  
,vineyard1 ,massachusetts1 showing a    
characteristic sand beach with long     
slope and low dunes4 ,note the three    
lines of breakers and the splash flows  
cutting little bays in the sand4  ,among
 the notable local winds are those which
 from their likeness to the ,fhn of the 
,swiss valleys receive that name4 ,fhns 
are produced where a body of air blowing
 against the slope of a continuous      
mountain range is lifted to a           
considerable height1 and1 on passing    
over the crest1 falls again to a low    
position4 ,in its ascent the air is     
cooled1 rarefied1 and to a great extent 
deprived of its moisture4 ,in descending
 it is recondensed1 and by the process  

by which its atoms are brought together 
its latent heat is made sensible4 ,there
 being but little watery vapour in the  
mass1 this heat is not much called for  
by that heat-storing fluid1 and so the  
air is warmed4 ,so far ,fhn winds have  
only been remarked as conspicuous       
features in ,switzerland and on the     
eastern face of the ,rocky ,mountains4  
,in the region about the head waters of 
the ,missouri and to the northward their
 influence in what are called the       
,chinook winds is distinctly to         
ameliorate the severe winter climate of 
the country4  ,in almost all great      
desert regions1 particularly in the     
typical ,sahara1 we find a variety of   
storm belonging to the whirlwind group1 
which1 owing to the nature of the       
country1 take on special                
characteristics4 ,these desert storms   
take up from the verdureless earth great
 quantities of sand and other fine      
dbris1 which often so clouds the air as 
to bring the darkness of night at       

midday4 ,their whirlings appear in size 
to be greater than those which produce  
tornadoes or waterspouts1 but less than 
hurricanes or cyclones4 ,little1        
however1 is known about them4 ,they have
 not been well observed by              
meteorologists4 ,in some ways they are  
important1 for the reason that they     
serve to carry the desert sand into     
regions previously verdure-clad1 and    
thus to extend the bounds of the        
desolate fields in which they originate4
 ,where they blow off to the seaward1   
they convey large quantities of dust    
into the ocean1 and thus serve to wear  
down the surface of the land in regions 
where there are no rivers to effect that
 action in the normal way4              
,notwithstanding its swift motion when  
impelled by differences in weight1 the  
movements of the air have had but little
 direct and immediate influence on the  
surface of the earth4 ,the greater part 
of the work which it does1 as we shall  
see hereafter1 is done through the      

waters which it impels and bears about4 
,yet where winds blow over verdureless  
surfaces the effect of the sand which   
they sweep before them is often         
considerable4 ,in regions of arid       
mountains the winds often drive trains  
of sand through the valleys1 where the  
sharp particles cut the rocks almost as 
effectively as torrents of water would1 
distributing the wearing over the width 
of the valley4 ,the dust thus blown1    
from a desert region may1 when it       
attains a country covered with          
vegetation1 gradually accumulate on its 
surface1 forming very thick deposits4   
,thus in northwestern ,china there is a 
wide area where dust accumulations blown
 from the arid districts of central     
,asia have gradually heaped up in the   
course of ages to the depth of thousands
 of feet1 and this although much of the 
dbris is continually being borne away by
 the action of the rain waters as they  
journey toward the sea4 ,such dust      
accumulations occur in other parts of   

the world1 particularly in the districts
 about the upper ,mississippi and in the
 valleys of the ,rocky ,mountains1 but  
nowhere are they so conspicuous as in   
the region first mentioned4  ,where     
prevailing winds from the sea1 from     
great lakes1 and even from considerable 
rivers1 blow against sandy shores or    
cliffs of the same nature1 large        
quantities of sand and dust are often   
driven inland from the coast line4 ,in  
most cases these wind-borne materials   
take on the form of dunes1 or heaps of  
sand1 varying from a few feet to several
 hundred feet in height4 ,it is         
characteristic of these hills of blown  
sand that they move across the face of  
the country4 ,under favourable          
conditions they may journey scores of   
miles from the shore4 ,the marching of a
 dune is effected through the rolling up
 of the sand on the windward side of the
 elevation1 when it is impelled by the  
current of air to the crest where it    
falls into the lee or shelter which the 

hill makes to the wind4 ,in this way in 
the course of a day the centre of the   
dune1 if the wind be blowing furiously1 
may advance a measurable distance from  
the place it occupied before4 ,by fits  
and starts this ongoing may be          
indefinitely continued4 ,a notable and  
picturesque instance of the march of a  
great dune may be had from the case in  
which one of them overwhelmed in the    
last century the village of ,eccles in  
southeastern ,england4 ,the advancing   
sand gradually crept into the hamlet1   
and in the course of a decade           
dispossessed the people by burying their
 houses4 ,in time the summit of the     
church spire disappeared from view1 and 
for many years thereafter all trace of  
the hamlet was lost4 ,of late years1    
however1 the onward march of the sands  
has disclosed the church spire1 and in  
the course of another century the place 
may be revealed on its original site1   
unchanged except that the marching hill 
will be on its other side4  ,in the     

region about the head of the ,bay of    
,biscay the quantity of these marching  
sands is so great that at one time they 
jeopardized the agriculture of a large  
district4 ,the ,french ,government has  
now succeeded1 by carefully planting the
 surface of the country with grasses and
 other herbs which will grow in such    
places1 in checking the movement of the 
wind-blown materials4 ,by so doing they 
have merely hastened the process by     
which ,nature arrests the march of      
dunes4 ,as these heaps creep away from  
the sea1 they generally come into       
regions where a greater variety of      
plants flourish2 moreover1 their sand   
grains become decayed1 so that they     
afford a better soil4 ,gradually the mat
 of vegetation binds them down1 and in  
time covers them over so that only the  
expert eye can recognise their true     
nature4 ,only in desert regions can the 
march of these heaps be maintained for  
great distances4  ,characteristic dunes 
occur from point to point all along the 

,atlantic coast from the ,state of      
,maine to the northern coast of         
,florida4 ,they also occur along the    
coasts of our ,great ,lakes1 being      
particularly well developed at the      
southern end of ,lake ,michigan1 where  
they form1 perhaps1 the most notable    
accumulations within the limits of the  
,united ,states4  ,when blown sands     
invade a forest and the deposit is      
rapidly accumulated1 the trees are often
 buried in an undecayed condition4 ,in  
this state1 with certain chemical       
reactions which may take place in the   
mass1 the woody matter is apt to become 
replaced by silex dissolved from the    
sand1 which penetrates the tissues of   
the plants4 ,in this way salicified     
forests are produced1 such as are found 
in the region of the ,rocky ,mountains1 
where the trunks of the trees1 now very 
hard stone1 so perfectly preserve their 
original structure that when cut and    
polished they may be used for decorative
 purposes4 ,conspicuous as is this work 

of the dunes1 it is in a geological way 
much less important than that           
accomplished by the finer dust which    
drifts from one region of land to       
another or into the sea4 ,because of    
their weight1 the sand grains journey   
over the surface of the earth1 except1  
indeed1 where they are uplifted by whirl
 storms4 ,they thus can not travel very 
fast or far4 ,dust1 however1 rises into 
the air1 and journeys for indefinite    
distances4 ,we thus see how slight      
differences in the weight of substances 
may profoundly affect the conditions of 
their deportation4                      
,,the ,,system ,,of ,,waters4  ,the     
envelope of air wraps the earth         
completely about1 and1 though varying in
 thickness1 is everywhere present over  
its surface4 ,that of the waters is much
 less equally distributed4 ,because of  
its weight1 it is mainly gathered in the
 depths of the earth1 where it lies in  
the interstices of the rocks and in the 
great realm of the seas4 ,only a very   

small portion of the fluid is in the    
atmosphere or on the land4 ,perhaps less
 than a ten thousandth part of the whole
 is at any one time on this round from  
the seas through the air to the land and
 back to the great reservoir4  ,the     
great water store of the earth is       
contained in two distinct realms--in the
 oceans1 where the fluid is concentrated
 in a quantity which fills something    
like nine tenths of the hollows formed  
by the corrugations of the earth's      
surface2 and in the rocks1 where it is  
stored in a finely divided form1 partly 
between the grains of the stony matter  
and partly in the substance of its      
crystals1 where it exists in a          
combination1 the precise nature of which
 is not well known1 but is called water 
of crystallization4 ,on the average1 it 
seems likely that the materials of the  
earth1 whether under the sea or on the  
land1 have several per cent of their    
mass of the fluid4  ,it is not yet known
 to what depth the water-bearing section

 of the earth extends2 but1 as we shall 
see more particularly hereafter when we 
come to consider volcanoes1 the lavas   
which they send up to the surface are   
full of contained water1 which passes   
from them in the form of steam4 ,the    
very high temperature of these volcanic 
ejections makes it necessary for us to  
suppose that they come from a great     
depth4 ,it is difficult to believe that 
they originate at less than a hundred   
miles below the earth's surface4 ,if1   
then1 the rocks contain an average of   
even five per cent of water to the depth
 of one hundred miles1 the quantity of  
the fluid stored within the earth is    
greater than that which is contained in 
the reservoir of the ocean4 ,the oceans1
 on the average1 are not more than three
 miles deep2 spread evenly over the     
surface of the whole earth1 their depth 
would be less than two miles1 while the 
water in the rocks1 if it could be added
 to the seas1 would make the total depth
 seven miles or more4 ,as we shall note 

hereafter1 the processes of formation of
 strata tend to imprison water in the   
beds1 which in time is returned to the  
earth's surface by the forces which     
operate within the crust4  ,although the
 water in the seas is1 as we have seen1 
probably less than one half of the store
 which the earth possesses1 the part it 
plays in the economy of the planet is in
 the highest measure important4 ,the    
underground water operates solely to    
promote certain changes which take place
 in the mineral realm4 ,its effect1     
except in volcanic processes1 are       
brought about but slowly1 and are       
limited in their action4 ,the movements 
of this buried water are exceedingly    
gradual2 the forces which impel it about
 and which bring it to do its work      
originate in the earth4 ,in the seas the
 fluid has an exceeding freedom of      
motion2 it can obey the varied impulses 
which the solar energy imposes upon it4 
,the rle of these wonderful actions     
which we are about to trace includes    

almost everything which goes on upon the
 surface of the planet--that which      
relates to the development of animal and
 vegetable life1 as well as to the vast 
geological changes which the earth is   
undergoing4  ,if the surface of the     
earth were uniformly covered with water 
to the depth of ten thousand feet or    
more1 every particle of fluid would1 in 
a measure1 obey the attraction of the   
sun1 of the moon1 and1 theoretically1   
also of all the other bodies in space1  
on the principle that every particle of 
matter in the universe exercises a      
gravitative effect on every other4 ,as  
it is1 owing to the divided condition of
 the water on the earth's surface1 only 
that which is in the ocean and larger   
seas exhibits any measurable influence  
from these distant attractions4 ,in     
fact1 only the tides produced by the    
moon and sun are of determinable        
magnitude1 and of these the lunar is of 
greater importance1 the reason being the
 near position of our satellite to our  

own sphere4 ,the solar tide is four     
tenths as great as the lunar4 ,the water
 doubtless obeys in a slight way the    
attraction of the other celestial       
bodies1 but the motions thus imparted   
are too small to be discerned2 they are 
lost in the great variety of influences 
which affect all the matter on the      
earth4  ,although the tides are due to  
the attraction of the solar bodies1     
mainly to that of the moon1 the mode in 
which the result is brought about is    
somewhat complicated4 ,it may briefly   
and somewhat incompletely be stated as  
follows3 ,owing to the fact that the    
attracting power of the earth is about  
eighty times greater than that of the   
moon1 the centre of gravity of the two  
bodies lies within the earth4 ,about    
this centre the spheres revolve1 each in
 a way swinging around the other4 ,at   
this point there is no centrifugal      
motion arising from the revolution of   
the pair of spheres1 but on the side of 
the earth opposite the moon1 some six   

thousand miles away1 the centrifugal    
force is considerable1 becoming         
constantly greater as we pass away from 
the turning point4 ,at the same time the
 attraction of the moon on the water    
becomes less4 ,thus the tide opposite   
the satellite is formed4 ,on the side   
toward the moon the same centrifugal    
action operates1 though less effectively
 than in the other case1 for the reason 
that the turning point is nearer the    
surface2 but this action is re-enforced 
by the greater attraction of the moon1  
due to the fact that the water is much  
nearer that body4  ,in the existing     
conditions of the earth1 what we may    
call the normal run of the tides is     
greatly interrupted4 ,only in the       
southern ocean can the waters obey the  
lunar and solar attraction in anything  
like a normal way4 ,in that part of the 
earth two sets of tides are discernible1
 the one and greater due to the moon1   
the other1 much smaller1 to the sun4 ,as
 these tides travel round at different  

rates1 the movements which they produce 
are sometimes added to each other and   
sometimes subtracted--that is1 at times 
they come together1 while again the     
elevation of one falls in the hollow of 
the other4 ,once again supposing the    
earth to be all ocean covered1          
computation shows that the tides in such
 a sea would be very broad waves1       
having1 indeed1 a diameter of half the  
earth's circumference4 ,those produced  
by the moon would have an altitude of   
about one foot1 and those by the sun of 
about three inches4 ,the geological     
effects of these swayings would be very 
slight2 the water would pass over the   
bottom to and fro twice each day1 with a
 maximum journey of a hundred or two    
feet each way from a fixed point4 ,this 
movement would be so slow that it could 
not stir the fine sediment2 its only    
influence would perhaps be to help feed 
the animals which were fixed upon the   
bottom by drawing the nurture-bringing  
water by their mouths4  ,although the   

divided condition of the ocean perturbs 
the action of the tides1 so that except 
by chance their waves are rarely with   
their centres where the attracting      
bodies tend to make them1 the influence 
of these divisions is greatly to        
increase the geological or              
change-bringing influences arising from 
these movements4 ,when from the southern
 ocean the tides start to the northward 
up the bays of the ,atlantic1 the       
,pacific1 or the ,indian ,ocean1 they   
have1 as before noted1 a height of      
perhaps less than two feet4 ,as they    
pass up the narrowing spaces the waves  
become compressed--that is1 an equal    
volume of moving water has less         
horizontal room for its passage1 and is 
forced to rise higher4 ,we see a        
tolerably good illustration of the same 
principle when we observe a wind-made   
wave enter a small recess of the shore1 
the sides of which converge in the      
direction of the motion4 ,with the      
diminished room1 the wave gains in      

height4 ,it thus comes about that the   
tide throughout the ,atlantic basin is  
much higher than in the southern ocean4 
,on the same principle1 when the tide   
rolls in against the shores every       
embayment of a distinct kind1 whose     
sides converge toward the head1 packs up
 the tidal wave1 often increasing its   
height in a remarkable way4 ,when these 
bays are wide-mouthed and of elongate   
triangular form1 with deep bottoms1 the 
tides which on their outer parts have a 
height of ten or fifteen feet may attain
 an altitude of forty or fifty feet at  
the apex of the triangle4  ,we have     
already noted the fact that the tide1   
such as runs in the southern ocean1     
exercises little or no influence upon   
the bottom of the sea over which it     
moves4 ,as the height of the confined   
waters increases1 the range of their    
journey over the bottom as the wave     
comes and goes rapidly increases4 ,when 
they have an elevation of ten feet they 
can probably stir the finer mud on the  

ocean floor1 and in shallow water move  
yet heavier particles4 ,in the          
embayments of the land1 where a great   
body of water journeys like an          
alternating river into extensive basins1
 the tidal action becomes intense2 the  
current may be able to sweep along large
 stones quite as effectively as a       
mountain torrent4 ,thus near ,eastport1 
,me41 where the tides have a maximum    
rise and fall of over twenty feet1 the  
waters rush in places so swiftly that at
 certain stages of the movement they are
 as much troubled as those at the rapids
 of the ,st4 ,lawrence4 ,in such        
portions of the shore the tides do      
important work in carving channels into 
the lands4  ,along the shores of the    
continents about the ,north ,atlantic1  
where the tides act in a vigorous       
manner1 we almost everywhere find an    
underwater shelf extending from the     
shore with a declivity of only five to  
ten feet to the mile toward the centre  
of the sea1 until the depth of about    

five hundred feet is attained2 from this
 point the bottom descends more steeply 
into the ocean's depth4 ,it is probable 
that the larger part of the material    
composing these continental shelves has 
been brought to its position by tidal   
action4 ,each time the tidal wave sweeps
 in toward the shore it urges the finer 
particles of sediment along with it4    
,when it moves out it drags them on the 
return journey toward the depths of the 
sea4 ,if this shelf were perfectly      
horizontal1 the two journeys of the sand
 and mud grains would be of the same    
length2 but as the movement takes place 
up and down a slope1 the bits will      
travel farther under the impulse which  
leads them downward than under that     
which impels them up4 ,the result will  
be that the particles will travel a     
little farther out from the shore each  
time it is swung to and fro in the      
alternating movement of the tide4  ,the 
effect of tidal movement in nurturing   
marine life is very great4 ,it aids the 

animals fixed on the bottoms of the deep
 seas to obtain their provision of food 
and their share of oxygen by drawing the
 water by their bodies4 ,all regions    
which are visited by strong tides       
commonly have in the shallows near the  
shores a thick growth of seaweed which  
furnishes an ample provision of food for
 the fishes and other forms of animal   
life4  ,a peculiar effect arising from  
tidal action is believed by students of 
the phenomena to be found in the slowing
 of the earth's rotation on its axis4   
,the tides rotate around the earth from 
east to west1 or rather1 we should say1 
the solid mass of the earth rubs against
 them as it spins from west to east4 ,as
 they move over the bottom and as they  
strike against the shores this push of  
the great waves tends in a slight       
measure to use up the original spinning 
impulse which causes the earth's        
rotation4 ,computation shows that the   
amount of this action should be great   
enough gradually to lengthen the day1 or

 the time occupied by the earth in      
making a complete revolution on the     
polar axis4 ,the effect ought to be     
great enough to be measurable by        
astronomers in the course of a thousand 
years4 ,on the other hand1 the records  
of ancient eclipses appear pretty       
clearly to show that the length of the  
day has not changed by as much as a     
second in the course of three thousand  
years4 ,this evidence does not require  
us to abandon the supposition that the  
tides tend to diminish the earth's rate 
of rotation4 ,it is more likely that the
 effect of the reduction in the earth's 
diameter due to the loss of heat which  
is continually going on counterbalances 
the influence of the tidal friction4 ,as
 the diameter of a rotating body        
diminishes1 the tendency is for the mass
 to spin more rapidly2 if it expands1 to
 turn more slowly1 provided in each case
 the amount of the impulse which leads  
to the turning remains the same4 ,this  
can be directly observed by whirling a  

small weight attached to a string in    
such a manner that the cord winds around
 the finger with each revolution2 it    
will be noted that as the line shortens 
the revolution is more quickly          
accomplished4 ,we can readily conceive  
that the earth is made up of weights    
essentially like that used in the       
experiment1 each being drawn toward the 
centre by the gravitative stress1 which 
is like that applied to the weight by   
the cord4  ,the fact that the days      
remain of the same length through vast  
periods of time is probably due to this 
balance between the effects of tidal    
action and those arising from the loss  
of heat--in other words1 we have here   
one of those delicate arrangements in   
the way of counterpoise which serve to  
maintain the balanced conditions of the 
earth's surface amid the great conflicts
 of diverse energies which are at work  
in and upon the sphere4  ,it should be  
understood that the effects of the      
attraction which produces tides are much

 more extensive than they are seen to be
 in the movements of the sea4 ,so long  
as the solar and planetary spheres      
remain fluid1 the whole of their masses 
partake of the movement4 ,it is a       
consequence of this action1 as the      
computations of ,prof4 ,george ,darwin  
has shown1 that the moon1 once nearer   
the earth than it is at present1 has by 
a curious action of the tidal force been
 pushed away from the centre of our     
sphere1 or rather the two bodies have   
repelled each other4 ,an ,american      
student of the problem1 ,mr4 ,t4,j4,j4  
,see1 has shown that the same action has
 served to give to the double stars the 
exceeding eccentricity of their orbits4 
,although these recent studies of tidal 
action in the celestial sphere are of   
the utmost importance to the theory of  
the universe1 for they may lead to      
changes in the nebular hypotheses1 they 
are as yet too incomplete and are1      
moreover1 too mathematical to be        
presented in an elementary treatise such

 as this4                    99       99
       99       99       99  ,we now    
turn to another class of waves which are
 of even more importance than those of  
the tides--to the undulations which are 
produced by the action of the wind on   
the surface of the water4 ,while the    
tide waves are limited to the open      
ocean1 and to the seas and bays which   
afford them free entrance1 wind waves   
are produced everywhere where water is  
subjected to the friction of air which  
flows over it4 ,while tidal waves come  
upon the shores but twice each day1 the 
wind waves of ordinary size which roll  
in from the ocean deliver their blows at
 intervals of from three to ten seconds4
 ,although the tidal waves sometimes1 by
 a packing-up process1 attain the height
 of fifty feet1 their average altitude  
where they come in contact with the     
shore probably does not much exceed four
 feet2 usually they come in gently4 ,it 
is likely that in a general way the     
ocean surges which beat against the     

coast are of greater altitude4  ,wind   
waves are produced and perform their    
work in a manner which we shall now     
describe4 ,when the air blows over any  
resisting surface1 it tends1 in a way   
which we can hardly afford here to      
describe1 to produce motions4 ,if the   
particle is free to move under the      
impulse which it communicates1 it bears 
it along2 if it is linked together in   
the manner of large masses1 which the   
wind can not transport1 it tends to set 
it in motion in an alternating way4 ,the
 sounds of our musical instruments which
 act by wind are due to these           
alternating vibrations1 such as all air 
currents tend to produce4 ,an olian harp
 illustrates the action which we are    
considering4 ,moving over matter which  
has the qualities that we denote by the 
term fluid1 the swayings which the air  
produces are of a peculiar sort1 though 
they much resemble those of the fiddle  
string4 ,the surface of the liquid rises
 and falls in what we term waves1 the   

size of which is determined by the      
measure of fluidity1 and by the energy  
of the wind4 ,thus1 because fresh water 
is considerably lighter than salt1 a    
given wind will produce in a given      
distance for the run of the waves       
heavier surges in a lake than it will in
 the sea4 ,for this reason the surges in
 a great storm which roll on the ocean  
shore1 because of the wide water over   
which they have gathered their impetus1 
are in size very much greater than those
 of the largest lakes1 which do not     
afford room for the development of great
 undulations4  ,to the eye1 a wave in   
the water appears to indicate that the  
fluid is borne on before the wind4      
,examination1 however1 shows that the   
amount of motion in the direction in    
which the wind is blowing is very       
slight4 ,we may say1 indeed1 that the   
essential feature of a wave is found in 
the transmission of impulse rather than 
in the movement of the fluid matter4 ,a 
strip of carpet when shaken sends       

through its length undulations which are
 almost exactly like water waves4 ,if we
 imagine ourselves placed in a particle 
of water1 moving in the swayings of a   
wave in the open and deep sea1 we may   
conceive ourselves carried around in an 
ellipse1 in each revolution returning   
through nearly the same orbit4 ,now and 
then1 when the particle came to the     
surface1 it would experience the slight 
drift which the continual friction of   
the wind imposes on the water4 ,if the  
wave in which the journey was made lay  
in the trade winds1 where the           
long-continued1 steadfast blowing had   
set the water in motion to great depths1
 the orbit traversed would be moving    
forward with some rapidity2 where also  
the wind was strong enough to blow the  
tops of the waves over1 forming         
white-caps1 the advance of the particle 
very near the surface would be speedy4  
,notwithstanding these corrections1     
waves are to be regarded each as a store
 of energy1 urging the water to sway    

much in the manner of a carpet strip1   
and by the swaying conveying the energy 
in the direction of the wave movement4  
,the rate of movement of wind waves     
increases with their height4 ,slight    
undulations go forward at the rate of   
less than half a mile an hour4 ,the     
greater surges of the deeps when swept  
by the strongest winds move with the    
speed which1 though not accurately      
determined1 has been estimated by the   
present writer as exceeding forty miles 
an hour4 ,as these surges often have a  
length transverse to the wind of a mile 
or more1 a width of about an eighth of a
 mile1 and a height of from thirty-five 
to forty-five feet1 the amount of energy
 which they transmit is very great4 ,if 
it could be effectively applied to the  
shores in the manner in which the energy
 of exploding gunpowder is applied by   
cannon shot1 it is doubtful whether the 
lands could have maintained their       
position against the assaults of the    
sea4 ,but there are reasons stated below

 why the ocean waves can use only a very
 small part of their energy in rending  
the rocks against which they strike on  
the coast line4  ,in the first place1 we
 should note that wind waves have very  
little influence on the bottom of the   
deep sea4 ,if an observer could stand on
 the sea floor at the depth of a mile   
below a point over which the greatest   
waves were rolling1 he could not with   
his unaided senses discern that the     
water was troubled4 ,he would1 indeed1  
require instruments of some delicacy to 
find out that it moved at all4 ,making  
the same observations at the depth of a 
thousand feet1 it is possible that he   
would note a slight swaying motion in   
the water1 enough sensibly to affect his
 body4 ,at five hundred feet in depth   
the movement would probably be          
sufficient to disturb fine mud4 ,at two 
hundred feet1 the rasping of the surge  
on the bottom would doubtless be        
sufficient to push particles of coarse  
sand to and fro4 ,at one hundred feet in

 depth1 the passage of the surge would  
be strong enough to urge considerable   
pebbles before it4 ,thence up the slope 
the driving action would become more and
 more intense until we attained the     
point where the wave broke4 ,it should  
furthermore be noted that1 while the    
movement of the water on the floor of   
the deep sea as the wave passes overhead
 would be to and fro1 with every advance
 in the shallowing and consequent       
increased friction on the bottom1 the   
forward element in the movement would   
rapidly increase4 ,near the coast line  
the effect of the waves is continually  
to shove the detritus up the slopes of  
the continental shelf4 ,here we should  
note the fact that on this shelf the    
waves play a part exactly the opposite  
of that effected by the tides4 ,the     
tides1 as we have noted1 tend to drag   
the particles down the slope1 while the 
waves operate to roll them up the       
declivity4  ,as the wave in advancing   
toward the shore ordinarily comes into  

continually shallowing water1 the       
friction on the bottom is               
ever-increasing1 and serves to diminish 
the energy the surge contains1 and      
therefore to reduce its proportions4 ,if
 this action operated alone1 the        
subtraction which the friction makes    
would cause the surf waves which roll in
 over a continental shelf to be very    
low1 probably in height less than half  
that which they now attain4 ,in fact1   
however1 there is an influence at work  
to increase the height of the waves at  
the expense of its width4 ,noting that  
the friction rapidly increases with the 
shallowing1 it is easy to see that this 
resistance is greatest on the advancing 
front of the wave1 and least on its     
seaward side4 ,the result is that the   
front moves more slowly than the rear1  
so that the wave is forced to gain in   
height2 but for the fact that the total 
friction which the wave encounters takes
 away most of its impetus1 we might have
 combers a hundred feet high rolling    

upon the shelving shores which almost   
everywhere face the seas4  ,as the wave 
shortens its width and gains in relative
 height1 though not in actual elevation1
 another action is introduced which has 
momentous consequences4 ,the water in   
the bottom of the wave is greatly       
retarded in its ongoing by its friction 
over the sea floor1 while the upper part
 of the surge is much less affected in  
this way4 ,the result is that at a      
certain point in the advance1 the place 
of which is determined by the depth1 the
 size1 and the speed of the undulation1 
the front swiftly steepens until it is  
vertical1 and the top shoots forward to 
a point where it is no longer supported 
by underlying water1 when it plunges    
down in what is called the surf or      
breaker4 ,in this part of the wave's    
work the application of the energy which
 it transmits differs strikingly from   
the work previously done4 ,before the   
wave breaks1 the only geological task   
which it accomplishes is effected by    

forcing materials up the slope1 in which
 movement they are slightly ground over 
each other until they come within the   
battering zone of the shore1 where they 
may be further divided by the action of 
the mill which is there in operation4   
,when the wave breaks on the shore it   
operates in the following manner3       
,first1 the overturning of its crest    
sends a great mass of water1 it may be  
from the height of ten or more feet1    
down upon the shore4 ,thus falling water
 has not only the force due to its drop 
from the summit of the wave1 but it has 
a share of the impulse due to the       
velocity with which the surge moved     
against the shore4 ,it acts1 in a word1 
like a hammer swung down by a strong    
arm1 where the blow represents not only 
the force with which the weight would   
fall of itself1 but the impelling power 
of the man's muscles4 ,any one who will 
expose his body to this blow of the surf
 will recognise how violent it is2 he   
may1 if the beach be pebbly1 note how it

 drives the stones about2 fragments the 
size of a man's head may be hurled by   
the stroke to the distance of twenty    
feet or more2 those as large as the fist
 may be thrown clear beyond the limits  
of the wave4 ,so vigorous is this stroke
 that the sound of it may sometimes be  
heard ten miles inland from the coast   
where it is delivered4  ,moving forward 
up the slope of a gently inclined beach1
 the fragments of the wave are likely to
 be of sufficient volume to permit them 
to regather into a secondary surge1     
which1 like the first1 though much      
smaller1 again rises into a wall1       
forming another breaker4 ,under         
favourable conditions as many as four or
 five of these successive diminishing   
surf lines may be seen4 ,the present    
writer has seen in certain cases as many
 as a dozen in the great procession1 the
 lowest and innermost only a few inches 
high1 the outer of all with a height of 
perhaps twenty feet4  ,along with the   
direct bearing action of the surf goes a

 to-and-fro movement1 due to the rushing
 up and down of the water on the beach4 
,this swashing affects not only the     
broken part of the waves1 but all the   
water between the outer breaker and the 
shore4 ,these swayings in the surf belt 
often swing the dbris on the inner      
margin over a range of a hundred feet or
 more1 the movement taking place with   
great swiftness1 affecting the pebbles  
to the depth of several inches1 and     
grinding the bits together in a violent 
way4 ,listening to the turmoil of a     
storm1 we can on a pebbly beach         
distinctly hear the sound of the        
downward stroke1 a crashing tone1 and   
the roar of the rolling stones4  ,as    
waves are among the interesting things  
in the world1 partly on account of their
 living quality and partly because of   
their immediate and often exceeding     
interest to man1 we may here note one or
 two peculiar features in their action4 
,in the first place1 as the reader who  
has gained a sense of the changes in    

form of action may readily perceive1 the
 beating of waves on the shore converts 
the energy which they possess into heat4
 ,this probably warms the water during  
great storms1 so that by the hand we may
 note the difference in temperature next
 the coast line and in the open waters4 
,this relative warmth of the surf water 
is perhaps a matter of some importance  
in limiting the development of ice along
 the shore line2 it may also favour the 
protection of the coast life against the
 severe cold of the winter season4  ,the
 waves which successively come against  
the shore in any given time1            
particularly if a violent wind is       
blowing on to the coast1 are usually of 
about the same size4 ,when1 however1 in 
times of calm an old sea1 as it is      
called1 is rolling in1 the surges may   
occasionally undergo very great         
variations in magnitude4 ,not           
infrequently these occasional waves are 
great enough to overwhelm persons who   
are upon the rocks next the shore4      

,these greater surges are probably to be
 accounted for by the fact that in the  
open sea waves produced by winds blowing
 in different directions may run on with
 their diverse courses and varied       
intervals until they come near the      
shore4 ,running in together1 it very    
well happens that two of the surges     
belonging to different sets may combine 
their forces1 thus doubling the swell4  
,the danger which these conjoined waves 
bring is obviously greatest on cliff    
shores1 where1 on account of the depth  
of water1 the waves do not break until  
they strike the steep4                  
99       99       99       99       99  
,having considered in a general way the 
action of waves as they roll in to the  
shore1 bearing with them the solar      
energy which was contributed to them by 
the winds1 we shall now take up in some 
detail the work which goes on along the 
coast line--work which is mainly        
accomplished by wave action4  ,on most  
coast lines the observer readily notes  

that the shore is divided into two      
different kinds of faces--those where   
the inner margin of the wave-swept belt 
comes against rocky steeps1 and those   
bordered by a strand altogether composed
 of materials which the surges have     
thrown up4 ,these may be termed for     
convenience cliff shores and wall-beach 
shores4 ,we shall begin our inquiry with
 cliff shores1 for in those sections of 
the coast line the sea is doing its most
 characteristic and important work of   
assaulting the land4 ,if the student has
 an opportunity to approach a set of    
cliffs of hard rock in time of heavy    
storm1 when the waves have somewhere    
their maximum height1 he should seek    
some headland which may offer him safe  
foothold whence he can behold the       
movements which are taking place4 ,if he
 is so fortunate as to have in view1 as 
well may be the case1 cliffs which      
extend down into deep water1 and others 
which are bordered by rude and generally
 steeply sloping beaches covered with   

large stones1 he may perceive that the  
waves come in against the cliffs which  
plunge into deep water without taking on
 the breaker form4 ,in this case the    
undulation strikes but a moderate blow2 
the wave is not greatly broken4 ,the    
part next the rock may shoot up as a    
thin sheet to a considerable height2 it 
is evident that while the ongoing wave  
applies a good deal of pressure to the  
steep1 it does not deliver its energy in
 the effective form of a blow as when   
the wave overturns1 or in the consequent
 rush of the water up a beach slope4 ,it
 is easy to perceive that firm-set rock 
cliffs1 with no beaches at their bases1 
can almost indefinitely withstand the   
assaults4 ,on the steep and stony beach1
 because of its relatively great        
declivity1 the breaker or surf forms far
 in1 and even in its first plunge often 
attains the base of the precipice4 ,the 
blow of the overfalling as well as that 
of the inrush moves about stones of     
great size2 those three feet or more in 

diameter are often hurled by the action 
against the base of the steep1 striking 
blows1 the sharp note of which can often
 be heard above the general roar which  
the commotion produces4 ,the needlelike 
crags forming isles standing at a       
distance from the shore1 such as are    
often found along hard rock coasts1 are 
singularly protected from the action of 
effective waves4 ,the surges which      
strike against them are unarmed with    
stones1 and the water at their bases is 
so deep that it does not sway with the  
motion with sufficient energy to move   
them on the bottom4 ,where a cliff is in
 this condition1 it may endure until an 
elevation of the coast line brings its  
base near the level of the sea1 or until
 the process of decay has detached a    
sufficient quantity of stone to form a  
talus or inclined plane reaching near to
 the water level4  ,as before noted1 it 
is the presence of a sloping beach      
reaching to about the base of the cliff 
which makes it possible for the waves to

 strike at with a hammer instead of with
 a soft hand4 ,battering at the base of 
the cliff1 the surges cut a crease along
 the strip on which they strike1 which  
gradually enters so far that the        
overhanging rock falls of its own       
weight4 ,the fragments thus delivered to
 the sea are in turn broken up and used 
as battering instruments until they are 
worn to pieces4 ,we may note that in a  
few months of heavy weather the stones  
of such a fall have all been reduced to 
rudely spherical forms4 ,observations   
made on the eastern face of ,cape ,ann1 
,mass41 where the seas are only         
moderately heavy1 show that the storms  
of a single winter reduce the fragments 
thrown into the sea from the granite    
quarries to spheroidal shapes1 more than
 half of their weight commonly being    
removed in the form of sand and small   
pebbles which have been worn from their 
surfaces4  ,we can best perceive the    
effect of battering action which the sea
 applies to the cliffs by noting the    

points where1 owing to some chance      
features in the structure in the rock1  
it has proved most effective4 ,where a  
joint or a dike1 or perhaps a softer    
layer1 if the rocks be bedded1 causes   
the wear to go on more rapidly1 the     
waves soon excavate a recess in which   
the pebbles are retained1 except in     
stormy weather1 in an unmoved condition4
 ,when the surges are heavy1 these      
stones are kept in continuous motion1   
receding as the wave goes back1 and     
rushing forward with its impulse until  
they strike against the firm-set rock at
 the end of the chasm4 ,in this way they
 may drive in a cut having the length of
 a hundred feet or more from the face of
 the precipice4 ,in most cases the roofs
 over these sea caves fall in1 so that  
the structure is known as a chasm4      
,occasionally these roofs remain1 in    
which case1 for the reason that the     
floor of the cutting inclines upward1 an
 opening is made to the surface at their
 upper end1 forming what is called in   

,new ,england a spouting horn2 from the 
inland end of the tunnel the spray may  
be thrown far into the air4 ,as long as 
the cave is closed at this inner end1   
and is not so high but that it may be   
buried beneath a heavy wave1 the        
inrushing water compresses the air in   
the rear parts of the opening4 ,when the
 wave begins to retreat this air blows  
out1 sending a gust of spray before it1 
the action resembling the discharge of a
 great gun from the face of a           
fortification4 ,it often happens that   
two chasms converging separate a rock   
from the cliff4 ,then a lowering of the 
coast may bring the mass to the state of
 a columnar island1 such as abound in   
the ,hebrides and along various other   
shores4  ,if a cliff shore retreats     
rapidly1 it may be driven back into the 
shore1 and its face assumes the curve of
 a small bay4 ,with every step in this  
change the bottom is sure to become     
shallower1 so that the waves lose more  
and more of their energy in friction    

over the bottom4 ,moreover1 in entering 
a bay the friction which the waves      
encounter in running along the sides is 
greater than that which they meet in    
coming in upon a headland or a straight 
shore4 ,the result is1 with the inward  
retreat of the steep it enters on       
conditions which diminish the           
effectiveness of the wave stroke4 ,the  
embayment also is apt to hold detritus1 
and so forms in time a beach at the foot
 of the cliff1 over which the waves     
rarely are able to mount with such      
energy as will enable them to strike the
 wall in an effective manner4 ,with this
 sketch of the conditions of a cliff    
shore1 we will now consider the fate of 
the broken-tip rock which the waves have
 produced on that section of the coast  
land4  ,by observation of sea-beaten    
cliffs the student readily perceives    
that a great amount of rocky matter has 
been removed from most cliff-faced      
shores4 ,not uncommonly it can be shown 
that such sea faces have retreated for  

several miles4 ,the question now arises1
 ,what becomes of the matter which has  
been broken up by the wave action8 ,in  
some part the rock1 when pulverized by  
the pounding to which it is subjected1  
has dissolved in the water4 ,probably   
ninety per cent of it1 however1 retains 
the visible state1 and has a fate       
determined by the size of the fragments 
of which it is composed4 ,if these be as
 fine as mud1 so that they may float in 
the water1 they are readily borne away  
by the currents which are always created
 along a storm-swept shore1 particularly
 by the undertow or bottom              
outcurrent--the sea-puss1 as it is      
sometimes called--that sweeps along the 
bottom from every shore1 against which  
the waves form a surf4 ,if as coarse as 
sand grains1 or even very small pebbles1
 they are likely to be drawn out1       
rolling over the bottom to an indefinite
 distance from the sea margin4 ,the     
coarser stones1 however1 either remain  
at the foot of the cliff until they are 

beaten to pieces1 or are driven along   
the shore until they find some embayment
 into which they enter4 ,the journey of 
such fragments may1 when the wind       
strikes obliquely to the shore1 continue
 for many miles2 the waves1 running with
 the wind1 drive the fragments in       
oscillating journeys up and down the    
beach1 sometimes at the rate of a mile  
or more a day4 ,the effect of this      
action can often be seen where a vessel 
loaded with brick or coal is wrecked on 
the coast4 ,in a month fragments of the 
materials may be stretched along for the
 distance of many miles on either side  
of the point where the cargo came       
ashore4 ,entering an embayment deep     
enough to restrain their further        
journey1 the fragments of rock form a   
boulder beach1 where the bits roll to   
and fro whenever they are struck by     
heavy surges4 ,the greater portion of   
them remain in this mill until they are 
ground to the state of sand and mud4    
,now and then one of the fragments is   

tossed up beyond the reach of the waves1
 and is contributed to the wall of the  
beach4 ,in very heavy storms these      
pebbles which are thrown inland may     
amount in weight to many tons for each  
mile of shore4  ,the study of a pebbly  
beach1 drawn from crest to the deep     
water outside1 will give an idea as to  
the history of its work4 ,on either horn
 of the crescent by which the pebbles   
are imported into the pocket we find the
 largest fragments4 ,if the shore of the
 bay be long1 the innermost part of the 
recess may show even only very small    
pebbles1 or perhaps only fine sand1 the 
coarser material having been worn out in
 the journey4 ,on the bottom of the bay1
 near low tide1 we begin to find some   
sand produced by the grinding action4   
,yet farther out1 below high-tide mark1 
there is commonly a layer of mud which  
represents the finer products of the    
mill4  ,boulder beaches are so quick in 
answering to every slight change in the 
conditions which affect them that they  

seem almost alive4 ,if by any chance the
 supply of detritus is increased1 they  
fill in between the horns1 diminish the 
incurve of the bay1 and so cause its    
beach to be more exposed to heavy waves4
 ,if1 on the other hand1 the supply of  
grist to the mill is diminished1 the    
beach becomes more deeply incurved1 and 
the wave action is proportionately      
reduced4 ,we may say1 in general1 that  
the curve of these beaches represents a 
balance between the consumption and     
supply of the pebbles which they grind  
up4 ,the supply of pebbles brought along
 the shore by the waves is in many cases
 greatly added to by a curious action of
 seaweeds4 ,if the bottom of the water  
off the coast is covered by these       
fragments1 as is the case along many    
coast lines within the old glaciated    
districts1 the spores of alg are prone  
to take root upon them4 ,fastening      
themselves in those positions1 and      
growing upward1 the seaweeds may attain 
considerable size4 ,being provided with 

floats1 the plant exercises a certain   
lifting power on the stone1 and finally 
the tugging action of the waves on the  
fronds may detach the fragments from the
 bottom1 making them free to journey    
toward the shore4 ,observing from near  
at hand the straight wall of the wave in
 times of heavy storm1 the present      
writer has seen in one view as many as a
 dozen of these plant-borne stones1     
sometimes six inches in diameter1       
hanging in the walls of water as it was 
about to topple over4 ,as soon as they  
strike the wave-beaten part of the shore
 these stones are apt to become         
separated from the plants1 though we can
 often notice the remains or prints of  
the attachments adhering to the surface 
of the rock4 ,where the pebbles off the 
shore are plenty1 a rocky beach may be  
produced by this process of importation 
through the agency of seaweeds without  
any supply being brought by the waves   
along the coast line4  ,returning to    
sand beaches1 we enter the most         

interesting field of contact between    
seas and lands4 ,probably nine tenths of
 all the coast lines of the open ocean  
are formed of arenaceous material4 ,in  
general1 sand consists of finely broken 
crystals of silica or quartz4 ,these    
bits are commonly distinctly faceted2   
they rarely have a spherical form4 ,not 
only do accumulations of sand border    
most of the shore line1 but they protect
 the land against the assaults of the   
sea1 and this in the following curious  
manner3 ,when shore waves beat pebbles  
against each other1 they rapidly wear to
 bits2 we can hear the sound of the     
wearing action as the wave goes to and  
fro4 ,we can often see that the water is
 discoloured by the mud or powdered     
rock4 ,when1 however1 the waves tumble  
on a sandy coast1 they make but a       
muffled sound1 and produce no mud4 ,in  
fact1 the particles of sand do not touch
 each other when they receive the blow4 
,between them there lies a thin film of 
water1 drawn in by the attraction known 

as capillarity1 which sucks the fluid   
into a sponge or between plates of glass
 placed near together4 ,the stroke of   
the waves slightly compresses this      
capillary water1 but the faces of the   
grains are kept apart as sheets of glass
 may be observed to be restrained from  
contact when water is between them4 ,if 
the reader would convince himself as to 
the condition of the sand grains and the
 water which is between them1 he may do 
so by pressing his foot on the wet beach
 which the wave has just left4 ,he will 
observe that it whitens and sinks a     
little under the pressure1 but returns  
in good part to its original form when  
the foot is lifted4 ,in the experiment  
he has pushed a part of the contained   
water aside1 but he has not brought the 
grains together2 they do not make the   
sound which he will often hear when the 
sand is dry4 ,the result is that the    
sand on the seashore may wear more in   
going the distance of a mile in the dry 
sand dune than in travelling for        

hundreds along the wet shore4  ,if the  
rock matter in the state of sand wore as
 rapidly under the heating of the waves 
as it does in the state of pebbles1 the 
continents would doubtless be much      
smaller than they are4 ,those coasts    
which have no other protection than is  
afforded by a low sand beach are often  
better guarded against the inroads of   
the sea than the rock-girt parts of the 
continents4 ,it is on account of this   
remarkable endurance of sand of the     
action of the waves that the stratified 
rocks which make up the crust of the    
earth are so thick and are to such an   
extent composed of sand grains4  ,the   
tendency of the dbris-making influences 
along the coast line is to fill in the  
irregularities which normally exist     
there2 to batter off the headlands1     
close up the bays and harbours1 and     
generally to reduce the shores to       
straight lines4 ,where the tide has     
access to these inlets1 it is constantly
 at work in dragging out the detritus   

which the waves make and thrust into the
 recesses4 ,these two actions contend   
with each other1 and determine the      
conditions of the coast line1 whether   
they afford ports for commerce or are   
sealed in by sand bars1 as are many     
coast lines which are not tide-swept1 as
 that of northern ,africa1 which faces  
the ,mediterranean1 a nearly tideless   
sea4 ,the same is the case with the     
fresh-water lakes2 even the greater of  
them are often singularly destitute of  
shelters which can serve the use of     
ships1 and this because there are no    
tides to keep the bays and harbours     
open4                           ,,the   
,,ocean ,,currents4  ,the system of     
ocean currents1 though it exhibits much 
complication in detail1 is in the main  
and primarily dependent on the action of
 the constant air streams known as the  
trade winds4 ,with the breath from the  
lips over a basin of water we can       
readily make an experiment which shows  
in a general way the method in which the

 winds operate in producing the         
circulation of the sea4 ,blowing upon   
the surface of the water in the basin1  
we find that even this slight impulse at
 once sets the upper part in motion1 the
 movement being of two kinds--pulsating 
movements or waves are produced1 and at 
the same time the friction of the air on
 the surface causes its upper part to   
slide over the under4 ,with little      
floats we can shortly note that the     
stream which forms passes to the farther
 side of the vessel1 there divides1 and 
returns to the point of beginning1      
forming a double circle1 or rather two  
ellipses1 the longer sides of which are 
parallel with the line of the air       
current4 ,watching more closely1 aiding 
the sight by the particles which float  
at various distances below the surface1 
we note the fact that the motion which  
was at first imparted to the surface    
gradually extends downward until it     
affects the water to the depth of some  
inches4  ,in the trade-wind belt the    

ocean waters to the depth of some       
hundreds of feet acquire a continuous   
movement in the direction in which they 
are impelled by those winds4 ,this      
motion is most rapid at the surface and 
near the tropics4 ,it diminishes        
downwardly in the water1 and also toward
 the polar sides of the trade-wind      
districts4 ,thus the trades produce in  
the sea two broad1 slow-moving1 deep    
currents1 flowing in the northern       
hemisphere toward the southwest1 and in 
the southern hemisphere toward the      
northwest4 ,coming down upon each other 
obliquely1 these broad streams meet     
about the middle of the tropical belt4  
,here1 as before noted1 the air of the  
trade winds leaves the surface and rises
 upward4 ,the waters being retained on  
their level1 form a current which moves 
toward the west4 ,if the earth within   
the tropics were covered by a universal 
sea1 the result of this movement would  
be the institution of a current which1  
flowing under the equator1 would girdle 

the sphere4  ,with a girdling equatorial
 current1 because of the intense heat of
 the tropics and the extreme cold of the
 parallels beyond the fortieth degree of
 latitude1 the earth would be           
essentially uninhabitable to man1 and   
hardly so to any forms of life4 ,its    
surface would be visited by fierce winds
 induced by the very great differences  
of temperature which would then prevail4
 ,owing1 however1 to the barriers which 
the continents interpose to the motions 
of these windward-setting tropical      
currents1 all the water which they bear1
 when it strikes the opposing shores1 is
 diverted to the right and left1 as was 
the stream in the experiment with the   
basin and the breath1 the divided       
currents seeking ways toward high       
latitudes1 conveying their store of heat
 to the circumpolar lands4 ,so effective
 is this transfer of temperature that a 
very large part of the heat which enters
 the waters in the tropical region is   
taken out of that division of the       

earth's surface and distributed over the
 realms of sea and land which lie beyond
 the limits of the vertical sun4 ,thus  
the ,gulf ,stream1 the northern branch  
of the ,atlantic tropical current1 by   
flowing into the ,north ,atlantic1      
contributes to the temperature of the   
region within the ,arctic ,circle more  
heat than actually comes to that        
district by the direct influx from the  
sun4  ,the above statements as to the   
climatal effect of the ocean streams    
show us how important it is to obtain a 
sufficient conception as to the way in  
which these currents now move and what  
we can of their history during the      
geologic ages4 ,this task can not yet be
 adequately done4 ,the fields of the sea
 are yet too imperfectly explored to    
afford us all the facts required to make
 out the whole story4 ,only in the case 
of our ,gulf ,stream can we form a full 
conception as to the journey which the  
waters undergo and the consequence of   
their motion4 ,in the case of this      

current1 observations clearly show that 
it arises from the junction near the    
equatorial line of the broad stream     
created by the two trade-wind belts4    
,uniting at the equator1 these produce a
 westerly setting current1 having the   
width of some hundred miles and a depth 
of several hundred feet4 ,its velocity  
is somewhat greater than a mile an hour4
 ,the centre of the current1 because of 
the greater strength of the northern as 
compared with the southern trades1 is   
considerably south of the equator4 ,when
 this great slow-moving stream comes    
against the coast of ,south ,america1 it
 encounters the projecting shoulder of  
that land which terminates at ,cape ,st4
 ,roque4 ,there it divides1 as does a   
current on the bows of an anchored ship1
 a part--rather more than one half--of  
the stream turning to the northward1 the
 remainder passing toward the southern  
pole2 this northerly portion becomes    
what is afterward known as the ,gulf    
,stream1 the history of which we shall  

now briefly follow4  ,flowing by the    
northwesterly coast of ,south ,america1 
the northern share of the tropical      
current1 being pressed in against the   
land by the trade winds1 is narrowed1   
and therefore acquires at once a swifter
 flow1 the increased speed being due to 
conditions like those which add to the  
velocity of the water flowing through a 
hose when it comes to the constriction  
of the nozzle4 ,attaining the line of   
the southeastern or ,lesser ,antilles1  
often known as the ,windward ,islands1 a
 part of this current slips through the 
interspaces between these isles and     
enters the ,gulf of ,mexico4 ,another   
portion1 failing to find sufficient room
 through these passages1 skirts the     
,antilles on their eastern and northern 
sides1 passes by and among the ,bahama  
,islands1 there to rejoin the part of   
the stream which entered the ,caribbean4
 ,this ,caribbean portion of the tide   
spreads widely in that broad sea1 is    
constricted again between ,cuba and     

,yucatan1 again expands in the ,gulf of 
,mexico1 and is finally poured forth    
through the ,straits of ,florida as a   
stream having the width of forty or     
fifty miles1 a depth of a thousand feet 
or more1 and a speed of from three to   
five miles an hour1 exceeding in its    
rate of flow the average of the greatest
 rivers1 and conveying more water than  
do all the land streams of the earth4   
,in this part of its course the deep and
 swift stream from the ,gulf of ,mexico1
 afterward to be named the ,gulf        
,stream1 receives the contribution of   
slower moving and shallower currents    
which skirted the ,antilles on their    
eastern verge4 ,the conjoined waters    
then move northward1 veering toward the 
east1 at first as a swift river of the  
sea having a width of less than a       
hundred miles and of great depth2 with  
each step toward the pole this stream   
widens1 diminishing proportionately in  
depth2 the speed of its current         
decreases as the original impetus is    

lost1 and the baffling winds set its    
surface waters to and fro in an         
irregular way4 ,where it passes ,cape   
,hatteras it has already lost a large   
share of its momentum and much of its   
heat1 and is greatly widened4  ,although
 the current of the ,gulf ,stream       
becomes more languid as we go northward1
 it for a very long time retains its    
distinction from the waters of the sea  
through which it flows4 ,sailing        
eastward from the mouth of the          
,chesapeake1 the navigator can often    
observe the moment when he enters the   
waters of this current4 ,this is notable
 not only in the temperature1 but in the
 hue of the sea4 ,north of that line the
 sharpness of the parting wall becomes  
less distinct1 the stream spreads out   
broadly over the surface of the         
,atlantic1 yet its thermometric effects 
are distinctly traceable to ,iceland and
 ,nova ,zembla1 and the tropical        
driftwood which it carries affords the  
principal timber supply of the          

inhabitants of the first-named isle4    
,attaining this circumpolar realm1 and  
finally losing the impulse which bore it
 on1 the water of the ,gulf ,stream     
partly returns to the southward in a    
relatively slight current which bears   
the fluid along the coast of ,europe    
until it re-enters the system of        
tropical winds and the currents which   
they produce4 ,a larger portion         
stagnates in the circumpolar region1 in 
time slowly to return to the tropical   
district in a manner afterward to be    
described4 ,although the ,gulf ,stream  
in the region north of ,cape ,hatteras  
is so indistinct that its presence was  
not distinctly recognised until the     
facts were subjected to the keen eye of 
,benjamin ,franklin1 its effects in the 
way of climate are so great that we must
 attribute the fitness of northern      
,europe for the uses of civilized man to
 its action4 ,but for the heat which    
this stream brings to the realm of the  
,north ,atlantic1 ,great ,britain would 

be as sterile as ,labrador1 and the     
,scandinavian region1 the cradle-land of
 our race1 as uninhabitable as the      
bleakest parts of ,siberia4  ,it is a   
noteworthy fact that when the equatorial
 current divides on the continents      
against which it flows1 the separate    
streams1 although they may follow the   
shores for a certain distance toward the
 poles1 soon diverge from them1 just as 
the ,gulf ,stream passes to the seaward 
from the eastern coast of the ,united   
,states4 ,the reason for this movement  
is readily found in the same principle  
which explains the oblique flow of the  
trades and counter trades in their      
passage to and from the equatorial belt4
 ,the particle of water under the       
equator1 though it flows to the west1   
has1 by virtue of the earth's rotation1 
an eastward-setting velocity of a       
thousand miles an hour4 ,starting toward
 the poles1 the particle is ever coming 
into regions of the sea where the fluid 
has a less easterly movement1 due to the

 earth's rotation on its axis4          
,consequently the journeying water by   
its momentum tends to move off in an    
easterly course4 ,attaining high        
latitudes and losing its momentum1 it   
abides in the realm long enough to      
become cooled4  ,we have already noted  
the fact that only a portion of the     
waters sent northward in the ,gulf      
,stream and the other currents which    
flow from the equator to the poles is   
returned by the surface flow which sets 
toward the equator along the eastern    
side of the basins4 ,the largest share  
of the tide effects its return journey  
in other ways4 ,some portion of this    
remainder sets equatorward in local cold
 streams1 such as that which pours forth
 through ,davis ,strait into ,baffin    
,bay1 flowing under the ,gulf ,stream   
waters for an unknown distance toward   
the tropics4 ,there are several of these
 local as yet little known streams1     
which doubtless bring about a certain   
amount of circulation between the polar 

regions and the tropical districts4     
,their effect is1 however1 probably     
small as compared with that massive     
drift which we have now to note4  ,the  
tropical waters when they attain high   
latitudes are constantly cooled1 and are
 overlaid by the warmer contributions of
 that tide1 and are thus brought lower  
and lower in the sea4 ,when they start  
downward they have1 as observations     
show1 a temperature not much above the  
freezing point of salt water4 ,they do  
not congeal for the reason that the salt
 of the ocean lowers the point at which 
the water solidifies to near #bh ,fahr4 
,the effect of this action is gradually 
to press down the surface cold water    
until it attains the very bottom in all 
the circumpolar regions4 ,at the same   
time this descending water drifts along 
the bottom of the ocean troughs toward  
the equatorial realm4 ,as this cold     
water is heavier than that which is of  
higher temperature and nearer the       
surface1 it has no tendency to rise4    

,being below the disturbing influences  
of any current save its own1 it does not
 tend1 except in a very small measure1  
to mingle with the warmer overlying     
fluid4 ,the result is that it continues 
its journey until it may come within the
 tropics without having gained a        
temperature of more than #ce ,fahr41 the
 increase in heat being due in small    
measure to that which it receives from  
the earth's interior and that which it  
acquires from the overlying warmer      
water4 ,attaining the region of the     
tropical current1 this drift water from 
the poles gradually rises1 to take the  
place of that which goes poleward1      
becomes warm1 and again starts on its   
surface journey toward the arctic and   
antarctic regions4  ,nothing is known as
 to the rate of this bottom drift from  
the polar districts toward the equator1 
but1 from some computation which he has 
made1 the writer is of the opinion that 
several centuries is doubtless required 
for the journey from the ,arctic ,circle

 to the tropics4 ,the speed of the      
movement probably varies2 it may at     
times require some thousand years for   
its accomplishment4 ,the effect of the  
bottom drift is to withdraw from seas in
 high latitudes the very cold water     
which there forms1 and to convey it     
beneath the seas of middle latitudes to 
a realm where it is well placed for the 
reheating process4 ,if all the cold     
water of circumpolar regions had to     
journey over the surface to the equator1
 the perturbing effect of its flow on   
the climates of various lands would be  
far greater than it is at present4      
,where such cold currents exist the     
effect is to chill the air without      
adding much to the rainfall2 while the  
currents setting northward not only warm
 the regions near which they flow1 but  
by so doing send from the water surfaces
 large quantities of moisture which fall
 as snow or rain4 ,thus the ,gulf       
,stream1 directly and indirectly1       
probably contributes more than half the 

rainfall about the ,atlantic basin4 ,the
 lack of this influence on the northern 
part of ,north ,america and ,asia causes
 those lands to be sterilized by cold1  
although destitute of permanent ice and 
snow upon their surfaces4  ,we readily  
perceive that the effect of the oceanic 
circulation upon the temperatures of    
different regions is not only great but 
widely contrasted4 ,by taking from the  
equatorial belt a large part of the heat
 which falls within that realm1 it      
lowers the temperature to the point     
which makes the district fit for the    
occupancy of man1 perhaps1 indeed1      
tenable to all the higher forms of life4
 ,this same heat removed to high        
latitudes tempers the winter's cold1 and
 thus makes a vast realm inhabitable    
which otherwise would be locked in      
almost enduring frosts4 ,furthermore1   
this distribution of temperatures tends 
to reduce the total wind energy by      
diminishing the trades and counter      
trades which are due to the variations  

of heat which are encountered in passing
 polarward from the equator4 ,still     
further1 but for this circulation of    
water in the sea1 the oceans about the  
poles would be frozen to their very     
bottom1 and this vast sheet of ice might
 be extended southward to within the    
parallels of fifty degrees north and    
south latitude1 although the waters     
under the equator might at the same time
 be unendurably hot and unfit for the   
occupancy of living beings4  ,a large   
part of the difficulties which          
geologists encounter in endeavouring to 
account for the changes of the past     
arise from the evidences of great       
climatal revolutions which the earth has
 undergone4 ,in some chapters of the    
great stone book1 whose leaves are the  
strata of the earth1 we find it plainly 
written in the impressions made by      
fossils that all the lands beyond the   
equatorial belt have undergone changes  
which can only be explained by the      
supposition that the heat and moisture  

of the countries have been subjected to 
sudden and remarkable changes4 ,thus in 
relatively recent times thick-leaved    
plants which retained their vegetation  
in a rather tender state throughout the 
year have flourished near to the poles1 
while shortly afterward an ice sheet1   
such as now covers the greater part of  
,greenland1 extended down to the line of
 the ,ohio ,river at ,cincinnati4       
,although these changes of climate are1 
as we shall hereafter note1 probably due
 to entangled causes1 we must look upon 
the modifications of the ocean streams  
as one of the most important elements in
 the causation4 ,we can the more readily
 imagine such changes to be due to the  
alterations in the course and volume of 
the ocean current when we note how      
trifling peculiarities in the geography 
of the shores--features which are likely
 to be altered by the endless changes   
which occur in the form of a            
continent--affect the run of these      
currents4 ,thus the growth of coral     

reefs in southern ,florida1 and1 in     
general1 the formation of that          
peninsula1 by narrowing the exit of the 
great current from the ,gulf of ,mexico1
 has probably increased its velocity4   
,if ,florida should again sink down1    
that current would go forth into the    
,north ,atlantic with the speed of about
 a mile an hour1 and would not have     
momentum enough to carry its waters over
 half the vast region which they now    
traverse4 ,if the lands about the       
western border of the ,caribbean ,sea1  
particularly the ,isthmus of ,darien1   
should be depressed to a considerable   
depth below the ocean level1 the        
tropical current would enter the        
,pacific ,ocean1 adding to the          
temperature of its waters all the       
precious heat which now vitalizes the   
,north ,atlantic region4 ,such a        
geographic accident would not only      
profoundly alter the life conditions of 
that part of the world1 but it would    
make an end of ,european civilization4  

,in the chapter on climatal changes     
further attention will be given to the  
action of ocean currents from the point 
of view of their influence on the heat  
and moisture of different parts of the  
world4 ,we now have to consider the last
 important influence of ocean           
currents--that which they directly      
exercise on the development of organic  
life4 ,the most striking effect of this 
nature which the sea streams bring about
 is caused by the ceaseless             
transportation to which they subject the
 eggs and seeds of animals and plants1  
as well as the bodies of the mature form
 which are moved about by the flowing   
waters4 ,but for the existence of these 
north and south flowing currents1 due to
 the presence of the continental        
barriers1 the living tenants of the seas
 would be borne along around the earth1 
always in the same latitude1 and        
therefore exposed to the same conditions
 of temperature4 ,in this state of      
affairs the influences which now make   

for change in organic species would be  
far less than they are4 ,journeying in  
the great whirlpools which the          
continental barriers make out of the    
westward setting tropical currents1     
these organic species are ever being    
exposed to alterations in their         
temperature conditions which we know to 
be favourable to the creation of those  
variations on which the advance of      
organic life so intimately depends4     
,thus the ocean currents not only help  
to vary the earth by producing changes  
in the climate of both sea and land1    
breaking up the uniformity which would  
otherwise characterize regions at the   
same distance from the equator1 but they
 induce1 by the consequences of the     
migrations which they enforce1 changes  
in the organic tenants of the sea4      
,another immediate effect of ocean      
streams arises where their currents of  
warm water come against shores or       
shallows of the sea4 ,at these points1  
if the water have a tropical            

temperature1 we invariably find a vast  
and rapid development of marine animals 
and plants1 of which the coral-making   
polyps are the most important4 ,in such 
positions the growth of forms which     
secrete solid skeletons is so rapid that
 great walls of their remains accumulate
 next the shore1 the mass being built   
outwardly by successive growths until   
the realm of the land may be extended   
for scores of miles into the deep4 ,in  
other cases vast mounds of this organic 
dbris may be accumulated in mid ocean   
until its surface is interspersed with  
myriads of islands1 all of which mark   
the work due to the combined action of  
currents and the marine life which they 
nourish4 ,probably more than four fifths
 of all the islands in the tropical belt
 are due in this way to the             
life-sustaining action of the currents  
which the trade winds create4  ,there   
are many secondary influences of a less 
important nature which are due to the   
ocean streams4 ,the reader will find on 

most wall-maps of the world certain     
areas in the central part of the oceans 
which are noted as ,sargassum seas1 of  
which that of the ,north ,atlantic1 west
 and south of the ,azore ,islands1 is   
one of the most conspicuous4 ,in these  
tracts1 which in extent may almost be   
compared with the continents1 we find   
great quantities of floating seaweed1   
the entangled fronds of which often form
 a mass sufficiently dense to slightly  
restrain the speed of ships4 ,when the  
men on the caravels of ,columbus entered
 this tangle1 they were alarmed lest    
they should be unable to escape from its
 toils4 ,it is a curious fact that these
 weeds of the sea while floating do not 
reproduce by spores the structures which
 answer to the seeds of higher plants1  
but grow only by budding4 ,it seems     
certain that they could not maintain    
their place in the ocean but for the    
action of the currents which convey the 
bits rent off from the shores where the 
plant is truly at home4 ,this vast      

growth of plant life in the ,sargassum  
basins doubtless contributed            
considerable and important deposits of  
sediment to the sea floors beneath the  
waters which it inhabits4 ,certain      
ancient strata1 known as the ,devonian  
black shale1 occupying the ,ohio valley 
and the neighbouring parts of ,north    
,america to the east and north of that  
basin1 appear to be accumulations which 
were made beneath an ancient ,sargassum 
sea4  ,the ocean currents have greatly  
favoured and in many instances          
determined the migrations not only of   
marine forms1 but of land creatures as  
well4 ,floating timber may bear the eggs
 and seeds of many forms of life to     
great distances until the rafts are cast
 ashore in a realm where1 if the        
conditions favour1 the creatures may    
find a new seat for their life4 ,seeds  
of plants incased in their often dense  
envelopes may1 because they float1 be   
independently carried great distances4  
,so it comes about that no sooner does a

 coral or other island rise above the   
waters of the sea than it becomes       
occupied by a varied array of plants4   
,the migrations of people1 even down to 
the time of the voyages which discovered
 ,america1 have in large measure been   
controlled by the run of the ocean      
streams4 ,the tropical set of the waters
 to the westward helped ,columbus on his
 way1 and enabled him to make a journey 
which but for their assistance could    
hardly have been accomplished4 ,this    
same current in the northern part of the
 ,gulf ,stream opposed the passage of   
ships from northern ,europe to the      
westward1 and to this day affects the   
speed with which their voyages are made4
                       ,,the ,,circuit  
,,of ,,the ,,rain4  ,we have now to     
consider those movements of the water   
which depend upon the fact that at      
ordinary temperatures the sea yields to 
the air a continued and large supply of 
vapour1 a contribution which is made in 
lessened proportion by water in all     

stages of coldness1 and even by ice when
 it is exposed to dry air4 ,this        
evaporation of the sea water is         
proportional to the temperature and to  
the dryness of the air where it rests   
upon the ocean4 ,it probably amounts on 
the average to somewhere about three    
feet per annum2 in regions favourably   
situated for the process1 as on the west
 coast of northern ,africa1 it may be   
three or four times as much1 while in   
the cold and humid air about the poles  
it may be as little as one foot4 ,when  
contributed to the air1 the water enters
 on the state of vapour1 in which state 
it tends to diffuse itself freely       
through the atmosphere by virtue of the 
motion which is developed in particles  
when in the vaporous or gaseous state4  
,the greater part of the water          
evaporated from the seas probably finds 
its way as rain at once back into the   
deep1 yet a considerable portion is     
borne away horizontally until it        
encounters the land4 ,the precipitation 

of the water from the air is primarily  
due to the cooling to which it is       
subjected as it rises in the atmosphere4
 ,over the sea the ascent is            
accomplished by the simple diffusion of 
the vapour or by the uprise through the 
arial shaft1 such as that near the      
equator or over the centres of the      
whirling storms4 ,it is when the air    
strikes the slopes of the land that we  
find it brought into a condition which  
most decidedly tends to precipitate its 
moisture4 ,lifted upward1 the air as it 
ascends the slopes is brought into      
cooler and more rarefied conditions4    
,losing temperature and expanding1 it   
parts with its water for the same reason
 that it does in the ascending current  
in the equatorial belt or in the        
chimneys of the whirl storms4 ,a general
 consequence of this is that wherever   
moisture-laden winds from the sea       
impinge upon a continent they lay down a
 considerable part of the water which   
they contain4  ,if all the lands were of

 the same height1 the rain would        
generally come in largest proportion    
upon their coastal belt1 or those       
portions of the shore-line districts    
over which the sea winds swept4 ,but as 
these winds vary in the amount of the   
watery vapour which they contain1 and as
 the surface of the land is very        
irregular1 the rainfall is the most     
variable feature in the climatal        
conditions of our sphere4 ,near the     
coasts it ranges from two or three      
inches in arid regions--such as the     
western part of the ,sahara and portions
 of the coast regions of ,chili and     
,peru--to eight hundred inches about the
 head waters of the ,brahmapootra ,river
 in northern ,india1 where the high     
mountains are swept over by the         
moisture-laden airs from the            
neighbouring sea4 ,here and there       
detached mountainous masses produce a   
singular local increase in the amount of
 the rainfall4 ,thus in the lake        
district in northwestern ,england the   

rainfall on the seaward side of         
mountains1 not over four thousand feet  
high1 is very much greater than it is on
 the other slope1 less than a score of  
miles away4 ,these local variations are 
common all over the world1 though they  
are but little observed4  ,in general1  
the central parts of continents are     
likely to receive much less rainfall    
than their peripheral portions4 ,thus   
the central districts of ,north         
,america1 ,asia1 and ,australia--three  
out of the five continental masses--have
 what we may call interior deserts4     
,africa has one such1 though it is north
 of the centre1 and extends to the      
shores of the ,mediterranean and the    
,atlantic4 ,the only continent without  
this central nearly rainless field is   
,south ,america1 where the sole         
characteristic arid district is situated
 on the western slope of the            
,cordilleran range4 ,in this case the   
peculiarity is due to the fact that the 
strong westerly setting winds which     

sweep over the country encounter no high
 mountains until they strike the ,andean
 chain4 ,they journey up a long and     
rather gradual slope1 where the         
precipitation is gradually induced1 the 
process being completed when they strike
 the mountain wall4 ,passing over its   
summit1 they appear as dry winds on the 
,pacific coast4  ,even while the winds  
frequently blow in from the sea1 as     
along the western coast of the          
,americas1 they may come over water     
which is prevailingly colder than the   
land4 ,this is characteristically the   
case on the western faces of the        
,american continent1 where the sea is   
cooled by the currents setting toward   
the equator from high latitudes4 ,such  
cool sea air encountering the warm land 
has its temperature raised1 and         
therefore does not tend to lay down its 
burden of moisture1 but seeks to take up
 more4 ,on this account the rainfall in 
countries placed under such conditions  
is commonly small4  ,by no means all the

 moisture which comes upon the earth    
from the atmosphere descends in the form
 of rain or snow4 ,a variable1 large1   
though yet undetermined amount falls in 
the form of dew4 ,dew is a precipitation
 of moisture which has not entered the  
peculiar state which we term fog or     
cloud1 but has remained invisible in the
 air4 ,it is brought to the earth       
through the radiation of heat which     
continually takes place1 but which is   
most effective during the darkened half 
of the day1 when the action is not      
counterbalanced by the sun's rays4      
,while the sun is high and the air is   
warm there is a constant absorption of  
moisture in large part from the ground  
or from the neighbouring water areas1   
probably in some part from those        
suspended stores of water1 the clouds1  
if such there be in the neighbourhood4  
,we can readily notice how clouds       
drifting in from the sea often melt into
 the dry air which they encounter4 ,late
 in the afternoon1 even before the sun  

has sunk1 the radiation of heat from the
 earth1 which has been going on all the 
while1 but has been less considerable   
than the incurrent of temperature1 in a 
way overtakes that influx4 ,the air next
 the surface becomes cooled from its    
contact with the refrigerating earth1   
and parts with its moisture1 forming a  
coating of water over everything it     
touches4 ,at the same time the moisture 
escaping from the warmed under earth    
likewise drops back upon its cooled     
surface almost as soon as it has        
escaped4 ,the thin sheet of water       
precipitated by this method is quickly  
returned to the air when it becomes     
warmed by the morning sunshine1 but     
during the night quantities of it are   
absorbed by the plants2 very often1     
indeed1 with the lowlier vegetation it  
trickles down the leaves and enters the 
earth about the base of the stem1 so    
that the roots may appropriate it4 ,our 
maize1 or ,indian corn1 affords an      
excellent example of a plant which1     

having developed in a land of droughts1 
is well contrived1 through its          
capacities for gathering dew1 to protect
 itself against arid conditions4 ,in an 
ordinary dew-making night the leaves of 
a single stem may gather as much as half
 a pint of water1 which flows down their
 surfaces to the roots4 ,so efficient is
 this dew supply1 this nocturnal        
cloudless rain1 that on the western     
coast of ,south ,america and elsewhere1 
where the ordinary supply of moisture is
 almost wanting1 many important plants  
are able to obtain from it much of the  
water which they need4 ,the effect is   
particularly striking along seashores1  
where the air1 although it may not have 
the humidity necessary for the formation
 of rain1 still contains enough to form 
dew4  ,it is interesting to note that   
the quantity of dew which falls upon an 
area is generally proportioned to the   
amount of living vegetation which it    
bears4 ,the surfaces of leaves are very 
efficient agents of radiation1 and the  

tangle which they make offers an amount 
of heat-radiating area many times as    
great as that afforded by a surface of  
bared earth4 ,moreover1 the ground      
itself can not well cool down to the    
point where it will wring the moisture  
out of the air1 while the thin membranes
 of the plants readily become so cooled4
 ,thus vegetation by its own structure  
provides itself with means whereby it   
may be in a measure independent of the  
accidental rainfall4 ,we should also    
note the fact that the dewfall is a     
concomitant of cloudless skies4 ,the    
quantity which is precipitated in a     
cloudy night is very small1 and this for
 the reason that when the heavens are   
covered the heat from the earth can not 
readily fly off into space4 ,under these
 conditions the temperature of the air  
rarely descends low enough to favour the
 precipitation of dew4  ,having noted   
the process by which in the rain circuit
 the water leaves the sea and the       
conditions of distribution when it      

returns to the earth1 we may now trace  
in more detail the steps in this great  
round4 ,first1 we should take note of   
the fact that the water after it enters 
the air may come back to the surface of 
the earth in either of two              
ways--directly in the manner of dewfall1
 or in a longer circuit which leads it  
through the state of clouds4 ,as yet we 
are not very well informed as to the law
 of the cloud-making1 but certain       
features in this picturesque and most   
important process have been tolerably   
well ascertained4  ,rising upward from  
the sea1 the vapour of water commonly   
remains transparent and invisible until 
it attains a considerable height above  
the surface1 where the cooling tends to 
make it assume again the visible state  
of cloud particles4 ,the formation of   
these cloud particles is now believed to
 depend on the fact that the air is full
 of small dust motes1 exceedingly small 
bits of matter derived from the many    
actions which tend to bring comminuted  

solid matter into the air1 as1 for      
instance1 the combustion of meteoric    
stones1 which are greatly heated by     
friction in their swift course through  
the air1 the ejections of volcanoes1 the
 smoke of forest and other fires1 etc4  
,these tiny bits1 floating in the air1  
because of their solid nature radiate   
their heat1 cool the air which lies     
against them1 and thereby precipitate   
the water in the manner of dew1 exactly 
as do the leaves and other structures on
 the surface of the earth4 ,in fact1 dew
 formation is essentially like cloud    
formation1 except that in the one case  
the water is gathered on fixed bodies1  
and in the other on floating objects4   
,each little dust raft with its cargo of
 condensed water tends1 of course1 to   
fall downward toward the earth's        
surface1 and1 except for the winds which
 may blow upward1 does so fall1 though  
with exceeding slowness4 ,its rate of   
descent may be only a few feet a day4   
,it was falling before it took on the   

load of water2 it will fall a little    
more rapidly with the added burden1 but 
even in a still air it might be months  
or years before it would come to the    
ground4 ,the reason for this slow       
descent may not at first sight be plain1
 though a little consideration will make
 it so4  ,if we take a shot of small    
size and a feather of the same weight1  
we readily note that their rate of      
falling through the air may vary in the 
proportion of ten to one or more4 ,it is
 easy to conceive that this difference  
is due to the very much less friction   
which the smaller body encounters in its
 motion by the particles of air4 ,with  
this point in mind1 the student should  
observe that the surface presented by   
solid bodies in relation to their solid 
contents is the greater the smaller the 
diameter4 ,a rough1 though not very     
satisfactory1 instance of this principle
 may be had by comparing the surface and
 interior contents of two boxes1 one ten
 feet square and the other one foot     

square4 ,the larger has six hundred feet
 of surface to one thousand cubic feet  
of interior1 or about half a square foot
 of outer surface to the cubic foot of  
contents2 while the smaller box has six 
feet of surface for the single cubic    
foot of interior1 or about ten times the
 proportion of exterior to contents4    
,the result is that the smaller         
particles encounter more friction in    
moving toward the earth1 until1 in the  
case of finely divided matter1 such as  
the particles of carbon in the smoke    
from an ordinary fire1 the rate of      
down-falling may be so small as to have 
little effect in the turbulent          
conditions of atmospheric motion4       
,illustration3 ,pocket ,creek1 ,cape    
,ann1 ,massachusetts4 ,note the         
relatively even size of the pebbles1 and
 the splash wave which sets them in     
motion4  ,the little drops of water     
which gather round dust motes1 falling  
but slowly toward the earth1 are free to
 obey the attractions which they        

exercise upon each other--impulses which
 are partly gravitative and partly      
electrical4 ,we have no precise         
knowledge concerning these movements1   
further than that they serve to         
aggregate the myriad little floats into 
cloud forms1 in which the rafts are     
brought near together1 but do not       
actually touch each other4 ,they are    
possibly kept apart by electrical       
repulsion4 ,in this state of association
 without union the divided water may    
undergo the curiously modified          
aggregations which give us the varied   
forms of clouds4 ,as yet we know little 
as to the cause of cloud shapes4 ,we    
remark the fact that in the higher of   
these agglomerations of condensed       
vapour1 the clouds which float at an    
elevation of from twenty to thirty      
thousand feet or more1 the masses are   
generally thin1 and arranged more or    
less in a leaflike form1 though even    
here a tendency to produce spherical    
clouds is apparent4 ,in this high realm 

floating water is probably in the frozen
 state1 answering to the form of dew1   
which we call hoar frost4 ,the lower    
clouds1 gathering in the still air1 show
 very plainly the tendency to           
agglomerate into spheres1 which appears 
to be characteristic of all vaporous    
material which is free to move by its   
own impulses4 ,it is probable that the  
spherical shape of clouds is more or    
less due to the same conditions as      
gathered the stellar matter from the    
ancient nebular chaos into the celestial
 spheres4 ,upon these spherical         
aggregations of the clouds the winds act
 in extremely varied ways4 ,the cloud   
may be rubbed between opposite currents1
 and so flattened out into a long       
streamer2 it may take the same form by  
being carried off by a current in the   
manner of smoke from a fire2 the spheres
 may be kept together1 so as to form the
 patchwork which we call mackerel sky2  
or they may be actually confounded with 
each other in a vast common cloud-heap4 

,in general1 where the process of       
aggregation of two cloud bodies occurs1 
changes of temperature are induced in   
the masses which are mixed together4 ,if
 the temperature resulting from this    
association of cloud masses is an       
average increase1 the cloud may become  
lighter1 and in the manner of a balloon 
move upward4 ,each of the motes in the  
cloud with its charge of vapour may be  
compared with the ballast of the        
balloon2 if they are warmed1 they send  
forth a part of their load of condensed 
water again to the state of invisible   
vapour4 ,rising to a point where it     
cools1 the vapour gathers back on the   
rafts and tends again to weight the     
cloud downward4 ,the ballast of an      
ordinary balloon has to be thrown away  
from its car2 but if some arrangement   
for condensing the moisture from the air
 could be contrived1 a balloon might be 
brought into the adjustable state of a  
cloud1 going up or down according as it 
was heated or cooled4  ,when the        

formation of the drop of water or       
snowflake begins1 the mass is very      
small4 ,if in descending it encounters  
great thickness of cloud1 the bit may   
grow by further condensation until it   
becomes relatively large4 ,generally in 
this way we may account for the         
diversities in the size of raindrops or 
snowflakes4 ,it often happens that the  
particles after taking on the form of   
snowflakes encounter in their descent   
air so warm that they melt into         
raindrops1 or1 if only partly melted1   
reach the surface as sleet4 ,or1        
starting as raindrops1 they may freeze1 
and in this simple state may reach the  
earth1 or after freezing they may gather
 other frozen water about them1 so that 
the hailstone has a complicated         
structure which1 from the point of view 
of classification1 is between a raindrop
 and a snowflake4  ,in the process of   
condensation--indeed1 in the steps which
 precede the formation of rain and      
snow--there is often more or less trace 

of electrical action2 in fact1 a part of
 the energy which was involved in the   
vapourization of water1 on its          
condensation1 even on the dust motes    
appears to be converted into electrical 
action1 which probably operates in part 
to keep the little aggregates of water  
asunder4 ,when they coalesce in drops or
 flakes1 this electricity often assumes 
the form of lightning1 which represents 
the swift passage of the electric store 
from a region where it is most abundant 
to one where it is less so4 ,the        
variations in this process of conveying 
the electricity are probably great4 ,in 
general1 it probably passes1 much as an 
electric current is conveyed1 through a 
wire from the battery which produces the
 force4 ,in other cases1 where the      
tension is high1 or1 in other words1    
where the discharge has to be hastened1 
we have the phenomena of lightning in   
which the current burns its way along   
its path1 as it may traverse a slender  
wire1 vapourizing it as it goes4 ,in    

general1 the lightning flash expends its
 force on the air conductors1 or lines  
of the moist atmosphere along which it  
breaks its path1 its energy returning   
into the vapour which it forms or the   
heat which it produces in the other     
parts of the air4 ,in some cases1       
probably not one in the thousand of the 
flashes1 the charge is so heavy that it 
is not used up in its descent toward the
 earth1 and so electrifies1 or1 as we   
say1 strikes1 some object attached to   
the earth1 through which it passes to   
the underlying moisture1 where it finds 
a convenient place to take on a quiet   
form4 ,almost all these hurried         
movements of electrical energy which    
intensely heat and light the air which  
they traverse fly from one part of a    
cloud to another1 or cross from cloud   
sphere to cloud sphere2 of those which  
start toward the earth1 many are        
exhausted before they reach its surface1
 and even those that strike convey but a
 portion of their original impulse to   

the ground4  ,the wearing-out effect of 
lightning in its journey along the air  
conductors in its flaming passages is   
well illustrated by what happens when   
the charge strikes a wire which is not  
large enough freely to convey it4 ,the  
wire is heated1 generally made white    
hot1 often melted1 and perhaps scattered
 in the form of vapour4 ,in doing this  
work the electricity may1 and often is1 
utterly dissipated--that is1 changed    
into heat4 ,it has been proposed to take
 advantage of this principle in         
protecting buildings from lightning by  
placing in them many thin wires1 along  
which the current will try to make its  
way1 being exhausted in melting or      
vaporizing the metal through which it   
passes4  ,there are certain other forms 
of lightning1 or at least of electrical 
discharges1 which produce light and     
which may best be described in this     
connection4 ,it occasionally happens    
that the earth becomes so charged that  
the current proceeds from its surface to

 the clouds4 ,more rarely1 and under    
conditions which we do not understand1  
the electric energy is gathered into a  
ball-like form1 which may move slowly   
along the surface until it suddenly     
explodes4 ,it is a common feature of all
 these forms of lightning which we have 
noted that they ordinarily make in their
 movement considerable noise4 ,this is  
due to the sudden displacement of the   
air which they traverse--displacement   
due to the action of heat in separating 
the particles4 ,it is in all essential  
regards similar to the sounds made by   
projectiles1 such as meteors or swift   
cannon shots1 as they fly through the   
air4 ,it is even more comparable to the 
sound produced by exploding gunpowder4  
,the first sound effect from the        
lightning stroke is a single rending    
note1 which endures no longer--indeed1  
not as long--as the explosion of a      
cannon4 ,heard near by1 this note is    
very sharp1 reminding one of the sound  
made by the breaking of glass4 ,the     

rolling1 continuous sound which we      
commonly hear in thunder is1 as in the  
case of the noise produced by cannon1   
due to echo from the clouds and the     
earth4 ,thunder is ordinarily much more 
prolonged and impressive in a           
mountainous country than in a region of 
plains1 because the steeps about the    
hearer reverberate the original single  
crash4  ,the distribution of            
thunderstorms is as yet not well        
understood1 but it appears in many cases
 that they are attendants on the        
advancing face of cyclones and          
hurricanes1 the area in front of these  
great whirlstorms being subjected to the
 condensation and irregular air         
movements which lead to the development 
of much electrical energy4 ,there are1  
however1 certain parts of the earth     
which are particularly subjected to     
lightning flashes4 ,they are common in  
the region near the equator1 where the  
ascending currents bring about heavy    
rains1 which mean a rapid condensation  

and consequent liberation of electrical 
energy4 ,they diminish in frequency     
toward the arctic regions4 ,an observer 
at the pole would probably fail ever to 
perceive strong flashes4 ,for the same  
reason thunderstorms are more frequent  
in summer1 the time when the difference 
in temperature between the surface and  
the upper air is greatest1 when1        
therefore1 the uprushes of air are      
likely to be most violent4 ,they appear 
to be more common in the night than in  
the daytime1 for the reason that        
condensation is favoured by the cooling 
which occurs in the dark half of the    
day4 ,it is rare1 indeed1 that a        
thunderstorm occurs near midday1 a      
period when the air is in most cases    
taking up moisture on account of the    
swiftly increasing heat4  ,there are    
other forms of electrical discharges not
 distinctly connected with the then     
existing condensation of moisture4 ,what
 the sailors call ,st4 ,elmo's fire--a  
brush of electric light from the mast   

tops and other projections of the       
ship--indicates the passage of          
electrical energy between the vessel and
 the atmosphere4 ,similar lights are    
said sometimes to be seen rising from   
the surface of the water4 ,such         
phenomena are at present not            
satisfactorily explained4 ,perhaps in   
the same group of actions comes the     
so-called ,jack-o'-lantern or           
,will-o'-the-wisp fires flashing from   
the earth in marshy places1 which are   
often described by the common people1   
but have never been observed by a       
naturalist4 ,if this class of           
illuminations really exists1 we have to 
afford them some other explanation than 
that they are emanations of             
self-inflamed phosphoretted hydrogen1 a 
method of accounting for them which     
illogically finds a place in many       
treatises on atmospheric phenomena4 ,a  
gas of any kind would disperse itself in
 the air2 it could not dance about as   
these lights are said to do1 and there  

is no chemical means known whereby it   
could be produced in sufficient purity  
and quantity from the earth to produce  
the effects which are described4#c      
,footnote #c3 ,the present writer has   
made an extended and careful study of   
marsh and swamp phenomena1 and is very  
familiar with the aspect of these fields
 in the nighttime4 ,he has never been   
able to see any sign of the             
,jack-o'-lantern light4 ,looking fixedly
 into any darkness1 such as is afforded 
by the depths of a wood1 the eye is apt 
to imagine the appearance of faint      
lights4 ,those who have had to do with  
outpost duty in an army know how the    
anxious sentry1 particularly if he is   
new to the soldier's trade1 will often  
imagine that he sees lights before him4 
,sometimes the pickets will be so       
convinced of the fact that they see     
lights that they will fire upon the     
fiction of the imaginations4 ,these     
facts make it seem probable that the    
,jack-o'-lantern and his companion1 the 

,will-o'-the-wisp1 are stories of the   
overcredulous4  ,in the upper air1 or   
perhaps even beyond the limits of the   
field which deserves the name1 in the   
regions extending from the poles to near
 the tropics1 there occur electric      
glowings commonly known as the aurora   
borealis4 ,this phenomenon occurs in    
both hemispheres4 ,these illuminations1 
though in some way akin to those of     
lightning1 and though doubtless due to  
some form of electrical action1 are     
peculiar in that they are often attended
 by glows as if from clouds1 and by     
pulsations which indicate movements not 
at electric speed4 ,as yet but little is
 known as to the precise nature of these
 curious storms4 ,it has been claimed1  
however1 that they are related to the   
sun spots2 those periods when the solar 
spots are plenty1 at intervals of about 
eleven years1 are the times of auroral  
discharges4 ,still further1 it seems    
probable that the magnetic currents of  
the earth1 that circling energy which   

encompasses the sphere1 moving round in 
a general way parallel to the equator1  
are intensified during these            
illuminations of the circumpolar skies4 
,,geological ,,work ,,of ,,water4  ,we  
turn now to the geological work which is
 performed by falling water4 ,where the 
rain or snow returns from the clouds to 
the sea1 the energy of position given to
 the water by its elevation above the   
earth through the heat which it acquired
 from the sun is returned to the air    
through which it falls or to the ocean  
surface on which it strikes4 ,in this   
case the circuit of the rain is short   
and without geological consequence which
 it is worth while to consider1 except  
to note that the heat thus returned is  
likely to be delivered in another realm 
than that in which the falling water    
acquired the store1 thus in a small way 
modifying the climate4 ,when1 however1  
the precipitation occurs on the surface 
of the land1 the drops of frozen or     
fluid water apply a part of their energy

 in important geological work1 the like 
of which is not done where they return  
at once to the sea4  ,illustration3     
,fig4 #aj4--,showing the diverse action 
of rain on wooded and cleared fields1 a1
 wooded area2 b1 tilled ground4  ,we    
shall first consider what takes place   
when the water in the form of drops of  
rain comes to the surface of the land4  
,descending as they do with a           
considerable speed1 these raindrops     
apply a certain amount of energy to the 
surface on which they fall4 ,although   
the beat of a raindrop is proverbially  
light1 the stroke is not ineffective4   
,observing what happens where the action
 takes place on the surface of bare     
rock1 we may notice that the grains of  
sand or small pebbles which generally   
abound on such surfaces1 if they be not 
too steeply inclined1 dance about under 
the blows which they receive4 ,if we    
could cover hard plate glass1 a much    
firmer material than ordinary stone1    
with such bits1 we should soon find that

 its surface would become scratched all 
over by the friction4 ,moreover1 the    
raindrops perceptibly urge the small    
detached bits of stone down the slopes  
toward the streams4  ,if all the earth's
 surface were bare rocks1 the blow of   
the raindrops would deserve to be       
reckoned among the important influences 
which lead to the wearing of land4 ,as  
it is1 when a country is in a state of  
,nature1 only a small part of its       
surface is exposed to this kind of      
wearing4 ,where there is rain enough to 
effect any damage1 there is sure to be  
sufficient vegetation to interpose a    
living and self-renewed covering between
 the rocks and the rain4 ,even the      
lichens which coat what at first sight  
often seems to be bare rock afford an   
ample covering for this purpose4 ,it is 
only where man bares the field by       
stripping away and overturning this     
protecting vegetation that the raindrops
 cut away the earth4 ,the effect of     
their action can often be noted by      

observing how on ploughed ground a flat 
stone or a potsherd comes after a rain  
to cap a little column4 ,the geologist  
sometimes finds in soft sandstones that 
the same action is repeated in a larger 
way where a thin fragment of hard rock  
has protected a column many feet in     
height against the rain work which has  
shorn down the surrounding rock4  ,when 
water strikes the moistened surface it  
at once loses the droplike form which   
all fluids assume when they fall through
 the air4#d  ,footnote #d3 ,this        
principle of the spheroidal form in     
falling fluids is used in making        
ordinary bird shot4 ,the melted lead    
drops through sievelike openings1 the   
resulting spheres of the metal being    
allowed to fall into water which chills 
them4 ,iron shot1 used in cutting stone1
 where they are placed between the saw  
and the surface of the rock1 are also   
made in the same manner4 ,the descending
 fluid divides into drops because it is 
drawn out by the ever-increasing speed  

of the falling particles1 which soon    
make the stream so thin that it can not 
hold together4  ,when the raindrops     
coalesce on the surface of the earth1   
the rle of what we may call land water  
begins4 ,thenceforward until the fluid  
arrives at the surface of the sea it is 
continually at work in effecting a great
 range of geological changes1 only a few
 of which can well be traced by the     
general student4 ,the work of land water
 is due to three classes of             
properties--to the energy with which it 
is endowed by virtue of its height above
 the sea1 a power due to the heat of the
 sun2 to the capacity it has for taking 
substances into solution2 and to its    
property of giving some part of its own 
substance to other materials with which 
it comes in contact4 ,the first of these
 groups of properties may be called     
dynamical2 the others1 chemical4  ,the  
dynamic value of water when it falls    
upon the land is the amount of energy it
 can apply in going down the slope which

 separates it from the sea4 ,a ton of   
the fluid1 such as may gather in an     
ordinary rain on a thousand square feet 
of ground in the highlands of a         
country--say at an elevation of a       
thousand feet above the sea--expends    
before it comes to rest in the great    
reservoir as much energy as would be    
required to lift that weight from the   
ocean's surface to the same height4 ,the
 ways in which this energy may be       
expended we shall now proceed in a      
general way to trace4  ,as soon as the  
water has been gathered1 from its drop  
to its sheet state--a process which     
takes place as soon as it falls--the    
fluid begins its downward journey4 ,on  
this way it is at once parted into two  
distinct divisions1 the surface water   
and the ground water3 the former courses
 more or less swiftly1 generally at the 
rate of a mile or more an hour1 in the  
light of day2 the latter enters the     
interstices of the earth1 slowly        
descends therein to a greater or less   

depth1 and finally1 journeying perhaps  
at the rate of a mile a year1 rejoins   
the surface water1 escaping through the 
springs4 ,the proportion of these two   
classes1 the surface and the ground     
water1 varies greatly1 and an           
intermixture of them is continually     
going on4 ,thus on the surface of bare  
rock or frozen earth all the rain may go
 away without entering the ground4 ,on  
very sandy fields the heaviest rainfall 
may be taken up by the porous earth1 so 
that no streams are found4 ,on such     
surfaces the present writer has observed
 that a rainfall amounting to six inches
 in depth in two hours produced no      
streams whatever4 ,we shall first follow
 the history of the surface water1      
afterward considering the work which the
 underground movements effect4  ,if the 
student will observe what takes place on
 a level ploughed field--which1 after   
all1 will not be perfectly level1 for   
all fields are more or less             
undulating--he will note that1 though   

the surface may have been smoothed by a 
roller until it appears like a floor1   
the first rain1 where the fall takes    
place rapidly enough to produce surface 
streams1 will create a series of little 
channels which grow larger as they      
conjoin1 the whole appearing to the eye 
like a very detailed map1 or rather     
model1 of a river system2 it is1 indeed1
 such a system in miniature4 ,if he will
 watch the process by which these       
streamlet beds are carved1 he will      
obtain a tolerably clear idea as to that
 most important work which the greater  
streams do in carving the face of the   
lands4 ,the water is no sooner gathered 
into a sheet than1 guided by the        
slightest irregularities which it       
encounters1 it begins to flow4 ,at first
 the motion is so slow that it does not 
disturb its bed1 but at some points in  
the bottom of the sheet the movement    
soon becomes swift enough to drag the   
grains of sand and clay from their      
adhesions1 bearing them onward4 ,as soon

 as this beginning of a channel is      
formed the water moves more swiftly in  
the clearer way2 it therefore cuts more 
rapidly1 deepening and enlarging its    
channel1 and making its motion yet more 
free4 ,the tiny rills join the greater1 
all their channels sway to and fro as   
directed this way and that by chance    
irregularities1 until something like    
river basins are carved out1 those      
gentle slopes which form broad valleys  
where the carving has been due to the   
wanderings of many streams4 ,if the     
field be large1 considerable though     
temporary brooks may be created1 which  
cut channels perhaps a foot in depth4   
,at the end of this miniature stream    
system we always find some part of the  
waste which has been carved out4 ,if the
 streamlet discharges into a pool1 we   
find the tiny representative of deltas1 
which form such an important feature on 
the coast line where large rivers enter 
seas or lakes4 ,along the lines of the  
stream we may observe here and there    

little benches1 which are the equivalent
 in all save size of the terraces that  
are generally to be observed along the  
greater streams4 ,in fact1 these        
accidents of an acre help in a most     
effective way the student to understand 
the greater and more complicated        
processes of continental erosion4  ,a   
normal river--in fact1 all the greater  
streams of the earth--originates in high
 country1 generally in a region of      
mountains4 ,here1 because of the        
elevation of the region1 the streams    
have cut deep gorges or extensive       
valleys1 all of which have slopes       
leading steeply downward to torrent     
beds4 ,down these inclined surfaces the 
particles worn off from the hard rock by
 frost and by chemical decay gradually  
work their way until they attain the bed
 of the stream4 ,the agents which assist
 gravitation in bearing this detritus   
downward are many1 but they all work    
together for the same end4 ,the stroke  
of the raindrop accomplishes something1 

though but little2 the direct washing   
action of the brooklets which form      
during times of heavy rain1 but dry out 
at the close of the storm1 do a good    
deal of the work2 thawing and freezing  
of the water contained in the mass of   
detritus help the movement1 for1        
although the thrust is in both          
directions1 it is most effective        
downhill2 the wedges of tree roots1     
which often penetrate between and under 
the stones1 and there expand in their   
process of growth1 likewise assist the  
downward motion4 ,the result is that on 
ordinary mountain slopes the layer of   
fragments constituting the rude soil is 
often creeping at the rate of from some 
inches to some feet a year toward the   
torrent bed4 ,if there be cliffs at the 
top of the slope1 as is often the case1 
very extensive falls of rock may take   
place from it1 the masses descending    
with such speed that they directly      
attain the stream4 ,if the steeps be low
 and the rock divided into vertical     

joints1 especially where there is a soft
 layer at the base of the steep1        
detached masses from the precipice may  
move slowly and steadfastly down the    
slope1 so little disturbed in their     
journey that trees growing upon their   
summits may continue to develop for the 
thousands of years before the mass      
enters the stream bed4  ,although the   
fall of rocks from precipices does not  
often take place in a conspicuously     
large way1 all great mountain regions   
which have long been inhabited by man   
abound in traditions and histories of   
such accidents4 ,within a century or two
 there have been a dozen or more        
catastrophes of this nature in the      
inhabited valleys of the ,alps4 ,as     
these accidents are at once instructive 
and picturesque1 it is well to note     
certain of them in some detail4 ,at     
,yvorgne1 a little parish on the north  
shore of the ,rhne1 just above the lake 
of ,geneva1 tradition tells that an     
ancient village of the name was         

overwhelmed by the fall of a great      
cliff4 ,the vast dbris forming the steep
 slope which was thus produced now bears
 famous vineyards1 but the vintners     
fancy that they from time to time hear  
deep in the earth the ringing of the    
bells which belonged to the overwhelmed 
church4 ,in #ahjf the district of       
,goldau1 just north of ,lake ,lucerne1  
was buried beneath the ruins of a peak  
which1 resting upon a layer of clay1    
slipped away like a launching ship on   
the surface of the soft material4 ,the  
dbris overwhelmed a village and many    
detached houses1 and partly filled a    
considerable lake4 ,the wind produced by
 this vast rush of falling rock was so  
great that people were blown away by it2
 some1 indeed1 were killed in this      
singular manner4  ,the most interesting 
field of these ,swiss mountain falls is 
a high mountain valley of               
amphitheatrical form1 known as the      
,diablerets1 or the devil's own         
district4 ,this great circus1 which lies

 at the height of about four thousand   
feet above the sea1 is walled around on 
its northern side by a precipice1 above 
which rest1 or rather once rested1 a    
number of mountain peaks of great bulk4 
,the region has long been valued for the
 excellent pasturage which the head of  
the valley affords4 ,two costly roads1  
indeed1 have been built into it to      
afford footpaths for the flocks and     
herds and their keepers in the summer   
season4 ,through this human experience  
with the valley1 we have a record of    
what has gone on in this part of the    
mountain wilderness4 ,within the period 
of history and tradition1 three very    
great mountain falls have occurred in   
this field1 each having made its memory 
good by widespread disaster which it    
brought to the people of the chalets4   
,the last of these was brought about by 
the fall of a great peak which spread   
itself out in a vast field of ruins in  
the valley below4 ,the belt of          
destruction was about half a mile wide  

and three miles long4 ,when the present 
writer last saw it1 a quarter of a      
century ago1 it was still a wilderness  
of great rocks1 but here and there the  
process of their decay was giving a     
foothold for herbage1 and in a few      
centuries the field will doubtless be so
 verdure-clad that its story will not be
 told on its face4 ,it is likely1       
however1 to be preserved in the memory  
of the people1 and this through a       
singular and pathetic tradition which   
has grown up about the place1 one which1
 if not true1 comes at least among the  
legends which we should like to believe4
  ,as told the present writer by a      
native of the district1 it happened     
when1 in the nighttime the mountain came
 down1 the herdsmen and their cows      
gathered in the chalets--stout buildings
 which are prepared to resist avalanches
 of snow4 ,in one of these1 which was   
protected from crushing by the position 
of the stones which covered it1 a       
solitary herdsman found himself alive in

 his unharmed dwelling4 ,with him in the
 darkness were the cows1 a store of food
 and water1 and his provisions for the  
long summer season4 ,with nothing but   
hope to animate him1 he set to work     
burrowing upward among the rocks1       
storing the dbris in the room of the    
chalet4 ,he toiled for some months1 but 
finally emerged to the light of day1    
blanched by his long imprisonment in the
 darkness1 but with the strength to bear
 him to his home4 ,in place of the      
expected warm welcome1 the unhappy man  
found himself received as a ghost4 ,he  
was exorcised by the priest and driven  
away to the distance4 ,it was only when 
long afterward his path of escape was   
discovered that his history became      
known4  ,returning to the account of the
 dbris which descends at varied speed   
into the torrents1 we find that when the
 detritus encounters the action of these
 vigorous streams it is rapidly ground  
to pieces while it is pushed down the   
steep channels to the lower country4    

,where the stones are of such size that 
the stream can urge them on1 they move  
rapidly2 at least in times when the     
torrent is raging4 ,they beat over each 
other and against the firm-set rocks2   
the more they wear1 the smaller they    
become1 and the more readily they are   
urged forward4 ,where the masses are too
 large to be stirred by the violent     
current1 they lie unmoved until the     
pounding of the rolling stones reduces  
them to the proportions where they may  
join the great procession4 ,ordinarily  
those who visit mountains behold their  
torrents only in their shrunken state1  
when the waters stir no stones1 and fail
 even to bear a charge of mud1 all      
detachable materials having been swept  
away when the streams course with more  
vigour4 ,in storm seasons the conditions
 are quite otherwise2 then the swollen  
torrents1 their waters filled with clay 
and sand1 bear with them great          
quantities of boulders1 the collisions  
of which are audible above the muffled  

roar of the waters1 attesting the very  
great energy of the action4  ,when the  
waste on a mountain slope lies at a     
steep angle1 particularly where the     
accumulation is due to the action of    
ancient glaciers1 it not infrequently   
happens that when the ground is softened
 with frost great masses of the material
 rush down the slope in the manner of   
landslides4 ,the observer readily notes 
that in many mountain regions1 as1 for  
instance1 in the ,white ,mountains of   
,new ,hampshire1 the steep slopes are   
often seamed by the paths of these great
 landslides4 ,their movement1 indeed1 is
 often begun by sliding snow1 which     
gives an impulse to the rocks and earth 
which it encounters in its descent4 ,at 
a place known as the ,wylie ,notch1 in  
the ,white ,mountains1 in the early part
 of this century1 a family of that name 
was buried beneath a mass of glacial    
waste which had hung on the mountain    
slope from the ancient days until a     
heavy rain1 following on a period of    

thaw1 impelled the mass down the slope4 
,although there have been few such      
catastrophes noted in this country1 it  
is because our mountains have not been  
much dwelt in4 ,as they become thickly  
inhabited as the ,alps are1 men are sure
 to suffer from these accidents4  ,as   
the volume of a mountain torrent        
increases through the junction of many  
tributaries1 the energy of its moving   
waters becomes sufficient to sweep away 
the fragments which come to its bed4    
,before this stage is attained the      
stream rarely touches the solid under   
rock of the mountain1 the base of the   
current resting upon the larger loose   
stones which it was unable to stir4 ,in 
this pebble-paved section1 because the  
stream could not attack the foundation  
rock1 we find no gorges--in fact1 the   
whole of this upper section of the      
torrent system is peculiarly conditioned
 by the fact that the streams are       
dealing not with bed-rock1 but with     
boulders or smaller loose fragments4 ,if

 they cut a little channel1 the         
materials from either side slip the     
faster1 and soon repave the bed4 ,but   
when the streams have by a junction     
gained strength1 and can keep their beds
 clear1 they soon carve down a gorge    
through which they descend from the     
upper mountain realm to the larger      
valleys1 where their conjoined waters   
take on a riverlike aspect4 ,it should  
be noted here that the cutting power of 
the water moving in the torrent or in   
the wave1 the capacity it has for       
abrading rock1 resides altogether in the
 bits of stone or cutting tools with    
which it is armed4 ,pure water1 because 
of its fluidity1 may move over or       
against firm-set stones for ages without
 wearing them2 but in proportion as it  
moves rocky particles of any size1 the  
larger they are1 the more effective the 
work1 it wears the rock over which it   
flows4 ,a capital instance of this may  
be found where a stream from a hose is  
used in washing windows4 ,if the water  

be pure1 there is no effect upon the    
glass2 but if it be turbid1 containing  
bits of sand1 in a little while the     
surface will appear cloudy from the     
multitude of line scratches which the   
hard bits impelled by the water have    
inflicted upon it4 ,a somewhat similar  
case occurs where the wind bears sand   
against window panes or a bottle which  
has long lain on the shore4 ,the glass  
will soon be deeply carved by the       
action1 assuming the appearance which we
 term ground4 ,this principle is made   
use of in the arts4 ,glass vessels or   
sheets are prepared for carving by      
pasting paper cut into figures on their 
surfaces4 ,the material is then exposed 
to a jet of air or steam-impelling sand 
grains2 in a short time all the surface 
which has not been protected by paper   
has its polish destroyed and is no      
longer translucent4  ,the passage from  
the torrent to the river1 though not in 
a geographical way distinct1 is         
indicated to the observant eye by a     

simple feature--namely1 the appearance  
of alluvial terraces1 those more or less
 level heaps of water-borne dbris which 
accumulate along the banks of rivers1   
which1 indeed1 constitute the difference
 between those streams and torrents4    
,where the mountain waters move swiftly1
 they manage to bear onward the waste   
which they receive4 ,even where the     
blocks of stone cling in the bed1 it is 
only a short time before they are again 
set in motion or ground to pieces4 ,if  
by chance the detritus accumulates      
rapidly1 the slope is steepened and the 
work of the torrent made more efficient4
 ,as the torrent comes toward the base  
of the mountains1 where it neither finds
 nor can create steep slopes over which 
to flow1 its speed necessarily          
diminishes4 ,with each reduction in this
 feature its carrying power very rapidly
 diminishes4 ,thus water flowing at the 
rate of ten miles an hour can urge      
stones four times the mass that it can  
move when its speed is reduced to half  

that rate4 ,the result is that on the   
lowlands1 with their relatively gentle  
slopes1 the combined torrents1 despite  
the increase in the volume of the stream
 arising from their confluence1 have to 
lay down a large part of their load of  
detritus4  ,if we watch where a torrent 
enters a mountain river1 we observe that
 the main stream in a way sorts over the
 waste contributed to it1 bearing on    
only those portions which its rate of   
flow will permit it to carry1 leaving   
the remainder to be built into the bank 
in the form of a rude terrace4 ,this    
accumulation may not extend far below   
the point where the torrent which       
imported the dbris joins the main       
stream2 a little farther down1 however1 
we are sure to find another such        
junction and a second accumulation of   
terrace material4 ,as these             
contributions increase1 the terrace     
accumulations soon become continuous1   
lying on one side or the other of the   
river1 sometimes bordering both banks of

 the stream4 ,in general1 it can be said
 that so long as the rate of fall of the
 torrent exceeds one hundred feet to the
 mile it does not usually exhibit these 
shelves of detritus4 ,below that rate of
 descent they are apt to be formed4     
,much1 however1 depends upon the amount 
of detritus which the stream bears and  
the coarseness of it2 moreover1 where   
the water goes through a gorge in the   
manner of a flume with steep rocky      
sides1 it can urge a larger amount      
before it than when it traverses a wide 
valley1 through which it passes1 it may 
be1 in a winding way4  ,at first sight  
it may seem rather a fine distinction to
 separate torrents from rivers by the   
presence or absence of terraces4 ,as we 
follow down the stream1 however1 and    
study its action in relation to these   
terraces1 and the peculiar history of   
the detritus of which they are composed1
 we perceive that these latter          
accumulations are very important        
features4 ,beginning at first with small

 and imperfect alluvial plains1 the     
river1 as it descends toward the sea1   
gaining in store of water and in the    
amount of dbris which comes with that   
water from the hills1 while the rate of 
fall and consequent speed of the current
 are diminished1 soon comes to a stage  
where it is engaged in an endless       
struggle with the terrace materials4 ,in
 times of flood1 the walls of the       
terraces compel the tide to flow over   
the tops of these accumulations4 ,owing 
to the relative thinness of the water   
beyond the bed1 and to the growth of    
vegetation there1 the current moves more
 slowly1 and therefore lays down a      
considerable deposit of the silt and    
sand which it contains4 ,this may result
 during a single flood in lifting the   
level of the terrace by some inches in  
height1 still further serving to        
restrict the channel4 ,along the banks  
of the ,mississippi and other large     
rivers the most of this detritus falls  
near the stream2 a little of it         

penetrates to the farther side of the   
plains1 which often have a width of ten 
miles or more4 ,the result is that a    
broad elevation is constructed1 a sort  
of natural mole or levee1 in a measure  
damming the flood waters1 which can now 
only enter the back swamps through the  
channels of the tributary streams4 ,each
 of these back swamps normally          
discharges into the main stream through 
a little river of its own1 along the    
banks of which the natural levees do not
 develop4  ,we have now to note a       
curious swinging movement of rivers     
which was first well observed by the    
skilful engineers of ,british ,india4   
,this movement can best be illustrated  
by its effects4 ,if on any river which  
winds through alluvial plains a jetty is
 so constructed as to deflect the stream
 at any point1 the course which it      
follows will be altered during its      
subsequent flow1 it may be1 for the     
distance of hundreds of miles4 ,it will 
be perceived that in its movements a    

river normally strikes first against one
 shore and then against the other4 ,its 
water in a general way moves as does a  
billiard ball when it flies from one    
cushion to another4 ,it is true that in 
a torrent we have the same conditions of
 motion2 but there the banks are either 
of hard rock or1 if of detritus1 they   
are continually moving into the stream  
in the manner before described4 ,in the 
case of the river1 however1 its points  
of collision are often on soft banks1   
which are readily undermined by the     
washing action of the stream4 ,in the   
ordinary course of events1 the river    
beginning1 we may imagine1 with a       
straight channel1 had its current       
deflected by some obstacle1 it may be   
even by the slight pressure of a        
tributary stream1 is driven against one 
bank2 thence it rebounds and strikes the
 other4 ,at each point of impinge it    
cuts the alluvium away4 ,it can bear on 
only a small portion of that which it   
thus obtains2 the greater part of the   

material is deposited on the opposite   
side of the stream1 but a little lower  
down1 where it makes a shallow4 ,on     
these shallows water-loving plants and  
even certain trees1 such as the willows 
and poplars1 find a foothold4 ,when the 
stream rises1 the sediment settles in   
this tangle1 and soon extends the       
alluvial plain from the neighbouring    
bank1 or in rarer cases the river comes 
to flow on either side of an island of  
its own construction4 ,the natural      
result of this billiard-ball movement of
 the waters is that the path of the     
stream is sinuous4 ,the less its rate of
 fall and the greater the amount of silt
 it obtains from its tributaries1 the   
more winding its course becomes4 ,this  
gain in those parts of the river's      
curvings where deposition tends to take 
place may be accelerated by             
tree-planting4 ,thus a skilful owner of 
a tract of land on the south bank of the
 ,ohio ,river1 by assiduously planting  
willow trees on the front of his        

property1 gained in the course of thirty
 years more than an acre in the width of
 his arable land4 ,when told by the     
present writer that he was robbing his  
neighbours on the other side of the     
stream1 he claimed that their ignorance 
of the laws of river motion was         
sufficient evidence that they did not   
deserve to own land4  ,in the primitive 
state of a country the water-loving     
plants1 particularly the trees which    
flourish in excessively humid           
conditions1 generally make a certain    
defence against these incursions of the 
streams4 ,but when a river has gained an
 opening in the bank it can1 during a   
flood1 extend its width often to the    
distance of hundreds of feet4 ,during   
the inundations of the ,mississippi the 
river may at times be seen to eat away  
acres of land in a single day along one 
of the outcurves of its banks4 ,the     
undermined forests falling into the     
flood join the great procession of drift
 timber1 composed of trees which have   

been similarly uprooted1 which occupies 
the middle part of the stream4 ,this    
driftwood belt often has a width of     
three or four hundred feet1 the         
entangled stems and branches making it  
difficult for a boat to pass from one   
side of the river to the other4         
,illustration3 ,fig4 #aa4--,oxbows and  
cut-off4 ,showing the changes in the    
course of a river in its alluvial plain4
  ,when the curves of a river have been 
developed to a certain point 7see ,fig4 
#aa71 when they have attained what is   
called the oxbow form1 it often happens 
that the stream breaks through the      
isthmus which connects one of the       
peninsulas with the mainland4 ,where1 as
 is not infrequently the case1 the bend 
has a length of ten miles or more1 the  
water just above and below the new-made 
opening is apt to differ in height by   
some feet4 ,plunging down the declivity1
 the stream1 flowing with great         
velocity1 soon enlarges the channel so  
that its whole tide may take the easier 

way4 ,when this result is accomplished1 
the old curve is deserted1 sand bars are
 formed across their mouths1 which may  
gradually grow to broad alluvial plains1
 so that the long-surviving1            
crescent-shaped lake1 the remnant of the
 river bed1 may be seen far from the    
present course of the ever-changing     
stream4 ,gradually the accumulations of 
vegetable matter and the silt brought in
 by floods efface this moat or oxbow    
cut-off1 as it is so commonly termed4   
,as soon as the river breaks through the
 neck of a peninsula in the manner above
 described1 the current of the stream   
becomes much swifter for many miles     
below and above the opening4 ,slowly1   
however1 the slopes are rearranged      
throughout its whole course1 yet for a  
time the stream near the seat of the    
change becomes straighter than before1  
and this for the reason that its swifter
 current is better able to dispose of   
the dbris which is supplied to it4 ,the 
effect of a change in the current       

produced by such new channels as we have
 described as forming across the        
isthmuses of bends is to perturb the    
course of the stream in all its         
subsequent downward length4 ,thus an    
oxbow cut-off formed near the junction  
of the ,ohio and ,mississippi may tend  
more or less to alter the swings of the 
,mississippi all the way to the ,gulf of
 ,mexico4  ,although the swayings of the
 streams to and fro in their alluvial   
plains will give the reader some idea as
 to the struggle which the greater      
rivers have with the dbris which is     
committed to them1 the full measure of  
the work and its consequences can only  
be appreciated by those who have studied
 the phenomena on the ground4 ,a river  
such as the ,mississippi is endlessly   
endeavouring to bear its burden to the  
sea4 ,if its slope were a uniform       
inclined plane1 the task might readily  
be accomplished2 but in this1 as in     
almost all other large water ways1 the  
slope of the bed is ever diminishing    

with its onward course4 ,the same water 
which in the mountain torrent of the    
,appalachians or ,cordilleras rolled    
along stones several feet in diameter   
down slopes of a hundred feet or more to
 the mile can in the lower reaches of   
the stream move no pebbles which are    
more than one fourth of an inch in      
diameter over slopes which descend on   
the average about half a foot in a mile4
 ,thus at every stage from the torrent  
to the sea the detritus has from time to
 time to rest within the alluvial banks1
 there awaiting the decay which slowly  
comes1 and which may bring it to the    
state where it may be dissolved in the  
water1 or divided into fragments so     
small that the stream may bear them on4 
,a computation which the present writer 
has made shows that1 on the average1 it 
requires about forty thousand years for 
a particle of stone to make its way down
 the ,mississippi to the sea after it   
has been detached from its original bed4
 ,of course1 some bits may make the     

journey straightforwardly2 others may   
require a far greater time to accomplish
 the course which the water itself makes
 at most in a few weeks4 ,this long     
delay in the journey of the detritus--a 
delay caused by its frequent rests in   
the alluvial plain--brings about        
important consequences which we will now
 consider4  ,as an alluvial plain is    
constructed1 we generally find at the   
base pebbly material which fell to the  
bottom in the current of the main stream
 as the shores grew outward4 ,above this
 level we find the deposits laid down by
 the flood waters containing no pebbles1
 and this for the reason that those     
weightier bits remained in the stream   
bed when the tide flowed over the plain4
 ,as the alluvial deposit is laid down1 
a good deal of vegetable matter was     
built into it4 ,generally this has      
decayed and disappeared4 ,on the surface
 of the plain there has always been     
growing abundant vegetation1 the remains
 of which decayed on the surface in the 

manner which we may observe at the      
present day4 ,this decomposing vegetable
 matter within and upon the porous      
alluvial material produces large        
quantities of carbonic acid1 a gas which
 readily enters the rain water1 and     
gives it a peculiar power of breaking up
 rock matter4 ,acting on the dbris1 this
 gas-charged water rapidly brings about 
a decay of the fragments4 ,much of the  
material passes at once into solution in
 this water1 and drains away through the
 multitudinous springs which border the 
river4 ,as this matter is completely    
dissolved1 as is sugar in water1 it goes
 straight away to the sea without ever  
again entering the alluvium4 ,in many1  
if not most1 cases this dissolving work 
which is going on in alluvial terraces  
is sufficient to render a large part of 
the materials which they contain into   
the state where it disappears in an     
unseen manner2 thus while the annual    
floods are constantly laying down       
accumulations on the surface of these   

plains1 the springs are bearing it away 
from below4  ,in this way1 through the  
decomposition which takes place in them1
 all those river terraces where much    
vegetable matter is mingled with the    
mineral substances1 become laboratories 
in which substances are brought into    
solution and committed to the seas4 ,we 
find in the water of the ocean a great  
array of dissolved mineral substances2  
it1 indeed1 seems probable that the sea 
water contains some share1 though       
usually small1 of all the materials     
which rivers encounter in their journey 
over and under the lands4 ,as the waters
 of the sea obtain but little of this   
dissolved matter along the coast1 it    
seems likely that the greater share of  
it is brought into the state of solution
 in the natural laboratories of the     
alluvial plains4  ,here and there along 
the sides of the valleys in which the   
rivers flow we commonly find the remains
 of ancient plains lying at more or less
 considerable heights above the level of

 the streams4 ,generally these deposits1
 which from their form are called       
terraces1 represent the stages of       
down-wearing by which the stream has    
carved out its way through the rocks4   
,the greater part of these ancient      
alluvial plains has been removed through
 the ceaseless swinging of the stream to
 and fro in the valley which it has     
excavated4  ,in all the states of       
alluvial plains1 whether they be the    
fertile deposits near the level of the  
streams which built them1 or the poorer 
and ruder surfaced higher terraces1 they
 have a great value to mankind4 ,men    
early learned that these lands were of  
singularly uniform goodness for         
agricultural use4 ,they are so light    
that they were easily delved with the   
ancient pointed sticks or stone hoes1 or
 turned by the olden1 wooden plough4    
,they not only give a rich return when  
first subjugated1 but1 owing to the     
depth of the soil and the frequency with
 which they are visited by fertilizing  

inundations1 they yield rich harvests   
without fertilizing for thousands of    
years4 ,it is therefore not surprising  
that we find the peoples who depended   
upon tillage for subsistence first      
developed on the great river plains4    
,there1 indeed1 were laid the           
foundations of our higher civilization2 
there alone could the state which       
demands of its citizens fixed abodes and
 continuous labour take rise4 ,in the   
conditions which these fields of        
abundance afforded1 dense populations   
were possible1 and all the arts which   
lead toward culture were greatly        
favoured4 ,thus it is that the          
civilization of ,china1 ,india1 ,persia1
 and ,egypt1 the beginnings of man's    
higher development1 began near the      
mouths of the great river valleys4      
,these fields were1 moreover1 most      
favourably placed for the institution of
 commerce1 in that the arts of          
navigation1 originating in the sheltered
 reaches of the streams1 readily found  

its way through the estuaries to the    
open sea4  ,passing down the reaches of 
a great river as it approaches the sea1 
we find that the alluvial plains usually
 widen and become lower4 ,at length we  
attain a point where the flood waters   
cover the surface for so large a part of
 the year that the ground is swampy and 
untillable unless it is artificially and
 at great expense of labour won to      
agriculture in the manner in which this 
task has been effected in the lower     
portion of the ,rhine ,valley4 ,still   
farther toward the sea1 the plain       
gradually dips downward until it passes 
below the level of the waters4 ,through 
this mud-flat section the stream        
continues to cut channels1 but with the 
ever-progressive slowing of its motion  
the burden of fine mud which it carries 
drops to the bottom1 and constantly     
closes the paths through which the water
 escapes4 ,every few years they tend to 
break a new way on one side or the other
 of their former path4 ,some of the     

greatest engineering work done in modern
 times has been accomplished by the     
engineers engaged in controlling the    
exits of large rivers to the sea4 ,the  
outbreak of the ,yellow ,river in #ahhg1
 in which the stream1 hindered by its   
own accumulations1 forced a new path    
across its alluvial plains1 destroyed a 
vast deal of life and property1 and made
 the new exit seventy miles from the    
path which it abandoned4  ,below the    
surface of the open water the alluvial  
deposits spread out into a broad fan1   
which slopes gradually to a point where1
 in the manner of the continental shelf1
 the bottom descends steeply into deep  
water4  ,it is the custom of naturalists
 to divide the lower section of river   
deposits--that part of the accumulation 
which is near the sea--from the other   
alluvial plains1 terming the lower      
portion the delta4 ,the word originally 
came into use to describe that part of  
the alluvium accumulated by the ,nile   
near its mouth1 which forms a fertile   

territory shaped somewhat like the      
fourth letter of the ,greek alphabet4   
,although the definition is good in the 
,egyptian instance1 and has a certain   
use elsewhere1 we best regard all the   
detritus in a river valley which is in  
the state of repose along the stream to 
its utmost branches as forming one great
 whole4 ,it is1 indeed1 one of the most 
united of the large features which the  
earth exhibits4 ,the student should     
consider it as a continuous inclined    
plane of diminishing slope1 extending   
from the base of the torrents to the    
sea1 and of course ramifying into the   
several branches of the river system4   
,he should further bear in mind the fact
 that it is a vast laboratory where rock
 material is brought into the soluble   
state for delivery to the seas4  ,the   
diversity in the form of river valleys  
is exceedingly great4 ,almost all the   
variety of the landscape is due to this 
impress of water action which has       
operated on the surface in past ages4   

,when first elevated above the sea1 the 
surface of the land is but little       
varied2 at this stage in the development
 the rivers have but shallow valleys1   
which generally cut rather straight away
 over the plain toward the sea4 ,it is  
when the surface has been uplifted to a 
considerable height1 and especially     
when1 as is usually the case1 this      
uplifting action has been associated    
with mountain-building1 that valleys    
take on their accented and picturesque  
form4 ,the reason for this is easily    
perceived3 it lies in the fact that the 
rocks over which the stream flows are   
guided in the cutting which they effect 
by the diversities of hardness in the   
strata that they encounter4 ,the work   
which it does is performed by the hard  
substances that are impelled by the     
current1 principally by the sand and    
pebbles4 ,these materials1 driven along 
by the stream1 become eroding tools of  
very considerable energy4 ,as will be   
seen when we shortly come to describe   

waterfalls1 the potholes formed at those
 points afford excellent evidence as to 
the capacity of stream-impelled bits of 
stone to cut away the firmest bed rocks4
 ,naturally the ease with which this    
carving work is done is proportionate to
 the energy of the currents1 and also to
 the relative hardness of the moving    
bits and the rocks over which they are  
driven4  ,so long as the rocks lie      
horizontally in their natural           
construction attitude the course of the 
stream is not much influenced by the    
variations in hardness which the bed    
exhibits4 ,where the strata are very    
firm there is likely to be a narrow     
gorge1 the steeps of which rise on      
either side with but slight alluvial    
plains2 where the beds are soft the     
valley widens1 perhaps again to contract
 where in the course of its descent it  
encounters another hard layer4 ,where1  
however1 the beds have been subjected to
 mountain-building1 and have been thrown
 into very varied attitudes by folding  

and faulting1 the stream now here and   
now there encounters beds which either  
restrain its flow or give it freedom4   
,the stream is then forced to cut its   
way according to the positions of the   
various underlying strata4 ,this effect 
upon its course is not only due to the  
peculiarities of uplifted rocks1 but to 
manifold accidents of other nature3     
veins and dikes1 which often interlace  
the beds with harder or softer          
partitions than the country rock2 local 
hardenings in the materials1 due to     
crystallization and other chemical      
processes1 often create indescribable   
variations which are more or less       
completely expressed in the path of the 
stream4  ,when a land has been newly    
elevated above the sea there is         
often--we may say1 indeed1 generally--a 
very great difference between the height
 of its head waters and the ocean level4
 ,in this condition of a country the    
rivers have what we may call a new      
aspect2 their valleys are commonly      

narrow and rather steep1 waterfalls are 
apt to abound1 and the alluvial terraces
 are relatively small in extent4 ,stage 
by stage the torrents cut deeper2 the   
waste which they make embarrasses the   
course of the lower waters1 where no    
great amount of down-cutting is possible
 for the reason that the bed of the     
stream is near sea level4 ,at the same  
time the alluvial materials1 building   
out to sea1 thus diminish the slope of  
the stream4 ,in the extreme old age of  
the river system the mountains are eaten
 down so that the torrent section       
disappears1 and the stream becomes of   
something like a uniform slope2 the     
higher alluvial plains gradually waste  
away1 until in the end the valley has no
 salient features4 ,at this stage in the
 process1 or even before it is attained1
 the valley is likely to be submerged   
beneath the sea1 where it is buried     
beneath the deposits formed on the      
floor2 or a further uplift of the land  
may occur with the result that the      

stream is rejuvenated2 or once more     
endowed with the power to create        
torrents1 build alluvial plains1 and do 
the other interesting work of a normal  
river4  ,it rarely1 if ever1 happens    
that a river valley attains old age     
before it has sunk beneath the sea or   
been refreshed by further upliftings4   
,in the unstable conditions of the      
continents1 one or the other of these   
processes1 sometimes in different places
 both together1 is apt to be going on4  
,thus if we take the case of the        
,mississippi and its principal          
tributaries1 the ,ohio and ,missouri1 we
 find that for many geological ages the 
mountains about their sources have      
frequently1 if not constantly1 grown    
upward1 so that their torrent sections1 
though they have worn down tens of      
thousands of feet1 are still high above 
the sea level1 perhaps on the average as
 high as they have ever been4 ,at the   
same time the slight up-and-down        
swayings of the shore lands1 amounting  

in general to less than five hundred    
feet1 have greatly affected the channels
 of the main river and its tributaries  
in their lower parts4 ,not long ago the 
,mississippi between ,cairo and the     
,gulf flowed in a rather steep-sided    
valley probably some hundreds of feet in
 depth1 which had a width of many miles4
 ,then at the close of the last ,glacial
 period the region sank down so that the
 sea flooded the valley to a point above
 the present junction of the ,ohio      
,river with the main stream4 ,since then
 alluvial plains have filled this       
estuary to even beyond the original     
mouth4 ,in many other of our ,southern  
rivers1 as along the shore from the     
,mississippi to the ,hudson1 the streams
 have not brought in enough detritus to 
fill their drowned valleys1 which have  
now the name of bays1 of which the      
,delaware and ,chesapeake on the        
,atlantic coast1 and ,mobile ,bay on the
 ,gulf of ,mexico1 are good examples4   
,the failure of ,chesapeake and         

,delaware ,bays to fill with dbris in   
the measure exhibited by the more       
southern valleys is due to the fact that
 the streams which flow into them to a  
great extent drain from a region thickly
 covered with glacial waste1 a mass     
which holds the flood waters1 yielding  
the supply but slowly to the torrents1  
which there have but a slight cutting   
power4  ,in our sketch of river valleys 
no attention has been given to the      
phenomena of waterfalls1 those accidents
 of the flow which1 as we have noted1   
are particularly apt to characterize    
rivers which have not yet cut down to   
near the sea level4 ,where the normal   
uniform descent which is characteristic 
of a river's bed is interrupted by a    
sudden steep1 the fact always indicates 
the occurrence of one of a number of    
geological actions4 ,the commonest cause
 of waterfalls is due to a sudden change
 in the character of horizontal or at   
least nearly level beds over which the  
stream may flow4 ,where after coursing  

for a distance over a hard layer the    
stream comes to its edge and drops on a 
soft or easily eroded stratum1 it will  
cut this latter bed away1 and create a  
more or less characteristic waterfall4  
,tumbling down the face of the hard     
layer1 the stream acquires velocity2 the
 dbris which it conveys is hurled       
against the bottom1 and therefore cuts  
powerfully1 while before1 being only    
rubbed over the stone as it moved along1
 it cut but slightly4 ,masses of ice    
have the same effect as stones4 ,bits   
dropping from the ledge are often swept 
round and round by the eddies1 so that  
they excavate an opening which prevents 
their chance escape4 ,in these confined 
spaces they work like augers1 boring a  
deep1 well-like cavity4 ,as the bits of 
stone wear out they are replaced by     
others1 which fall in from above4       
,working in this way1 the fragments     
often develop regular well-like         
depressions1 the cavities of which work 
back under the cliffs1 and by the       

undermining process deprive the face of 
the wall of its support1 so that it     
tumbles in ruin to the base1 there to   
supply more material for the potholing  
action4  ,waterfalls of the type above  
described are by far the commonest of   
those which occur out of the torrent    
districts of a great river system4 ,that
 of ,niagara is an excellent specimen of
 the type1 which1 though rarely         
manifested in anything like the dignity 
of the great fall1 is plentifully shown 
throughout the ,mississippi ,valley and 
the basin of the ,great ,lakes4 ,within 
a hundred miles of ,niagara there are at
 least a hundred small waterfalls of the
 same type4 ,probably three quarters of 
all the larger accidents of this nature 
are due to the conditions of a hard bed 
overlying softer strata4  ,falls are    
also produced in very many instances by 
dikes which cross the stream4 ,so1 too1 
though rarely1 only one striking        
instance being known1 an ancient coral  
reef which has become buried in strata  

may afford rock of such hardness that   
when the river comes to cross it it     
forms a cascade1 as at the ,falls of the
 ,ohio1 at ,louisville1 ,ky4 ,it is a   
characteristic of all other falls1      
except those first mentioned1 that they 
rarely plunge with a clean downward leap
 over the face of a precipice which     
recedes at its base1 but move downward  
over an irregular sloping surface4  ,in 
the torrent district of rivers          
waterfalls are commonly very numerous1  
and are generally due to the varying    
hardness in the rocks which the streams 
encounter4 ,here1 where the cutting     
action is going on with great rapidity1 
slight differences in the resistance    
which the rocks make to the work will   
lead to great variations in the form of 
the bed over which they flow1 while on  
the more gently sloping bottoms of the  
rivers1 where the dbris moves slowly1   
such variations would be unimportant in 
their effect4 ,when the torrents escape 
into the main river valleys1 in regions 

where the great streams have cut deep   
gorges1 they often descend from a great 
vertical height1 forming wonderful      
waterfalls1 such as those which occur in
 the famous ,lauterbrunnen ,valley of   
,switzerland or in that of the ,yosemite
 in ,california4 ,this group of cascades
 is peculiar in that the steep of the   
fall is made not by the stream itself1  
but by the action of a greater river or 
of a glacier which may have some time   
taken its place4  ,waterfalls have an   
economic as well as a picturesque       
interest in that they afford sources of 
power which may be a very great         
advantage to manufacturers4 ,thus along 
the ,atlantic coast the streams which   
come from the ,appalachian highlands1   
and which have hardly escaped from their
 torrent section before they attain the 
sea1 afford numerous cataracts which    
have been developed so that they afford 
a vast amount of power4 ,between the    
,james on the south and the ,ste4 ,croix
 on the north more than a hundred of    

these ,appalachian rivers have been     
turned to economic use4 ,the industrial 
arts of this part of the country depend 
much upon them for the power which      
drives their machinery4 ,the whole of   
the ,united ,states1 because of the     
considerable size of its rivers and     
their relatively rapid fall1 is richly  
endowed with this source of energy1     
which1 originating in the sun's heat and
 conveyed through the rain1 may be made 
to serve the needs of man4 ,in view of  
the fact that recent inventions have    
made it possible to convert this energy 
of falling water into the form of       
electricity1 which may be conveyed to   
great distances1 it seems likely that   
our rivers will in the future be a great
 source of national wealth4  ,we must   
turn again to river valleys1 there to   
trace certain actions less evident than 
those already noted1 but of great       
importance in determining these features
 of the land4 ,first1 we have to note   
that in the valley or region drained by 

a river there is another degrading or   
down-wearing action than that which is  
accomplished by the direct work of the  
visible stream4 ,all over such a valley 
the underground waters1 soaking through 
the soil and penetrating through the    
underlying rock1 are constantly removing
 a portion of the mineral matter which  
they take into solution and bear away to
 the sea4 ,in this way1 deprived of a   
part of their substance1 the rocks are  
continually settling down by underwear  
throughout the whole basin1 while they  
are locally being cut down by the action
 of the stream4 ,hence in part it comes 
about that in a river basin we find two 
contrasted features--the general and    
often slight slope of a country toward  
the main stream and its greater         
tributaries1 and the sharp indentation  
of the gorge in which the streams flow1 
these latter caused by the immediate and
 recent action of the streams4  ,if now 
the reader will conceive himself        
standing at any point in a river basin1 

preferably beyond the realms of the     
torrents1 he may with the guidance of   
the facts previously noted1 with a      
little use of the imagination1 behold   
the vast perceptive which the history of
 the river valley may unfold to him4 ,he
 stands on the surface of the soil1 that
 dbris of the rocks which is just       
entering on its way to the ocean4 ,in   
the same region ten thousand years ago  
he would have stood upon a surface from 
one to ten feet higher than the present 
soil covering4 ,a million years ago his 
station would have been perhaps five    
hundred feet higher than the surface4   
,ten million years in the past1 a period
 less than the lifetime of certain      
rivers1 such as the ,french ,broad      
,river in ,north ,carolina1 the soil was
 probably five thousand feet or more    
above its present plane4 ,there are1    
indeed1 cases where river valleys appear
 to have worked down without            
interruption from the subsidence of the 
land beneath the sea to the depth of at 

least two miles4 ,looking upward through
 the space which the rocks once         
occupied1 we can conceive the action of 
the forces in their harmonious          
co-operation which have brought the     
surface slowly downward4 ,we can imagine
 the ceaseless corrosion due to the     
ground water1 bringing about a constant 
though slow descent of the whole        
surface4 ,again and again the streams1  
swinging to and fro under the guidance  
of the underlying rock1 or from the     
obstacles which the dbris they carried  
imposed upon them1 have crossed the     
surface4 ,now and then perhaps the      
wearing was intensified by glacial      
action1 for an ice sheet often cuts with
 a speed many times as great as that    
which fluid water can accomplish4 ,on   
the whole1 this exercise of the         
constructive imagination in conceiving  
the history of a river valley is one of 
the most enlarging tasks which the      
geologist can undertake4  ,where in a   
river valley there are many lateral     

streams1 and especially where the       
process of solution carried on by the   
underground waters is most effective1 as
 compared with erosive work done in the 
bed of the main river1 we commonly find 
the valley sloping gently toward its    
centre1 the rivers having but slight    
steeps near their banks4 ,on the other  
hand1 where1 as occasionally happens1 a 
considerable stream fed by the rain and 
snow fall in its torrent section courses
 for a great distance over high1 arid   
plains1 on which the ground water and   
the tributaries do but little work1 the 
basin may slope with very slight        
declivity to the river margins1 and     
there descend to great depths1 forming  
very deep gorges1 of which the ,colorado
 ,caon is the most perfect type4 ,as    
instances of these contrasted           
conditions1 we may take1 on the one     
hand1 the upper ,mississippi1 where the 
grades toward the main stream are gentle
 and the valley gorge but slightly      
exhibited2 on the other1 the            

above-mentioned ,colorado1 which bears a
 great tide of waters drawn from the    
high and relatively rainy region of the 
,rocky ,mountains across the vast       
plateau lying in an almost rainless     
country4 ,in this section nearly all the
 down-wearing has been brought about in 
the direct path of the stream1 which has
 worn the elevated plain into a deep    
gorge during the slow uprising of the   
table-land to its present height4 ,in   
this way a defile nearly a mile in depth
 has been created in a prevailingly     
rather flat country4 ,this gorge has    
embranchments where the few great       
tributaries have done like work1 but1 on
 the whole1 this river flows in an      
almost unbroken channel1 the excavation 
of which has been due to its swift1     
pebble-bearing waters4  ,the tendency of
 a newly formed river is to cut a more  
or less distinct caon4 ,as the basin    
becomes ancient1 this element of the    
gorge tends to disappear1 the reason for
 this being that1 while the river bed is

 high above the sea1 the current is     
swift and the down-cutting rapid1 while 
the slow subsidence of the country on   
either side--a process which goes on at 
a uniform rate--causes the surface of   
that region to be left behind in the    
race for the sea level4 ,as the stream  
bed comes nearer the sea level its rate 
of descent is diminished1 and so the    
outlying country gradually overtakes it4
  ,in regions where the winters are very
 cold the effect of ice on the          
development of the stream beds both in  
the torrent and river sections of the   
valley is important4 ,this work is      
accomplished in several diverse ways4   
,in the first place1 where the stream is
 clear and the current does not flow too
 swiftly1 the stones on the bottom      
radiate their heat through the water1   
and thus form ice on their surfaces1    
which may attain considerable thickness4
 ,as ice is considerably lighter than   
water1 the effect is often to lift up   
the stones of the bed if they be not too

 large2 when thus detached from the     
bottom1 they are easily floated down    
stream until the ice melts away4 ,the   
ice which forms on the surface of the   
water likewise imprisons the pebbles    
along the banks1 and during the         
subsequent thaw may carry them hundreds 
of miles toward the sea4 ,it seems      
likely1 from certain observations made  
by the writer1 that considerable stones 
may thus be carried from the ,alleghany 
,river to the main ,mississippi4        
,perhaps the most important effect of   
ice on river channels is accomplished   
when in a time of flood the ice field   
which covered the stream1 perhaps to the
 depth of some feet1 is broken up into  
vast floes1 which drift downward with   
the current4 ,when1 as on the ,ohio1    
these fields sometimes have the area of 
several hundred acres1 they often       
collide with the shores1 especially     
where the stream makes a sharp bend4    
,urged by their momentum1 these ice     
floes pack into the semblance of a dam1 

which may have a thickness of twenty1   
thirty1 or even fifty feet4 ,beginning  
on the shore1 where the collision takes 
place1 the dam may swiftly develop clear
 across the stream1 so that in a few    
minutes the way of the waters is        
completely blocked4 ,the on-coming ice  
shoots up upon the accumulation1        
increases its height1 and extends it up 
stream1 so that in an hour the mass     
completely bars the current4 ,the waters
 then heap up until they break their way
 over the obstacle1 washing its top     
away1 until the whole is light enough to
 be forced down the stream1 where1 by   
the friction it encounters on the bottom
 and sides of the channel1 it is broken 
to pieces4 ,it is easy to see that such 
moving dams of ice may sweep the bed of 
a river as with a great broom4          
,sometimes where the gorges do not form 
a stationary dam large cakes of ice     
become turned on edge and pack together 
so that they roll down the stream like  
great wheels1 grinding the bed rock as  

they go4  ,in high northern countries1  
as in ,siberia1 the rivers1 even the    
deepest1 often become so far frozen that
 their channels are entirely obstructed4
 ,where1 as in the case of these        
,siberian rivers1 the flow is from south
 to north1 it often happens that the    
spring thaw sets in before the more     
northern beds of the main stream are    
released from their bondage of frost4   
,in this case the inundations have to   
find new paths on either side of the    
obstructed way4 ,the result is a type of
 valleys characterized by very irregular
 and changeable stream beds1 the rivers 
having no chance to organize themselves 
into the shapely curves which they      
ordinarily follow4  ,the supply which   
finds its way to a river is composed1 as
 has been already incidentally noted1 in
 part of the water which courses        
underground for a greater or less       
distance before it emerges to the       
surface1 and in part of that which moves
 directly over the ground4 ,these two   

shares of water have somewhat different 
histories4 ,on the share of these two   
depends the stability of the flow4      
,where1 as in ,new ,england and other   
glaciated countries1 the surface of the 
earth is covered with a thick layer of  
sand and gravel1 which1 except when     
frozen1 readily admits the water2 the   
rainfall is to a very great extent      
absorbed by the earth1 and only yielded 
slowly to the streams4 ,in these cases  
floods are rare and of no great         
destructive power4 ,again1 where also   
the river basin is covered by a dense   
mantle of forests1 the ground beneath   
which is coated1 as is the case in      
primeval woods1 with a layer of         
decomposing vegetation a foot or more in
 depth1 this spongy mass retains the    
water even more effectively than the    
open-textured glacial deposits above    
referred to4 ,when the woods1 however1  
are removed from such an area1 the rain 
may descend to the streams almost as    
speedily as it finds its way to the     

gutters from the house roofs4 ,it thus  
comes about that all regions1 when      
reduced to tillage1 and where the       
rainfall is enough to maintain a good   
agriculture1 are1 except when they have 
a coating of glacial waste1 exceedingly 
liable to destructive inundations4      
,unhappily1 the risk of river floods is 
peculiarly great in all the regions of  
the ,united ,states lying much to the   
east of the ,rocky ,mountains1 except in
 the basin of the ,great ,lakes and in  
the district of ,new ,england1 where the
 prevalence of glacial sands and gravels
 affords the protection which we have   
noted4 ,throughout this region the      
rainfall is heavy1 and the larger part  
of it is apt to come after the ground   
has become deeply snow-covered4 ,the    
result is a succession of devastating   
floods which already are very damaging  
to the works of man1 and promise to     
become more destructive as time goes on4
 ,more than in any other country1 we    
need the protection which forests can   

give us against these disastrous        
outgoings of our streams4               
,,lakes4  ,in considering the journey of
 water from the hilltops to the sea1 we 
should take some account of those pauses
 which it makes on its way when for a   
time it falls into the basin of a lake4 
,these arrests in the downward motion of
 water1 which we term lakes1 are        
exceedingly numerous2 their proper      
discussion would1 indeed1 require a     
considerable volume4 ,we shall here note
 only the more important of their       
features1 those which are of interest to
 the general student4  ,the first and   
most noteworthy difference in lakes is  
that which separates the group of dead  
seas from the living basins of fresh    
water4 ,when a stream attains a place   
where its waters have to expand into the
 lakelike form1 the current moves in a  
slow manner1 and the broad surface      
exposed to the air permits a large      
amount of evaporation4 ,if the basin be 
large in proportion to the amount of the

 incurrent water1 this evaporation may  
exceed the supply1 and produce a sea    
with no outlet1 such as we find in the  
,dead ,sea of ,judea1 in that at ,salt  
,lake1 ,utah1 and in a host of other    
less important basins4 ,if the rate of  
evaporation be yet greater in proportion
 to the flow1 the lake may altogether   
dry away1 and the river be evaporated   
before it attains the basin where it    
might accumulate4 ,in that case the     
river is said to sink1 but1 in place of 
sinking into the earth1 its waters      
really rise into the air4 ,many such    
sinks occur in the central portion of   
the ,rocky ,mountain district4 ,it is   
important to note that the process of   
evaporation we are describing takes     
place in the case of all lakes1 though  
only here and there is the air so dry   
that the evaporation prevents the basin 
from overflowing at the lowest point on 
its rim1 forming a river which goes     
thence to the sea4 ,even in the case of 
the ,great ,lakes of ,north ,america a  

considerable part of the water which    
flows into them does not go to the ,st4 
,lawrence and thence to the sea4 ,as    
long as the lake finds an outlet to the 
sea its waters contain but little more  
dissolved mineral matter than that we   
find in the rivers4 ,but because all    
water which has been in contact with the
 earth has some dissolved mineral       
substances1 while that which goes away  
by evaporation is pure water1 a lake    
without an outlet gradually becomes so  
charged with these materials that it can
 hold no more in solution1 but proceeds 
to lay them down in deposits of that    
compound substance which from its       
principal ingredient we name salt4 ,the 
water of dead seas1 because of the      
additional weight of the substances     
which it holds1 is extraordinarily      
buoyant4 ,the swimmer notes a difference
 in this regard in the waters of rivers 
and fresh-water lakes and those of the  
sea1 due to this same cause4 ,but in    
those of dead seas1 saturated with      

saline materials1 the human body can not
 sink as it does in the ordinary        
conditions of immersion4 ,it is easy to 
understand how the salt deposits which  
are mined in many parts of the world    
have generally1 if not in all cases1    
been formed in such dead seas4#e        
,footnote #e3 ,in some relatively rare  
cases salt deposits are formed in       
lagoons along the shores of arid lands1 
where the sea occasionally breaks over  
the beach into the basin1 affording     
waters which are evaporated1 leaving    
their salt behind them4  ,it is an      
interesting fact that almost all the    
known dead seas have in recent          
geological times been living lakes--that
 is1 they poured over their brims4 ,in  
the ,cordilleras from the line between  
,canada and the ,united ,states to      
central ,mexico there are several of    
these basins4 ,all of those which have  
been studied show by their old shore    
lines that they were once brimful1 and  
have only shrunk away in modern times4  

,these conditions point to the          
conclusion that the rainfall in         
different regions varies greatly in the 
course of the geologic ages4 ,further   
confirmation of this is found in the    
fact that very great salt deposits exist
 on the coast of ,louisiana and in      
northern ,europe--regions in which the  
rainfall is now so great in proportion  
to the evaporation that dead seas are   
impossible4  ,turning now to the        
question of how lake basins are formed1 
we note a great variety in the          
conditions which may bring about their  
construction4 ,the greatest agent1 or at
 least that which operates in the       
construction of the largest basins1 are 
the irregular movements of the earth1   
due to the mountain-building forces4    
,where this work goes on on a large     
scale1 basin-shaped depressions are     
inevitably formed4 ,if all those which  
have existed remained1 the large part of
 the lands would be covered by them4 ,in
 most cases1 however1 the cutting action

 of the streams has been sufficient to  
bring the drainage channels down to the 
bottom of the trough1 while the influx  
of sediments has served to further the  
work by filling up the cavities4 ,thus  
at the close of the ,cretaceous period  
there was a chain of lakes extending    
along the eastern base of the ,rocky    
,mountains1 constituting fresh-water    
seas probably as large as the so-called 
,great ,lakes of ,north ,america4 ,but  
the rivers1 by cutting down and tilling 
up1 have long since obliterated these   
water areas4 ,in other cases the        
tiltings of the continent1 which        
sometimes oppose the flow of the        
streams1 may for a time convert the     
upper part of a river basin which       
originally sloped gently toward the sea 
into a cavity4 ,several cases of this   
description occurred in ,new ,england in
 the closing stages of the ,glacial     
period1 when the ground rose up to the  
northward4  ,we have already noted the  
fact that the basin of a dead sea       

becomes in course of time the seat of   
extensive salt deposits4 ,these may1    
indeed1 attain a thickness of many      
hundred feet4 ,if now in the later      
history of the country the tract of land
 with the salt beneath it were traversed
 by a stream1 its underground waters may
 dissolve out the salt and in a way     
restore the basin to its original       
unfilled condition1 though in the second
 state that of a living lake4 ,it seems 
very probable that a portion at least of
 the areas of ,lakes ,ontario1 ,erie1   
and ,huron may be due to this removal of
 ancient salt deposits1 remains of which
 lie buried in the earth in the region  
bordering these basins4  ,by far the    
commonest cause of lake basins is found 
in the irregularities of the surface    
which are produced by the occupation of 
the country by glaciers4 ,when these    
great sheets of ice lie over a land1    
they are in motion down the slopes on   
which they rest2 they wear the bed rocks
 in a vigorous manner1 cutting them down

 in proportion to their hardness4 ,as   
these rocks generally vary in the       
resistance which they oppose to the ice1
 the result is that when the glacier    
passes away the surface no longer       
exhibits the continued down slope which 
the rivers develop1 but is warped in a  
very complicated way4 ,these depressions
 afford natural basins in which lakes   
gather2 they may vary in extent from a  
few square feet to many square miles4   
,when a glacier occupies a country1 the 
melting ice deposits on the surface of  
the earth a vast quantity of rocky      
dbris1 which was contained in its mass4 
,this detritus is irregularly           
accumulated2 in part it is disposed in  
the form of moraines or rude mounds made
 at the margin of the glacier1 in part  
as an irregular sheet1 now thick1 now   
thin1 which covers the whole of the     
field over which the ice lay4 ,the      
result of this action is the formation  
of innumerable pools1 which continue to 
exist until the streams have cut        

channels through which their waters may 
drain away1 or the basins have become   
filled with detritus imported from the  
surrounding country or by peat          
accumulations which the plants form in  
such places4  ,doubtless more than nine 
tenths of all the lake basins1          
especially those of small size1 which   
exist in the world are due to           
irregularities of the land surface which
 are brought about by glacial action4   
,although the greater part of these     
small basins have been obliterated since
 the ice left this country1 the number  
still remaining of sufficient size to be
 marked on a good map is inconceivably  
great4 ,in ,north ,america alone there  
are probably over a hundred and fifty   
thousand of these glacial lakes1        
although by far the greater part of     
those which existed when the glacial    
sheet disappeared have been obliterated4
  ,yet another interesting group of     
fresh-water lakes1 or rather we should  
call them lakelets from their small     

size1 owes its origin to the curious    
underground excavations or caverns which
 are formed in limestone countries4 ,the
 water enters these caverns through what
 are termed sink holes--basins in the   
surface which slope gently toward a     
central opening through which the water 
flows into the depths below4 ,the cups  
of the sink holes rarely exceed half a  
mile in diameter1 and are usually much  
smaller4 ,their basins have been        
excavated by the solvent and cutting    
actions of the rain water which gathers 
in them to be discharged into the cavern
 below4 ,it often happens that after a  
sink hole is formed some slight accident
 closes the downward-leading shaft1 so  
that the basin holds water2 thus in     
parts of the ,united ,states there are  
thousands of these nearly circular      
pools1 which in certain districts1 as in
 southern ,kentucky1 serve to vary the  
landscape in much the same manner as the
 glacial lakes of more northern         
countries4  ,some of the most beautiful 

lakes in the world1 though none more    
than a few miles in diameter1 occupy the
 craters of extinct volcanoes4 ,when for
 a time1 or permanently1 a volcano      
ceases to do its appointed work of      
pouring forth steam and molten rock from
 the depths of the earth1 the pit in the
 centre of the cone gathers the rain    
water1 forming a deep circular lake1    
which is walled round by the precipitous
 faces of the crater4 ,if the volcano   
reawakens1 the water which blocks its   
passage may be blown out in a moment1   
the discharge spreading in some cases to
 a great distance from the cone1 to be  
accumulated again when the vent ceases  
to be open4 ,the most beautiful of these
 volcanic lakes are to be found in the  
region to the north and south of ,rome4 
,the original seat of the ,latin state  
was on the shores of one of these crater
 pools1 south of the ,eternal ,city4    
,lago ,bolsena1 which lies to the       
northward1 and is one of the largest    
known basins of this nature1 having a   

diameter of about eight miles1 is a     
crater lake4 ,the volcanic cone to which
 it belongs1 though low1 is of great    
size1 showing that in its time of       
activity1 which did not endure very     
long1 this crater was the seat of mighty
 ejections4 ,the noblest specimen of    
this group of basins is found in ,crater
 ,lake1 ,oregon1 now contained in one of
 the national parks of the ,united      
,states4  ,inclosed bodies of water are 
formed in other ways than those         
described2 the list above given includes
 all the important classes of action    
which produce these interesting         
features4 ,we should now note the fact  
that1 unlike the seas1 the lakes are to 
be regarded as temporary features in the
 physiography of the land4 ,one and all1
 they endure for but brief geologic     
time1 for the reason that the streams   
work to destroy them by filling them    
with sediment and by carving out        
channels through which their waters     
drain away4 ,the nature of this action  

can well be conceived by considering    
what will take place in the course of   
time in the ,great ,lakes of ,north     
,america4 ,as ,niagara ,falls cut back  
at the average rate of several feet a   
year1 it will be but a brief geologic   
period before they begin to lower the   
waters of ,lake ,erie4 ,it is very      
probable1 indeed1 that in twenty        
thousand years the waters of that basin 
will be to a great extent drained away4 
,when this occurs1 another fall or rapid
 will be produced in the channel which  
leads from ,lake ,huron to ,lake ,erie4 
,this in turn will go through its       
process of retreat until the former     
expanse of waters disappears4 ,the      
action will then be continued at the    
outlets of ,lakes ,michigan and         
,superior1 and in time1 but for the     
interposition of some actions which     
recreate these basins1 their floors will
 be converted into dry land4  ,it is    
interesting to note that lakes owe in a 
manner the preservation of their basins 

to an action which they bring about on  
the waters that flow into them4 ,these  
rivers or torrents commonly convey great
 quantities of sediment1 which serve to 
rasp their beds and thus to lower their 
channels4 ,in all but the smaller       
lakelets these turbid waters lay down   
all their sediment before they attain   
the outlet of the basin4 ,thus they flow
 away over the rim rock in a perfectly  
pure state--a state in which1 as we have
 noted before1 water has no capacity for
 abrading firm rock4 ,thus where the    
,niagara ,river passes from ,lake ,erie 
its clean water hardly affects the stone
 over which it flows4 ,it only begins to
 do cutting work where it plunges down  
the precipice of the ,falls and sets in 
motion the fragments which are          
constantly falling from that rocky face4
 ,these ,falls could not have begun as  
they did on the margin of ,lake ,ontario
 except for the fact that when the      
,niagara ,river began to flow1 as in    
relatively modern times1 it found an old

 precipice on the margin of ,lake       
,ontario1 formed by the waves of the    
lake1 down which the waters fell1 and   
where they obtained cutting tools with  
which to undermine the steep which forms
 the ,falls4  ,many great lakes1        
particularly those which we have just   
been considering1 have repeatedly       
changed their outlets1 according as the 
surface of the land on which they lie   
has swayed up and down in various       
directions1 or as glacial sheets have   
barred or unbarred the original outlets 
of the basins4 ,thus in the ,laurentian 
,lakes above ,ontario the geologist     
finds evidence that the drainage lines  
have again and again been changed4 ,for 
a time during the ,glacial period1 when 
,lake ,ontario and the valley of the    
,st4 ,lawrence was possessed by the ice1
 the discharge was southward into the   
upper ,mississippi or the ,ohio4 ,at a  
later stage channels were formed leading
 from ,georgian ,bay to the eastern part
 of ,ontario4 ,yet later1 when the      

last-named lake was bared1 an ice dam   
appears to have remained in the ,st4    
,lawrence1 which held back the waters to
 such a height that they discharged     
through the valley of the ,mohawk into  
the ,hudson4 ,furthermore1 at some time 
before the ,glacial period1 we do not   
know just when1 there appears to have   
been an old ,niagara ,river1 now filled 
with drift1 which ran from ,lake ,erie  
to ,ontario1 a different channel from   
that occupied by the present stream4    
,the effects of lakes on the river      
systems with which they are connected is
 in many ways most important4 ,where    
they are of considerable extent1 or     
where even small they are very numerous1
 they serve to retain the flood waters1 
delivering them slowly to the excurrent 
streams4 ,in rising one foot a lake may 
store away more water than the river by 
its consequent rise at the point of     
outflow will carry away in many months1 
and this for the simple reason that the 
lake may be many hundred or even        

thousand times as wide as the stream4   
,moreover1 as before noted1 the sediment
 gathered by the stream above the level 
of the lake is deposited in its basin1  
and does not affect the lower reaches of
 the river4 ,the result is that great   
rivers1 such as drain from the          
,laurentian ,lakes1 flow clear water1   
are exempt from floods1 are essentially 
without alluvial plains or terraces1 and
 form no delta deposits4 ,in all these  
features the ,st4 ,lawrence ,river      
affords a wonderful contrast to the     
,mississippi4 ,moreover1 owing to the   
clear waters1 though it has flowed for a
 long time1 it has never been able to   
cut away the slight obstructions which  
form its rapids1 barriers which probably
 would have been removed if its waters  
had been charged with sediment4         
,illustration3 ,muir ,glacier1 ,alaska1 
showing crevasses and dust layer on     
surface of ice4                         
,,chapter ,,vi4                         
,,glaciers4   ,we have already noted the

 fact that the water in the clouds is   
very commonly in the frozen state2 a    
large part of that fluid which is       
evaporated from the sea attains the     
solid form before it returns to the     
earth4 ,nevertheless1 in descending1 at 
least nine tenths of the precipitation  
returns to the fluid state1 and does the
 kind of work which we have noted in our
 account of water4 ,where1 however1 the 
water arrives on the earth in the frozen
 condition1 it enters on a rle totally  
different from that followed by the     
fluid material4  ,beginning its descent 
to the earth in a snowflake1 the little 
mass falls slowly1 so that when it comes
 against the earth the blow which it    
strikes is so slight that it does no    
effective work4 ,in the state of snow1  
even in the separate flakes1 the frozen 
water contains a relatively large amount
 of air4 ,it is this air indeed1 which1 
by dividing the ice into many flakes    
that reflect the light1 gives it the    
white colour4 ,this important point can 

be demonstrated by breaking transparent 
ice into small bits1 when we perceive   
that it has the hue of snow4 ,much the  
same effect is given where glass is     
powdered1 and for the same reason4  ,as 
the snowflakes accumulate layer on layer
 they imbed air between them1 so that   
when the material falls in a feathery   
shape--say to the depth of a foot--more 
than nine tenths of the mass is taken up
 by the air-containing spaces4 ,as these
 cells are very small1 the circulation  
in them is slight1 and so the layer     
becomes an admirable non-conductor1     
having this quality for the same reason 
that feathers have it--i4e41 because the
 cells are small enough to prevent the  
circulation of the air1 so that the heat
 which passes has to go by conduction1  
and all gases are very poor conductors4 
,the result is that a snow coating is in
 effect an admirable blanket4 ,when the 
sun shines upon it1 much of the heat is 
reflected1 and as the temperature does  
not penetrate it to any depth1 only the 

superficial part is melted4 ,this molten
 water takes up in the process of       
melting a great deal of heat1 so that   
when it trickles down into the mass it  
readily refreezes4 ,on the other hand1  
the heat going out from the earth1 the  
store accumulated in its superficial    
parts in the last warm season1 together 
with the small share which flows out    
from the earth's interior1 is held in by
 this blanket1 which it melts but       
slowly4 ,thus it comes about that in    
regions of long-enduring snowfall the   
ground1 though frozen to the depth of a 
foot or more at the time when the       
accumulation took place1 may be thawed  
out and so far warmed that the          
vegetation begins to grow before the    
protecting envelope of snow has melted  
away4 ,certain of the early flowers of  
high latitudes1 indeed1 begin to blossom
 beneath the mantle of finely divided   
ice4  ,in those parts of the earth which
 for the most part receive only a       
temporary coating of snow the effect of 

this covering is inconsiderable4 ,the   
snow water is yielded to the earth1 from
 which it has helped to withdraw the    
frost1 so that in the springtime1 the   
growing season of plants1 the ground    
contains an ample store of moisture for 
their development4 ,where the snowfall  
accumulates to a great thickness1       
especially where it lodges in forests1  
the influence of the icy covering is    
somewhat to protract the winter and thus
 to abbreviate the growing season4      
,where snow rests upon a steep slope1   
and gathers to the depth of several     
feet1 it begins to creep slowly down the
 declivity in a manner which we may     
often note on house roofs4 ,this motion 
is favoured by the gradual though       
incomplete melting of the flakes as the 
heat penetrates the mass4 ,making a     
section through a mass of snow which has
 accumulated in many successive falls1  
we note that the top may still have the 
flaky character1 but that as we go down 
the flakes are replaced by adherent     

shotlike bodies1 which have arisen from 
the partial melting and gathering to    
their centres of the original expanded  
crystalline bits4 ,in this process of   
change the mass can move particle by    
particle in the direction in which      
gravity impels it4 ,the energy of its   
motion1 however1 is slight1 yet it can  
urge loose stones and forest waste down 
hill4 ,sometimes1 as in the cemetery at 
,augusta1 ,me41 where stone monuments or
 other structures1 such as iron         
railings1 are entangled in the moving   
mass1 it may break them off and convey  
them a little distance down the slope4  
,so long as the summer sun melts the    
winter's snow1 even if the ground be    
bare but for a day1 the rle of action   
accomplished by the snowfall is of      
little geological consequence4 ,when it 
happens that a portion of the deposit   
holds through the summer1 the region    
enters on the glacial state1 and its    
conditions undergo a great revolution1  
the consequences of which are so        

momentous that we shall have to trace   
them in some detail4 ,fortunately1 the  
considerations which are necessary are  
not recondite1 and all the facts are of 
an extremely picturesque nature4        
,taking such a region as ,new ,england1 
where all the earth is life-bearing in  
the summer season1 and where the glacial
 period of the winter continues but for 
a short time1 we find that here and     
there on the high mountains the snow    
endures throughout most of the summer1  
but that all parts of the surface have a
 season when life springs into activity4
 ,on the top of ,mount ,washington1 in  
the ,white ,mountains of ,new           
,hampshire1 in a cleft known as         
,tuckerman's ,ravine1 where the deposit 
accumulates to a great depth1 the       
snow-ice remains until midsummer4 ,it   
is1 indeed1 evident that a very slight  
change in the climatal conditions of    
this locality would establish a         
permanent accumulation of frozen water  
upon the summit of the mountain4 ,if the

 crest were lifted a thousand feet      
higher1 without any general change in   
the heat or rainfall of the district1   
this effect would be produced4 ,if with 
the same amount of rainfall as now comes
 to the earth in that region more of it 
fell as snow1 a like condition would be 
established4 ,furthermore1 with an      
increase of rainfall to something like  
double that which now descends the snow 
bore the same proportion to the         
precipitation which it does at present1 
we should almost certainly have the peak
 above the permanent snow line1 that    
level below which all the winter's fall 
melts away4 ,these propositions are     
stated with some care1 for the reason   
that the student should perceive how    
delicate may be--indeed1 commonly       
is--the balance of forces which make the
 difference between a seasonal and a    
perennial snow covering4  ,as soon as   
the snow outlasts the summer1 the region
 which it occupies is sterilized to     
life4 ,from the time the snow begins to 

hold over the warm period until it      
finally disappears1 that field has to be
 reckoned out of the habitable earth1   
not only to man1 but to the lowliest    
organisms4#f  ,footnote #f3 ,in certain 
fields of permanent snow1 particularly  
near their boundaries1 some very lowly  
forms of vegetable life may develop on a
 frozen surface1 drawing their          
sustenance from the air1 and supplied   
with water by the melting which takes   
place during the summertime4 ,these     
forms include the rare phenomenon termed
 red snow4  ,if the snow in a glaciated 
region lay where it fell1 the result    
would be a constant elevation of the    
deposit year by year in proportion to   
the annual excess of deposition over the
 melting or evaporation of the material4
 ,but no sooner does the deposit attain 
any considerable thickness than it      
begins to move in the directions of     
least resistance1 in accordance with    
laws which the students of glaciers are 
just beginning to discern4 ,in small    

part this motion is accomplished by     
avalanches or snow slides1 phenomena    
which are in a way important1 and       
therefore merit description4            
,immediately after a heavy snowfall1 in 
regions where the slopes are steep1 it  
often happens that the deposit which at 
first clung to the surface on which it  
lay becomes so heavy that it tends to   
slide down the slope2 a trifling action1
 the slipping1 indeed1 of a single      
flake1 may begin the movement1 which at 
first is gradual and only involves a    
little of the snow4 ,gathering velocity1
 and with the materials heaped together 
from the junction of that already in    
motion with that about to be moved1 the 
avalanche in sliding a few hundred feet 
down the slope may become a deep stream 
of snow-ice1 moving with great celerity4
 ,at this stage it begins to break off  
masses of ice from the glaciers over    
which it may flow1 or even to move large
 stones4 ,armed with these1 it rends the
 underlying earth4 ,after it has flowed 

a mile it may have taken up so much     
earth and material that it appears like 
a river of mud4 ,owing to the fact that 
the energy which bears it downward is   
through friction converted into heat1 a 
partial melting of the mass may take    
place1 which converts it into what we   
call slush1 or a mixture of snow and    
water4 ,finally1 the torrent is         
precipitated into the bottom of a       
valley1 where in time the frozen water  
melts away1 leaving only the stony      
matter which it bore as a monument to   
show the termination of its flow4  ,it  
was the good fortune of the writer to   
see in the ,swiss ,oberland one very    
great avalanche1 which came from the    
high country through a descent of       
several thousand feet to the surface of 
the ,upper ,grindelwald ,glacier4 ,the  
first sign of the action was a vague    
tremor of the air1 like that of a great 
organ pipe when it begins to vibrate1   
but before the pulsations come swiftly  
enough to make an audible note4 ,it was 

impossible to tell when this tremor     
came1 but the wary guide1 noting it     
before his charge could perceive        
anything unusual1 made haste for the    
middle of the glacier4 ,the vibration   
swelled to a roar1 but the seat of the  
sound amid the echoing cliffs was       
indeterminable4 ,finally1 from a valley 
high up on the southern face of the     
glacier1 there leaped forth first a     
great stone1 which sprang with          
successive rebounds to the floor of ice4
 ,then in succession other stones and   
masses of ice which had outrun the flood
 came thicker and thicker1 until at the 
end of about thirty seconds the steep   
front of the avalanche appeared like a  
swift-moving wall4 ,attaining the       
cliffs1 it shot forth as a great        
cataract1 which during the continuance  
of the flow--which lasted for several   
minutes--heaped a great mound of        
commingled stones and ice upon the      
surface of the glacier4 ,the mass thus  
brought down the steep was estimated at 

about three thousand cubic yards1 of    
which probably the fiftieth part was    
rock material4 ,an avalanche of this    
volume is unusual1 and the proportion of
 stony matter borne down exceptionally  
great2 but by these sudden motions of   
the frozen water a large part of the    
snow deposited above the zone of        
complete melting is taken to the lower  
valleys1 where it may disappear in the  
summer season1 and much of the erosion  
accomplished in the mountains is brought
 about by these falls4  ,in all ,alpine 
regions avalanches are among the most   
dreaded accidents4 ,their occurrence1   
however1 being dependent upon the shape 
of the surface1 it is generally possible
 to determine in an accurate way the    
liability of their happening in any     
particular field4 ,the ,swiss take      
precaution to protect themselves from   
their ravages as other folk do to       
procure immunity from floods4 ,thus the 
authorities of many of the mountain     
hamlets maintain extensive forests on   

the sides of the villages whence the    
downfall may be expected1 experience    
having shown that there is no other     
means so well calculated to break the   
blow which these great snowfalls can    
deliver1 as thick-set trees which1      
though they are broken down for some    
distance1 gradually arrest the stream4  
,as long as the region occupied by      
permanent snow is limited to sharp      
mountain peaks1 relief by the           
precipitation of large masses to the    
level below the snow line is easily     
accomplished1 but manifestly this kind  
of a discharge can only be effective    
from a very small field4 ,where the     
relief is not brought about by these    
tumbles of snow1 another mode of        
gravitative action accomplishes the     
result1 though in a more roundabout way1
 through the mechanism of glaciers4  ,we
 have already noted the fact that the   
winter's snow upon our hillsides        
undergoes a movement in the direction of
 the slope4 ,what we have now to        

describe in a rather long story         
concerning glaciers rests upon movements
 of the same nature1 though they are in 
certain features peculiarly dependent on
 the continuity of the action from year 
to year4 ,it is desirable1 however1 that
 the student should see that there is at
 the foundation no more mystery in      
glacial motion than there is in the     
gradual descent of the snow after it has
 lain a week on a hillside4 ,it is only 
in the scale and continuity of the      
action that the greatest glacial        
envelope exceeds those of our temporary 
winters--in fact1 whenever the snow     
falls the earth it covers enters upon an
 ice period which differs only in degree
 from that from which our hemisphere is 
just escaping4  ,where the reader is so 
fortunate as to be able to visit a      
region of glaciers1 he had best begin   
his study of their majestic phenomena by
 ascending to those upper realms where  
the snow accumulates from year to year4 
,he will there find the natural         

irregularities of the rock surface in a 
measure evened over by a vast sheet of  
snow1 from which only the summits of the
 greater mountains rise4 ,he may soon   
satisfy himself that this sheet is of   
great depth1 for here and there it is   
intersected by profound crevices4 ,if   
the visit is made in the season when    
snow falls1 which is commonly during    
most of the year1 he may observe1 as    
before noted in our winter's snow1 that 
the deposit1 though at first flaky1     
attains at a short distance below the   
surface a somewhat granular character1  
though the shotlike grains fall apart   
when disturbed4 ,yet deeper1 ordinarily 
a few feet below the surface1 these     
granules are more or less cemented      
together2 the mass thus loses the       
quality of snow1 and begins to appear   
like a whitish ice4 ,looking down one of
 the crevices1 where the light          
penetrates to the depth of a hundred    
feet or more1 he may see that the bluish
 hue somewhat increases with the depth4 

,a trace of this colour is often visible
 even in the surface snow on the        
glacier1 and sometimes also in our      
ordinary winter fields4 ,in a hole made 
with a stick a foot or more in depth a  
faint cerulean glimmer may generally be 
discerned2 but the increased blueness of
 the ice as we go down is conspicuous1  
and readily leads us to the conclusion  
that the air1 to which1 as we before    
noted1 the whiteness of the snow is due1
 is working out of the mass as the      
process of compaction goes on4 ,in a    
glacial district this snow mass above   
the melting line is called the nv4      
,remembering that the excess of snow    
beyond the melting in a nv district     
amounts1 it may be1 to some feet of     
material each year1 we easily come to   
the conclusion that the mass works down 
the slope in the manner which it does   
even where the coating is impermanent4  
,this supposition is easily confirmed3  
by observing the field we find that the 
sheet is everywhere drawing away from   

the cliffs1 leaving a deep fissure      
between the nv and the precipices4 ,this
 crevice is called by the ,german-,swiss
 guides the ,bergschrund4 ,passage over 
it is often one of the most difficult   
feats to accomplish which the ,alpine   
explorer has to undertake4 ,in fact1 the
 very appearance of the surface1 which  
is that of a river with continuous down 
slopes1 is sufficient evidence that the 
mass is slowly flowing toward the       
valleys4 ,following it down1 we almost  
always come to a place where it passes  
from the upper valleys to the deeper    
gorges which pierce the skirts of the   
mountain4 ,in going over this projection
 the mass of snow-ice breaks to pieces1 
forming a crowd of blocks which march   
down the slope with much more speed than
 they journeyed when united in the      
higher-lying fields4 ,in this condition 
and in this part of the movement the    
snow-ice forms what are called the      
seracs1 or curds1 as the word means in  
the ,french-,swiss dialect4 ,slipping   

and tumbling down the steep slope on    
which the seracs develop1 the ice       
becomes broken into bits1 often of small
 size4 ,these fragments are quickly     
reknit into the body of ice1 which we   
shall hereafter term the glacier1 and in
 this process the expulsion of the air  
goes on more rapidly than before1 and   
the mass assumes a more transparent     
icelike quality4  ,the action of the ice
 in the pressures and strains to which  
it is subjected in joining the main     
glacier and in the further part of its  
course demand for their understanding a 
revision of those notions as to rigidity
 and plasticity which we derive from our
 common experience with objects4 ,it is 
hard to believe that ice can be moulded 
by pressure into any shape without      
fracturing1 provided the motion is      
slowly effected1 while at the same time 
it is as brittle as ice to a sudden     
blow4 ,we see1 however1 a similar       
instance of contrasted properties in the
 confection known as molasses candy1 a  

stick of which may be indefinitely bent 
if the flexure is slowly made1 but will 
fly to pieces like glass if sharply     
struck4 ,ice differs from the sugary    
substance in many ways2 especially we   
should note that while it may be        
squeezed into any form1 it can not be   
drawn out1 but fractures on the         
application of a very slight tension4   
,the conditions of its movement we will 
inquire into further on1 when we have   
seen more of its action4  ,entering on  
the lower part of its course1 that where
 it flows into the region below the snow
 line1 the ice stream is now confined   
between the walls of the valley1 a      
channel which in most cases has been    
shaped before the ice time1 by a        
mountain torrent1 or perhaps by a slower
 flowing river4 ,in this part of its    
course the likeness of a glacial stream 
to one of fluid water is manifest4 ,we  
see that it twists with the turn of the 
gorge1 widens where the confining walls 
are far apart1 and narrows where the    

space is constricted4 ,although the     
surface is here and there broken by     
fractures1 it is evident that the       
movement of the frozen current1 though  
slow1 is tolerably free4 ,by placing    
stakes in a row across the axis of a    
glacier1 and observing their movement   
from day to day1 or even from hour to   
hour if a good theodolite is used for   
the purpose1 we note that the movement  
of the stream is fastest in the middle  
parts1 as in the case of a river1 and   
that it slows toward either shore1      
though it often happens1 as in a stream 
of molten water1 that the speediest part
 of the current is near one side4       
,further observations have indicated    
that the movement is most rapid on the  
surface and least at the bottom1 in     
which the stream is also riverlike4 ,it 
is evident1 in a word1 that though the  
ice is not fluid in strict sense1 the   
bits of which it is made up move in     
substantially the manner of fluids--that
 is1 they freely slip over each other4  

,we will now turn our attention to some 
important features of a detailed sort   
which glaciers exhibit4  ,if we visit a 
glacier during the part of the year when
 the winter snows are upon it1 it may   
appear to have a very uninterrupted     
surface4 ,but as the summer heat        
advances1 the mask of the winter coating
 goes away1 and we may then see the     
structure of the ice4 ,first of all we  
note in all valley glaciers such as we  
are observing that the stream is        
overlaid by a quantity of rocky waste1  
the greater part of which has come down 
with the avalanches in the manner before
 described1 though a small part may have
 been worn from the bed over which the  
ice flows4 ,in many glaciers1           
particularly as we approach their       
termination1 this sheet of earth and    
rock materials often covers the ice so  
completely that the novice in such      
regions finds it difficult to believe   
that the ice is under his feet4 ,if the 
explorer is minded to take the rough    

scramble1 he can often walk for miles on
 these masses of stone without seeing1  
much less setting foot on any frozen    
water4 ,in some of the ,alaskan glaciers
 this coating may bear a forest growth4 
,in general1 this material1 which is    
called moraine1 is distributed in bands 
parallel to the sides of the glaciers1  
and the strips may amount to a half     
dozen or more4 ,those on the sides of   
the ice have evidently been derived from
 the precipices which they have passed4 
,those in the middle have arisen from   
the union of the moraines formed in two 
or more tributary valleys4              
,illustration3 ,fig4 #ab4--,map of      
glaciers and moraines near ,mont ,blanc4
  ,where the avalanches fall most       
plentifully1 the stones lie buried with 
the snow1 and only melt out when the    
stream attains the region where the     
annual waste of its surface exceeds the 
snowfall4 ,in this section we can see   
how the progressive melting gradually   
brings the rocky dbris into plain view4 

,here and there we will find a boulder  
perched on a pedestal of ice1 which     
indicates a recent down-wearing of the  
field4 ,a frequent sound in these       
regions arises from the tumble of the   
stones from their pedestals or the      
slipping of the masses from the sharp   
ridge which is formed by the protection 
given to the ice through the thick      
coating of detritus on its surface4     
,these movements of the moraines often  
distribute their waste over the glacier1
 so that in its lower part we can no    
longer trace the contributions from the 
several valleys1 the whole area being   
covered by the dbris4 ,at the end of the
 ice stream1 where its forward motion is
 finally overcome by the warmth which it
 encounters1 it leaves in a rude heap1  
extending often like a wall across the  
valley1 all the coarse fragments which  
it conveys4 ,this accumulation1 composed
 of all the lateral moraines which have 
gathered on the ice by the fall of      
avalanches1 is called the terminal      

moraine4 ,as the ice stream itself      
shrinks1 a portion of the detritus next 
the boundary wall is apt to be left     
clinging against those slopes4 ,it is   
from the presence of these heaps in     
valleys now abandoned by glaciers that  
we obtain some information as to the    
former greater extent of glacial action4
  ,the next most noticeable feature is  
the crevasse4 ,these fractures often    
exist in very great numbers1 and        
constitute a formidable barrier in the  
explorer's way4 ,the greater part of    
these ruptures below the serac zone run 
from the sides of the stream toward the 
centre without attaining that region4   
,these are commonly pointed up stream2  
their formation is due to the fact that1
 owing to the swifter motion in the     
central parts of the stream1 the ice in 
that section draws away from the        
material which is moving more slowly    
next the shore4 ,as before noted1 these 
ice fractures when drawn out naturally  
form fissures at right angles to the    

direction of the strain4 ,in the middle 
portions of the ice other fissures form1
 though more rarely1 which appear to    
depend on local strains brought about   
through the irregularity of the surface 
over which the ice is flowing4  ,if the 
observer is fortunate1 he may in his    
journey over the glacier have a chance  
to see and hear what goes on when       
crevasses are formed4 ,first he will    
hear a deep1 booming sound beneath his  
feet1 which merges into a more          
splintering note as the crevice1 which  
begins at the bottom or in the distance1
 comes upward or toward him4 ,when the  
sound is over1 he may not be able to see
 a trace of the fracture1 which at first
 is very narrow4 ,but if the break      
intersect any of the numerous shallow   
pools which in a warm summer's day are  
apt to cover a large part of the        
surface1 he may note a line of bubbles  
rushing up through the water1 marking   
the escape of the air from the glacier1 
some remnant of that which is imprisoned

 in the original snow4 ,even where this 
indication is wanting1 he can sometimes 
trace the crevice by the hissing sound  
of the air streams where they issue from
 the ice4 ,if he will take time to note 
what goes on1 he can usually in an hour 
or two behold the first invisible crack 
widen until it may be half an inch      
across4 ,he may see how the surface     
water hastens down the opening1 a little
 river system being developed on the    
surface of the ice as the streams make  
their way to one or more points of      
descent4 ,in doing this work they       
excavate a shaft which often becomes    
many feet in diameter1 down which their 
waters thunder to the base of the       
glacier4 ,this well-like opening is     
called a moulin1 or mill1 a name which1 
as we shall see1 is well deserved from  
the work which falling waters           
accomplish4 ,although the institution of
 the moulin shaft depends upon the      
formation of a crevice1 it often happens
 that as the ice moves farther on its   

journey its walls are again thrust      
together1 soldered in the manner        
peculiar to ice1 so that no trace of the
 rupture remains except the shaft which 
it permitted to form4 ,like everything  
else in the glacier1 the moulin slowly  
moves down the slope1 and remains open  
as long as it is the seat of descending 
waters produced by the summer melting4  
,when it ceases to be kept open from the
 summer1 its walls are squeezed together
 in the fashion that the crevices are   
closed4  ,forming here and there1 and   
generally in considerable numbers1 the  
crevices of a glacier entrap a good deal
 of the morainal dbris1 which falls     
through them to the bottom of the       
glacier4 ,smaller bits are washed into  
the moulin1 by the streams arising from 
the melting ice1 which is brought about 
by the warm sun of the summer1 and      
particularly by the warm rains of that  
season4 ,on those glaciers where1 owing 
to the irregularity of the bottom over  
which the ice flows1 these fractures are

 very numerous1 it may happen that all  
the detritus brought upon the surface of
 the glacier by avalanches finds its way
 to the floor of the ice4  ,although it 
is difficult to learn what is going on  
at the under surface of the glacier1 it 
is possible directly and indirectly to  
ascertain much concerning the peculiar  
and important work which is there done4 
,the intrepid explorer may work his way 
in through the lateral fissures1 and    
even with care safely descend some of   
the fissures which penetrate the central
 parts of a shallow ice stream4 ,there1 
it may be at the depth of a hundred feet
 or more1 he will find a quantity of    
stones1 some of which may be in size    
like to a small house held in the body  
of the ice1 but with one side resting   
upon the bed rock4 ,he may be so        
fortunate as to see the stone actually  
in process of cutting a groove in the   
bed rock as it is urged forward by the  
motion of the glacier4 ,the cutting is  
not altogether in the fixed material1   

for the boulder itself is also worn and 
scored in the work4 ,smaller pebbles are
 caught in the space between the erratic
 and the motionless rock and ground to  
bits4 ,if in his explorations the       
student finds his way to the part of the
 floor on which the waters of a moulin  
fall1 he may have a chance to observe   
how the stones set in motion serve to   
cut the bed rock1 forming elongated     
potholes much as in the case of ordinary
 waterfalls1 or at the base of those    
shafts which afford the beginnings of   
limestone caverns4  ,the best way to    
penetrate beneath the glacier is through
 the arch of the stream which always    
flows from the terminal face of the ice 
river4 ,even in winter time every large 
glacier discharges at its end a         
considerable brook1 the waters of which 
have been melted from the ice in small  
part by the outflow of the earth's heat2
 mainly1 however1 by the warmth produced
 in the friction of the ice on itself   
and on its bottom--in other words1 by   

the conversion of that energy of        
position1 of which we have often to     
speak1 into heat4 ,in the summer time   
this subglacial stream is swollen by the
 surface waters descending through the  
crevices and the moulins which come from
 them1 so that the outflow often forms a
 considerable river1 and thus excavates 
in the ice a large or at least a long   
cavern1 the base of which is the bed    
rock4 ,in the autumn1 when the          
superficial melting ceases1 this gallery
 can often be penetrated for a          
considerable distance1 and affords an   
excellent way to the secrets of the     
under ice4 ,the observer may here see   
quantities of the rock material held in 
the grip of the ice1 and forced to a    
rude journey over the bare foundation   
stones4 ,now and then he may find the   
glacial mass in large measure made up of
 stones1 the admixture extending many   
feet above the bottom of the cavern1    
perhaps to the very top of the arch4 ,he
 may perchance find that these stones   

are crushing each other where they are  
in contact4 ,the result will be brought 
about by the difference in the rate of  
advance of the ice1 which moves the     
faster the higher it is above the       
surface over which it drags1 and thus   
forces the stones on one level over     
those below4 ,where the waters of the   
subglacial stream have swept the bed    
rock clean of dbris its surface is      
scored1 grooved1 and here and there     
polished in a manner which is           
accomplished only by ice action1 though 
some likeness to it is afforded where   
stones have been swept over for ages by 
blowing sand4 ,here and there1 often in 
a way which interrupts the cavern       
journey1 the shrunken stream1 unable to 
carry forward the dbris1 deposits the   
material in the chamber1 sometimes      
filling the arch so completely that the 
waters are forced to make a detour4     
,this action is particularly            
interesting1 for the reason that in     
regions whence glaciers have disappeared

 the deposits formed in the old ice     
arches often afford singularly perfect  
moulds of those caverns which were      
produced by the ancient subglacial      
streams4 ,these moulds are termed       
eskers4  ,if the observer be attentive1 
he will note the fact that the waters   
emerging from beneath the considerable  
glacier are very much charged with mud4 
,if he will take a glass of the water at
 the point of escape1 he will often     
find1 on permitting it to settle1 that  
the sediment amounts to as much as one  
twentieth of the volume4 ,while the     
greater part of this detritus will      
descend to the bottom of the vessel in  
the course of a day1 a portion of it    
does not thus fall4 ,he may also note   
that this mud is not of the yellowish   
hue which he is accustomed to behold in 
the materials laid down by ordinary     
rivers1 but has a whitish colour4       
,further study will reveal the fact that
 the difference is due to the lack of   
oxidation in the case of the glacial    

detritus4 ,river muds forming slowly and
 during long-continued exposure to the  
action of the air have their contained  
iron much oxidized1 which gives them a  
part of their darkened appearance4      
,moreover1 they are somewhat coloured   
with decayed vegetable matter4 ,the     
waste from beneath the glacier has been 
quickly separated from the bed rock1 all
 the faces of the grains are freshly    
fractured1 and there is no admixture of 
organic matter4 ,the faces of the       
particles thus reflect light in         
substantially the same way as powdered  
glass or pulverized ice1 and            
consequently appear white4  ,a little   
observation will show the student that  
this very muddy character of waters     
emerging from beneath the glacier is    
essentially peculiar to such streams as 
we have described4 ,ascending any of the
 principal valleys of ,switzerland1 he  
may note that some of the streams flow  
waters which carry little sediment even 
in times when they are much swollen1    

while others at all seasons have the    
whitish colour4 ,a little further       
exploration1 or the use of a good map1  
will show him that the pellucid streams 
receive no contributions of glacial     
water1 while those which look as if they
 were charged with milk come1 in part at
 least1 from the ice arches4 ,from some 
studies which the writer has made in    
,swiss valleys1 it appears that the     
amount of erosion accomplished on equal 
areas of similar rock by the descent of 
the waters in the form of a glacier or  
in that of ordinary torrents differs    
greatly4 ,moving in the form of ice1 or 
in the state of ice-confined streams1   
the mass of water applies very many     
times as much of its energy of position 
to grinding and bearing away the rocks  
as is accomplished where the water      
descends in its fluid state4  ,the      
effect of the intense ice action above  
noted is rapidly to wear away the rocks 
of the valley in which the glacier is   
situated4 ,this work is done not only in

 a larger measure but in a different way
 from that accomplished by torrents4 ,in
 the case of the latter1 the stream bed 
is embarrassed by the rubbish which     
comes into it2 only here and there can  
it attack the bed rock by forcing the   
stones over its surface4 ,only in a few 
days of heavy rain each year is its work
 at all effective2 the greater part of  
the energy of position of its waters is 
expended in the endless twistings and   
turnings of its stream1 which result    
only in the development of heat which   
flies away into the atmosphere4 ,in the 
ice stream1 owing to its slow movement  
and to the detritus which it forces     
along the bottom1 a vastly greater part 
of the energy which impels it down the  
slope is applied to rock cutting4 ,none 
of the boulders1 even if they are yards 
in diameter1 obstruct its motion2 small 
and great alike are to it good          
instruments wherewith to attack the bed 
rocks4 ,the fragments are never left to 
waste by atmospheric decay1 but are to a

 very great extent used up in mechanical
 work1 while the most of the detritus   
which comes to a torrent is left in a   
coarse state when it is delivered to the
 stream2 the larger part of that which  
the glacier transports is worn out in   
its journey4 ,to a great extent it is   
used up in attacking the bed rock4 ,in  
most cases the dbris in the terminal    
moraine is evidently but a small part of
 what entered the ice during its journey
 from the uplands2 the greater part has 
been worn out in the rude experiences to
 which it has been subjected4  ,it is   
evident that even in the regions now    
most extensively occupied by glaciers   
the drainage systems have been shaped by
 the movement of ordinary streams--in   
other words1 ice action is almost       
everywhere1 even in the regions about   
the poles1 an incidental feature in the 
work of water1 coming in only to modify 
the topography1 which is mainly moulded 
by the action of fluid water4 ,when1    
owing to climatal changes1 a valley such

 as those of the ,alps is occupied by a 
glacial stream1 the new current proceeds
 at once1 according to its evident      
needs1 to modify the shape of its       
channel4 ,an ordinary torrent1 because  
of the swiftness of its motion1 which   
may1 in general1 be estimated at from   
three to five miles an hour1 can convey 
away the precipitation over a very      
narrow bed4 ,therefore its channel is   
usually not a hundredth part as wide as 
the gorge or valley in which it lies4   
,but when the discharge takes place by a
 glacier1 the speed of which rarely     
exceeds four or five feet a day1 the ice
 stream because of its slow motion has  
to fill the trough from side to side1 it
 has to be some thousand times as deep  
and wide as the torrent4 ,the result is 
that as soon as the glacial condition   
arises in a country the ice streams     
proceed to change the old ,v-shaped     
torrent beds into those which have a    
broad ,u-like form4 ,the practised eye  
can in a way judge how long a valley has

 been subjected to glacial action by the
 extent to which it has been widened by 
this process4  ,in the valleys of       
,switzerland and other mountain         
districts which have been attentively   
studied it is evident that glacial      
action has played a considerable part in
 determining their forms4 ,but the work 
has been limited to that part of the    
basin in which the ice is abundantly    
provided with cutting tools in the stone
 which have found their way to the base 
of the stream4 ,in the region of the nv1
 where the contributions of rocky matter
 to the surface of the deposit made from
 the few bare cliffs which rise above   
the sheet of snow is small1 the snow-ice
 does no cutting of any consequence4    
,where it passes over the steep at the  
head of the deep valley into which it   
drains1 and is riven into the seracs1   
such stony matter as it may have        
gathered is allowed to fall to the      
bottom1 and so comes into a position    
where it may do effective work4 ,from   

this serac section downward the now     
distinct ice river1 being in general    
below the snow line1 has everywhere     
cliffs1 on either side from which the   
contributions of rock material are      
abundant4 ,hence this part of the       
glacier1 though it is the wasting       
portion of its length1 does all the     
cutting work of any consequence which is
 performed4 ,it is there that the       
underrunning streams become charged with
 sediment1 which1 as we have noted1 they
 bear in surprising quantities1 and it  
is therefore in this section of the     
valley that the impress of the ice work 
is the strongest4 ,its effect is not    
only to widen the valley and deepen it1 
but also to advance the deep section    
farther up the stream and its           
tributaries4 ,the step in the stream    
beds which we find at the seracs appears
 to mark the point in the course of the 
glacier where1 owing to the falling of  
stones to its base1 as well as to its   
swifter movements and the firmer state  

of the ice1 it does effective wearing4  
,there are many other features connected
 with glaciers which richly repay the   
study of those who have a mind to       
explore in the manner of the physicist  
interested in ice actions the difficult 
problems which they afford2 but as these
 matters are not important from the     
point of view of this work1 no mention  
of them will here be made4 ,we will now 
turn our attention to that other group  
of glaciers commonly termed continental1
 which now exist about either pole1 and 
which at various times in the earth's   
history have extended far toward the    
equator1 mantling over vast extents of  
land and shallow sea4 ,the difference   
between the ice streams of the mountains
 and those which we term continental    
depends solely on the areas of the      
fields and the depth of the             
accumulation4 ,in an ordinary ,alpine   
region the nv districts1 where the snow 
gathers1 are relatively small4 ,owing to
 the rather steep slopes1 the frozen    

water is rapidly discharged into the    
lower valleys1 where it melts away4     
,both in the nv and in the distinct     
glacier of the lower grounds there are1 
particularly in the latter1 projecting  
peaks1 from which quantities of stone   
are brought down by avalanches or in    
ordinary rock falls1 so that the ice is 
abundantly supplied with cutting tools1 
which work from its surface down to its 
depths4  ,as the glacial accumulation   
grows in depth there are fewer peaks    
emerging from it1 and the streams which 
it feeds rise the higher until they     
mantle over the divides between the     
valleys4 ,thus by imperceptible stages  
valley glaciers pass to the larger form1
 usually but incorrectly termed         
continental4 ,we can1 indeed1 in going  
from the mountains in the tropics to the
 poles1 note every step in this         
transition1 until in ,greenland we      
attain the greatest ice mass in the     
world1 unless that about the southern   
pole be more extensive4 ,in the         

,greenland glacier the ice sheet covers 
a vast extent of what is probably a     
mountain country1 which is certainly of 
this nature in the southern part of the 
island1 where alone we find portions of 
the earth not completely covered by the 
deep envelope4 ,thanks to the labours of
 certain hardy explorers1 among whom    
,nansen deserves the foremost place1 we 
now know something as to the conditions 
of this vast ice field1 for it has been 
crossed from shore to shore4 ,the       
results of these studies are most       
interesting1 for they afford us a clew  
as to the conditions which prevail over 
a large part of the earth during the    
,glacial period from which the planet is
 just escaping1 and in the earlier ages 
when glaciation was likewise extensive4 
,we shall therefore consider in a       
somewhat detailed way the features which
 the ,greenland glacier presents4       
,starting from the eastern shore of that
 land1 if we may thus term a region     
which presents itself mainly in the form

 of ice1 we find next the shore a coast 
line not completely covered with ice and
 snow1 but here and there exhibiting    
peaks which indicate that if the frozen 
mantle were removed the country would   
appear deeply intersected with fiords in
 the manner exhibited in the regions to 
the south of ,greenland or the          
,scandinavian peninsula4 ,the ice comes 
down to the sea through the valleys1    
often facing the ocean for great        
distances with its frozen cliffs4       
,entering on this seaward portion of the
 glacier1 the observer finds that for   
some distance from the coast line the   
ice is more or less rifted with         
crevices1 the formation of which is     
doubtless due to irregularities of the  
rock bottom over which it moves4 ,these 
ruptures are so frequent that for some  
miles back it is very difficult to find 
a safe way4 ,finally1 however1 a point  
is attained where these breaks rather   
suddenly disappear1 and thence inward   
the ice rises at the rate of upward     

slope of a few feet to the mile in a    
broad1 nearly smooth incline4 ,in the   
central portion of the region for a     
considerable part of the territory the  
ice has very little slope4 ,thence it   
declines toward the other shore1        
exhibiting the same features as were    
found on the eastern versant until near 
the coast1 when again the surface is    
beset with crevices which continue to   
the margin of the sea4  ,although the   
explorations of the central field of    
,greenland are as yet incomplete1       
several of these excursions into or     
across the interior have been made1 and 
the identity of the observations is such
 that we can safely assume the whole    
region to be of one type4 ,we can       
furthermore run no risk in assuming that
 what we find in ,greenland1 at least so
 far as the unbroken nature of the      
central ice field is concerned1 is what 
must exist in every land where the      
glacial envelope becomes very deep4 ,in 
,greenland it seems likely that the     

depth of the ice is on the average more 
than half a mile1 and in the central    
part of the realm the sheet may well    
have a much greater profundity2 it may  
be nearly a mile deep4 ,the most        
striking feature--that of a vast        
unbroken expanse1 bordered by a region  
where the ice is ruptured--is traceable 
wherever very extensive and presumably  
deep deposits of ice have been examined4
 ,as we shall see hereafter1 these      
features teach us much as to the        
conditions of glacial action--a matter  
which we shall have to examine after we 
have completed our general survey as to 
the changes which occur during glacial  
periods4  ,in the present state of that 
wonderful complex of actions which we   
term climate1 glaciers are everywhere1  
so far as our observations enable us to 
judge1 generally in process of decrease4
 ,in ,switzerland1 although the ancients
 even in ,roman days were in contact    
with the ice1 they were so unobservant  
that they did not even remark that the  

ice was in motion4 ,only during the last
 two centuries have we any observations 
of a historic sort which are of value to
 the geologist4 ,fortunately1 however1  
the signs written on the rock tell the  
story1 except for its measurement in    
terms of years1 as clearly as any       
records could give it4 ,from this       
testimony of the rocks we perceive that 
in the geological yesterday1 though it  
may have been some tens of thousands of 
years ago1 the ,swiss glaciers1 vastly  
thickened1 and with their horizontal    
area immensely expanded1 stretched over 
the ,alpine country1 so that only here  
and there did any of the sharper peaks  
rise above the surface4 ,these vast     
glaciers1 almost continually united on  
their margins1 extended so far that     
every portion of what is now the ,swiss 
,republic was covered by them4 ,their   
front lay on the southern lowlands of   
,germany1 on the ,jura district of      
,france2 on the south1 it stretched     
across the valley of the ,po as far as  

near ,milan4 ,we know this old ice front
 by the accumulations of rock dbris     
which were brought to it from the       
interior of the mountain realm4 ,we can 
recognise the peculiar kinds of stone1  
and with perfect certainty trace them to
 the bed rock whence they were riven4   
,moreover1 we can follow back through   
the same evidence the stages of retreat 
of the glaciers1 until they lost their  
broad continental character and assumed 
something like their present valley     
form4 ,up the valley of any of the great
 rivers1 as1 for instance1 that of the  
,rhne above the lake of ,geneva1 we note
 successive terminal moraines which     
clearly indicate stages in the retreat  
of the ice when for a time it ceased to 
go backward1 or even made a slight      
temporary readvance4 ,it is easily seen 
that on such occasions the stones       
carried to the ice front would be       
accumulated in a heap1 while during the 
time when day by day the glacier was    
retreating the rock waste would be left 

broadcast over the valley4  ,as we go up
 from the course of the glacial streams 
we note that the successive moraines    
have their materials in a progressively 
less decayed state4 ,far away from the  
heap now forming1 and in proportion to  
the distance1 the stones have in a      
measure rotted1 and the heaps which they
 compose are often covered with soil and
 occupied by forests4 ,within a few     
miles of the ice front the stones still 
have a fresh aspect4 ,when we arrive    
within1 say1 half a mile of the moraine 
now building1 we come to the part of the
 glacial retreat of which we have some  
written or traditional account4 ,this is
 in general to the effect that the      
wasting of the glaciers is going on in  
this century as it went on in the past4 
,occasionally periods of heavy snow     
would refresh the ice streams1 so that  
for a little time they pushed their     
fronts farther down the valley4 ,the    
writer has seen during one of these     
temporary advances the interesting      

spectacle of ice destroying and         
overturning the soil of a small field   
which had been planted in grain4  ,it   
should be noted that these temporary    
advances of the ice are not due to the  
snowfall of the winter or winters       
immediately preceding the forward       
movement4 ,so slow is the journey of the
 ice from the nv field to the end of a  
long glacier that it may require        
centuries for the store accumulated in  
the uplands to affect the terminal      
portion of the stream4 ,we know that the
 bodies of the unhappy men who have been
 lost in the crevices of the glacier are
 borne forward at a uniform and         
tolerably computable rate until they    
emerge at the front1 where the ice melts
 away4 ,in at least one case the remains
 have appeared after many years in the  
dbris which is contributed to the       
moraine4 ,on account of this slow       
feeding of the glacial stream1 we       
naturally may expect to find1 as we do1 
in fact1 that a great snowfall of many  

years ago1 and likewise a period when   
the winter's contribution has been      
slight1 would influence the position of 
the terminal point of the ice stream at 
different times1 according to its       
length4 ,if the length of the flow be   
five miles1 it may require twenty or    
thirty years for the effect to be       
evident2 while if the stream be ten     
miles long1 the influence may not be    
noted in less than threescore years4    
,thus it comes about that at the present
 time in the same glacial district some 
streams may be advancing while others   
are receding1 though1 on the whole1 the 
ice is generally in process of          
shrinkage4 ,if the present rate of      
retreat should be maintained1 it seems  
certain that at the end of three        
centuries the ,swiss glaciers as a whole
 will not have anything like their      
present area1 and many of the smaller   
streams will entirely disappear4        
,following the method of the illustrious
 ,louis ,agassiz1 who first attentively 

traced the evidence which shows the     
geologically recent great extension of  
glaciers by studying the evidence of the
 action in fields they no longer occupy1
 geologists have now inspected a large  
part of the land areas with a view to   
finding the proofs of such ice work4 ,so
 far as these indications are concerned1
 the indications which they have had to 
trace are generally of a very           
unmistakable character4 ,rarely1 indeed1
 does a skilled student of such         
phenomena have to search in any region  
for more than a day before he obtains   
indubitable evidence which will enable  
him to determine whether or not the     
field has recently been occupied by an  
enduring ice sheet--one which survives  
the summer season and therefore deserves
 the name of glacier4 ,the indications  
which he has to consider consist in the 
direction and manner in which the       
surface materials have been carried1 the
 physical conditions of these materials1
 the shape of the surface of the        

underlying rock as regards its general  
contour1 and the presence or absence of 
scratches and groovings on its surface4 
,as these records of ice action are of  
first importance in dealing with this   
problem1 and as they afford excellent   
subjects for the study of those who     
dwell in glaciated regions1 we shall    
note them in some detail4  ,the         
geologist recognises several ways in    
which materials may be transported on   
the surface of the earth4 ,they may be  
cast forth by volcanoes1 making their   
journey by being shot through the air1  
or by flowing in lava streams2 it is    
always easy at a glance1 save in very   
rare instances1 to determine whether    
fragments have thus been conveyed4      
,again1 the detritus may be moved by the
 wind2 this action is limited2 it only  
affects dust1 sand1 and very small      
pebbles1 and is easily discriminated4   
,the carriage may be effected by river  
or marine currents2 here1 again1 the    
size of the fragments moved is small1   

and the order of their arrangement      
distinctly traceable4 ,the fragments may
 be conveyed by ice rafts2 here1 too1   
the observer can usually limit the      
probabilities he has to consider by     
ascertaining1 as he can generally do1   
whether the region which he is observing
 has been below a sea or lake4 ,in a    
word1 the before-mentioned agents of    
transportation are of somewhat          
exceptional influence1 and in most cases
 can1 as explanations of rock           
transportation1 be readily excluded4    
,when1 therefore1 the geologist finds a 
country abundantly covered with sand1   
pebbles1 and boulders arranged in an    
irregular way1 he has generally only to 
inquire whether the material has been   
carried by rivers or by glaciers4 ,this 
discrimination can be quickly and       
critically effected4 ,in the first      
place1 he notes that rivers only in     
their torrent sections can carry large  
fragments of rock1 and that in all cases
 the fragments move down hill4 ,further1

 that where deposits are formed1 they   
have more or less the form of alluvial  
deposits4 ,if now the observations show 
that the rock waste occupying the       
surface of any region has been carried  
up hill and down1 across the valleys1   
particularly if there are here and there
 traces of frontal moraines1 the        
geologist is entitled to suppose--he    
may1 indeed1 be sure--that the carriage 
has been effected by a glacial sheet4   
,important corroborative evidence of ice
 action is generally to be found by     
inspecting the bed rock below the       
detritus1 which indicates glacial       
action4 ,even if it be somewhat decayed1
 as is apt to be the case where the ice 
sheet long since passed away1 the bed   
rock is likely to have a warped surface2
 it is cast into ridges and furrows of a
 broad1 flowing aspect1 such as liquid  
water never produces1 which1 indeed1 can
 only be created by an ice sheet moving 
over the surface1 cutting its bed in    
proportion to the hardness of the       

material4 ,furthermore1 if the bed rock 
have a firm texture1 and be not too much
 decayed1 we almost always find upon it 
grooves or scratches1 channels carved by
 the stones embedded in the body of the 
ice1 and drawn by its motion over the   
fixed material4 ,thus the proof of      
glacial extension in the last ice epoch 
is made so clear that accurate maps can 
be prepared showing the realm of its    
action4 ,this task is as yet incomplete1
 although it is already far advanced4   
,while the study of glaciers began in   
,europe1 inquiries concerning their     
ancient extension have been carried     
further and with more accuracy in ,north
 ,america than in any other part of the 
world4 ,we may therefore well begin our 
description of the limits of the ice    
sheets with this continent4 ,imagining a
 seafarer to have approached ,america by
 the ,north ,atlantic1 as did the       
,scandinavians1 and that his voyage came
 perhaps a hundred thousand years or    
more before that of ,leif ,ericsson1 he 

would have found an ice front long      
before he attained the present shores of
 the land4 ,this front may have extended
 from south of ,greenland1 off the      
shores of the present ,grand ,banks of  
,newfoundland1 thence and westward to   
central or southern ,new ,jersey4 ,this 
cliff of ice was formed by a sheet which
 lay on the bottom of the sea4 ,on the  
,new ,jersey coast the ice wall left the
 sea and entered on the body of the     
continent4 ,we will now suppose that the
 explorer1 animated with the valiant    
scientific spirit which leads the men of
 our day to seek the poles1 undertook a 
land journey along the ice front across 
the continent4 ,from the ,new ,jersey   
coast the traveller would have passed   
through central ,pennsylvania1 where1   
although there probably detached        
outlying glaciers lying to the southward
 as far as central ,virginia1 the main  
front extended westward into the ,ohio  
,valley4 ,in southern ,ohio a tongue of 
the ice projected southwardly until it  

crossed the ,ohio ,river1 where         
,cincinnati now lies1 extending a few   
miles to the southward of the stream4   
,thence it deflected northwardly1       
crossing the ,mississippi1 and again the
 ,missouri1 with a tongue or lobe which 
went far southward in that ,state4 ,then
 again turning to the northwest1 it     
followed in general the northern part of
 the ,missouri basin until it came to   
within sight of the ,rocky ,mountains4  
,there the ice front of the main glacier
 followed the trend of the mountains at 
some distance from their face for an    
unknown extent to the northward4 ,in the
 ,cordilleras1 as far south as southern 
,colorado1 and probably in the ,sierra  
,nevada to south of ,san ,francisco1 the
 mountain centres developed local       
glaciers1 which in some places were of  
very great size1 perhaps exceeding any  
of those which now exist in             
,switzerland4 ,it will thus be seen that
 nearly one half of the present land    
area of ,north ,america was beneath a   

glacial covering1 though1 as before     
noted1 the region about the ,gulf of    
,mexico may have swayed upward when the 
northern portion of the land was borne  
down by the vast load of ice which      
rested upon it4 ,notwithstanding this   
possible addition to the land1 our      
imaginary explorer would have found the 
portion of the continent fit for the    
occupancy of life not more than half as 
great as it is at present4  ,in the     
,eurasian continent there was no such   
continuous ice sheet as in ,north       
,america1 but the glaciers developed    
from a number of different centres1 each
 moving out upon the lowlands1 or1 if   
its position was southern1 being limited
 to a particular mountain field4 ,one of
 these centres included ,scandinavia1   
northern ,germany1 ,great ,britain about
 as far south as ,london1 and a large   
part of ,ireland1 the ice covering the  
intermediate seas and extending to the  
westward1 so that the passage of the    
,north ,atlantic was greatly restricted 

between this ice front and that of      
,north ,america4 ,another centre1 before
 noted1 was formed in the ,alps2 yet    
another1 of considerable area1 in the   
,pyrenees2 other less studied fields    
existed in the ,apennines1 in the       
,caucasus1 the ,ural1 and the other     
mountains of northern ,asia4 ,curiously 
enough1 however1 the great region of    
plains in ,siberia does not appear to   
have been occupied by a continuous ice  
sheet1 though the similar region in     
,north ,america was deeply embedded in a
 glacier4 ,coincident with this         
development of ice in the eastern part  
of the continent1 the ice streams of the
 ,himalayan ,mountains1 some of which   
are among the greatest of our upland    
glaciers1 appear to have undergone but a
 moderate extension4 ,many other of the 
,eurasian highlands were probably       
ice-bound during the last ,glacial      
period1 but our knowledge concerning    
these local fields is as yet imperfect4 
,in the southern hemisphere the lands   

are of less extent and1 on the whole1   
less studied than in the northern realm4
 ,here and there where glaciers exist1  
as in ,new ,zealand and in the southern 
part of ,south ,america1 observant      
travellers have noticed that these ice  
fields have recently shrunk away4       
,whether the time of greatest extension 
and of retreat coincided with that of   
the ice sheets in the north is not yet  
determined2 the problem1 indeed1 is one 
of some difficulty1 and may long remain 
undecided4 ,it seems1 however1 probable 
that the glaciers of the southern       
hemisphere1 like those in the north1 are
 in process of retreat4 ,if this be     
true1 then their time of greatest       
extension was probably the same as that 
of the ice sheets about the southern    
pole4 ,from certain imperfect reports   
which we have concerning evidences of   
glaciation in ,central ,america and in  
the ,andean district in the northern    
part of ,south ,america1 it seems       
possible that at one time the upland ice

 along the ,cordilleran chain existed   
from point to point along that system of
 elevations1 so that the widest interval
 between the fields of permanent snow   
with their attendant glaciers did not   
much exceed a thousand miles4           
,observing the present gradual retreat  
of those ice remnants which remain mere 
shreds and patches of the ancient       
fields1 it seems at first sight likely  
that the extension and recession of the 
great glaciers took place with exceeding
 slowness4 ,measured in terms of human  
life1 in the manner in which we gauge   
matters of man's history1 this process  
was doubtless slow4 ,there are reasons1 
however1 to believe that the coming and 
going were1 in a geological sense1      
swift2 they may have1 indeed1 been for a
 part of the time of startling rapidity4
 ,going back to the time of geological  
yesterday1 before the ice began its     
development in the northern hemisphere1 
all the evidence we can find appears to 
indicate a temperate climate extending  

far toward the north pole4 ,the ,miocene
 deposits found within twelve degrees1  
or a little more than seven hundred     
miles1 of the north pole1 and fairly    
within the realm of lowest temperature  
which now exists on the earth1 show by  
the plant remains which they contain    
that the conditions permitted the growth
 of forests1 the plants having a        
tolerably close resemblance to those    
which now freely develop in the southern
 portion of the ,mississippi ,valley4   
,among them there are species which had 
the habit of retaining their broad1     
rather soft leaves throughout the winter
 season4 ,the climate appears1 in a     
word1 to have been one where the mean   
annual temperature must have been thirty
 degrees or more higher than the present
 average of that realm4 ,although such  
conditions near the sea level are not   
inconsistent with the supposition that  
glaciers existed in the higher mountains
 of the north1 they clearly deny the    
possibility of the realm being occupied 

by continental glaciers4  ,although the 
,pliocene deposits formed in high       
latitudes have to a great extent been   
swept away by the subsequent glacial    
wearing1 they indicate by their fossils 
a climatal change in the direction of   
greater cold4 ,we trace this change1    
though obscurely1 in a progressive      
manner to a point where the records are 
interrupted1 and the next interpretable 
indication we have is that the ice sheet
 had extended to somewhere near the     
limits which we have noted4 ,we are then
 driven to seek what we can concerning  
the sojourn of the ice on the land by   
the amount of wearing which it has      
inflicted upon the areas which it       
occupied4 ,this evidence has a certain1 
though1 as we shall see1 a limited      
value4  ,when the students of glacial   
action first began the great task of    
interpreting these records1 they were   
led to suppose that the amount of rock  
cutting which was done by the ice was   
very great4 ,observing what goes on1 in 

the manner we have noted1 beneath a     
valley glacier such as those of         
,switzerland1 they saw that the ice work
 went on rapidly1 and concluded that if 
the ice remained long at work in a      
region it must do a vast deal of        
erosion4 ,they were right in a part of  
their premises1 but1 as we shall see1   
probably in another part wrong4 ,looking
 carefully over the field where the ice 
has operated1 we note that1 though at   
first sight the area appears to have    
lost all trace of its preglacial river  
topography1 this aspect is due mainly to
 the irregular way in which the glacial 
waste is laid down4 ,close study shows  
us that we may generally trace the old  
stream valleys down to those which were 
no larger than brooks4 ,it is true that 
these channels are generally and in many
 places almost altogether filled in with
 rubbish1 but a close study of the      
question has convinced the writer1 and  
this against a previous view1 that the  
amount of erosion in ,new ,england and  

,canada1 where the work was probably as 
great as anywhere1 has not on the       
average exceeded a hundred feet1 and    
probably was much less than that amount4
  ,even in the region north of ,lake    
,ontario1 over which the ice was deep   
and remained for a long time1 the amount
 of erosion is singularly small4 ,thus  
north of ,kingston the little valleys in
 the limestone rocks which were cut by  
the preglacial streams1 though somewhat 
encumbered with drift1 remain almost as 
distinct as they are on similar strata  
in central ,kentucky1 well south of the 
field which the ice occupied4 ,in fact1 
the ice sheet appears to have done the  
greatest part of its work and to have   
affected the surface most in the belt of
 country a few hundred miles in width   
around the edges of the sheet4 ,it was  
to be expected that in a continental    
glacier1 as in those of mountain        
valleys1 the most of the dbris should be
 accumulated about the margin where the 
materials dropped from the ice4 ,but why

 the cutting action should be greatest  
in that marginal field is not at first  
sight clear4 ,to explain this and other 
features as best we may1 we shall now   
consider the probable history of the    
great ice march in advance and retreat1 
and then take up the conditions which   
brought about its development and its   
disappearance4  ,ice is in many ways the
 most remarkable substance with which   
the physicist has to deal1 and among its
 eminent peculiarities is that it       
expands in freezing1 while the rule is  
that substances contract in passing from
 the fluid to the solid state4 ,on this 
account frozen water acts in a unique   
manner when subjected to pressure4 ,for 
each additional atmosphere of           
pressure--a weight amounting to about   
fifteen pounds to the square inch--the  
temperature at which the ice will melt  
is lowered to the amount of sixteen     
thousandths of a degree centigrade4 ,if 
we take a piece of ice at the           
temperature of freezing and put upon it 

a sufficient weight1 we inevitably bring
 about a small amount of melting4 ,where
 we can examine the mass under          
favourable conditions1 we can see the   
fluid gather along the lines of the     
crystals or other bits of which the ice 
is composed4 ,we readily note this      
action by bringing two pieces of ice    
together with a slight pressure2 when   
the pressure is removed1 they will      
adhere4 ,the adhesion is brought about  
not by any stickiness of the materials1 
for the substance has no such property4 
,it is accomplished by melting along the
 line of contact1 which forms a film of 
water1 that at once refreezes when the  
pressure is withdrawn4 ,when a firm     
snowball is made by even pressing snow1 
innumerable similar adhesions grow up in
 the manner described4 ,the fact is     
that1 given ice at the temperature at   
which it ordinarily forms1 pressure upon
 it will necessarily develop melting4   
,the consequences of pressure melting as
 above described are in glaciers        

extremely complicated4 ,because the ice 
is built into the glacier at a          
temperature considerably below the      
freezing point1 it requires a great     
thickness of the mass before the        
superincumbent weight is sufficient to  
bring about melting in its lower parts4 
,if we knew the height at which a       
thermometer would have stood in the     
surface ice of the ancient glacier which
 covered the northern part of ,north    
,america1 we could with some accuracy   
compute how thick it must have been     
before the effect of pressure alone     
would have brought about melting2 but   
even then we should have to reckon the  
temperature derived from the grinding of
 the ice over the floor and the crushing
 of rocks there effected1 as well as the
 heat which is constantly though slowly 
coming forth from the earth's interior4 
,the result is that we can only say that
 at some depth1 probably less than a    
mile1 the slowly accumulating ice would 
acquire such a temperature that1        

subjected to the weight above it1 the   
material next the bottom would become   
molten1 or at least converted into a    
sludgelike state1 in which it could not 
rub against the bottom1 or move stones  
in the manner of ordinary glaciers4  ,as
 fast as the ice assumed this liquid or 
softened state1 it would be squeezed out
 toward the region where1 because of the
 thinning of the glacier1 it would enter
 a field where pressure melting did not 
occur4 ,it would then resume the solid  
state1 and thence journey to the margin 
of the ice in the ordinary manner4 ,we  
thus can imagine how such a glacier as  
occupied the northern part of this      
continent could have moved from the     
central parts toward its periphery1 as  
we can not do if we assume that the     
glacier everywhere lay upon the bed     
rock4 ,there is no slope from ,lake     
,erie to the ,ohio ,river at            
,cincinnati4 ,knowing that the ice moved
 down this line1 there are but two      
methods of accounting for its motion3   

either the slope of the upper surface to
 the northward was so steep that the    
mass would have been thus urged down1   
the upper parts dragging the bottom     
along with them1 or the ice sheet for   
the greater part of its extent rested   
upon pressure-molten water1 or sludge   
ice1 which was easily squeezed out      
toward the front4 ,the first supposition
 appears inadmissible1 for the reason   
that the ice would have to be many miles
 deep at ,hudson ,bay in order that its 
upper surface should have slope enough  
to overcome the rigidity of the material
 and bring about the movement4 ,we know 
that any such depth is not supposable4  
,the recent studies in ,greenland supply
 us with strong corroborative evidence  
for the support of the view which is    
here urged4 ,the wide central field of  
that area1 where the ice has an         
exceeding slight declivity1 and is      
unruptured by crevices1 can not be      
explained except on the supposition that
 it rests on pressure-molten water4 ,the

 thinner section next the shore1 where  
the glacier is broken up by those       
irregular movements which its wrestle   
with the bottom inevitably induces1     
shows that there it is in contact with  
the bed rock1 for it behaves exactly as 
do the valley glaciers of like          
thickness4  ,the view above suggested as
 to the condition of continental        
glaciers enables us to explain not only 
their movements1 but the relatively     
slight amount of wearing which they     
brought about on the lands they         
occupied4 ,beginning to develop in      
mountain regions1 or near the poles on  
the lowlands1 these sheets1 as soon as  
they attained the thickness where the   
ice at their bottom became molten1 would
 rapidly advance for great distances    
until they attained districts where the 
melting exceeded the supply of frozen   
material4 ,in this excursion only the   
marginal portion of the glacier would do
 erosive work4 ,this would evidently be 
continued for the greatest amount of    

time near the front or outer rim of the 
ice field1 for there1 we may presume1   
that for the longest time the cutting   
rim would rest upon the bed rock of the 
country4 ,as the ice receded1 this rim  
would fall back2 thus in the retreat as 
in the advance the whole of the field   
would be subjected to a certain amount  
of erosion4 ,on this supposition we     
should expect to find that the front of 
a continental glacier1 fed with         
pressure-molten water from all its      
interior district1 which became         
converted into ice1 would attain much   
warmer regions than the valley streams1 
where all the flow took place in the    
state of ice1 and1 furthermore1 that the
 speed of the going on the margin would 
be much more rapid than in the ,alpine  
streams4 ,these suppositions are well   
borne out by the study of existing      
continental ice sheets1 which move with 
singular rapidity at their fronts1 and  
by the ancient glaciers1 which evidently
 extended into rather warm fields4      

,thus1 when the ice front lay at the    
site of ,cincinnati1 at six hundred feet
 above the sea1 there were no glaciers  
in the mountains of ,north ,carolina1   
though those rise more than five        
thousand feet higher in the air1 and are
 less than two hundred miles farther    
south4 ,it is therefore evident that the
 continental glacier at this time pushed
 southward into a comparatively warm    
country in a way that no stream moving  
in the manner of a valley glacier could 
possibly have done4  ,the continental   
glaciers manage in many cases to convey 
detritus from a great distance4 ,thus1  
when the ice sheet advanced southwardly 
from the regions north of the ,great    
,lakes1 they conveyed quantities of the 
dbris from that section as far south as 
the ,ohio ,river4 ,in part this rubbish 
was dragged forward by the ice as the   
sheet advanced2 in part it was urged    
onward by the streams of liquid water   
formed by the ordinary process of ice   
melting4 ,such subglacial rivers appear 

to have been formed along the margins of
 all the great glaciers4 ,we can        
sometimes trace their course by the     
excavation which they have made1 but    
more commonly by the long ridges of     
stratified sand and gravel which were   
packed into the caverns excavated by    
these subglacial rivers1 which are known
 to glacialists as eskers1 or as serpent
 kames4 ,in many cases we can trace     
where these streams flowed up stream in 
the old river valleys until they        
discharged over their head waters4 ,thus
 in the valley of the ,genesee1 which   
now flows from ,pennsylvania1 where it  
heads against the tributaries of the    
,ohio and ,susquehanna1 to ,lake        
,ontario1 there was during the ,glacial 
epoch a considerable river which        
discharged its waters into those of the 
,ohio and the ,susquehanna over the     
falls at the head of its course4        
,illustration3 ,front of ,muir ,glacier1
 showing ice entering the sea2 also     
small icebergs4  ,the effect of         

widespread glacial action on a country  
such as ,north ,america appears to have 
been1 in the first place1 to disturb the
 attitude of the land by bearing down   
portions of its surface1 a process which
 led to the uprising of other parts     
which lay beyond the realm of the ice4  
,within the field of glaciation1 so far 
as the ice rested bodily on the surface1
 the rocks were rapidly worn away4 ,a   
great deal of the dbris was ground to   
fine powder1 and went far with the      
waters of the under-running streams4 ,a 
large part was entangled in the ice1 and
 moved forward toward the front of the  
glacier1 where it was either dropped at 
the margin or1 during the recession of  
the glacier1 was laid upon the surface  
as the ice melted away4 ,the result of  
this erosion and transportation has been
 to change the conditions of the surface
 both as regards soil and drainage4 ,as 
the reader has doubtless perceived1     
ordinary soil is1 outside of the river  
valleys1 derived from the rock beneath  

where it lies4 ,in glaciated districts  
the material is commonly brought from a 
considerable distance1 often from miles 
away4 ,these ice-made soils are rarely  
very fertile1 but they commonly have a  
great endurance for tillage1 and this   
for the reason that the earth is        
refreshed by the decay of the pebbles   
which they contain4 ,moreover1 while the
 tillable earth of other regions usually
 has a limited depth1 verging downward  
into the semisoil or subsoil which      
represent the little changed bed rocks1 
glacial deposits can generally be       
ploughed as deeply as may prove         
desirable4  ,the drainage of a country  
recently affected by glaciers is always 
imperfect4 ,owing to the irregular      
erosion of the bed rocks1 and to the yet
 more irregular deposition of the       
detritus1 there are very numerous lakes 
which are only slowly filled up or by   
erosion provided with drainage channels4
 ,though several thousand years have    
passed by since the ice disappeared from

 ,north ,america1 the greater part of   
the area of these fresh-water basins    
remains1 the greater number of them1    
mostly those of small size1 have become 
closed4  ,where an ice stream descends  
into the sea or into a large lake1 the  
depth of which is about as great as the 
ice is thick1 the relative lightness of 
the ice tends to make it float1 and it  
shortly breaks off from the parent mass1
 forming an iceberg4 ,where1 as is      
generally the case in those glaciers    
which enter the ocean1 a current sweeps 
by the place where the berg is formed1  
it may enter upon a journey which may   
carry the mass thousands of miles from  
its origin4 ,the bergs separated from   
the ,greenland glaciers1 and from those 
about the south pole1 are often of very 
great size2 sometimes1 indeed1 they are 
some thousand feet in thickness1 and    
have a length of several miles4 ,it     
often happens that these bergs are      
formed of ice1 which contains in its    
lower part a large amount of rock dbris4

 ,as the submerged portion of the       
glacier melts in the sea water1 these   
stones are gradually dropped to the     
bottom1 so that the cargo of one berg   
may be strewed along a line many hundred
 miles in length4 ,it occasionally      
happens that the ice mass melts more    
slowly in those parts which are in the  
air than in its under-water portions4   
,it thus becomes top-heavy and          
overturns1 in which case such stony     
matter as remains attains a position    
where it may be conveyed for a greater  
distance than if the glacier were not   
capsized4 ,it is likely1 indeed1 that   
now and then fragments of rock from     
,greenland are dropped on the ocean     
floor in the part of the ,atlantic which
 is traversed by steamers between our   
,atlantic ports and ,great ,britain4    
,except for the risks which they bring  
to navigators1 icebergs have no         
considerable importance4 ,it is true    
they somewhat affect the temperature of 
sea and air1 and they also serve to     

convey fragments of stone far out to sea
 in a way that no other agent can       
effect2 but1 on the whole1 their        
influence on the conditions of the earth
 is inconsiderable4  ,icebergs in       
certain cases afford interesting indices
 as to the motion of oceanic currents1  
which1 though moving swiftly at a depth 
below the surface1 do not manifest      
themselves on the plain of the sea4     
,thus in the region about ,greenland1   
particularly in ,davis ,strait1 bergs   
have been seen forcing their way        
southward at considerable speed through 
ordinary surface ice1 which was either  
at rest or moving in the opposite       
direction4 ,the train of these bergs1   
which moves upward from the south polar 
continent1 west of ,patagonia1 indicates
 also in a very emphatic way the        
existence of a very strong              
northward-setting current in that part  
of the ocean4                    99     
99       99       99       99  ,we have 
now to consider the causes which could  

bring about such great extensions of the
 ice sheet as occurred in the last      
,glacial period4 ,here again we are upon
 the confines of geological knowledge1  
and in a field where there are no       
well-cleared ways for the understanding4
 ,in facing this problem1 we should     
first note that those who are of the    
opinion that a ,glacial period means a  
very cold climate in the regions where  
the ice attained its extension are      
probably in error4 ,natural as it may   
seem to look for exceeding cold as the  
cause of glaciation1 the facts show us  
that we can not hold this view4 ,in     
,siberia and in the parts of ,north     
,america bordering on the ,arctic ,sea  
the average cold is so intense that the 
ground is permanently frozen--as it is1 
for instance1 in the ,klondike          
district--to the depth of hundreds of   
feet1 only the surface thawing out      
during the warm summers4 ,all this      
region is cold enough for glaciers1 but 
there is not sufficient snowfall to     

maintain them4 ,on the other hand1 in   
,greenland1 and in a less though        
conspicuous degree in ,scandinavia1     
where the waters of the ,north ,atlantic
 somewhat diminish the rigour of the    
cold1 and at the same time bring about a
 more abundant snowfall1 the two actions
 being intimately related1 we have very 
extensive glaciers4 ,such facts1 which  
could be very much extended1 make it    
clear that the climate of glacial       
periods must have been characterized by 
a great snowfall1 and not by the most   
intense cold4  ,it is evident that what 
would be necessary again to envelop the 
boreal parts of ,north ,america with a  
glacial sheet would not be a            
considerable decrease of heat1 but an   
increase in the winter's contribution of
 frozen water4 ,even if the heat        
released by this snowfall elevated the  
average temperature of the winter1 as it
 doubtless would in a considerable      
measure1 it would not melt off the snow4
 ,that snowfall tends to warm the air by

 setting free the heat which was engaged
 in keeping the water in a state of     
vapour is familiarly shown by the       
warming which attends an ordinary       
snowstorm4 ,even if the fall begin with 
a temperature of about #j ,fahr41 the   
air is pretty sure to rise to near the  
freezing point4  ,it is evident that no 
great change of temperature is required 
in order to bring about a very          
considerable increase in the amount of  
snowfall4 ,in the ordinary succession of
 seasons we often note the occurrence of
 winters during which the precipitation 
of snow is much above the average1      
though it can not be explained by a     
considerable climatal change4 ,we have  
to account for these departures from the
 normal weather by supposing that the   
atmospheric currents bring in more than 
the usual amount of moisture from the   
sea during the period when great falls  
of snow occur4 ,in fact1 in explaining  
variations in the humidity of the land1 
whether those of a constant nature or   

those that are to be termed accidental1 
we have always to look to those features
 which determine the importation of     
vapour from the great field of the ocean
 where it enters the air4 ,we should    
furthermore note that these             
peculiarities of climate are dependent  
upon rather slight geographic accidents4
 ,thus the snowfall of northern ,europe1
 which serves to maintain the glaciation
 of that region1 and1 curiously enough1 
in some measure its general warmth1     
depends upon the movement of the ,gulf  
,stream from the tropics to high        
latitudes4 ,if by any geographical      
change1 such as would occur if ,central 
,america were lowered so as to make a   
free passage for its waters to the      
westward1 the glaciers of ,greenland and
 of ,scandinavia would disappear1 and at
 the same time the temperature of those 
would be greatly lowered4 ,thus the most
 evident cause of glaciation must be    
sought in those alterations of the land 
which affect the movement of the oceanic

 currents4  ,applying this principle to 
the northern hemisphere1 we can in a way
 imagine a change which would probably  
bring about a return of such an ice     
period as that from which the boreal    
realm is now escaping4 ,let us suppose  
that the region of not very high land   
about ,bering ,strait should sink down  
so as to afford the ,kuro ,siwo1 or     
,north ,pacific equivalent of our ,gulf 
,stream1 an opportunity to enter the    
,arctic ,sea with something like the    
freedom with which the ,north ,atlantic 
current is allowed to penetrate to high 
latitudes4 ,it seems likely that this   
,pacific current1 which in volume and   
warmth is comparable to that of the     
,atlantic1 would so far elevate the     
temperature of the arctic waters that   
their wide field would be the seat of a 
great evaporation4 ,noting once again   
the fact that the ,greenland glaciers1  
as well as those of ,norway1 are        
supplied from seas warmed by the ,gulf  
,stream1 we should expect the result of 

this change would be to develop similar 
ice fields on all the lands near that   
ocean4  ,applying the data gathered by  
,dr4 ,croll for the ,gulf ,stream1 it   
seems likely that the average annual    
temperature induced in the ,arctic ,sea 
by the free entrance of the ,japan      
current would be between #bj and #cj    
,fahr4 ,this would convert this wide    
realm of waters into a field of great   
evaporation1 vastly increasing the      
annual precipitation4 ,it seems also    
certain that the greater part of this   
precipitation would be in the form of   
snow4 ,it appears to the writer that    
this cause alone may be sufficient to   
account for the last ,glacial period in 
the northern hemisphere4 ,as to the     
probability that the region about       
,bering ,strait may have been lowered in
 the manner required by this view1 it   
may be said that recent studies on the  
region about ,mount ,st4 ,elias show    
that during or just after the ice epoch 
the shores in that portion of ,alaska   

were at least four thousand feet lower  
than at present4 ,as this is but a      
little way from the land which we should
 have to suppose to be lowered in order 
to admit the ,japan current1 we could   
fairly conclude that the required change
 occurred4 ,as for the cause of the land
 movement1 geologists are still in      
doubt4 ,they know1 however1 that the    
attitudes of the land are exceedingly   
unstable1 and that the shores rarely for
 any considerable time maintain their   
position4 ,it is probable that these    
swayings of the earth's surface are due 
to ever-changing combinations of the    
weight in different parts of the crust  
and the strains arising from the        
contraction of its inner parts4  ,in the
 larger operations of ,nature the       
effects which we behold1 however simple1
 are rarely the products of a single    
cause4 ,in fact1 there are few actions  
so limited that they can fairly be      
referred to one influence4 ,it is       
therefore proper to state that there are

 many other actions besides those above 
noted which probably enter into those   
complicated equations which determine   
the climatal conditions of the earth4   
,to have these would carry us into      
difficult and speculative inquiries4    
,as before remarked1 all the regions    
which have been subjected to glaciation 
are still each year brought temporarily 
into the glacial state4 ,this fact      
serves to show us that the changes      
necessary to produce great ice sheets   
are not necessarily of a startling      
nature1 however great the consequences  
may be4 ,assuming1 then1 that relatively
 slight alterations of climate may cause
 the ice sheet to come and go1 we may   
say that all the influences which have  
been suggested by the students of       
glaciation1 and various other slighter  
causes which can not be here noted1 may 
have co-operated to produce the peculiar
 result4 ,in this equation geographic   
change has affected the course of the   
ocean currents1 and has probably been   

the most influential1 or at least the   
commonest1 cause to which we must       
attribute the extension of ice sheets4  
,next1 alterations of the solar heat may
 be looked to as a change-bringing      
action2 unfortunately1 however1 we have 
no direct evidence that this is an      
efficient cause4 ,thirdly1 the          
variations in the eccentricity of the   
earth's orbit1 combined with the        
precession of the equinoxes and the     
rotation of the apsides1 may be regarded
 as operative4 ,the last of all1 changes
 in the constitution of the atmosphere1 
have to be taken into account4 ,to these
 must be added1 as before remarked1 many
 less important actions which influence 
this marvellously delicate machine1 the 
work of which is expressed in the       
phenomena assembled under the name of   
climate4  ,evidence is slowly           
accumulating which serves to show that  
glacial periods of greater or less      
importance have been of frequent        
occurrence at all stages in the history 

of the earth of which we have a distinct
 record4 ,as these accidents write their
 history upon the ground alone1 and in a
 way impermanently1 it is difficult to  
trace the ice times of ancient          
geological periods4 ,the scratches on   
the bed rocks1 and the accumulations of 
detritus formed as the ice disappeared1 
have alike been worn away by the agents 
of decay4 ,nevertheless1 we can trace   
here and there in the older strata      
accumulations of pebbly matter often    
containing large boulders1 which clearly
 were shaped and brought together by    
glacial action4 ,these are found in some
 instances far south of the region      
occupied by the glaciers during the last
 ice epoch4 ,they occur in rocks of the 
,cambrian or ,silurian age in eastern   
,tennessee and western ,north ,carolina2
 they are also found in ,india beyond   
the limits to which glaciers have       
attained in modern times4  ,in closing  
this inadequate account of glacial      
action1 a story which for its complete  

telling would require many volumes1 it  
is well for the reader to consider once 
again how slight are the changes of     
climate which may alternately withdraw  
large parts of the land from the uses of
 life1 and again quickly restore the    
fields to the service of plants and     
animals4 ,he may well imagine that these
 changes1 by driving living creatures to
 and fro1 profoundly affect the history 
of their development4 ,this matter will 
be dealt with in the volume concerning  
the history of organic beings4  ,when   
the ice went off from the northern part 
of this continent1 the surface of the   
country1 which had been borne down by   
the weight of the glacier1 still        
remained depressed to a considerable    
depth below the level of the sea1 the   
depression varying from somewhere about 
one hundred feet in southern ,new       
,england to a thousand feet or more in  
high latitudes4 ,over this region1 which
 lay beneath the level of the sea1 the  
glacier1 when it became thin enough to  

float1 was doubtless broken up into     
icebergs1 in the manner which we now    
behold along the coast of ,greenland4   
,where the shore was swept by a strong  
current1 these bergs doubtless drifted  
away2 but along the most of the coast   
line they appear to have lain thickly   
grouped next the shores1 gradually      
delivering their loads of stones and    
finer dbris to the bottom4 ,these masses
 of floating ice in many cases seem to  
have prevented the sea waves from       
attaining the shore1 and thus hindered  
the formation of those beaches which in 
their present elevated condition enable 
us to interpret the old position of the 
sea along coast lines which have been   
recently elevated4 ,here and there1     
however1 from ,new ,jersey to           
,greenland1 we find bits of these       
ancient shores which clearly tell the   
story of that down-sinking of the land  
beneath the burden of the ice which is  
such an instructive feature in the      
history of that period4                 

,,chapter ,,vii4                        
,,the ,,work ,,of ,,underground ,,water4
   ,we have already noted two means by  
which water finds its way underground4  
,the simplest and largest method by     
which this action is effected is by     
building in the fluid as the grains of  
the rock are laid down on the floors of 
seas or lakes4 ,the water thus          
imprisoned is firmly inclosed in the    
interstices of the stone1 it in time    
takes up into its mass a certain amount 
of the mineral materials which are      
contained in the deep-buried rocks4 ,the
 other portion of the ground water--that
 with which we are now to be specially  
concerned--arises from the rain which   
descends into the crevices of the earth2
 it is therefore peculiar to the lands4 
,for convenience we shall term the      
original embedded fluid rock water1 and 
that which originates from the rain     
crevice water1 the two forming the mass 
of the earth water4  ,the crevice water 
of the earth1 although forming at no    

time more than a very small fraction of 
the hidden fluid1 is an exceedingly     
potent geological agent1 doing work     
which1 though unseen1 yet affords the   
very foundations on which rest the life 
alike of land and sea4 ,when this water 
enters the earth1 though it is purified 
of all mineral materials1 it has already
 begun to acquire a share of a gaseous  
substance1 carbonic acid1 or1 as        
chemists now term it1 carbon dioxide1   
which enables the fluid to begin its rle
 of marvellous activities4 ,in its      
descent as rain1 probably even before it
 was gathered in drops in the cloud     
realm1 the water absorbs a certain      
portion of this gas from the atmosphere4
 ,entering the realm of the soil1 where 
the decaying organic matter plentifully 
gives forth carbon dioxide1 a further   
store of the gas is acquired4 ,at the   
ordinary pressure of the air1 water may 
take in many times its bulk of the gas4 
,the immediate effect of carbonic acid  
when it is absorbed by water is greatly 

to increase the capacity which that     
fluid has for taking mineral matters    
into solution4 ,when charged with this  
gas1 in the measure in which it may be  
in the soil1 water is able to dissolve  
about fifty times as much limestone as  
it can in its perfectly pure form take  
up4 ,a familiar instance of this        
peculiar capacity which the gas gives   
may often be seen where the water from a
 soda-water fountain drips upon the     
marble slab beneath4 ,in a few years    
this slab will be considerably corroded1
 though pure water would in the same    
time have had no effect upon it4  ,the  
first and by far the most important     
effect of crevice water is exercised    
upon the soil1 which is at once the     
product of this action1 and the         
laboratory where the larger part of the 
work is done4 ,penetrating between the  
grains of the detrital covering1 held in
 large quantities in the coating1 and   
continually in slow motion1 the         
gas-charged water takes a host of       

substances into solution1 and brings    
them into a condition where they may    
react upon each other in the chemical   
manner4 ,these materials are constantly 
being offered to the roots of plants and
 brought in contact with the underlying 
rock which has not passed into the state
 of soil4 ,the changes induced in this  
stony matter lead to its breaking up1 or
 at least to its softening to the point 
where the roots can penetrate it and    
complete its destruction4 ,thus it comes
 about that the water which to a great  
extent divides the rocks into the state 
of soil1 which is continually wearing   
away the material on the surface1 or    
leaching it out through the springs1 is 
also at work in restoring the layer from
 beneath4  ,the greater part of the     
water which enters the soil does not    
penetrate to any great depth in the     
underlying rocks1 but finds its way to  
the surface after no long journey in the
 form of small springs4 ,generally those
 superficial springs do not emerge      

through distinct channels1 but move1    
though slowly1 in a massive way down the
 slopes until they enter a water course4
 ,along the banks of any river1 however 
small1 or along the shores of the sea1 a
 pit a few inches deep just above the   
level of the water will be quickly      
filled by a flow from this sheet which  
underlies the earth4 ,at a distance from
 the stream this sheet spring is in     
contact with the bed rocks1 and may be  
many feet below the surface1 but it     
comes to the level of the river or the  
sea near their margins4 ,here and there 
the shape of the bed rocks1 being like  
converging house roofs1 causes the      
superficial springs to form small       
pipelike channels for the escape of     
their gathered waters1 and the flow     
emerges at a definite point4 ,almost all
 these sources of considerable flow are 
due to the action of the water on the   
underlying rock1 where we shall now     
follow that portion of the crevice water
 which penetrates deeply into the earth4

  ,almost all rocks1 however firm they  
may appear to be1 are divided by        
crevices which extend from the soil     
level it may be to the depths of        
thousands of feet4 ,these rents are in  
part due to the strains of              
mountain-building1 which tend to disrupt
 the firmest stone1 leaving open        
fractures4 ,they are also formed in     
other ways1 as by the imperfectly       
understood agencies which produce joint 
planes4 ,it often happens that where    
rocks are highly tilted water finds its 
way downward between the layers1 which  
are imperfectly soldered together1 or a 
bed of coarse material1 such as         
sandstone or conglomerate1 may afford an
 easy way by which the water may descend
 for miles beneath the surface4 ,passing
 through rocks which are not readily    
soluble1 the water1 already to a great  
extent supplied with mineral matter by  
its journey through the soil1 may not do
 much excavating work1 and even after a 
long time may only slightly enlarge the 

spaces in which it may be stored or the 
channels by which it discharges to the  
surface4 ,hence it comes about that in  
many countries1 even where the waters   
penetrate deeply1 they do not afford    
large springs4 ,it is otherwise where   
the crevice waters enter limestones     
composed of materials which are readily 
dissolved4 ,in such places we find the  
rain so readily entering the underlying 
rock that no part of the fall goes at   
once to the brooks1 but all has a long  
underground journey4  ,in any limestone 
district where the beds of the material 
are thick and tolerably pure--as1 for   
instance1 in the cavern district of     
southern ,kentucky--the traveller who   
enters the region notes at once that the
 usual small streams which in every     
region of considerable rainfall he is   
accustomed to see intersecting the      
surface of the country are entirely     
absent4 ,in their place he notes        
everywhere pitlike depressions of       
bowl-shaped form1 the sink holes to     

which we have already adverted4 ,through
 the openings in the bottom of these the
 rain waters descend into the depths of 
the earth4 ,although the most of these  
depressions have but small openings in  
their bottom1 now and then one occurs   
with a vertical shaft sufficiently large
 to permit the explorer to descend into 
it1 though he needs to be lowered down  
in the manner of a miner who is entering
 a shaft4 ,in fact1 the journey is      
nearly always one of some hazard2 it    
should not be undertaken save with many 
precautions to insure safety4  ,when one
 is lowered away through an open sink   
hole1 though the descent may at first be
 somewhat tortuous1 the explorer soon   
finds himself swinging freely in the    
air1 it may be at a point some hundred  
feet above the base of the bottle-shaped
 shaft or dome into which he has        
entered4 ,commonly the neck of the      
bottle is formed where the water has    
worked its way through a rather sandy   
limestone1 a rock which was not readily 

dissolved by the water4 ,in the pure and
 therefore easily cut limestone layers  
the cavity rapidly expands until the    
light of the lantern may not disclose   
its walls4 ,farther down there is apt to
 be a shelf composed of another impure  
limestone1 which extends off near the   
middle of the shaft4 ,if the explorer   
can land upon this shelf1 he is sure to 
find that from this imperfect floor the 
cavern extends off in one or more       
horizontal galleries1 which he may      
follow for a great distance until he    
comes to the point where there is again 
a well-like opening through the hard    
layer1 with another dome-shaped base    
beneath4 ,returning to the main shaft1  
the explorer may continue his descent   
until he attains the base of this       
vertical section of the cave1 where he  
is likely to find himself delivered in a
 pool of water of no great depth1 the   
bottom of which is occupied by a        
quantity of small1 hard stones of a     
flinty nature1 which have evidently come

 from the upper parts of the cavern4    
,the close observer will have noted that
 here and there in the limestone there  
are flinty bits1 such as those which he 
finds in the pool4 ,from the bottom of  
the dome a determined inquirer can often
 make his way along the galleries which 
lead from that level1 though it may be  
after a journey of miles to the point   
where he emerges from the cavern on the 
banks of an open-air river4  ,although a
 journey by way of the sink holes       
through a cavern system is to be        
commended for the reason that it is the 
course of the caverning waters1 it is1  
on the whole1 best to approach the cave 
through their exits along the banks of a
 stream or through the chance openings  
which are here and there made by the    
falling in of their roofs4 ,one         
advantage of this cavity of entrance is 
that we can thus approach the cavern in 
times of heavy rain when the processes  
which lead to their construction are in 
full activity4 ,coming in this way to   

one of the domes formed beneath a sink  
hole1 we may observe in rainy weather   
that the water falling down the deep    
shaft strikes the bottom with great     
force2 in many of the ,kentucky caves it
 falls from a greater height than       
,niagara4 ,at such times the stones in  
the basin at the bottom of the shaft are
 vigorously whirled about1 and in their 
motion they cut the rocks in the bottom 
of the basin--in fact1 this cavity is a 
great pot hole1 like those at the base  
of open-air cascades4 ,it is now easy to
 interpret the general principles which 
determine the architecture of the cavern
 realm4  ,when it first enters the earth
 all the work which the water does in   
the initial steps of cavern formation is
 effected by solution4 ,as the crevice  
enlarges and deepens1 the stream        
acquires velocity1 and begins to use the
 bits of hard rock in boring4 ,it works 
downward in this way by the mixed       
mechanical and chemical action until it 
encounters a hard layer4 ,then the water

 creeps horizontally through the soft   
stratum1 doing most of its work by      
solution1 until it finds a crevice in   
the floor through which it can excavate 
farther in the downward direction2 so it
 goes on in the manner of steps until it
 burrows channels to the open stream4   
,in time the vertical fall under the    
sink hole will cut through the hard     
layer1 when the water1 abandoning the   
first line of exit1 will develop another
 at a lower level1 and so in time it    
comes about that there may be several   
stories of the cave1 the lowest being   
the last to be excavated4 ,of the total 
work thus done1 only a small part is    
accomplished by the falling of the      
water1 acting through the boring action 
of its tools1 the bits of stone before  
mentioned2 the principal part of the    
task is done by the solvent action of   
the carbonated waters on the limestone4 
,in the system of caverns known as the  
,mammoth ,cave1 in ,kentucky1 the writer
 has estimated that at least nine tenths

 of the stone was removed in the state  
of solution4  ,when first excavated1 the
 chambers of a limestone cavern have    
little beauty to attract the eye4 ,the  
curves of the walls are sometimes       
graceful1 but the aspect of the         
chambers1 though in a measure grand1 is 
never charming4 ,when1 however1 the     
waters have ceased to carve the         
openings1 when they have been drained   
away by the formation of channels on a  
lower level1 there commonly sets in a   
process known as stalactitization1 which
 transforms the scene into one of       
singular beauty4 ,we have already noted 
the fact that everywhere in ordinary    
rocks there are crevices through which  
water1 moving under the pressure of the 
fluid which is above1 may find its way  
slowly downward4 ,in the limestone roofs
 of caverns1 particularly in those of   
the upper story1 this ooze of water     
passes through myriads of unseen        
fissures at a rate so slow that it often
 evaporates in the dry air without      

dropping to the floor4 ,when it comes   
out of the rocks the water is charged   
with various salts of lime2 when it     
evaporates it leaves the material behind
 on the roof4 ,where the outflow is so  
slight that the fluid does not gather   
into drops1 it forms an incrustation of 
limy matter1 which often gathers in     
beautiful flowerlike forms1 or perhaps  
in the shape of a sheet of alabaster4   
,where drops are formed1 a small1       
pendent cone grows downward from the    
ceiling1 over which the water flows1 and
 on which it evaporates4 ,this cone     
grows slowly downward until it may      
attain the floor of the chamber1 which  
has a height of thirty feet or more4 ,if
 all the water does not evaporate1 that 
which trickles off the apex of the cone1
 striking on the floor1 is splashed out 
into a thin sheet1 so that it evaporates
 in a speedy manner1 lays down its      
limestone1 and thus builds another and  
ruder cone1 which grows upward toward   
that which is pendent above it4         

,finally1 they grow together1 enlarged  
by the process which constructed them1  
until a mighty column may be formed1    
sculptured as if by the hands of a      
fantastic architect4  ,illustration3    
,fig4 #ac4--,stalactites and stalagmites
 on roof and floor of a cavern4 ,the    
arrows show the direction of the moving 
water4  ,all the while that subterranean
 streams are cutting the caverns        
downward the open-air rivers into which 
they discharge are deepening their beds1
 and thereby preparing for the          
construction of yet lower stories of    
caves4 ,these open-air streams commonly 
flow in steep-sided1 narrow valleys1    
which themselves were caves until the   
galleries became so wide that they could
 no longer support the roof4 ,thus we   
often find that for a certain distance  
the roof over a large stream has fallen 
in1 so that the water flows in the open 
air4 ,then it will plunge under an arch 
and course1 it may be1 for some miles1  
before it again arrives at a place where

 the roof has disappeared1 or perhaps   
attains a field occupied by rocks of    
another character1 in which caverns were
 not formed4 ,at places these old river 
caverns are abandoned by the streams1   
which find other courses4 ,they form    
natural tunnels1 which are not          
infrequently of considerable length4    
,one such in southwestern ,virginia has 
been made useful for a railway passing  
from one valley to another1 thus sparing
 the expense of a costly excavation4    
,where the remnant of the arch is small1
 it is commonly known as a natural      
bridge1 of which that in ,rockbridge    
,county1 in ,virginia1 is a very noble  
example4 ,arches of this sort are not   
uncommon in many cavern countries2 five 
such exist in ,carter ,county1          
,kentucky1 a district in the eastern    
part of that ,state which abounds in    
caverns1 though none of them are of     
conspicuous height or beauty4#g         
,footnote #g3 ,it is reported that one  
of these natural bridges of ,carter     

,county has recently fallen down4 ,this 
is the natural end of these features4   
,as before remarked1 they are but the   
remnants of much more extensive roofs   
which the processes of decay have       
brought to ruin4  ,at this stage of his 
studies on cavern work the student will 
readily conceive that1 as the surface of
 the country overlying the cave is      
incessantly wearing down1 the upper     
stories of the system are continually   
disappearing1 while new ones are forming
 at the present drainage level of the   
country4 ,in fact1 the attentive eye can
 in such a district find here and there 
evidences of this progressive           
destruction4 ,not only do the caves wear
 out from above1 but their roofs are    
constantly falling to their floors1 a   
process which is greatly aided by the   
growth of stalactites4 ,forming in the  
crevices or joints between the stones1  
these rock growths sometimes prize off  
great blocks4 ,in other cases the weight
 of the pendent stalactite drags the    

ill-supported masses of the roof to the 
floor4 ,in this way a gallery originally
 a hundred feet below the surface may   
work its way upward to the light of day4
 ,the entrance by which the ,mammoth    
,cave is approached appears to have been
 formed in this manner1 and at several  
points in that system of caverns the    
effect of this action may be distinctly 
observed4  ,we must now go a step       
further on the way of subterranean      
water1 and trace its action in the      
depths below the plane of ordinary      
caves1 which1 as we have noted1 do not  
extend below the level of the main      
streams of the cavern district4 ,the    
first group of facts to be attended to  
is that exhibited by artesian wells4    
,these occur where rocks have been      
folded down into a basinlike form4 ,it  
often happens that in such a basin the  
rocks of which it is composed are some  
of them porous1 and others impervious to
 water1 and that the porous layers      
outcrop on the high margins of the      

depression and have water-tight layers  
over them4 ,these conditions can be well
 represented by supposing that we have  
two saucers1 one within the other1 with 
an intervening layer of sand which is   
full of water4 ,if now we bore an       
opening in the bottom of the uppermost  
saucer1 we readily conceive that the    
water will flow up through it4 ,in      
,nature we often find these basins with 
the equivalent of the sandy layer in the
 model just described rising hundreds of
 feet above the valley1 so that the     
artesian well1 so named from the village
 of ,artois1 near ,paris1 where the     
first opening of this nature was made1  
may yield a stream which will mount     
upward1 especially where piped1 to a    
great height4 ,at many places in the    
world it is possible by such wells to   
obtain a large supply of tolerably pure 
water1 but in general it is found to    
contain too large a supply of dissolved 
mineral matter or sulphuretted gases to 
be satisfactory for domestic purposes4  

,it may be well to note the fact that   
the greater part of the so-called       
artesian wells1 or borings which deliver
 water to a height above the surface1   
are not true artesian sources1 in that  
they do not send up the water by the    
action of gravitation1 but under the    
influence of gaseous pressure4  ,where1 
as in the case of upturned porous beds1 
the crevice water penetrates far below  
the earth's surface or the open-air     
streams which drain the water away1 the 
fluid acquires a considerable increase  
of temperature1 on the average about one
 degree ,fahrenheit for each eighty feet
 of descent4 ,it may1 indeed1 become so 
heated that if it were at the earth's   
surface it would not only burst into    
steam with a vast explosive energy1 but 
would actually shine in the manner of   
heated solids4 ,as the temperature of   
water rises1 and as the pressure on it  
increases1 it acquires a solvent power1 
and takes in rocky matter in a measure  
unapproached at the earth's surface4 ,at

 the depth of ten miles water beginning 
as inert rain would acquire the         
properties which we are accustomed to   
associate with strong acids4 ,passing   
downward through fissures or porous     
strata in the manner indicated in the   
diagram1 the water would take up1 by    
virtue of its heat and the gases it     
contained1 a share of many mineral      
substances which we commonly regard as  
insoluble4 ,gold and even platinum--the 
latter a material which resists all     
acids at ordinary temperatures--enters  
into the solution4 ,if now the water    
thus charged with mineral stores finds  
in the depths a shorter way to the      
surface than that which it descended1   
which may well happen by way of a deep  
rift in the rocks1 it will in its ascent
 reverse the process which it followed  
on going down4 ,it will deposit the     
several minerals in the order of their  
solubilities--that is1 the last to be   
taken in will be the first to be        
crystallized on the walls of the fissure

 through which the upflow is taking     
place4 ,the result will be the formation
 of a vein belonging to the variety     
known as fissure veins4  ,illustration3 
,fig4 #ad4--;,diagram of vein4 ,the     
different shadings show the variations  
in the nature of the deposits4  ,a vein 
deposit such as we are considering may1 
though rarely1 be composed of a single  
mineral4 ,most commonly we find the     
deposit arranged in a banded form in the
 manner indicated in the figure 7see    
diagram #ad74 ,sometimes one material   
will abound in the lower portions of the
 fissure and another in its higher      
parts1 a feature which is accounted for 
by the progressive cooling and          
relinquishment of pressure to which the 
water is subjected on its way to the    
surface4 ,with each decrement of those  
properties some particular substance    
goes out of the fluid1 which may in the 
end emerge in the form of a warm or hot 
spring1 the water of which contains but 
little mineral matter4 ,where1 however1 

the temperature is high1 some part of   
the deposit1 even a little gold1 may be 
laid down just about the spring in the  
deposits known as sinter1 which are     
often formed at such places4  ,in many  
cases the ore deposits are formed not   
only in the main channel of the fissure1
 but in all the crevices on either side 
of that way4 ,in this manner1 much as in
 the case of the growth of stalactitic  
matter between the blocks of stone in   
the roofs of a cavern1 large fragments  
of rock1 known as horses1 are often     
pushed out into the body of the vein4   
,in some instances the growth of the    
vein appears to enlarge the fissure or  
place of the deposit as the accumulation
 goes on1 the process being analogous to
 that by which a growing root widens the
 crevice into which it has penetrated4  
,in other instances the fissure formed  
by the force has remained wide open1 or 
at most has been but partly filled by   
the action of the water4  ,it not       
infrequently happens that the ascending 

waters of hot springs entering          
limestones have excavated extensive     
caves far below the surface of the      
earth1 these caverns being afterward in 
part filled by the ores of various      
metals4 ,we can readily imagine that the
 water at one temperature would excavate
 the cavern1 and long afterward1 when at
 a lower heat1 they might proceed to    
fill it in4 ,at a yet later stage1 when 
the surface of the country had worn down
 many thousands of feet below the       
original level1 the mineral stores of   
the caverns may be brought near the     
surface of the earth4 ,some of the most 
important metalliferous deposits of the 
,cordilleras are found in this group of 
hot-water caverns4 ,these caverns are   
essentially like those produced by cold 
water1 with the exception of the        
temperature of the fluid which does the 
work and the opposite direction of the  
flow4  ,in following crevice water which
 is free to obey the impulses of        
gravitation far down into the earth1 we 

enter on a realm where the rock or      
construction water1 that which was built
 into the stone at the time of its      
formation1 is plentiful4 ,where these   
two groups of waters come in contact an 
admixture occurs1 a certain portion of  
the rock water joining that in the      
crevices4 ,near the surface of the      
ground we commonly find that all the    
construction water has been washed out  
by this action4 ,yet if the rocks be    
compact1 or if they have layers of a    
soft and clayey nature1 we may find the 
construction water1 even in very old    
deposits1 remaining near the surface of 
the ground4 ,thus in the ancient        
,silurian beds of the ,ohio ,valley a   
boring carried a hundred feet below the 
level of the main rivers commonly       
discovers water which is clearly that   
laid down in the crevices of the        
material at the time when the rocks were
 formed in the sea4 ,in all cases this  
water contains a certain amount of gases
 derived from the decomposition of      

various substances1 but principally from
 the alteration of iron pyrite1 which   
affords sulphuretted hydrogen4 ,thus the
 water is forced to the surface with    
considerable energy1 and the well is    
often named artesian1 though it flows by
 gas pressure on the principle of the   
soda-water fountain1 and not by gravity1
 as in the case of true artesian wells4 
,the passage between the work done by   
the deeply penetrating surface water and
 that due to the fluid intimately       
blended with the rock built into the    
mass at the time of its formation is    
obscure4 ,we are1 however1 quite sure   
that at great depths beneath the earth  
the construction water acts alone not   
only in making veins1 but in bringing   
about many other momentous changes4 ,at 
a great depth this water becomes        
intensely heated1 and therefore tends to
 move in any direction where a chance   
fissure or other accident may lessen the
 pressure4 ,creeping through the rocks1 
and moving from zones of one temperature

 to another1 these waters bring about in
 the fine interstices chemical changes  
which lead to great alterations in the  
constitution of the rock material4 ,it  
is probably in part to these slow       
driftings of rock water that beds       
originally made up of small1 shapeless  
fragments1 such as compose clay slates1 
sandstones1 and limestones1 may in time 
be altered into crystalline rocks1 where
 there is no longer a trace of the      
original bits1 all the matter having    
been taken to pieces by the process of  
dissolving1 and reformed in the regular 
crystalline order4 ,in many cases we may
 note how a crystal after being made has
 been in part dissolved away and        
replaced by another mineral4 ,in fact1  
many of our rocks appear to have been   
again and again made over by the        
slow-drifting waters1 each particular   
state in their construction being due to
 some peculiarity of temperature or of  
mineral contents which the fluid held4  
,these metamorphic phenomena1 though    

important1 are obscure1 and their       
elucidation demands some knowledge of   
petrographic science1 that branch of    
geology which considers the principles  
of rock formation4 ,they will therefore 
not be further considered in this work4 
,,volcanoes4  ,of old it was believed   
that volcanoes represented the          
outpouring of fluid rock which came     
forth from the central realm of the     
earth1 a region which was supposed still
 to retain the liquid state through     
which the whole mass of our earth has   
doubtless passed4 ,recent studies1      
however1 have brought about a change in 
the views of geologists which is        
represented by the fact that we shall   
treat volcanic phenomena in connection  
with the history of rock water4  ,in    
endeavouring to understand the phenomena
 of volcanoes it is very desirable that 
the student should understand what goes 
on in a normal eruption4 ,the writer    
may1 therefore1 be warranted in         
describing some observations which he   

had an opportunity to make at an        
eruption of ,vesuvius in #ahhc1 when it 
was possible to behold far more than can
 ordinarily be discerned in such        
outbreaks--in fact1 the opportunity of a
 like nature has probably not been      
enjoyed by any other person interested  
in volcanic action4 ,in the winter of   
#ahhb-'hc ,vesuvius was subjected to a  
succession of slight outbreaks4 ,at the 
time of the observations about to be    
noted the crater had been reduced to a  
cup about three hundred feet in diameter
 and about a hundred feet deep4 ,the    
vertical shaft at the bottom1 through   
which the outbursts were taking place1  
was about a hundred feet across4 ,taking
 advantage of a heavy gale from the     
northwest1 it was practicable1          
notwithstanding the explosions1 to climb
 to the edge of the crater wall4        
,looking down into the throat of the    
volcano1 although the pit was full of   
whirling vapours and the heat was so    
great that the protection of a mask was 

necessary1 it was possible to see       
something of what was going on at the   
moment of an explosion4  ,the pipe of   
the volcano was full of white-hot lava4 
,even in a day of sunshine1 which was   
only partly obscured by the vapours     
which hung about the opening1 the heat  
of the lava made it very brilliant4     
,this mass of fluid rock was in         
continuous motion1 swaying violently up 
and down the tube4 ,from four to six    
times a minute1 at the moment of its    
upswaying1 it would burst as by the     
explosion of a gigantic bubble4 ,the    
upper portion of the mass was blown     
upward in fragments1 the discharge being
 like that of shot from a fowling piece2
 the fragments1 varying in size from    
small1 shotlike bits to masses larger   
than a man's head1 were shot up         
sometimes to the height of fifteen      
hundred feet above the point of         
ejection4 ,the wind1 blowing at the rate
 of about forty miles an hour1 drove the
 falling bits of rock to the leeward1 so

 that there was no considerable danger  
to be apprehended from them4 ,some      
seconds after the explosion they could  
be heard rattling down on the farther   
slope of the cone4 ,observations on the 
interval between the discharge and the  
fall of the fragments made it easy to   
compute the height to which they were   
thrown4  ,at the moment when the lava in
 the pipe opened for the passage of the 
vapour which created the explosion the  
movement1 though performed in a fraction
 of a second1 was clearly visible4 ,at  
first the vapour was colourless2 a few  
score feet up it began to assume a      
faint1 bluish hue2 yet higher1 when it  
was more expanded1 the tint changed to  
that of steam1 which soon became of the 
ordinary aspect1 and gathered in        
swift-revolving clouds4 ,the watery     
nature of the vapour was perfectly      
evident by its odour4 ,though commingled
 with sulphurous-acid gas1 it still had 
the characteristic smell of steam4 ,for 
a half hour it was possible to watch the

 successive explosions1 and even to make
 rough sketches of the scene4           
,occasionally the explosions would come 
in quick succession1 so that the lava   
was blown out of the tube2 again1 the   
pool would merely sway up and down in a 
manner which could be explained only by 
supposing that great bubbles of vapour  
were working their way upward toward the
 point where they could burst4 ,each of 
these bubbles probably filled a large   
part of the diameter of the pipe4 ,in   
general1 the phenomena recalled the     
escape of the jet from a geyser1 or1 to 
take a familiar instance1 that of steam 
from the pipe of a high-pressure engine4
 ,when the heat is great1 steam may     
often be seen at the mouth of the pipe  
with the same transparent appearance    
which was observed in the throat of the 
crater4 ,in the cold air of the mountain
 the vapour was rapidly condensed1      
giving a rainbow hue in the clouds when 
they were viewed at the right angle4    
,the observations were interrupted by   

the fact that the wind so far died away 
that large balls of the ejected lava    
began to fall on the windward side of   
the cone4 ,these fragments1 though      
cooled and blackened on their outside by
 their considerable journey up and down 
through the air1 were still so soft that
 they splashed when they struck the     
surface of cinders4  ,watching the cone 
from a distance1 one could note that    
from time to time the explosions1       
increasing in frequency1 finally        
attained a point where the action       
appeared to be continuous4 ,the         
transition was comparable to that which 
we may observe in a locomotive which1   
when it first gets under way1 gives     
forth occasional jets of steam1 but1    
slowly gaining speed1 finally pours     
forth what to eye and ear alike seem to 
be a continuous outrush4 ,all the       
evidence that we have concerning        
volcanic outbreaks corroborates that    
just cited1 and is to the effect that   
the essence of the action consists in   

the outbreak of water vapour at a high  
temperature1 and therefore endowed with 
very great expansive force4 ,along with 
this steam there are many other gases1  
which always appear to be but a very    
small part of the whole escape of a     
vaporous nature--in fact1 the volcanic  
steam1 so far as its chemical           
composition has been ascertained1 has   
the composition which we should expect  
to find in rock water which had been    
forced out from the rock by the tensions
 that high temperature creates4         
,because of its conspicuous nature1 the 
lava which flows from most volcanoes1 or
 is blown out from them in the form of  
finely divided ash1 is commonly regarded
 as the primary feature in a volcanic   
outbreak4 ,such is not really the case4 
,volcanic explosions may occur with very
 little output of fluid rock1 and that  
which comes forth may consist altogether
 of the finely divided bits of rock to  
which we give the name of ash4 ,in fact1
 in all very powerful explosions we may 

expect to find no lava flow1 but great  
quantities of this finely divided rock1 
which when it started from the depths of
 the earth was in a fluid state1 but was
 blown to pieces by the contained vapour
 as it approached the surface4  ,if the 
student is so fortunate as to behold a  
flood of lava coming forth from the     
flanks of a volcano1 he will observe    
that even at the very points of issue1  
where the material is white-hot and     
appears to be as fluid as water1 the    
whole surface gives forth steam4 ,on a  
still day1 viewed from a distance1 the  
path of a lava flow is marked by a dense
 cloud of this vapour which comes forth 
from it4 ,even after the lava has cooled
 so that it is safe to walk upon it1    
every crevice continues to pour forth   
steam4 ,years after the flowing has     
ceased1 and when the rock surface has   
become cool enough for the growth of    
certain plants upon it1 these crevices  
still yield steam4 ,it is evident1 in a 
word1 that a considerable part of a lava

 mass1 even after it escapes from the   
volcanic pipes1 is water which is       
intimately commingled with the rock1    
probably lying between the very finest  
grains of the heated substance4 ,yet    
this lava which has come forth from the 
volcano has only a portion of the water 
which it originally contained2 a large1 
perhaps the greater part1 has gone forth
 in the explosive way through the       
crater4 ,it is reasonably believed that 
the fluidity of lava is in considerable 
measure due to the water which it       
contains1 and which serves to give the  
mass the consistence of paste1 the      
partial fluidity of flour and rock      
grains being alike brought about in the 
same manner4  ,so much of the phenomena 
of volcanoes as has been above noted is 
intended to show the large part which   
interstitial water plays in volcanic    
action4 ,we shall now turn our attention
 again to the state of the deeply buried
 rock water1 to see how far we may be   
able by it to account for these strange 

explosive actions4 ,when sediments are  
laid down on the sea floor the materials
 consist of small1 irregularly shaped   
fragments1 which lie tumbled together in
 the manner of a mass of bricks which   
have been shot out of a cart4 ,water is 
buried in the plentiful interspaces     
between these bits of stone2 as before  
remarked1 the amount of this            
construction water varies4 ,in general1 
it is at first not far from one tenth   
part of the materials4 ,besides the     
fluid contained in the distinct spaces1 
there is a share which is held as       
combined water in the intimate structure
 of the crystals1 if such there be in   
the mass4 ,when this water is built into
 the stone it has the ordinary          
temperature of the sea bottom4 ,as the  
depositing actions continue to work1    
other beds are formed on the top of that
 which we are considering1 and in time  
the layer may be buried to the depth of 
many thousand feet4 ,there are reasons  
to believe that on the floors of the    

oceans this burial of beds containing   
water may have brought great quantities 
of fluid to the depth of twenty miles or
 more below the outer surface of the    
rocks4  ,illustration3 ,fig4            
#ae4--;,flow of lava invading a forest4 
,a tree in the distance is not          
completely burned1 showing that the     
molten rock had lost much of its        
original heat4  ,the effect of deep     
burial is to increase the heat of       
strata4 ,this result is accomplished in 
two different ways4 ,the direct effect  
arising from the imposition of weight1  
that derived from the mass of stratified
 material1 is1 as we know1 to bring     
about a down-sinking of the earth's     
crust4 ,in the measure of this falling1 
heat is engendered precisely as it is by
 the falling of a trip-hammer on the    
anvil1 with which action1 as is well    
known1 we may heat an iron bar to a high
 temperature4 ,it is true that this     
down-sinking of the surface under weight
 is in part due to the compression of   

the rocks1 and in part to the slipping  
away of the soft underpinning of more or
 less fluid rock4 ,yet further it is in 
some measure brought about by the       
wrinkling of the crust4 ,but all these  
actions result in the conversion of     
energy of position into heat1 and so far
 serve to raise the temperature of the  
rocks which are concerned in the        
movements4 ,by far the largest source of
 heat1 however1 is that which comes     
forth from the earth's interior1 and    
which was stored there in the olden day 
when the matter forming the earth       
gathered into the mass of our sphere4   
,this1 which we may term the original   
heat1 is constantly flowing forth into  
space1 but makes its way slowly1 because
 of the non-conductive1 or1 as we may   
phrase it1 the blanketing effect of the 
outer rock4 ,the effect of the strata is
 the same as that exercised by the      
non-conductive coatings which are put on
 steam boilers4 ,a more familiar        
comparison may be had from the blankets 

used for bedclothing4 ,if on top of the 
first blanket we put a second1 we keep  
warmer because the temperature of the   
lower one is elevated by the heat from  
our body which is held in4 ,in the crust
 of the earth each layer of rock resists
 the outflow of heat1 and each addition 
lifts the temperature of all the layers 
below4  ,when water-bearing strata have 
been buried to the depth of ten miles1  
the temperature of the mass may be      
expected to rise to somewhere between   
seven hundred and a thousand degrees    
,fahrenheit4 ,if the depth attained     
should be fifty miles1 it is likely that
 the temperature will be five times as  
great4 ,at such a heat the water which  
the rocks contain tends in a very       
vigorous way to expand and pass into the
 state of vapour4 ,this it can not      
readily do1 because of its close        
imprisonment2 we may say1 however1 that 
the tendency toward explosion is almost 
as great as that of ignited gunpowder4  
,such powder1 if held in small spaces in

 a mass of cast steel1 could be fired   
without rending the metal4 ,the gases   
would be retained in a highly           
compressed1 possibly in a fluid form4   
,if now it happens that any of the      
strain in the rocks such as lead to the 
production of faults produce fissures   
leading from the surface into this zone 
of heated water1 the tendency of the    
rocks containing the fluid1 impelled by 
its expansion1 will be to move with     
great energy toward the point of relief 
or lessened pressure which the crevice  
affords4 ,where rocks are in any way    
softened1 pressure alone will force them
 into a cavity1 as is shown by the fact 
that beds of tolerably hard clay stones 
in deep coal mines may be forced into   
the spaces by the pressure of the rocks 
which overlie them--in fact1 the expense
 of cutting out these in-creeping rocks 
is in some ,british mines a serious item
 in the cost of the product4  ,the      
expansion of the water contained in the 
deep-lying heated rocks probably is by  

far the most efficient agent in urging  
them toward the plane of escape which   
the fissure affords4 ,when the motion   
begins it pervades all parts of the rock
 at once1 so that an actual flow is     
induced4 ,so far as the movement is due 
to the superincumbent weight1 the       
tendency is at once to increase the     
temperature of the moving mass4 ,the    
result is that it may be urged into the 
fissure perhaps even hotter than when it
 started from the original bed place4   
,in proportion as the rocky matter wins 
its way toward the surface1 the pressure
 upon it diminishes1 and the contained  
vapours are freer to expand4 ,taking on 
the vaporous form1 the bubbles gather to
 each other1 and when they appear at the
 throat of the volcano they may1 if the 
explosions be infrequent1 assume the    
character above noted in the little     
eruption of ,vesuvius4 ,where1 however1 
the lava ascends rapidly through the    
channel1 it often attains the open air  
with so much vapour in it1 and this     

intimately mingled with the mass1 that  
the explosion rends the materials into  
an impalpably fine powder1 which may    
float in the air for months before it   
falls to the earth4 ,with a less violent
 movement the vapour bubbles expand in  
the lava1 but do not rend it apart1 thus
 forming the porous1 spongy rock known  
as pumice4 ,with a yet slower ascent a  
large part of the steam may go away1 so 
that we may have a flow of lava welling 
forth from the vent1 still giving forth 
steam1 but with a vapour whose tension  
is so lowered that the matter is not    
blown apart1 though it may boil         
violently for a time after it escapes   
into the air4  ,although the foregoing  
relatively simple explanation of        
volcanic action can not be said as yet  
to be generally accepted by geologists1 
the reasons are sufficient which lead us
 to believe that it accounts for the    
main features which we observe in this  
class of explosions--in other words1 it 
is a good working hypothesis4 ,we shall 

now proceed in the manner which should  
be followed in all natural inquiry to   
see if the facts shown in the           
distribution of volcanoes in space and  
time confirm or deny the view4  ,the    
most noteworthy feature in the          
distribution of volcanoes is that1 at   
the present time at least1 all active   
vents are limited to the sea floors or  
to the shore lands within the narrow    
range of three hundred miles from the   
coast4 ,wherever we find a coast line   
destitute of volcanoes1 as is the case  
with the eastern coast of ,north and    
,south ,america1 it appears that the    
shore has recently been carried into the
 land for a considerable distance--in   
other words1 old coast lines are        
normally volcanic2 that is1 here and    
there have vents of this nature4 ,thus  
the ,north ,atlantic1 the coasts of     
which appear to have gone inland for a  
great distance in geologically recent   
times1 is non-volcanic2 while the       
,pacific coast1 which for a long time   

has remained in its present position1   
has a singularly continuous line of     
craters near the shore extending from   
,alaska to ,tierra del ,fuego4 ,so      
uninterrupted is this line of volcanoes 
that if they were all in eruption it    
would very likely be possible to journey
 down the coast without ever being out  
of sight of the columns of vapour which 
they would send forth4 ,on the floor of 
the sea volcanic peaks appear to be very
 widely distributed2 only a few of      
them--those which attain the surface of 
the water--are really known1 but        
soundings show long lines of elevations 
which doubtless represent cones         
distributed along fault lines1 none of  
the peaks of sufficient height to break 
the surface of the sea4 ,it is likely1  
indeed1 that for one marine volcano     
which appears as an island there are    
scores which do not attain the surface4 
,volcanic islands exist and generally   
abound in the ocean and greater seas2   
every now and then we observe a new one 

forming as a small island1 which is apt 
to be washed away by the sea shortly    
after the eruption ceases1 the          
disappearance being speedy1 for the     
reason that the volcanic ashes of which 
these cones are composed drift away like
 snow before the movement of the waves4 
,if the waters of the ocean and seas    
were drained away so that we could      
inspect the portion of the earth's      
surface which they cover as readily as  
we do the dry lands1 the most           
conspicuous feature would be the        
innumerable volcanic eminences which lie
 hidden in these watery realms4         
,wherever the observer passed from the  
centres of the present lands he would   
note within the limits of those fields  
only mountains1 much modified by river  
action2 hills which the rivers had left 
in scarfing away the strata2 and dales  
which had been carved out by the flowing
 waters4 ,near the shore lines of the   
vanished seas he would begin to find    
mountains1 hills1 and vales occasionally

 commingled with volcanic peaks1 those  
structures built from the materials     
ejected from the vents4 ,passing the    
coast line to the seaward1 the hills and
 dales would quickly disappear1 and     
before long the mountains would vanish  
from his way1 and he would gradually    
enter on a region of vast rolling plains
 beset by volcanic peaks1 generally     
accumulated in long ranges1 somewhat    
after the manner of mountains1 but      
differing from those elevations not only
 in origin but in aspect1 the volcanic  
set of peaks being altogether made up of
 conical1 cup-topped elevations4  ,a    
little consideration will show us that  
the fact of volcanoes being in the limit
 to the sea floors and to a narrow      
fringe of shore next certain ocean      
borders is reconcilable with the view as
 to their formation which we have       
adopted4 ,we have already noted the fact
 that the continents are old1 which     
implies that the parts of the earth     
which they occupy have long been the    

seats of tolerably continuous erosion4  
,now and then they have swung down      
partly beneath the sea1 and during their
 submersion they received a share of    
sediments4 ,but1 on the whole1 all parts
 of the lands except strips next the    
coast may be reckoned as having been    
subjected to an excess of wearing action
 far exceeding the depositional work4   
,therefore1 as we readily see1          
underneath such land areas there has    
been no blanketing process going on     
which has served to increase the heat in
 the deep underlying rocks4 ,on the     
contrary1 it would be easy to show1 and 
the reader may see it himself1 that the 
progressive cooling of the earth has    
probably brought about a lowering of the
 temperature in all the section from the
 surface to very great depths1 so that  
not only is the rock water unaffected by
 increase of heat1 but may be actually  
losing temperature4 ,in other words1 the
 conditions which we assume bring about 
volcanic action do not exist beneath the

 old land4  ,beneath the seas1 except in
 their very greatest depths1 and perhaps
 even there1 the process of forming     
strata is continually going on4 ,next   
the shores1 sometimes for a hundred or  
two miles away to seaward1 the principal
 contribution may be the sediment worn  
from the lands by the waves and the     
rivers4 ,farther away it is to a large  
extent made up of the remains of animals
 and plants1 which when dying give their
 skeletons to form the strata4 ,much of 
the materials laid down--perhaps in all 
more than half--consist of volcanic     
dust1 ashes1 and pumice1 which drifts   
very long times before it finds its way 
to the bottom4 ,we have as yet no data  
of a precise kind for determining the   
average rate of accumulation of         
sediments upon the sea floor1 but from  
what is known of the wearing of the     
lands1 and the amount of volcanic waste 
which finds its way to the seas1 it is  
probably not less than about a foot in  
ten thousand years2 it is most likely1  

indeed1 much to exceed this amount4     
,from data afforded by the eruptions in 
,java and in other fields where the     
quantity of volcanic dust contributed to
 the seas can be estimated1 the writer  
is disposed to believe that the average 
rate of sedimentation on the sea floors 
is twice as great as the estimate above 
given4  ,accumulating at the average    
rate of one foot in ten thousand years1 
it would require a million years to     
produce a hundred feet of sediments2 a  
hundred million to form ten thousand    
feet1 and five hundred million to create
 the thickness of about ten miles of    
bed4 ,at the rate of two feet in ten    
thousand years1 the thickness           
accumulated would be about twenty miles4
 ,when we come to consider the duration 
of the earth's geologic history1 we     
shall find reasons for believing that   
the formation of sediment may have      
continued for as much as five hundred   
million years4  ,the foregoing inquiries
 concerning the origin of volcanoes show

 that at the present time they are      
clearly connected with some process     
which goes on beneath the sea4 ,an      
extension of the inquiry indicates that 
this relation has existed in earlier    
geological times2 for1 although the     
living volcanoes are limited to places  
within three hundred miles of the sea1  
we find lava flows1 ashes1 and other    
volcanic accumulations far in the       
interior of the continents1 though the  
energy which brought them forth to the  
earth's surface has ceased to operate in
 those parts of the land4 ,in these     
cases of continental volcanoes it       
generally1 if not always1 appears that  
the cessation of the activity attended  
the removal of the shore line of the    
ocean or the disappearance of great     
inland seas4 ,thus the volcanoes of the 
,yellowstone district may have owed     
their activity to the immense deposits  
of sediment which were formed in the    
vast fresh-water lakes which during the 
later ,cretaceous and early ,tertiary   

times stretched along the eastern face  
of the ,rocky ,mountains1 forming a     
,mediterranean ,sea in ,north ,america  
comparable to that which borders        
southern ,europe4 ,it thus appears that 
the arrangement of volcanoes with       
reference to sea basins has held for a  
considerable period in the past4 ,still 
further1 when we look backward through  
the successive formations of the earth's
 crust we find here and there evidences 
in old lava flows1 in volcanic ashes1   
and sometimes in the ruins of ancient   
cones which have been buried in the     
strata1 that igneous activity such as is
 now displayed in our volcanoes has     
been1 since the earliest days of which  
we have any record1 a characteristic    
feature of the earth4 ,there is no      
reason to suppose that this action has  
in the past been any greater or any less
 than in modern days4 ,all these facts  
point to the conclusion that volcanic   
action is due to the escape of rock     
water which has been heated to high     

temperatures1 and which drives along    
with it as it journeys toward a crevice 
the rock in which it has been confined4 
,we will now notice some other          
explanations of volcanic action which   
have obtained a certain credence4       
,first1 we may note the view that these 
ejections from craters are forced out   
from a supposed liquid interior of the  
earth4 ,one of the difficulties of this 
view is that we do not know that the    
earth's central parts are fluid--in     
fact1 many considerations indicate that 
such is not the case4 ,next1 we observe 
that we not infrequently find two       
craters1 each containing fluid lava1    
with the fluid standing at differences  
of height of several thousand feet1     
although the cones are situated very    
near each other4 ,if these lavas came   
from a common internal reservoir1 the   
principles which control the action of  
fluids would cause the lavas to be at   
the same elevation4 ,moreover1 this view
 does not provide any explanation of the

 fact that volcanoes are in some way    
connected with actions which go on on   
the floors of great water basins4 ,there
 is every reason to believe that the    
fractures in the rocks under the land   
are as numerous and deep-going as those 
beneath the sea4 ,if it were a mere     
question of access to a fluid interior1 
volcanoes should be equally distributed 
on land and sea floors4 ,last of all1   
this explanation in no wise accounts for
 the intermixture of water with the     
fluid rock4 ,we can not well believe    
that water could have formed a part of  
the deeper earth in the old days of     
original igneous fusion4 ,in that time  
the water must have been all above the  
earth in the vaporous state4  ,another  
supposition somewhat akin to that       
mentioned is that the water of the seas 
finds its way down through crevices     
beneath the floors of the ocean1 and1   
there coming in contact with an internal
 molten mass1 is converted into steam1  
which1 along with the fluid rock1       

escapes from the volcanic vent4 ,in     
addition to the objections urged to the 
preceding view1 we may say concerning   
this that the lava1 if it came forth    
under these circumstances1 would emerge 
by the short way1 that by which the     
water went down1 and not by the longer  
road1 by which it may be discharged ten 
thousand feet or more above the level of
 the sea4  ,the foregoing general       
account of volcanic action should       
properly be followed by some account of 
what takes place in characteristic      
eruptions4 ,this history of these       
matters is so ample that it would       
require the space of a great encyclopdia
 to contain them4 ,we shall therefore be
 able to make only certain selections   
which may serve to illustrate the more  
important facts4  ,by far the best-known
 volcanic cone is that of ,vesuvius1    
which has been subjected to tolerably   
complete record for about twenty-four   
hundred years4 ,about #ejj ,b4,c4 the   
,greeks1 who were ever on the search for

 places where they might advantageously 
plant colonies1 settled on the island of
 ,ischia1 which forms the western of    
what is now termed the ,bay of ,naples4 
,this island was well placed for tillage
 as well as for commerce1 but the       
enterprising colonists were again and   
again disturbed by violent outbreaks of 
one or more volcanoes which lie in the  
interior of this island2 at one time it 
appears that the people were driven away
 by these explosions4  ,in these        
pre-,christian days ,vesuvius1 then     
known as ,monte ,somma1 was not known to
 be a volcano1 it never having shown any
 trace of eruption4 ,it appeared as a   
regularly shaped mountain1 somewhat over
 two thousand feet high1 with a central 
depression about three miles in diameter
 at the top1 and perhaps two miles over 
at the bottom1 which was plainlike in   
form1 with some lakes of bitter water in
 the centre4 ,the most we know of this  
central cavity is connected with the    
insurrection of the slaves led by       

,spartacus1 the army of the revolters   
having camped for a time on the plain   
encircled by the crater walls4 ,the     
outer slopes of the mountain afforded   
then a remarkably fertile soil2 some    
traces1 indeed1 of the fertility have   
withstood the modern eruptions which    
have desolated its flanks4 ,this        
wonderful ,bay of ,naples became the    
seat of the fairest ,roman culture1 as  
well as of a very extended commerce4    
,toward the close of the first century  
of our era the region was perhaps       
richer1 more beautifully cultivated1 and
 the seat of a more elaborate luxury    
than any part of the shore line of      
,europe at the present day4 ,at the foot
 of the mountain1 on the eastern border 
of the bay1 the city of ,pompeii1 with a
 population of about fifty thousand     
souls1 was a considerable port1 with an 
extensive commerce1 particularly with   
,egypt4 ,the charming town was also a   
place of great resort for rich          
,egyptians who cared to dwell in        

,europe4 ,on the flanks of the mountain 
there was at least one large town1      
,herculaneum1 which appears to have been
 an association of rich men's           
residences4 ,on the eastern side of the 
bay1 at a point now known as ,bai1 the  
,roman ,government had a naval station1 
which in the year #gi was under the     
command of the celebrated ,pliny1 a most
 voluminous though unscientific writer  
on matters of natural history4 ,with him
 in that year there was his nephew1     
commonly known as the younger ,pliny1   
then a student of eighteen years1 but   
afterward himself an author4 ,these     
facts are stated in some detail1 for    
they are all involved in the great      
tragedy which we are now to describe4   
,for many years there had been no       
eruption about the ,bay of ,naples4 ,the
 volcanoes on ,ischia had been still for
 a century or more1 and the various     
circular openings on the mainland had   
been so far quiet that they were not    
recognised as volcanoes4 ,even the      

inquisitive ,pliny1 with his great      
learning1 was so little of a geologist  
that he did not know the signs which    
indicate the seat of volcanic action1   
though they are among the most          
conspicuous features which can meet the 
eye4 ,the ,greeks would doubtless have  
recognised the meaning of these physical
 signs4 ,in the year #fc the shores of  
the ,bay of ,naples were subjected to a 
distinctive earthquake4 ,others less    
severe followed in subsequent years4 ,in
 an early morning in the year #gi1 a    
servant aroused the elder ,pliny at ,bai
 with the news that there was a         
wonderful cloud rising from ,monte      
,somma4 ,the younger ,pliny states that 
in form it was like a pine tree1 the    
common species in ,italy having a long  
trunk with a crown of foliage on its    
summit1 shaped like an umbrella4 ,this  
crown of the column grew until it spread
 over the whole landscape1 darkening the
 field of view4 ,shortly after1 a       
despatch boat brought a message to the  

admiral1 who at once set forth for the  
seat of the disturbance4 ,he invited his
 nephew to accompany him1 but the       
prudent young man relates in his letters
 to ,tacitus1 from whom we know the     
little concerning the eruption which has
 come down to us1 that he preferred to  
do some reading which he had to attend  
to4 ,his uncle1 however1 went straight  
forward1 intending to land at some point
 on the shore at the foot of the cone4  
,he found the sea1 however1 so high that
 a landing was impossible2 moreover1 the
 fall of rock fragments menaced the     
ship4 ,he therefore cruised along the   
shore for some distance1 landing at a   
station probably near the present       
village of ,castellamare4 ,at this point
 the fall of ashes and pumice was very  
great1 but the sturdy old ,roman had his
 dinner and slept after it4 ,there is   
testimony that he snored loudly1 and was
 aroused only when his servants began to
 fear that the fall of ashes and stones 
would block the way out of his          

bedchamber4 ,when he came forth with his
 attendants1 their heads protected by   
planks resting on pillows1 he set out   
toward ,pompeii1 which was probably the 
place where he sought to land4 ,after   
going some distance1 the brave man fell 
dead1 probably from heart disease2 it is
 said that he was at the time           
exceedingly asthmatic4 ,no sooner were  
his servants satisfied that the life had
 passed from his body than they fled4   
,the remains were recovered after the   
eruption had ceased4 ,the younger ,pliny
 further relates that after his uncle   
left1 the cloud from the mountain became
 so dense that in midday the darkness   
was that of midnight1 and the earthquake
 shocks were so violent that wagons     
brought to the courtyard of the dwelling
 to bear the members of the household   
away were rolled this way and that by   
the quakings of the earth4  ,save for   
the above-mentioned few and unimportant 
details concerning the eruption1 we have
 no other contemporaneous account4 ,we  

have1 indeed1 no more extended story    
until ,dion ,cassius1 writing long after
 the event1 tells us that ,herculaneum  
and ,pompeii were overwhelmed2 but he   
mixes his story with fantastic legends  
concerning the appearance of gods and   
demons1 as is his fashion in his        
so-called history4 ,of all the ,roman   
writers1 he is perhaps the most         
untrustworthy4 ,fortunately1 however1 we
 have in the deposits of ashes which    
were thrown out at the time of this     
great eruption some basis for           
interpreting the events which took      
place4 ,it is evident that for many     
hours the ,vesuvian crater1 which had   
been dormant for at least five hundred  
years1 blew out with exceeding fury4 ,it
 poured forth no lava streams2 the      
energy of the uprushing vapours was too 
great for that4 ,the molten rock in     
their path was blown into fine bits1 and
 all the hard material cast forth as    
free dust4 ,in the course of the        
eruption1 which probably did not endure 

more than two days1 possibly not more   
than twenty-four hours1 ash enough was  
poured forth to form a thick layer which
 spread far over the neighbouring area  
of land and sea floor4 ,it covered the  
cities of ,herculaneum and ,pompeii to a
 depth of more than twenty feet1 and    
over a circle having a diameter of      
twenty miles the average thickness may  
have been something like this amount4   
,so deep was it that1 although almost   
all the people of these towns survived1 
it did not seem to them worth while to  
undertake to excavate their dwelling    
places4 ,at ,pompeii the covering did   
not overtop the higher of the low       
houses4 ,an amount of labour which may  
be estimated at not over one thirtieth  
of the value1 or at least the cost which
 had been incurred in building the city1
 would have restored it to a perfectly  
inhabitable state4 ,the fact that it was
 utterly abandoned probably indicates a 
certain superstitious view in connection
 with the eruption4  ,the fact that the 

people had time to flee from            
,herculaneum and ,pompeii1 bearing with 
them their more valuable effects1 is    
proved by the excavations at these      
places which have been made in modern   
times4 ,the larger part of ,pompeii and 
a considerable portion of ,herculaneum  
have been thus explored2 only rarely    
have human remains been found4 ,here and
 there1 particularly in the cellars1 the
 labourers engaged in the work of       
disinterring the cities note that their 
picks enter a cavity2 examining the     
space1 they find they have discovered   
the remains of a human skeleton4 ,it has
 recently been learned that by pouring  
soft plaster of ,paris into these       
openings a mould may be obtained which  
gives in a surprisingly perfect manner  
the original form of the body4 ,the     
explanation of this mould is as follows3
 ,along with the fall of cinders in an  
eruption there is always a great descent
 of rain1 arising from the condensation 
of the steam which pours forth from the 

volcano4 ,this water1 mingling with the 
ashes1 forms a pasty mud1 which often   
flows in vast streams1 and is sometimes 
known as mud lava4 ,this material has   
the qualities of cement--that is1 it    
shortly sets in a manner comparable to  
plaster of ,paris or ordinary mortar4   
,during the eruption of #gi this mud    
penetrated all the low places in        
,pompeii1 covering the bodies of the    
people1 who were suffocated by the fumes
 of the volcanic emanations4 ,we know   
that these people were not drowned by   
the inundation2 their attitudes show    
that they were dead before the flowing  
matter penetrated to where they lay4    
,it happened that ,pompeii lay beyond   
the influence of the subsequent great   
eruptions of ,vesuvius1 so that it      
afterward received only slight ash      
showers4 ,herculaneum1 on the other     
hand1 has century by century been more  
and more deeply buried until at the     
present time it is covered by many      
sheets of lava4 ,this is particularly to

 be regretted1 for the reason that1     
while ,pompeii was a seaport town of no 
great wealth or culture1 ,herculaneum   
was the residence place of the gentry1  
people who possessed libraries1 the     
records of which can be in many cases   
deciphered1 and from which we might hope
 to obtain some of the lost treasures of
 antiquity4 ,the papyrus rolls on which 
the books of that day were written1     
though charred by heat and time1 are    
still interpretable4  ,after the great  
explosion of #gi1 ,vesuvius sank again  
into repose4 ,it was not until #ajef    
that vigorous eruptions again began4    
,from time to time slight explosions    
occurred1 none of which yielded lava    
flows2 it was not until the date last   
mentioned that this accompaniment of the
 eruption began to appear4 ,in #afcf1   
after a repose of nearly a century and a
 half1 there came a very great outbreak1
 which desolated a wide extent of       
country on the northwestern side of the 
cone4 ,at this stage in the history of  

the crater the volcanic flow began to   
attain the sea4 ,washing over the edge  
of the old original crater of ,monte    
,somma1 and thus lowering its elevation1
 these streams devastated1 during the   
eruption just mentioned and in various  
other outbreaks1 a wide field of        
cultivated land1 overwhelming many      
villages4 ,the last considerable        
eruption which yielded large quantities 
of lava was that of #ahgb1 which sent   
its tide for a distance of about six    
miles4  ,since #afcf the eruptions of   
,vesuvius have steadily increased in    
frequency1 and1 on the whole1 diminished
 in violence4 ,in the early years of its
 history the great outbreaks were       
usually separated by intervals of a     
century or more1 and were of such energy
 that the lava was mostly blown to dust1
 forming clouds so vast that on two     
occasions at least they caused a        
midnight darkness at ,constantinople1   
nearly twelve hundred miles away4 ,this 
is as if a volcano at ,chicago should   

completely hide the sun in the city of  
,boston4 ,in the present state of       
,vesuvius1 the cone may be said to be in
 slight1 almost continuous eruption4    
,the old central valley which existed   
before the eruption of #gi1 and         
continued to be distinct for long after 
that time1 has been filled up by a      
smaller cone1 bearing a relatively tiny 
crater of vent1 the original wall being 
visible only on the eastern and northern
 parts of its circuit1 and here only    
with much diminished height4 ,on the    
western face the slope from the base of 
the mountain to the summit of the new   
cone is almost continuous1 though the   
trained eye can trace the outline of    
,monte ,somma--its position in a kind of
 bench1 which is traceable on that side 
of the long slope leading from the      
summit of the new cone to the sea4 ,the 
fact that the lavas of ,vesuvius have   
broken out on the southwestern side1    
while the old wall of the cone has      
remained unbroken on the eastern        

versant1 has a curious explanation4 ,the
 prevailing wind of ,naples is from the 
southwest1 being the strong counter     
trades which belong in that latitude4   
,in the old days when the ,monte ,somma 
cone was constructed these winds caused 
the larger part of the ashes to fall on 
the leeward side of the cone1 thus      
forming a thicker and higher wall around
 that part of the crater4  ,from the    
nature of the recent eruptions of       
,vesuvius it appears likely that the    
mountain is about to enter on a second  
period of inaction4 ,the pipes leading  
through the new cone are small1 and the 
mass of this elevation constitutes a    
great plug1 closing the old crater      
mouth4 ,to give vent to a large         
discharge of steam1 the whole of this   
great mass1 having a depth of nearly two
 thousand feet1 would have to be blown  
away4 ,it seems most likely that when   
the occasion for such a discharge comes1
 the vapours of the eruption will seek a
 vent through some other of the many    

volcanic openings which lie to the      
westward of this great cone4 ,the       
history of these lesser volcanoes points
 to the conclusion that when the path by
 way of ,vesuvius is obstructed they may
 give relief to the steam which is      
forcing its course to the surface4 ,two 
or three times since the eruption of    
,pliny1 during periods when ,vesuvius   
had long been quiet1 outbreaks have     
taken place on ,ischia or in the ,phlgrn
 ,fields1 a region dotted with small    
craters which lies to the west of       
,naples4 ,the last of these occurred in 
#aeeb1 and led to the formation of the  
beautiful little cone known as ,monte   
,nuovo4 ,this eruption took place near  
the town of ,puzzuoli1 a place which was
 then the seat of a university1 the     
people of which have left us records of 
the accident4  ,illustration3 ,fig4     
#af4--;,diagrammatic sections through   
,mount ,vesuvius1 showing changes in the
 form of the cone4 7,from ,phillips47   
,the outbreak which formed ,monte ,nuovo

 was slight but very characteristic4 ,it
 occurred in and beside a circular pool 
known as the ,lucrine ,lake1 itself an  
ancient crater4 ,at the beginning of the
 disturbance the ground opened in ragged
 cavities1 from which mud and ashes and 
great fragments of hard rock were hurled
 high in the air1 some of the stones    
ascending to a height of several        
thousand feet4 ,with slight             
intermissions this outbreak continued   
for some days1 resulting in the         
formation of a hill about five hundred  
feet high1 with a crater in its top1 the
 bottom of which lay near the level of  
the sea4 ,although this volcanic        
elevation1 being made altogether of     
loose fragments1 is rapidly wearing     
down1 while the crater is filling up1 it
 remains a beautiful object in the      
landscape1 and is also noteworthy for   
the fact that it is the only structure  
of this nature which we know from its   
beginning4 ,in the ,phlgrn ,field there 
are a number of other craters of small  

size1 with very low cones about them4   
,these appear to have been the product  
of brief1 slight eruptions4 ,that known 
as the ,solfatara1 though not in        
eruption during the historic period1 is 
interesting for the fact that from the  
crevices of the rocks about it there    
comes forth a continued efflux of       
carbonic-acid gas4 ,this substance      
probably arises from the effect of heat 
contained in old lavas which are in     
contact with limestone in the deep      
under-earth4 ,we know such limestones   
are covered by the lavas of ,vesuvius1  
for the reason that numerous blocks of  
the rock are thrown out during          
eruptions1 and are often found embedded 
in the lava streams4 ,it is an          
interesting fact that these craters of  
the ,phlgrn ,field1 lying between the   
seats of vigorous eruption on ,ischia   
and at ,vesuvius1 have never been in    
vigorous eruption4 ,their slight        
outbreaks seem to indicate that they    
have no permanent connection with the   

sources whence those stronger vents     
obtain their supply of heated steam4    
,the facts disclosed by the study of the
 ,vesuvian system of volcanoes afford   
the geologist a basis for many          
interesting conclusions4  ,in the first 
place1 he notes that the greater part of
 the cones1 all those of small size1 are
 made up of finely divided rock1 which  
may have been more or less cemented by  
the processes of change which go on     
within it4 ,it is thus clear that the   
lava flows are unessential--indeed1 we  
may say accidental--contributions to the
 mass4 ,in the case of ,vesuvius they   
certainly do not amount to as much as   
one tenth of the elevation due to the   
volcanic action4 ,the share of the lava 
in ,vesuvius is probably greater than   
the average1 for during the last six    
centuries this vent has been remarkably 
lavigerous4#h ,observation on the       
volcanoes of other districts show that  
the ,vesuvian group is in this regard   
not peculiar4 ,of nearly two hundred    

cones which the writer has examined1 not
 more than one tenth disclose distinct  
lavas4  ,footnote #h3 ,i venture to use 
this word in place of the phrase        
lava-yielding for the reason that the   
term is needed in the description of    
volcanoes4  ,an inspection of the old   
inner wall of ,monte ,somma in that     
portion where it is best preserved1 on  
the north side of the ,atria del        
,cavallo1 or ,horse ,gulch--so called   
for the reason that those who ascended  
,vesuvius were accustomed to leave their
 saddle animals there--we perceive that 
the body of the old cone is to a        
considerable extent interlaced with     
dikes or fissures which have been filled
 with molten lava that has cooled in its
 place4 ,it is evident that during the  
throes of an eruption1 when the lava    
stands high in the crater1 these rents  
are frequently formed1 to be filled by  
the fluid rock4 ,in fact1 lava          
discharges1 though they may afterward   
course for long distances in the open   

air1 generally break their way          
underground through the cindery cone1   
and first are disclosed at the distance 
of a mile or more from the inner walls  
of the crater4 ,their path is probably  
formed by riftings in the compacted     
ashes1 such as we trace on the steep    
sides of the ,atria del ,cavallo1 as    
before noted4 ,for the further history  
of these fissures1 we shall have to     
refer to facts which are better         
exhibited in the cone of tna4  ,the     
amount of rock matter which has been    
thrown forth from the volcanoes about   
the ,bay of ,naples is very great4 ,only
 a portion of it remains in the region  
around these cones2 by far the greater  
part has been washed or blown away4     
,after each considerable eruption a wide
 field is coated with ashes1 so that the
 tilled grounds appear as if entirely   
sterilized2 but in a short time the     
matter in good part disappears1 a       
portion of it decays and is leached     
away1 and the most of the remainder     

washes into the sea4 ,only the showers1 
which accumulate a deep layer1 are apt  
to be retained on the surface of the    
country4 ,a great deal of this powdered 
rock drifts away in the wind1 sometimes 
in great quantities1 as in those cases  
where it darkened the sky more than a   
thousand miles from the cone4 ,moreover1
 the water of the steam which brought   
about the discharges and the other gases
 which accompanied the vapour have left 
no traces of their presence1 except in  
the deep channels which the rain of the 
condensing steam have formed on the     
hillsides4 ,nevertheless1 after all     
these subtractions are made1 the        
quantity of volcanic matter remaining on
 the surface about the ,bay of ,naples  
would1 if evenly distributed1 form a    
layer several hundred feet in           
thickness--perhaps1 indeed1 a thousand  
feet in depth--over the territory in    
which the vents occur4 ,all this matter 
has been taken in relatively recent     
times from the depths of the earth4 ,the

 surprising fact is that no considerable
 and1 indeed1 no permanent subsidence of
 the surface has attended this          
excavation4 ,we can not believe that    
this withdrawal of material from the    
under-earth has resulted in the         
formation of open underground spaces4   
,we know full well that any such1 if it 
were of considerable size1 would quickly
 be crushed in by the weight of the     
overlying rocks4 ,we have1 indeed1 to   
suppose that these steam-impelled lavas1
 which are driven toward the vent whence
 they are to go forth in the state of   
dust or fluid1 come underground from    
distances away1 probably from beneath   
the floors of the sea to the westward4  
,although the shores of the ,bay of     
,naples have remained in general with   
unchanged elevation for about two       
thousand years1 they have here and there
 been subjected to slight oscillations  
which are most likely connected with the
 movement of volcanic matter toward the 
vents where it is to find escape4 ,the  

most interesting evidence of this nature
 is afforded by the studies which have  
been made on the ruins of the ,temple of
 ,serapis at ,puzzuoli4 ,this edifice   
was constructed in pre-,christian times 
for the worship of the ,egyptian god    
,serapis1 whose intervention was sought 
by sick people4 ,the fact that this     
divinity of the ,nile found a residence 
in this region shows how intimate was   
the relation between ,rome and ,egypt in
 this ancient day4 ,the ,serapeium was  
built on the edge of the sea1 just above
 its level4 ,when in modern days it     
began to be studied1 its floor was about
 on its original level1 but the few     
standing columns of the edifice afford  
indubitable evidence that this part of  
the shore has been lowered to the amount
 of twenty feet or more and then        
re-elevated4 ,the subsidence is proved  
by the fact that the upper part of the  
columns which were not protected by the 
dbris accumulated about them have been  
bored by certain shellfish1 known as    

,lithodomi1 which have the habit of     
excavating shelters in soft stone1 such 
as these marble columns afford4 ,at     
present the floor on which the ruin     
stands appears to be gradually sinking1 
though the rate of movement is very     
slow4  ,another evidence that the       
ejections may travel for a great        
distance underground on their way to the
 vent is afforded by the fact that      
,vesuvius and tna1 though near three    
hundred miles apart1 appear to exchange 
activities--that is1 their periods of   
outbreak are not simultaneous4 ,although
 these elements of the chronology of the
 two cones may be accidental1 taken with
 similar facts derived from other       
fields1 they appear to indicate that    
vents1 though far separated from each   
other1 may1 so to speak1 be fed from a  
common subterranean source4 ,it is a    
singular fact in this connection that   
the volcano of ,stromboli1 though       
situated between these two cones1 is in 
a state of almost incessant activity4   

,this probably indicates that the       
last-named vent derives its vapours from
 another level in the earth than the    
greater cones4 ,in this regard volcanoes
 probably behave like springs1 of which1
 indeed1 they may be regarded as a      
group4 ,the reader is doubtless aware   
that hot and cold springs often escape  
very near together1 the difference in   
the temperature being due to the depth  
from which their waters come forth4  ,as
 the accidents of volcanic explosion are
 of a nature to be very damaging to man1
 as well as to the lower orders of      
,nature1 it is fit that we should note  
in general the effect of the ,neapolitan
 eruptions on the history of            
civilization in that region4 ,as stated 
above1 the first ,greek settlements in  
this vicinity--those on the island of   
,ischia--were much disturbed by volcanic
 outbreaks1 yet the island became the   
seat of a permanent and prosperous      
colony4 ,the great eruption of #gi      
probably cost many hundred lives1 and   

led to the abandonment of two           
considerable cities1 which1 however1    
could at small cost have been recovered 
to use4 ,since that day various         
eruptions have temporarily desolated    
portions of the territory1 but only in  
very small fields have the ravages been 
irremediable4 ,where the ground was     
covered with dust1 it has in most places
 been again tillable1 and so rapid is   
the decay of the lavas that in a century
 after their flow has ceased vines can  
in most cases be planted on their       
surfaces4 ,the city of ,naples1 which   
lies amid the vents1 though not         
immediately in contact with any of them1
 has steadfastly grown and prospered    
from the pre-,christian times4 ,it is   
doubtful if any lives have ever been    
lost in the city in consequence of an   
eruption1 and no great inconvenience has
 been experienced from them4 ,now and   
then1 after a great ash shower1 the     
volcanic dust has to be removed1 but the
 labour is less serious than that       

imposed on many northern cities by a    
snowstorm4 ,through all these           
convulsions the tillage of the district 
has been maintained4 ,it has ever been  
the seat of as rich and profitable a    
husbandry as is afforded by any part of 
,italy4 ,in fact1 the ash showers1 as   
they import fine divided rock very rich 
in substances necessary for the growth  
of plants1 have in a measure served to  
maintain the fertility of the soil1 and 
by this action have in some degree      
compensated for the injury which they   
occasionally inflict4 ,comparing the    
ravages of the eruptions with those     
inflicted by war1 unnecessary disease1  
or even bad politics1 and we see that   
these natural accidents have been most  
merciful to man4 ,many a tyrant has     
caused more suffering and death than has
 been inflicted by these rude operations
 of ,nature4  ,from the point of view of
 the naturalist1 tna is vastly more     
interesting than ,vesuvius4 ,the bulk of
 the cone is more than twenty times as  

great as that of the ,neapolitan        
volcano1 and the magnitude of its       
explosions1 as well as the range of     
phenomena which they exhibit1           
incomparably greater4 ,it happens1      
however1 that while human history of the
 recorded kind has been intimately bound
 up with the tiny ,vesuvian cone1 partly
 because the relatively slight nature of
 its disturbances permitted men to dwell
 beside it1 the larger tna has expelled 
culture from the field near its vent1   
and has done the greater part of its    
work in the vast solitude which it has  
created4#i  ,footnote #i3 ,in part the  
excellent record of ,vesuvius is due to 
the fact that since the early ,christian
 centuries the priests of ,st4          
,januarius1 the patron of ,naples1 have 
been accustomed to carry his relics in  
procession whenever an eruption began4  
,the cessation of the outbreak has been 
written down to the credit of the saint1
 and thus we are provided with a long   
story of the successive outbreaks4  tna 

has been in frequent eruption for a very
 much longer time than ,vesuvius4 ,in   
the odes of ,pindar1 in the sixth       
century before ,christ1 we find records 
of eruptions4 ,it is said also that the 
philosopher ,empedocles sought fame and 
death by casting himself into the fiery 
crater4 ,there has thus in the case of  
this mountain been no such long period  
of repose as occurred in ,vesuvius4     
,though our records of the outbreaks are
 exceedingly imperfect1 they serve to   
show that the vent has maintained its   
activity much more continuously than is 
ordinarily the case with volcanoes4 tna 
is characteristically a lava-yielding   
cone2 though the amount of dust put     
forth is large1 the ratio of the fluid  
rock which flows away from the crater is
 very much greater than at ,vesuvius4   
,nearly half the cone1 indeed1 may be   
composed of this material4 ,our space   
does not permit anything like a         
consecutive story of the tnean eruptions
 since the dawn of history1 or even a   

full account of its majestic cone2 we   
can only note certain features of a     
particularly instructive nature which   
have been remarked by the many able men 
who have studied this structure and the 
effects of its outbreak4  ,the most     
important feature exhibited by tna is   
the vast size of its cone4 ,at its apex 
its height1 though variable from the    
frequent destruction and rebuilding of  
the crater walls1 may be reckoned as    
about eleven thousand feet4 ,the base on
 which the volcanic material lies is    
probably less than a thousand feet above
 the sea1 so that the maximum thickness 
of the heap of volcanic ejections is    
probably about two miles4 ,the average  
depth of this coating is probably about 
five thousand feet1 and1 as the cone has
 an average diameter of about thirty    
miles1 we may conclude that the cone now
 contains about a thousand cubic miles  
of volcanic materials4 ,great as is this
 mass1 it is only a small part of the   
ejected material which has gone forth   

from the vent4 ,all the matter which in 
its vaporous state went forth with the  
eruption1 the other gases and vapours   
thus discharged1 have disappeared4 ,so1 
too1 a large part of the ash and much of
 the lava has been swept away by the    
streams which drain the region1 and     
which in times of eruption are greatly  
swollen by the accompanying torrential  
rains4 ,the writer has estimated that if
 all the emanations from the            
volcano--solid1 fluid1 and              
gaseous--could be heaped on the cone1   
they would form a mass of between two   
and three thousand cubic miles in       
contents4 ,yet notwithstanding this     
enormous outputting of earthy matter1   
the earth on which the tnean cone has   
been constructed has not only failed to 
sink down1 but has been in process of   
continuous1 slow uprising1 which has    
lifted the surface more than a thousand 
feet above the level which it had at the
 time when volcanic action began in this
 field4 ,here1 even more clearly than in

 the case of ,vesuvius1 we see that the 
materials driven forth from the crater  
are derived not from just beneath its   
foundation1 but from a distance1 from   
realms which in the case of this insular
 volcano are beneath the sea floors4 ,it
 is certain that here the migration of  
rock matter1 impelled by the expansion  
of its contained water toward the vent1 
has so far exceeded that which has been 
discharged through the crater that an   
uprising of the surface such as we have 
observed has been brought about4        
,illustration3 ,mount tna1 seen from    
near ,catania4 ,the imperfect cones on  
the sky line to the left are those of   
small secondary eruptions4  ,there are  
certain peculiarities of ,mount tna     
which are due in part to its great size 
and in part to the climatal conditions  
of the region in which it lies4 ,the    
upper part of the mountain in winter is 
deeply snow-clad2 the frozen water      
often1 indeed1 forms great drifts in the
 gorges near the summit4 ,here it has   

occasionally happened that a layer of   
ashes has deeply buried the mass1 so    
that it has been preserved for years1   
becoming gradually more inclosed by the 
subsequent eruptions4 ,at one point     
where this compact snow--which has1     
indeed1 taken on the form of ice--has   
been revealed to view1 it has been      
quarried and conveyed to the towns upon 
the seacoast4 ,it is likely that there  
are many such masses of ice inclosed    
between the ash layers in the upper part
 of the mountain1 where1 owing to the   
height1 the climate is very cold4 ,this 
curious fact shows how perfect a        
non-conductor the ash beds of a volcano 
are to protect the frozen water from the
 heat of the rocks about the crater4    
,the furious rains which beset the      
mountain in times of great eruptions    
excavate deep channels on its sides4    
,the lava outbreaks which attend almost 
every eruption1 and which descend from  
the base of the cinder cone at the      
height of from five to eight thousand   

feet above the sea1 naturally find their
 way into these channels1 where they    
course in the manner of rivers until the
 lower and less valleyed section of the 
cone is reached4  ,such a lava flow     
naturally begins to freeze on the       
surface1 the lava at first becoming     
viscid1 much in the manner of cream on  
the surface of milk4 ,urged along by the
 more fluid lava underneath1 this viscid
 coating takes a ropy or corrugated     
form4 ,as the freezing goes deeper1 a   
firm stone roof may be formed across the
 gorge1 which1 when the current of lava 
ceases to flow from the crater1 permits 
the lower part of the stream to drain   
away1 leaving a long cavern or scries of
 caves extending far up the cone4 ,the  
nature of this action is exactly        
comparable to that which we may observe 
when on a frosty morning after rain we  
may find the empty channels which were  
occupied by rills of water roofed over  
with ice2 the ice roofs are temporary1  
while those of lava may endure for ages4

 ,some of these lava-stream caves have  
been disclosed1 in the manner of        
ordinary caverns1 by the falling of     
their roofs2 but the greater part are   
naturally hidden beneath the            
ever-increasing materials of the cone4  
,the lava-stream caves of tna are not   
only interesting because of their       
peculiarities of form1 which we shall   
not undertake to describe1 but also for 
the reason that they help us to account 
for a very peculiar feature in the      
history of the great cone4 ,on the      
slopes of the volcano1 below the upper  
cindery portion1 there are several      
hundred lesser cones1 varying from a few
 score to seven hundred feet in height4 
,each of these has its appropriate      
crater1 and has evidently been the seat 
of one or more eruptions4 ,as the       
greater part of these cones are ancient1
 many of them being almost effaced by   
the rain or buried beneath the ejections
 which have surrounded their bases since
 the time they were formed1 we are led  

to believe that many thousands of them  
have been formed during the history of  
the volcano4 ,the history of these      
subsidiary cones appears to be connected
 with the lava caves noted above4 ,these
 caverns1 owing to the irregularities of
 their form1 contain water4 ,they are1  
in fact1 natural cisterns1 where the    
abundant rainfall of the mountain finds 
here and there storage4 ,when1 during   
the throes of an eruption1 dikes such as
 we know often to penetrate the         
mountain1 are riven outward from the    
crater through the mass of the cone1 and
 filled with lava1 the heated rock must 
often come in contact with these masses 
of buried water4 ,the result of this    
would inevitably be the local generation
 of steam at a high temperature1 which  
would force its way out in a brief but  
vigorous eruption1 such as has been     
observed to take place when these       
peripheral volcanoes are formed4        
,sometimes it has happened that after   
the explosion the lava has found its way

 in a stream from the fissure thus      
opened4 ,that this explanation is       
sufficient is in a measure shown by     
observations on certain effects of lava 
flows from ,vesuvius4 ,the writer was   
informed by a very judicious observer1 a
 resident of ,naples1 who had interested
 himself in the phenomena of that       
volcano1 that the lava streams when they
 penetrated a cistern1 such as they     
often encounter in passing over villages
 or farmsteads1 vaporized the water1 and
 gave rise1 through the action of the   
steam1 to small temporary cones1 which1 
though generally washed away by the     
further flow of the liquid rock1 are    
essentially like those which we find on 
tna4 ,such subsidiary1 or1 as they are  
sometimes called1 parasitic cones1 are  
known about other volcanoes1 but nowhere
 are they so characteristic as on the   
flanks of that wonderful volcano4  ,a   
very conspicuous feature in the tnean   
cone consists of a great valley known as
 the ,val del ,bove1 or ,bull ,hollow1  

which extends from the base of the      
modern and ever-changeable cinder cone  
down the flanks of the older structure  
to near its base4 ,this valley has steep
 sides1 in places a thousand or more    
feet high1 and has evidently been formed
 by the down-settling of portions of the
 cone which were left without support by
 the withdrawal from beneath them of    
materials cast forth in a time of       
explosion4 ,in an eruption this         
remarkable valley was the seat of a vast
 water flood1 the fluid being cast forth
 from the crater at the beginning of the
 explosion4 ,in the mouths of this and  
other volcanoes1 after a long period of 
repose1 great quantities of water1      
gathering from rains or condensed from  
the steam which slowly escapes from     
these openings1 often pours like a flood
 down the sides of the mountains4 ,in   
the great eruption of ,galongoon1 in    
,java1 such a mass of water1 cast forth 
by a terrific explosion1 mingled with   
ashes1 so that the mass formed a thick  

mud1 was shot forth with such energy    
that it ravaged an area nearly eighty   
miles in diameter1 destroying the       
forests and their wild inhabitants1 as  
well as the people who dwelt within the 
range of the amazing disaster4 ,so      
powerfully was this water driven from   
the crater that the districts           
immediately at the base of the cone were
 in a manner overshot by the vast       
stream1 and escaped with relatively     
little injury4  ,when it comes forth    
from the base of the cinder cone1 or    
from one of the small peripheral        
craters1 the lava stream usually appears
 to be white hot1 and to flow with      
almost the ease of water4 ,it does not  
really have that measure of fluidity2   
its condition is rather that of thin    
paste2 but the great weight of the      
material--near two and a half times that
 of water--causes the movement down the 
slope to be speedy4 ,the central portion
 of the lava stream long retains its    
high temperature2 but the surface1      

cooling1 is first converted into a tough
 sheet1 which1 though it may bend1 can  
hardly be said to flow4 ,further        
hardening converts these outlying       
portions of the current into hard1      
glassy stone1 which is broken into      
fragments in a way resembling the ice on
 the surface of a river4 ,it thus comes 
about that the advancing front of the   
lava stream becomes covered1 and its    
motion hindered by the frozen rock1     
until the rate of ongoing may not exceed
 a few feet an hour1 and the appearance 
is that of a heap of stone slowly       
rolling down a slope4 ,now and then a   
crevice is formed1 through which a thin 
stream of liquid lava pours forth1 but  
the material1 having already parted with
 much of its heat1 rapidly cools1 and in
 turn becomes covered with the coating  
of frozen fragments4 ,in this state of  
the stream the lava flow stands on all  
sides high above the slope which it is  
traversing2 it is1 in fact1 walled in by
 its own solidified parts1 though it is 

urged forward by the contribution which 
continues to flow in the under arches4  
,in this state of the movement trifling 
accidents1 or even human interference1  
may direct the current this way or that4
  ,some of the most interesting chapters
 in the history of tna relate to the    
efforts of the people to turn these     
slow-moving streams so that their       
torrents might flow into wilderness     
places rather than over the fields and  
towns4 ,in the great flow of #affi1     
which menaced the city of ,catania1 a   
large place on the seashore to the      
southeast of the cone1 a public-spirited
 citizen1 ,seor ,papallardo1 protecting 
himself and his servants with clothing  
made of hides1 and with large shields1  
set forth armed with great hooks with   
the purpose of diverting the course of  
the lava mass4 ,he succeeded in pulling 
away the stones on the flank of the     
stream1 so that a flow of the molten    
rock was turned in another direction4   
,the expedient would probably have been 

successful if he had been allowed to    
continue his labours2 but the           
inhabitants of a neighbouring village1  
which was threatened by the off-shooting
 current which ,papallardo had created1 
took up arms and drove him and his      
retainers away4 ,the flow continued     
until it reached ,catania4 ,the people  
made haste to build the city walls on   
the side of danger higher than it was   
before1 but the tide mounted over its   
summit4  ,although the lavas which come 
forth from the volcano evidently have a 
high temperature1 their capacity for    
melting other rocks is relatively small4
 ,they scour these rocks1 because of    
their weight1 even more energetically   
than do powerful torrents of water1 but 
they are relatively ineffective in      
melting stone4 ,on tna and elsewhere we 
may often observe lavas which have      
flowed through forests4 ,when the tide  
of molten rock has passed by1 the trees 
may be found charred but not entirely   
burned away2 even stems a few inches in 

diameter retain strength enough to      
uphold considerable fringes and clots of
 the lava which has clung to them4      
,these facts bear out the conclusion    
that the fluidity of the heated stone   
depends in considerable measure on the  
water which is contained1 either in its 
fluid or vaporous state1 between the    
particles of the material4  ,if we      
consider the ,italian volcanoes as a    
whole1 we find that they lie in a long1 
discontinuous line extending from the   
northern part of the valley of the ,po1 
within sight of the ,alps1 to tna1 and  
in subterranean cones perhaps to the    
northern coast of ,africa4 ,at the      
northern end of the line we have a      
beautiful group of extinct volcanoes1   
known as the ,eugean ,mountains4 ,thence
 southward to southern ,tuscany craters 
are wanting1 but there is evidence of   
fissures in the earth which give forth  
thermal waters4 ,from southern ,tuscany 
southward through ,rome to ,naples there
 are many extinct craters1 none of which

 have been active in the historic       
period4 ,from ,naples southward the     
cones of this system1 about a dozen in  
number1 are on islands or close to the  
margin of the sea4 ,it is a noteworthy  
fact that the greater part of these     
shore or insular vents have been active 
since the dawn of history2 several of   
them frequently and furiously so1 while 
none of those occupying an inland       
position have been the seat of          
explosions4 ,this is a striking instance
 going to show the relation of these    
processes to conditions which are       
brought about on the sea bottom4  tna   
is1 as we have noticed1 a much more     
powerful volcano than ,vesuvius4 ,its   
outbreaks are more vigorous1 its        
emanations vastly greater in volume1 and
 the mass of its constructions many     
times as great as those accumulated in  
any other ,european cone4 ,there are1   
however1 a number of volcanoes in the   
world which in certain features surpass 
tna as much as that crater does         

,vesuvius4 ,of these we shall consider  
but two--,skaptar ,jokul1 of ,iceland1  
remarkable for the volume of its lava   
flow1 and ,krakatoa1 an island volcano  
between ,java and ,sumatra1 which was   
the seat of the greatest explosion of   
which we have any record4  ,the whole of
 ,iceland may be regarded as a volcanic 
mass composed mainly of lavas and ashes 
which have been thrown up by a group of 
volcanoes lying near the northern end of
 the long igneous axis which extends    
through the centre of the ,atlantic4    
,the island has been the seat of        
numerous eruptions2 in fact1 since its  
settlement by the ,northmen in #ajgj its
 sturdy inhabitants have been almost as 
much distressed by the calamities which 
have come from the internal heat as they
 have been by the enduring external     
cold4 ,they have1 indeed1 been between  
frost and fire4 ,the greatest recorded  
eruption of ,iceland occurred in #aghc1 
when the volcano of ,skaptar1 near the  
southern border of the island1 poured   

forth1 first1 a vast discharge of dust  
and ashes1 and afterward in the languid 
state of eruption inundated a series of 
valleys with the greatest lava flow of  
which we have any written record4 ,the  
dust poured forth into the upper air1   
being finely divided and in enormous    
quantity1 floated in the air for months1
 giving a dusky hue to the skies of     
,europe1 which led the common people and
 many of the learned to fear that the   
wrath of ,god was upon them1 and that   
the day of judgment was at hand4 ,even  
the poet ,cowper1 a man of high culture 
and education1 shared in this           
unreasonable view4  ,the lava flow in   
this eruption filled one of the         
considerable valleys of the island1     
drying up the river1 and inundating the 
plains on either side4 ,estimates which 
have been made as to the volume of this 
flow appear to indicate that it may have
 amounted to more than the bulk of the  
,mont ,blanc4  ,this great eruption1 by 
the direct effect of the calamity1 and  

by the famine due to the ravaging of the
 fields and the frightening of the fish 
from the shores which it induced1       
destroyed nearly one fifth of the       
,icelandic people4 ,it is1 in fact1 to  
be remembered as one of the three or    
four most calamitous eruptions of which 
we have any account1 and1 from the point
 of view of lava flow1 the greatest in  
history4  ,just a hundred years after   
the great ,skaptar eruption1 which      
darkened the skies of ,europe1 the      
island of ,krakatoa1 an isle formed by a
 small volcano in the straits of ,java1 
was the seat of a vapour explosion which
 from its intensity is not only         
unparalleled1 but almost unapproached in
 all accounts of such disturbances4     
,krakatoa had long been recognised as a 
volcanic isle2 it is doubtful1 however1 
if it had ever been seen in eruption    
during the three centuries or more since
 ,european ships began to sail by it    
until the month of ,may of the year     
above mentioned4 ,then an outbreak of   

what may be called ordinary violence    
took place1 which after a few days so   
far ceased that observers landed and    
took account of the changes which the   
convulsion had brought about4 ,for about
 three months there were no further     
signs of activity1 but on the #bith of  
,august a succession of vast explosions 
took place1 which blew away a great part
 of the island1 forming in its place a  
submarine crater two or three miles in  
diameter1 creating world-wide           
disturbances of sea and air4 ,the sounds
 of the outbreak were heard at a        
distance of sixteen hundred miles away4 
,the waves of the air attendant on the  
explosion ran round the earth at least  
once1 as was distinctly indicated by the
 self-recording barometers2 it is       
possible1 indeed1 that1 crossing each   
other in their east and west courses1   
these atmospheric tides twice girdled   
the sphere4 ,in effect1 the air over the
 crater was heaved up to the height of  
some tens of thousands of feet1 and     

thence rolled off in great circular     
waves1 such as may be observed in a pan 
of milk when a sharp blow pushes the    
bottom upward4  ,the violent stroke     
delivered to the waters of the sea      
created a vast wave1 which in the region
 where it originated rolled upon the    
shores with a surf wall fifty or more   
feet high4 ,in a few minutes about      
thirty thousand people were overwhelmed4
 ,the wave rolled on beyond its         
destructive limits much in the manner of
 the tide2 its influence was felt in a  
sharp rise and fall of the waters as far
 as the ,pacific coast of ,north        
,america1 and was indicated by the tide 
gauges in the ,atlantic as far north as 
the coast of ,europe4  ,owing to the    
violence of the eruption1 ,krakatoa     
poured forth no lava1 but the dust and  
ashes which ascended into the air--or1  
in other words1 the finely divided lava 
which escaped into the                  
atmosphere--probably amounted in bulk to
 more than twenty cubic miles4 ,the     

coarser part of this material1 including
 much pumice1 fell upon the seas in the 
vicinity1 where1 owing to its lightness1
 it was free to drift in the marine     
currents far and wide throughout the    
oceanic realm4 ,the finer particles1    
thrown high into the air1 perhaps to the
 height of nearly a hundred thousand    
feet--certainly to the elevation of more
 than half this amount--drifted far and 
wide in the atmosphere1 so that for     
years the air of all regions was clouded
 by it1 the sunrise and sunset having a 
peculiar red glow1 which the dust       
particles produce by the light which    
they reflect4 ,in this period1 at all   
times when the day was clear1 the sun   
appeared to be surrounded by a dusky    
halo4 ,in time the greater part of this 
dust was drawn down by gravity1 some    
portion of it probably falling on every 
square foot of the earth4 ,since the    
disappearance of the characteristic     
phenomena which it produced in the      
atmosphere1 ,european observers have    

noted the existence of faint clouds     
lying in the upper part of the air at   
the height of a hundred miles or more   
above the surface4 ,these clouds1 which 
were at first distinctly visible in the 
earliest stage of dawn and in the latest
 period of the sunset glow1 seemed to be
 in rapid motion to the eastward1 and to
 be mounting higher above the earth4 ,it
 has been not unreasonably supposed that
 these shining clouds represent portions
 of the finest dust from ,krakatoa1     
which has been thrown so far above the  
earth's attraction that it is separating
 itself from the sphere4 ,if this view  
be correct1 it seems likely that we may 
look to great volcanic explosions as a  
source whence the dustlike particles    
which people the celestial spaces may   
have come4 ,they may1 in a word1 be due 
to volcanic explosions occurring on this
 and other celestial spheres4  ,the     
question suggested above as to the      
possibility of volcanic ejections       
throwing matter from the earth beyond   

the control of its gravitative energy is
 one of great scientific interest4      
,computations 7not altogether           
trustworthy7 show that a body leaving   
the earth's surface under the conditions
 of a cannon ball fired vertically      
upward would have to possess a velocity 
at the start of at least seven miles a  
second in order to go free into space4  
,it would at first sight seem that we   
should be able to reckon whether        
volcanoes can propel earth matter upward
 with this speed4 ,in fact1 however1    
sufficient data are not obtainable2 we  
only know in a general way that the     
column of vapour rises to the height of 
thirty or forty thousand feet1 and this 
in eruptions of no great magnitude4 ,in 
an accident such as that at ,krakatoa1  
even if an observer were near enough to 
see clearly what was going on1 the      
chance of his surviving the disturbance 
would be small4 ,moreover1 the ascending
 vapours1 owing to their expansion of   
the steam in the column1 begin to fly   

out sideways on its periphery1 so that  
the upper part of the central section in
 the discharge is not visible from the  
earth4  ,it is in the central section of
 the uprushing mass1 if anywhere1 that  
the dust might attain the height        
necessary to put it beyond the earth's  
attraction1 bringing it fairly into the 
realm of the solar system1 or to the    
position where its own motion and the   
attraction of the other spheres would   
give it an independent orbital movement 
about the sun1 or perhaps about the     
earth4 ,we can only say that            
observations on the height of volcanic  
ejections are extremely desirable2 they 
can probably only be made from a        
balloon4 ,an ascension thus made beyond 
the cloud disk which the eruption       
produces might bring the observer where 
he could discern enough to determine the
 matter4 ,although the movements of the 
rocky particles could not be observed1  
the colour which they would give to the 
heavens might tell the story which we   

wish to know4 ,there is evidence that   
large masses of stone hurled up by      
volcanic eruption have fallen seven     
miles from the base of the cone4        
,assuming that the masses went straight 
upward at the beginning of their ascent1
 and that they were afterward borne     
outwardly by the expansion of the       
column1 computations which have a       
general but no absolute value appear to 
indicate that the masses attained a     
height of from thirty to fifty miles1   
and had an initial velocity which1 if   
doubled1 might have carried them into   
space4  ,last of all1 we shall note the 
conditions which attend the eruptions of
 submarine volcanoes4 ,such explosions  
have been observed in but a few         
instances1 and only in those cases where
 there is reason to believe that the    
crater at the time of its explosion had 
attained to within a few hundred feet of
 the sea level4 ,in these cases the     
ejections1 never as yet observed in the 
state of lava1 but in the condition of  

dust and pumice1 have occasionally      
formed a low island1 which has shortly  
been washed away by the waves4 ,knowing 
as we do that volcanoes abound on the   
sea floor1 the question why we do not   
oftener see their explosions disturbing 
the surface of the waters is very       
interesting1 but not as yet clearly     
explicable4 ,it is possible1 however1   
that a volcanic discharge taking place  
at the depth of several thousand feet   
below the surface of the water would not
 be able to blow the fluid aside so as  
to open a pipe to the surface1 but would
 expend its energy in a hidden manner   
near the ocean floor4 ,the vapours would
 have to expand gradually1 as they do in
 passing up through the rock pipe of a  
volcano1 and in their slow upward       
passage might be absorbed by the water4 
,the solid materials thrown forth would 
in this case necessarily fall close     
about the vent1 and create a very steep 
cone1 such1 indeed1 as we find indicated
 by the soundings off certain volcanic  

islands which appear only recently to   
have overtopped the level of the waters4
  ,as will be seen1 though inadequately 
from the diagrams of ,vesuvius1 volcanic
 cones have a regularity and symmetry of
 form far exceeding that afforded by the
 outlines of any other of the earth's   
features4 ,where1 as is generally the   
case1 the shape of the cone is          
determined by the distribution of the   
falling cinders or divided lava which   
constitutes the mass of most cones1 the 
slope is in general that known as a     
catenary curve--i4e41 the line formed by
 a chain hanging between two points at  
some distance from the vertical4 ,it is 
interesting to note that this graceful  
outline is a reflection or consequence  
of the curve described by the uprushing 
vapour4 ,the expansion in the ascending 
column causes it to enlarge at a        
somewhat steadfast rate1 while the speed
 of the ascent is ever diminishing4     
,precisely the same action can be seen  
in the like rush of steam and other     

gases and vapours from the cannon's     
mouth2 only in the case of the gun1 even
 of the greatest size1 we can not trace 
the movement for more than a few hundred
 feet4 ,in this column of ejection the  
outward movement from the centre carries
 the bits of lava outwardly from the    
centre of the shaft1 so that when they  
lose their ascending velocity they are  
drawn downward upon the flanks of the   
cone1 the amount falling upon each part 
of that surface being in a general way  
proportional to the thickness of the    
vaporous mass from which they descend4  
,the result is1 that the thickest part  
of the ash heap is formed on the upper  
part of the crater1 from which point the
 deposit fades away in depth in every   
direction4 ,in a certain measure the    
concentration toward the centre of the  
cone is brought about by the draught of 
air which moves in toward the ascending 
column4  ,although1 in general1         
ejections of volcanic matter take place 
through cones1 that being the inevitable

 form produced by the escaping steam1   
very extensive outpourings of lava1     
ejections which in mass probably far    
exceed those thrown forth through       
ordinary craters1 are occasionally      
poured out through fissures in the      
earth's crust4 ,thus in ,oregon1 ,idaho1
 and ,washington1 in eastern ,europe1 in
 southern ,india1 and at some other     
points1 vast flows1 which apparently    
took place from fissures1 have inundated
 great realms with lava ejections4 ,the 
conditions which appear to bring about  
these fissure eruptions of lava are not 
yet well understood4 ,a provisional and 
very probable account of the action can 
be had in the hypothesis which will now 
be set forth4  ,where any region has    
been for a long time the seat of        
volcanic action1 it is probable that a  
large amount of rock in a more or less  
fluid condition exists beneath its      
surface4 ,although the outrushing steam 
ejects much of this molten material1    
there are reasons to suppose that a yet 

greater part lies dormant in the        
underground spaces4 ,thus in the case of
 tna we have seen that1 though some     
thousands of miles of rock matter have  
come forth1 the base of the cone has    
been uplifted1 probably by the moving to
 that region of more or less fluid rock4
 ,if now a region thus underlaid by what
 we may call incipient lavas is         
subjected to the peculiar compressive   
actions which lead to mountain-building1
 we should naturally expect that such   
soft material would be poured forth1    
possibly in vast quantities through     
fault fissures1 which are so readily    
formed in all kinds of rock when subject
 to irregular and powerful strains1 such
 as are necessarily brought about when  
rocks are moved in mountain-making4 ,the
 great eruptions which formed the       
volcanic table-lands on the west coast  
of ,north ,america appear to have owed  
the extrusion of their materials to     
mountain-building actions4 ,this seems  
to have been the case also in some of   

those smaller areas where fissure flows 
occur in ,europe4 ,it is likely that    
this action will explain the greater    
part of these massive eruptions4  ,it   
need not be supposed that the rock      
beneath these countries1 which when     
forced out became lava1 was necessarily 
in the state of perfect fluidity before 
it was forced through the fissures4     
,situated at great depth in the earth1  
it was under a pressure so great that   
its particles may have been so brought  
together that the material was          
essentially solid1 though free to move  
under the great strains which affected  
it1 and acquiring temperature along with
 the fluidity which heat induces as it  
was forced along by the                 
mountain-building pressure4 ,as an      
illustration of how materials may become
 highly heated when forced to move      
particle on particle1 it may be well to 
cite the case in which the iron         
stringpiece on top of a wooden dam near 
,holyoke1 ,mass41 was affected when the 

barrier went away in a flood4 ,the iron 
stringer1 being very well put together1 
was1 it is said1 drawn out by the strain
 until it became sensibly reddened by   
the motion of its particles1 and finally
 fell hissing into the waters below4 ,a 
like heating is observable when metal is
 drawn out in making wire4 ,thus a mass 
of imperfectly fluid rock might in a    
forced journey of a few miles acquire a 
decided increase of temperature4        
,although the most striking volcanic    
action--all such phenomena1 indeed1 as  
commonly receives the name--is exhibited
 finally on the earth's surface1 a great
 deal of work which belongs in the same 
group of geological actions is          
altogether confined to the deep-lying   
rock1 and leads to the formation of     
dikes which penetrate the strata1 but do
 not rise to the open air4 ,we have     
already noted the fact that dikes abound
 in the deeper parts of volcanic cones1 
though the fissures into which they find
 their way are seldom riven up to the   

surface4 ,in the same way beneath the   
ground in non-volcanic countries we may 
discover at a great depth in the older1 
much-changed rock a vast number of these
 crevices1 varying from a few inches to 
a hundred feet or more in width1 which  
have been filled with lavas1 the rock   
once molten having afterward cooled4 ,in
 most cases these dikes are disclosed to
 us through the down-wearing of the     
earth that has removed the beds into    
which the dikes did not penetrate1 thus 
disclosing the realm in which the       
disturbances took place4  ,where1 as is 
occasionally the case in deep mines1 or 
on some bare rocky cliff of great       
height1 we can trace a dike in its      
upward course through a long distance1  
we find that we can never distinctly    
discover the lower point of its         
extension4 ,no one has ever seen in a   
clear way the point of origin of such an
 injection4 ,we can1 however1 often     
follow it upward to the place where     
there was no longer a rift into which it

 could enter4 ,in its upward path the   
molten matter appears generally to have 
followed some previously existing       
fracture1 a joint plane or a fault1     
which generally runs through the rocks  
on those planes4 ,we can observe        
evidence that the material was in the   
state of igneous fluidity by the fact   
that it has baked the country rocks on  
either side of the fissure1 the amount  
of baking being in proportion to the    
width of the dike1 and thus to the      
amount of heat which it could give      
forth4 ,a dike six inches in diameter   
will sometimes barely sear its walls1   
while one a hundred feet in width will  
often alter the strata for a great      
distance on either side4 ,in some       
instances1 as in the coal beds near     
,richmond1 ,va41 dikes occasionally cut 
through beds of bituminous coal4 ,in    
these cases we find that the coal has   
been converted into coke for many feet  
either side of a considerable injection4
 ,the fact that the dike material was   

molten is still further shown by the    
occurrence in it of fragments which it  
has taken up from the walls1 and which  
may have been partly melted1 and in most
 cases have clearly been much heated4   
,where dikes extend up through          
stratified beds which are separated from
 each other by distinct layers1 along   
which the rock is not firmly bound      
together1 it now and then happens1 as   
noted by ,mr4 ,g4,k4 ,gilbert1 of the   
,united ,states ,geological ,survey1    
that the lava has forced its way        
horizontally between these layers1      
gradually uplifting the overlying mass1 
which it did not break through1 into a  
dome-shaped elevation4 ,these side flows
 from dikes are termed laccolites1 a    
word which signifies the pool-like      
nature of the stony mass which they form
 between the strata4  ,in many regions1 
where the earth has worn down so as to  
reveal the zone of dikes which was      
formed at a great depth1 the surface of 
the country is fairly laced with these  

intrusions4 ,thus on ,cape ,ann1 a rocky
 isle on the east coast of              
,massachusetts1 having an area of about 
twenty square miles1 the writer1 with   
the assistance of his colleague1 ,prof4 
,r4,s4 ,tarr1 found about four hundred  
distinct dikes exhibited on the shore   
line where the rocks had been swept bare
 by the waves4 ,if the census of these  
intrusions could have been extended over
 the whole island1 it would probably    
have appeared that the total number     
exceeded five thousand4 ,in other       
regions square miles can be found where 
the dikes intercepted by the surface    
occupy an aggregate area greater than   
that of the rocks into which they have  
been intruded4  ,now and then1 but      
rarely1 the student of dikes finds one  
where the bordering walls1 in place of  
having the clean-cut appearance which   
they usually exhibit1 has its sides     
greatly worn away and much melted1 as if
 by the long-continued passage of the   
igneous fluid through the crevice4 ,such

 dikes are usually very wide1 and are   
probably the paths through which lavas  
found their way to the surface of the   
earth1 pouring forth in a volcanic      
eruption4 ,in some cases we can trace   
their relation to ancient volcanic cones
 which have worn down in all their part 
which were made up of incoherent        
materials1 so that there remains only   
the central pipe1 which has been        
preserved from decay by the coherent    
character of the lava which filled it4  
,the hypothesis that dikes are driven   
upward into strata by the pressure of   
the beds which overlie materials hot and
 soft enough to be put in motion when a 
fissure enters them1 and that their     
movement upward through the crevice is  
accounted for by this pressure1 makes   
certain features of these intrusions    
comprehensible4 ,seeing that very long1 
slender dikes are found penetrating the 
rock1 which could not have had a high   
temperature1 it becomes difficult to    
understand how the lava could have      

maintained its fluidity2 but on the     
supposition that it was impelled forward
 by a strong pressure1 and that the     
energy thus transmitted through it was  
converted into heat1 we discover a means
 whereby it could have been retained in 
the liquid condition1 even when forced  
for long distances through very narrow  
channels4 ,moreover1 this explanation   
accounts for the fact which has long    
remained unexplained that dikes1 except 
those formed about volcanic craters1    
rarely1 if ever1 rise to the surface4   
,the materials contained in dikes differ
 exceedingly in their chemical and      
mineral character4 ,these variations are
 due to the differences in ,nature of   
the deposits whence they come1 and also 
in a measure to exchanges which take    
place between their own substance and   
that of the rocks between which they are
 deposited4 ,this process often has     
importance of an economic kind1 for it  
not infrequently leads to the formation 
of metalliferous veins or other         

aggregations of ores1 either in the dike
 itself or in the country rock4 ,the way
 in which this is brought about may be  
easily understood by a familiar example4
 ,if flesh be placed in water which has 
the same temperature1 no exchange of    
materials will take place2 but if the   
water be heated1 a circulation will be  
set up1 which in time will bring a large
 part of the soluble matter into the    
surrounding water4 ,this movement is    
primarily dependent on differences of   
temperature1 and consequently           
differences in the quantity of soluble  
substances which the water seeks to take
 up4 ,when a dike is injected into      
cooler rocks1 such a slow circulation is
 induced4 ,the water contained in the   
interstices of the stone becomes charged
 with mineral materials1 if such exist  
in positions where it can obtain        
possession of them1 and as cooling goes 
on1 these dissolved materials are       
deposited in the manner of veins4 ,these
 veins are generally laid down on the   

planes of contact between the two kinds 
of stone1 but they may be formed in any 
other cavities which exist in the       
neighbourhood4 ,the formation of such   
veins is often aided by the considerable
 shrinkage of the lava in the dike1     
which1 when it cools1 tends to lose     
about fifteen per cent of its volume1   
and is thus likely to leave a crevice   
next the boundary walls4 ,ores thus     
formed afford some of the commonest and 
often the richest mineral deposits4 ,at 
,leadville1 in ,colorado1 the great     
silver-bearing lodes probably were      
produced in this manner1 wherein lavas1 
either those of dikes or those which    
flowed in the open air1 have come in    
contact with limestones4 ,the mineral   
materials originally in the once molten 
rock or in the limy beds was1 we        
believe1 laid down on ancient sea floors
 in the remains of organic forms1 which 
for their particular uses took the      
materials from the old sea water4 ,the  
vein-making action has served to        

assemble these scattered bits of metal  
into the aggregation which constitutes a
 workable deposit4 ,in time1 as the     
rocks wear down1 the materials of the   
veins are again taken into solution and 
returned to the sea1 thence perhaps to  
tread again the cycle of change4  ,in   
certain dikes1 and sometimes also1      
perhaps1 in lavas known as basalts1     
which have flowed on the surface1 the   
rock when cooling1 from the shrinkage   
which then occurs1 has broken in a very 
regular way1 forming hexagonal columns  
which are more or less divided on their 
length by joints4 ,when worn away by the
 agencies of decay1 especially where the
 material forms steep cliffs1 a highly  
artificial effect is produced1 which is 
often compared1 where cut at right      
angles to the columns1 to pavements1 or1
 where the division is parallel to the  
columns1 to the pipes of an organ4      
,what we know of dikes inclines us to   
the opinion that as a whole they        
represent movements of softened rock    

where the motion-compelling agent is not
 mainly the expansion of the contained  
water which gives rise to volcanic      
ejection1 but rather in large part due  
to the weight of superincumbent strata  
setting in motion materials which were  
somewhat softened1 and which tended to  
creep1 as do the clays in deep coal     
mines4 ,it is evident1 however2 it is1  
moreover1 quite natural1 that dike work 
is somewhat mingled with that produced  
by the volcanic forces2 but while the   
line between the two actions is not     
sharp1 the discrimination is important1 
and occurs with a distinctness rather   
unusual on the boundary line between two
 adjacent fields of phenomena4          
99       99       99       99       99  
,we have now to consider the general    
effects of the earth's interior heat so 
far as that body of temperature tends to
 drive materials from the depths of the 
earth to the surface4 ,this group of    
influences is one of the most important 
which operates on our sphere2 as we     

shall shortly see1 without such action  
the earth would in time become an unfit 
theatre for the development of organic  
life4 ,to perceive the effect of these  
movements1 we must first note that in   
the great rock-constructing realm of the
 seas organic life is constantly        
extracting from the water substances1   
such as lime1 potash1 soda1 and a host  
of other substances necessary for the   
maintenance of high-grade organisms1    
depositing these materials in the       
growing strata4 ,into these beds1 which 
are buried as fast as they form1 goes   
not only these earthy materials1 but a  
great store of the sea water as well4   
,the result would be in course of time a
 complete withdrawal into the depths of 
the earth of those substances which play
 a necessary part in organic            
development4 ,the earth would become    
more or less completely waterless on its
 surface1 and the rocks exposed to view 
would be composed mainly of silica1 the 
material which to a great extent resists

 solution1 and therefore avoids the     
dissolving which overtakes most other   
kinds of rocks4 ,here comes in the      
machinery of the hot springs1 the dikes1
 and the volcanoes4 ,these agents1      
operating under the influence of the    
internal heat of the earth1 are         
constantly engaged in bearing the earthy
 matter1 particularly its precious more 
solvent parts1 back to the surface4 ,the
 hot springs and volcanoes work swiftly 
and directly1 and return the water1 the 
carbon dioxide1 and a host of other     
vaporizable and soluble and fusible     
substances to the realm of solar        
activity1 to the living surface zone of 
the earth4 ,the dikes operate less      
immediately1 but in the end to the same 
effect4 ,they lift their materials miles
 above the level where they were        
originally laid1 probably from a zone   
which is rarely if ever exposed to view1
 placing them near the surface1 where   
the erosive agents can readily find     
access to them4  ,of the three agents   

which serve to export earth materials   
from its depths1 volcanoes are doubtless
 the most important4 ,they send forth   
the greater part of the water which is  
expelled from the rocks4 ,various       
computations which the writer has made  
indicate that an ordinary volcano1 such 
as tna1 in times of most intense        
explosion1 may send forth in the form of
 steam one fourth of a cubic mile or    
more of water during each day of its    
discharge1 and in a single great        
eruption may pour forth several times   
this quantity4 ,in its history tna has  
probably returned to the atmosphere some
 hundred cubic miles of water which but 
for the process would have remained     
permanently locked up in its rock       
prison4  ,the ejection of rock material1
 though probably on the average less in 
quantity than the water which escapes1  
is also of noteworthy importance4 ,the  
volcanoes of ,java and the adjacent     
isles have1 during the last hundred and 
twenty years1 delivered to the seas more

 earth material than has been carried   
into those basins by the great rivers4  
,if we could take account of all the    
volcanic ejections which have occurred  
in this time1 we should doubtless find  
that the sum of the materials thus cast 
forth into the oceans was several times 
as great as that which was delivered    
from the lands by all the superficial   
agents which wear them away4 ,moreover1 
while the material from the land1 except
 the small part which is in a state of  
complete solution1 all falls close to   
the shore1 the volcanic waste1 because  
of its fine division or because of the  
blebs of air which its masses contain1  
may float for many years before it finds
 its way to the bottom1 it may be at the
 antipodes of the point at which it came
 from the earth4 ,while thus journeying 
through the sea the rock matter from the
 volcanoes is apt to become dissolved in
 water2 it is1 indeed1 doubtful if any  
considerable part of that which enters  
the ocean goes by gravitation to its    

floor4 ,the greater portion probably    
enters the state of solution and makes  
its way thence through the bodies of    
plants and animals again into the       
ponderable state4  ,if an observer could
 view the earth from the surface of the 
moon1 he would probably each day behold 
one of these storms which the volcanoes 
send forth4 ,in the fortnight of        
darkness1 even with the naked eye1 it   
would probably be possible to discern at
 any time several eruptions1 some of    
which would indicate that the earth's   
surface was ravaged by great            
catastrophes4 ,the nearer view of these 
actions shows us that although locally  
and in small measure they are harmful to
 the life of the earth1 they are in a   
large way beneficent4                   
,,chapter ,,viii4                       
,,the ,,soil4   ,the frequent mention   
which it has been necessary to make of  
soil phenomena in the preceding chapters
 shows how intimately this feature in   
the structure of the earth is blended   

with all the elements of its physical   
history4 ,it is now necessary for us to 
take up the phenomena of soils in a     
consecutive manner4  ,the study of any  
considerable river basin enables us to  
trace the more important steps which    
lead to the destructure and renovation  
of the earth's detrital coating4 ,in    
such an interpretation we note that     
everywhere the rocks which were built on
 the sea bottom1 and more or less made  
over in the great laboratory of the     
earth's interior1 are at the surface1   
when exposed to the conditions of the   
atmosphere1 in process of being taken to
 pieces and returned to the sea4 ,this  
action goes on everywhere2 every drop of
 rain helps it4 ,it is aided by frost1  
or even by the changes of expansion and 
contraction which occur in the rocks    
from variations of heat4 ,the result is 
that1 except where the slopes are steep1
 the surface is quickly covered with a  
layer of fragments1 all of which are in 
the process of decay1 and ready to      

afford some food to plants4 ,even where 
the rock appears bare1 it is generally  
covered with lichens1 which1 adhering to
 it1 obtain a share of nutriment from   
the decayed material which they help to 
hold on the slope4 ,when they have      
retained a thin sheet of the dbris1     
mosses and small flowering plants help  
the work of retaining the detritus4     
,soon the strong-rooted bushes and trees
 win a foothold1 and by sending their   
rootlets1 which are at first small but  
rapidly enlarge1 into the crevices1 they
 hasten the disruption of the stones4   
,if the construction of soil goes on    
upon a steep cliff1 the quantity        
retained on the slope may be small1 but 
at the base we find a talus1 composed of
 the fragments not held by the          
vegetation1 which gradually increases as
 the cliff wears down1 until the        
original precipice may be quite         
obliterated beneath a soil slope4 ,at   
first this process is rapid2 it becomes 
gradually slower and slower as the talus

 mounts up the cliff and as the cliff   
loses its steepness1 until finally a    
gentle slope takes the place of the     
steep4  ,from the highest points in any 
river valley to the sea level the       
broken-up rock1 which we term soil1 is  
in process of continuous motion4        
,everywhere the rain water1 flowing over
 the surface or soaking through the     
porous mass1 is conveying portions of   
the material which is taken into        
solution in a speedy manner to the sea4 
,everywhere the expansion of the soil in
 freezing1 or the movements imposed on  
it by the growth of roots1 by the       
overturning of trees1 or by the         
innumerable borings and burrowings which
 animals make in the mass1 is through   
the action of gravitation slowly working
 down the slope4 ,every little          
disturbance of the grains or fragments  
of the soil which lifts them up causes  
them when they fall to descend a little 
way farther toward the sea level4       
,working toward the streams1 the        

materials of the soil are in time       
delivered to those flowing waters1 and  
by them urged speedily1 though in most  
cases interruptedly1 toward the ocean4  
,there is another element in the        
movement of the soils which1 though less
 appreciable1 is still of great         
importance4 ,the agents of decay which  
produce and remove the detritus1 the    
chemical changes of the bed rock1 and   
the mechanical action which roots apply 
to them1 along with the solutional      
processes1 are constantly lowering the  
surface of the mass4 ,in this way we can
 often prove that a soil continuously   
existing has worked downward through    
many thousand feet of strata4 ,in this  
process of downgoing the country on     
which the layer rests may have greatly  
changed its form1 but the deposit1 under
 favourable conditions1 may continue to 
retain some trace of the materials which
 it derived from beds which have long   
since disappeared1 their position having
 been far up in the spaces now occupied 

by the air4 ,where the slopes are steep 
and streams abound1 we rarely find      
detritus which belonged in rock more    
than a hundred feet above the present   
surface of the soil4 ,where1 however1 as
 on those isolated table-lands or buttes
 which abound in certain portions of the
 ,mississippi ,valley1 as well as in    
many other countries1 we find a patch of
 soil lying on a nearly level surface1  
which for geologic ages has not felt the
 effect of streams1 we may discover1    
commingled in the dbris1 the harder     
wreckage derived from the decay of a    
thousand feet or more of vanished       
strata4  ,when we consider the effect of
 organic life on the processes which go 
on in the soil1 we first note the large 
fact that the development of all land   
vegetation depends upon the existence of
 this detritus--in a word1 on the slow  
movement of the decaying rocky matter   
from the point where it is disrupted to 
its field of rest in the depths of the  
sea4 ,the plants take their food from   

the portion of this rocky waste which is
 brought into solution by the waters    
which penetrate the mass4 ,on the plants
 the animals feed1 and so this vast     
assemblage of organisms is maintained4  
,not only does the land life maintain   
itself on the soil1 and give much to the
 sea1 but it serves in various ways to  
protect this detrital coating from too  
rapid destruction1 and to improve its   
quality4 ,to see the nature of this work
 we should visit a region where primeval
 forests still lie upon the slopes of a 
hilly region4 ,in the body of such a    
wood we find next the surface a coating 
of decayed vegetable matter1 made up of 
the falling leaves1 bark1 branches1 and 
trunks which are constantly descending  
to the earth4 ,ordinarily1 this layer is
 a foot or more in thickness2 at the top
 it is almost altogether composed of    
vegetable matter2 at the bottom it      
verges into the true soil4 ,an important
 effect of this decayed vegetation is to
 restrain the movement of the surface   

water4 ,even in the heaviest rains1     
provided the mass be not frozen1 the    
water is taken into it and delivered in 
the manner of springs to the larger     
streams4 ,we can better note the measure
 of this effect by observing the        
difference in the ground covered by this
 primeval forest and that which we find 
near by which has been converted into   
tilled fields4 ,with the same degree of 
rapidity in the flow1 the distinct      
stream channels on the tilled ground are
 likely to be from twenty to a hundred  
times in length what they are on the    
forest bed4 ,the result is that while   
the brook which drains the forested area
 maintains a tolerably constant flow of 
clean water1 the other from the tilled  
ground courses only in times of heavy   
rain1 and then is heavily charged with  
mud4 ,in the virgin conditions of the   
soil the downwear is very slow2 in its  
artificial state this wearing goes on so
 rapidly that the sloping fields are    
likely to be worn to below the soil     

level in a few score years4  ,not only  
does the natural coating of vegetation1 
such as our forests impose upon the     
country1 protect the soil from washing  
away1 but the roots of the larger plants
 are continually at work in various ways
 to increase the fertility and depth of 
the stratum4 ,in the form of slender    
fibrils these underground branches enter
 the joints and bed planes of the rock1 
and there growing they disrupt the      
materials1 giving them a larger surface 
on which decay may operate4 ,these bits1
 at first of considerable size1 are in  
turn broken up by the same action4      
,where the underlying rocks afford      
nutritious materials1 the branches of   
our tap-rooted trees sometimes find     
their way ten feet or more below the    
base of the true soil4 ,not only do they
 thus break up the stones1 but the      
nutrition which they obtain in the      
depths is brought up and deposited in   
the parts above the ground1 as well as  
in the roots which lie in the true soil1

 so that when the tree dies it becomes  
available for other plants4 ,thus in the
 forest condition of a country the      
amount of rock material contributed to  
the deposit in general so far exceeds   
that which is taken away to the rivers  
by the underground water as to insure   
the deepening of the soil bed to the    
point where only the strongest          
roots--those belonging to our tap-rooted
 trees--can penetrate through it to the 
bed rocks4  ,almost all forests are from
 time to time visited by winds which    
uproot the trees4 ,when they are thus   
rent from the earth1 the underground    
branches often form a disk containing a 
thick tangle of stones and earth1 and   
having a diameter of ten or fifteen     
feet4 ,the writer has frequently        
observed a hundred cubic feet of soil   
matter1 some of it taken from the depth 
of a yard or more1 thus uplifted into   
the air4 ,in the path of a hurricane or 
tornado we may sometimes find thousands 
of acres which have been subjected to   

this rude overturning--a natural        
ploughing4 ,as the roots rot away1 the  
dbris which they held falls outside of  
the pit1 thus forming a little hillock  
along the side of the cavity4 ,after a  
time the thrusting action of other roots
 and the slow motion of the soil down   
the slope restore the surface from its  
hillocky character to its original      
smoothness2 but in many cases the       
naturalist who has learned to discern   
with his feet may note these            
irregularities long after it has been   
recovered with the forest4  ,great as is
 the effect of plants on the soil1 that 
influence is almost equalled by the     
action of the animals which have the    
habit of entering the earth1 finding    
there a temporary abiding place4 ,the   
number of these ground forms is         
surprisingly great4 ,it includes1       
indeed1 a host of creatures which are   
efficient agents in enriching the earth4
 ,the species of earthworms1 some of    
which occupy forested districts as well 

as the fields1 have the habit of passing
 the soil material through their bodies1
 extracting from the mass such nutriment
 as it may contain4 ,in this manner the 
particles of mineral matter become      
pulverized1 and in a measure affected by
 chemical changes in the bodies of the  
creatures1 and are thus better fitted to
 afford plant food4 ,sometimes the      
amount of the earth which the creatures 
take in in moving through their burrows 
and void upon the surface is sufficient 
to form annually a layer on the surface 
of the ground having a depth of one     
twentieth of an inch or more4 ,it thus  
may well happen that the soil to the    
depth of two or three feet is completely
 overturned in the course of a few      
hundred years4 ,as the particles which  
the creatures devour are rather small1  
the tendency is to accumulate the finer 
portions of the soil near the surface of
 the earth1 where by solution they may  
contribute to the needs of the lowly    
plants4 ,it is probably due to the      

action of these creatures that small    
relics of ancient men1 such as stone    
tools1 are commonly found buried at a   
considerable depth beneath the earth1   
and rarely appear upon the surface      
except where it has been subjected to   
deep ploughing or to the action of      
running streams4  ,along with the       
earthworms1 the ants labour to overturn 
the soil2 frequently they are the more  
effective of the two agents4 ,the common
 species1 though they make no permanent 
hillocks1 have been observed by the     
writer to lay upon the surface each year
 as much as a quarter of an inch of sand
 and other fine materials which they    
have brought up from a considerable     
depth4 ,in many regions1 particularly in
 those occupied by glacial drift1 and   
pebbly alluvium along the rivers1 the   
effect of this action1 like that of     
earthworms1 is to bring to the surface  
the finer materials1 leaving the coarser
 pebbles in the depths4 ,in this way    
they have changed the superficial       

character of the soil over great areas2 
we may say1 indeed1 over a large part of
 the earth1 and this in a way which fits
 it better to serve the needs of the    
wild plants as well as the uses of the  
farmer4  ,many thousand species of      
insects1 particularly the larger        
beetles1 have the habit of passing their
 larval state in the under earth4 ,here 
they generally excavate burrows1 and    
thus in a way delve the soil4 ,as many  
of them die before reaching maturity1   
their store of organic matter is        
contributed to the mass1 and serves to  
nourish the plants4 ,if the student will
 carefully examine a section of the     
earth either in its natural or in its   
tilled state1 he will be surprised to   
find how numerous the grubs are4 ,they  
may often be found to the number of a   
score or more of each cubic foot of     
material4 ,many of the species which    
develop underground come from eggs which
 have carefully been encased in organic 
matter before their deposition in the   

earth4 ,thus some of the carrion beetles
 are in the habit of laying their eggs  
in the bodies of dead birds or field    
mice1 which they then bury to the depth 
of some inches in the earth4 ,in this   
way nearly all the small birds and      
mammals of our woods disappear from view
 in a few hours after they are dead4    
,other species make balls from the dung 
of cattle in which they lay their eggs1 
afterward rolling the little spheres1 it
 may be for hundreds of feet1 to the    
chambers in the soil which they have    
previously prepared4 ,in this way a     
great deal of animal matter is          
introduced into the earth1 and          
contributes to its fertility4  ,many of 
our small mammals have the habit of     
making their dwelling places in the     
soil4 ,some of them1 such as the moles1 
normally abide in the subterranean realm
 for all their lives4 ,others use the   
excavations as places of retreat4 ,in   
any case1 these excavations serve to    
move the particles of the soil about1   

and the materials which the animals drag
 into the earth1 as well as the         
excrement of the creatures1 act to      
enrich it4 ,this habit of taking food   
underground is not limited to the       
mammals2 it is common with the ants1 and
 even the earthworms1 as noted by       
,charles ,darwin in his wonderful essay 
on these creatures1 are accustomed to   
drag into their burrows bits of grass   
and the slender leaves of pines4 ,it is 
not known what purpose they attain by   
these actions1 but it is sufficiently   
common somewhat to affect the conditions
 of the soil4  ,the result of these     
complicated works done by animals and   
plants on the soil is that the material 
to a considerable depth are constantly  
being supplied with organic matter1     
which1 along with the mineral material1 
constitutes that part of the earth which
 can support vegetation4 ,experiment    
will readily show that neither crushed  
rock nor pure vegetable mould will of   
itself serve to maintain any but the    

lowliest vegetation4 ,it requires that  
the two materials be mixed in order that
 the earth may yield food for ordinary  
plants1 particularly for those which are
 of use to man1 as crops4 ,on this      
account all the processes above noted   
whereby the waste of plant and animal   
life is carried below the surface are of
 the utmost importance in the creation  
and preservation of the soil4 ,it has   
been found1 indeed1 in almost all cases1
 necessary for the farmer to maintain   
the fertility of his fields to plough-in
 quantities of such organic waste4 ,by  
so doing he imitates the work which is  
effected in virgin soil by natural      
action4 ,as the process is costly in    
time and material1 it is often neglected
 or imperfectly done1 with the result   
that the fields rapidly diminish in     
fertility4  ,the way in which the buried
 organic matter acts upon the soil is   
not yet thoroughly understood4 ,in part 
it accomplishes the results by the      
materials which on its decay it         

contributes to the soil in a state in   
which they may readily be dissolved and 
taken up by the roots into their sap2 in
 part1 however1 it is believed that they
 better the conditions by affording     
dwelling places for a host of lowly     
species1 such as the forms which are    
known as bacteria4 ,the organisms       
probably aid in the decomposition of the
 mineral matter1 and in the conversion  
of nitrogen1 which abounds in the air or
 the soil1 into nitrates of potash and  
soda--substances which have a very great
 value as fertilizers4 ,some effect is  
produced by the decay of the foreign    
matter brought into the soil1 which as  
it passes away leaves channels through  
which the soil water can more readily   
pass4  ,by far the most general and     
important effect arising from the decay 
of organic matter in the earth is to be 
found in the carbon dioxide which is    
formed as the oxygen of the air combines
 with the carbon which all organic      
material contains4 ,as before noted1    

water thus charged has its capacity for 
taking other substances into solution   
vastly increased1 and on this solvent   
action depends in large part the decay  
of the bed rocks and the solution of    
materials which are to be appropriated  
by the plants4  ,having now sketched the
 general conditions which lead to the   
formation of soils1 we must take account
 of certain important variations in     
their conditions due to differences in  
the ways in which they are formed and   
preserved4 ,these matters are not only  
of interest to the geologist1 but are of
 the utmost importance to the life of   
mankind1 as well as all the lower       
creatures which dwell upon the lands4   
,first1 we should note that soils are   
divisible into three great groups1      
which1 though not sharply parted from   
each other1 are sufficiently peculiar   
for the purposes of classification4     
,where the earth material has been      
derived from the rocks which nearly or  
immediately underlie it1 we have a group

 of soils which may be entitled those of
 immediate derivation--that is1 derived 
from rocks near by1 or from beds which  
once overlaid the level and have since  
been decayed away4 ,next1 we have       
alluvial soils1 those composed of       
materials which have been transported by
 streams1 commonly from a great         
distance1 and laid down on their flood  
plains4 ,third1 the soils the mineral   
matters of which have been brought into 
their position by the action of         
glaciers2 these in a way resemble those 
formed by rivers1 but the materials are 
generally imperfectly sorted1 coarse and
 fine being mingled together4 ,last of  
all1 we have the soils due to the       
accumulation of blown dust or blown     
sand1 which1 unlike the others1 occupy  
but a small part of the land surface4   
,it would be possible1 indeed1 to make  
yet another division1 including those   
areas which when emerging from the sea  
were covered with fine1 uncemented      
detritus ready at once to serve the     

purposes of a soil4 ,only here and      
there1 and but seldom1 do we find soils 
of this nature4  ,it is characteristic  
of soils belonging to the group to which
 we have given the title of immediate   
derivation that they have accumulated   
slowly1 that they move very gradually   
down the slopes on which they lie1 and  
that in all cases they represent1 with a
 part of their mass at least1 levels of 
rock which have disappeared from the    
region which they occupied4 ,the        
additions made to their mass are from   
below1 and that mass is constantly      
shrinking1 generally at a pretty rapid  
rate1 by the mineral matter which is    
dissolved and goes away with the spring 
water4 ,they also are characteristically
 thin on steep slopes1 thickening toward
 the base of the incline1 where the     
diminished grade permits the soil to    
move slowly1 and therefore to           
accumulate4  ,in alluvial soils we find 
accumulations which are characterized by
 growth on their upper surfaces1 and by 

the distant transportation of the       
materials of which they are composed4   
,in these deposits the outleaching      
removes vast amounts of the materials1  
but so long as the floods from time to  
time visit their surfaces the growth of 
the deposits is continued4 ,this growth 
rarely takes place from the waste of the
 bed rocks on which the alluvium lies4  
,it is characteristic of alluvial soils 
that they are generally made up of dbris
 derived from fields where the materials
 have undergone the change which we have
 noted in the last paragraph2 therefore 
these latter deposits have throughout   
the character which renders the mineral 
materials easily dissolved4 ,moreover1  
the mass as it is constructed is        
commonly mingled with a great deal of   
organic waste1 which serves to promote  
its fertility4 ,on these accounts       
alluvial grounds1 though they vary      
considerably in fertility1 commonly     
afford the most fruitful fields of any  
region4 ,they have1 moreover1 the signal

 advantage that they often may be       
refreshed by allowing the flood waters  
to visit them1 an action which but for  
the interference of man commonly takes  
place once each year4 ,thus in the      
valley of the ,nile there are fields    
which have been giving rich grain       
harvests probably for more than four    
thousand years1 without any other       
effective fertilizing than that derived 
from the mud of the great river4  ,the  
group of glaciated soils differs in many
 ways from either of those mentioned4   
,in it we find the mineral matter to    
have been broken up1 transported1 and   
accumulated without the influence of    
those conditions which ordinarily serve 
to mix rock dbris with organic matter   
during the process by which it is broken
 into bits4 ,when vegetation came to    
preoccupy the fields made desolate by   
glacial action1 it found in most places 
more than sufficient material to form   
soils1 but the greater part of the      
matter was in the condition of pebbles  

of very hard rock and sand grains1      
fragments of silex4 ,fortunately1 the   
broken-up state of this material1 by    
exposing a great surface of the rocky   
matter to decay1 has enabled the plants 
to convert a portion of the mass into   
earth fit for the uses of their roots4  
,but as the time which has elapsed since
 the disappearance of the glaciers is   
much less than that occupied in the     
formation of ordinary soil1 this decay  
has in most cases not yet gone very far1
 so that in a cubic foot of glaciated   
waste the amount of material available  
for plants is often only a fraction of  
that held in the soils of immediate     
derivation4  ,in the greater portion of 
the fields occupied by glacial waste the
 processes which lead to the            
introduction of organic matter into the 
earth have not gone far enough to set in
 effective work the great laboratory    
which has to operate in order to give   
fertile soil4 ,the pebbles hinder the   
penetration of the roots as well as the 

movement of insects and other animals4  
,there has not been time enough for the 
overturning of trees to bring about a   
certain admixture of vegetable matter   
with the soil--in a word1 the process of
 soil-making1 though the first          
condition1 that of broken-up rock1 has  
been accomplished1 is as yet very       
incomplete4 ,it needs1 indeed1 care in  
the introduction of organic matter for  
its completion4  ,it is characteristic  
of glacial soils that they are          
indefinitely deep4 ,this often is a     
disadvantageous feature1 for the reason 
that the soil water may pass so far down
 into the earth that the roots are often
 deprived of the moisture which they    
need1 and which in ordinary soils is    
retained near the surface by the hard   
underlayer4 ,on the other hand1 where   
the glacial waste is made up of pebbles 
formed from rocks of varied chemical    
composition1 which contain a            
considerable share of lime1 potash1     
soda1 and other substances which are    

required by plants1 the very large      
surface which they expose to decay      
provides the soil with a continuous     
enrichment4 ,in a cubic foot of pebbly  
glacial earth we often find that the    
mass offers several hundred times as    
much surface to the action of decay as  
is afforded by the underlying solid bed 
rock from which a soil of immediate     
derivation has to win its mineral       
supply4 ,where the pebbly glacial waste 
is provided with a mixture of vegetable 
matter1 the process of decay commonly   
goes forward with considerable rapidity4
 ,if the supply of such matter is large1
 such as may be produced by ploughing in
 barnyard manure or green crops1 the    
nutritive value of the earth may be     
brought to a very high point4  ,it is a 
familiar experience in regions where    
glacial soils exist that the earth      
beneath the swamps when drained is found
 to be extraordinarily well suited for  
farming purposes4 ,on inspecting the    
pebbles from such places1 we observe    

that they are remarkably decayed4 ,where
 the masses contain large quantities of 
feldspar1 as is the case in the greater 
part of our granitic and other          
crystalline rocks1 this material in its 
decomposition is converted into kaolin  
or feldspar clay1 and gives the stones a
 peculiar white appearance1 which marks 
the decomposition1 and indicates the    
process by which a great variety of     
valuable soil ingredients are brought   
into a state where they may be available
 for plants4  ,in certain parts of the  
glacial areas1 particularly in the      
region near the margin of the ice sheet1
 where the glacier remained in one      
position for a considerable time1 we    
find extensive deposits of silicious    
sand1 formed of the materials which     
settled from the under-ice stream1 near 
where they escaped from the glacial     
cavern4 ,these kames and sand plains1   
because of the silicious nature of their
 materials and the very porous nature of
 the soil which they afford1 are        

commonly sterile1 or at most render a   
profit to the tiller by dint of         
exceeding care4 ,thus in ,massachusetts1
 although the first settlers seized upon
 these grounds1 and planted their       
villages upon them because the forests  
there were scanty and the ground free   
from encumbering boulders1 were soon    
driven to betake themselves to those    
areas where the drift was less          
silicious1 and where the pebbles        
afforded a share of clay4 ,very         
extensive fields of this sandy nature in
 southeastern ,new ,england have never  
been brought under tillage4 ,thus on the
 island of ,martha's ,vineyard there is 
a connected area containing about thirty
 thousand acres which lies in a very    
favourable position for tillage1 but has
 been found substantially worthless for 
such use4 ,the farmers have found it    
more advantageous to clear away the     
boulders from the coarser drift in order
 to win soil which would give them fair 
returns4  ,those areas which are        

occupied by soil materials which have   
been brought into their position by the 
action of the wind may1 as regards their
 character1 be divided into two very    
distinct groups--the dunes and loess    
deposits4 ,in the former group1 where1  
as we have noted 7see page #abc71 the   
coarse sea sands or those from the      
shores of lakes are driven forward as a 
marching hillock1 the grains of the     
material are almost always silicious4   
,the fragments in the motion are not    
taken up into the air1 but are blown    
along the surface4 ,such dune           
accumulations afford an earth which is  
even more sterile than that of the      
glacial sand plains1 where there is     
generally a certain admixture of pebbles
 from rocks which by their decomposition
 may afford some elements of fertility4 
,fortunately for the interests of man1  
these wind-borne sands occupy but a     
small area2 in ,north ,america1 in the  
aggregate1 there probably are not more  
than one thousand square miles of such  

deposits4  ,where the rock material     
drifted by the winds is so fine that it 
may rise into the air in the form of    
dust1 the accumulations made of it      
generally afford a fertile soil1 and    
this for the reason that they are       
composed of various kinds of rock1 and  
not1 as in the case of dunes1 of nearly 
pure silica4 ,in some very rare cases1  
where the seashore is bordered by coral 
reefs1 as it is in parts of southern    
,florida1 and the strand is made up of  
limestone bits derived from the hard    
parts which the polyps secrete1 small   
dunes are made of limy material4 ,owing1
 however1 in part to the relatively     
heavy nature of this substance1 as well 
as to the rapid manner in which its     
grains become cemented together1 such   
limestone dunes never attain great size 
nor travel any distance from their point
 of origin4  ,as before noted1 dust     
accumulations form the soil in extended 
areas which lie to the leeward of great 
deserts4 ,thus a considerable part of   

western ,china and much of the ,united  
,states to the west of the ,mississippi 
is covered by these wind-blown earths4  
,wherever the rainfall is considerable  
these loess deposits have proved to have
 a high agricultural value4  ,where a   
region has an earth which has recently  
passed from beneath the sea or a great  
lake1 the surface is commonly covered by
 incoherent detritus which has escaped  
consolidation into hard rock by the fact
 that it has not been buried and thus   
brought into the laboratory of the      
earth's crust4 ,when such a region      
becomes dry land1 the materials are     
immediately ready to enter into the     
state of soil4 ,they commonly contain a 
good deal of waste derived from the     
organic life which dwelt upon the sea   
bottom and was embedded in the strata as
 they were formed4 ,where these         
accumulations are made in a lake1 the   
land vegetation at once possesses the   
field1 even a single year being         
sufficient for it to effect its         

establishment4 ,where the lands emerge  
from the sea1 it requires a few years   
for the salt water to drain away so that
 the earth can be fit for the uses of   
plants4 ,in a general way these         
sea-bottom soils resemble those formed  
in the alluvial plains4 ,they are1      
however1 commonly more sandy1 and their 
substances less penetrated by that decay
 which goes on very freely in the       
atmosphere because of the abundant      
supply of oxygen1 and but slowly on the 
sea floor4 ,moreover1 the marine        
deposits are generally made up in large 
part of silicious sand1 a material which
 is produced in large quantities by the 
disruption of the rocks along the sea   
coast4 ,the largest single field of     
these ocean-bottom soils of ,north      
,america is found in the lowland region 
of the southern ,united ,states1 a wide 
belt of country extending along the     
coast from the ,rio ,grande to ,new     
,york4 ,although the streams have       
channelled shallow valleys in the beds  

of this region1 the larger part of its  
surface still has the peculiar features 
of form and composition which were      
impressed upon it when it lay below the 
surface of the sea4  ,local variations  
in the character of the soil covering   
are exceedingly numerous1 and these     
differences of condition profoundly     
affect the estate of man4 ,we shall     
therefore consider some of the more     
important of these conditions1 with     
special reference to their origin4  ,the
 most important and distinctly marked   
variation in the fertility of soils is  
that which is produced by differences in
 the rainfall4 ,no parts of the earth   
are entirely lacking in rain1 but over  
considerable areas the precipitation    
does not exceed half a foot a year4 ,in 
such realms the soil is sterile1 and the
 natural coating of vegetation limited  
to those plants which can subsist on dew
 or which can take on an occasional     
growth at such times as moisture may    
come upon them4 ,with a slight increase 

in precipitation1 the soil rapidly      
increases in productivity1 so that we   
may say that where as much as about ten 
inches of water enters the earth during 
the summer half of the year1 it becomes 
in a considerable measure fit for       
agriculture4 ,observations indicate that
 the conditions of fertility are not    
satisfied where the rainfall is just    
sufficient to fill the pores of the     
soil2 there must be enough water        
entering the earth to bring about a     
certain amount of outflow in the form of
 springs4 ,the reason of this need      
becomes apparent when we study the      
evident features of those soils which1  
though from season to season charged    
with water1 do not yield springs1 but   
send the moisture away through the      
atmosphere4 ,wherever these conditions  
occur we observe that the soil in dry   
seasons becomes coated with a deposit of
 mineral matter1 which1 because of its  
taste1 has received the name of alkali4 
,the origin of this coating is as       

follows3 ,the pores of the soil1 charged
 from year to year with sufficient water
 to fill them1 become stored with a     
fluid which contains a very large amount
 of dissolved mineral matter--too much1 
indeed1 to permit the roots of plants1  
save a few species which have become    
accustomed to the conditions1 to do     
their appointed work4 ,in fact1 this    
water is much like that of the sea1     
which the roots of only a few of our    
higher plants can tolerate4 ,when the   
dry season comes on1 the heat of the sun
 evaporates the water at the surface1   
leaving behind a coating composed of the
 substances which the water contains4   
,the soil below acts in the manner of a 
lamp-wick to draw up fluid as rapidly as
 the heat burns it away4 ,when the soil 
water is as far as possible exhausted1  
the alkali coating may represent a      
considerable part of the soluble matter 
of the soil1 and in the next rainy      
season it may return in whole or in part
 to the under-earth1 again to be drawn  

in the manner before described to the   
upper level4 ,it is therefore only when 
a considerable share of the ground water
 goes forth to the streams in each year 
that the alkaline materials are in      
quantity kept down to the point where   
the roots of our crop-giving plants can 
make due use of the soil4 ,where1 in an 
arid region1 the ground can be watered  
from the enduring streams or from       
artificial reservoirs1 the main         
advantage arising from the process is   
commonly found in the control which it  
gives the farmer in the amount of the   
soil water4 ,he can add to the rainfall 
sufficient to take away the excess of   
mineral matter4 ,when such soils are    
first brought under tillage it is       
necessary to use a large amount of water
 from the canals1 in order to wash away 
the old store of alkali4 ,after that a  
comparatively small contribution will   
often keep the soil in excellent        
condition for agriculture4 ,it has been 
found1 however1 in the irrigated lands  

beside the ,nile that where too much    
saving is practised in the irrigation1  
the alkaline coating will appear where  
it has been unknown before1 and with it 
an unfitness of the earth to bear crops4
  ,although the crust of mineral matters
 formed in the manner above described is
 characteristic of arid countries1 and  
in general peculiar to them1 a similar  
deposit may under peculiar conditions be
 formed in regions of great rainfall4   
,thus on the eastern coast of ,new      
,england1 where the tidal marshes have  
here and there been diked from the sea  
and brought under tillage1 the dissolved
 mineral matters of the soil1 which are 
excessive in quantity1 are drawn to the 
surface1 forming a coating essentially  
like that which is so common in arid    
regions4 ,the writer has observed this  
crust on such diked lands1 having a     
thickness of an eighth of an inch4 ,in  
fact1 this alkali coating represents    
merely the extreme operation of a       
process which is going on in all soils1 

and which contributes much to their     
fertility4 ,when rain falls and passes  
downward into the earth1 it conveys the 
soluble matter to a depth below the     
surface1 often to beyond the point where
 our ordinary crop plants1 such as the  
small grains1 can have access to it1 and
 this for the reason that their roots do
 not penetrate deeply4 ,when dry weather
 comes and evaporation takes place from 
the surface1 the fluid is drawn up to   
the upper soil layer1 and there1 in     
process of evaporation1 deposits the    
dissolved materials which it contains4  
,thus the mineral matter which is fit   
for plant food is constantly set in     
motion1 and in its movement passes the  
rootlets of the plants4 ,it is probably 
on this account--at least in part--that 
very wet weather is almost as           
unfavourable to the farmer as           
exceedingly dry1 the normal alternation 
in the conditions being1 as is well     
known1 best suited to his needs4  ,so   
long as the earth is subjected to       

conditions in which the rainfall may    
bring about a variable amount of water  
in the superficial detrital layer1 we   
find normal fruitful soils1 though in   
their more arid conditions they may be  
fit for but few species of plants4      
,when1 by increasing aridity1 we pass to
 conditions where there is no tolerably 
permanent store of water in the dbris1  
the material ceases to have the         
qualities of a soil1 and becomes mere   
rock waste4 ,at the other extreme of the
 scale we pass to conditions where the  
water is steadfastly maintained in the  
interstices of the detritus1 and there  
again the characteristic of the soil and
 its fitness for the uses of land       
vegetation likewise disappear4 ,in a    
word1 true soil conditions demand the   
presence of moisture1 but that in       
insufficient quantities1 to keep the    
pores of the earth continually filled2  
where they are thus filled1 we have the 
condition of swamps4 ,between these     
extremes the level at which the water   

stands in the soil in average seasons is
 continually varying4 ,in rainy weather 
it may rise quite to the surface2 in a  
dry season it may sink far down4 ,as    
this water rises and falls1 it not only 
moves1 as before noted1 the soluble     
mineral materials1 but it draws the air 
into and expels it from the earth with  
each movement4 ,this atmospheric        
circulation of the soil1 as has been    
proved by experiment1 is of great       
importance in maintaining its fertility2
 the successive charges of air supply   
the needs of the microscopic underground
 creatures which play a large part in   
enriching the soil1 and the direct      
effect of the oxygen in promoting decay 
is likewise considerable4 ,a part of the
 work which is accomplished by          
overturning the earth in tillage        
consists in this introduction of the air
 into the pores of the soil1 where it   
serves to advance the actions which     
bring mineral matters into solution4    
,illustration3 ,mountain gorge1         

,himalayas1 ,india4 ,note the difference
 in the slope of the eroded rocks and   
the effect of erosion upon them2 also   
the talus slopes at the base of the     
cliffs which the torrent is cutting     
away4 ,on the left of the foreground    
there is a little bench showing a recent
 higher line of the water4  ,in the     
original conditions of any country which
 is the seat of considerable rainfall1  
and where the river system is not so far
 developed as to provide channels for   
the ready exit of the waters1 we        
commonly find very extensive swamps2    
these conditions of bad drainage almost 
invariably exist where a region has     
recently been elevated above the level  
of the sea1 and still retains the form  
of an irregular rolling plain common to 
sea floors1 and also in regions where   
the work done by glaciers has confused  
the drainage which the antecedent       
streams may have developed4 ,in an old1 
well-elaborated river system swamps are 
commonly absent1 or1 if they occur1 are 

due to local accidents of an unimportant
 nature4  ,for our purpose swamps may be
 divided into three groups--climbing    
bogs1 lake bogs1 and marine marshes4    
,the first two of these groups depend on
 the movements of the rain water over   
the land2 the third on the action of the
 tides4 ,beginning our account with the 
first and most exceptional of these     
groups1 we note the following features  
in their interesting history3  ,wherever
 in a humid region1 on a gentle         
slope--say with an inclination not      
exceeding ten feet to the mile--the soil
 is possessed by any species of plants  
whose stems grow closely together1 so   
that from their decayed parts a         
spongelike mass is produced1 we have the
 conditions which favour the development
 of climbing bogs4 ,beginning usually in
 the shores of a pool1 these plants1    
necessarily of a water-loving species1  
retain so much moisture in the spongy   
mass which they form that they gradually
 extend up the slope4 ,thus extending   

the margin of their field1 and at the   
same time thickening the deposit which  
they form1 these plants may build a     
climbing bog over the surface until     
steeps are attained where the           
inclination is so great that the        
necessary amount of water can not be    
held in the spongy mass1 or where1 even 
if so held1 the whole coating will in   
time slip down in the manner of an      
avalanche4  ,the greater part of the    
climbing bogs of the world are limited  
to the moist and cool regions of high   
latitudes1 where species of moss        
belonging to the genus ,sphagnum        
plentifully flourish4 ,these plants can 
only grow where they are continuously   
supplied with a bath of water about     
their roots4 ,they develop in lake bogs 
as far south as ,mexico1 but in the     
climbing form they are hardly traceable 
south of ,new ,england1 and are nowhere 
extensively developed within the limits 
of the ,united ,states4 ,in more        
northern parts of this continent1 and in

 northwestern ,europe1 particularly in  
the moist climate of ,ireland1 climbing 
bogs occupy great areas1 and hold up    
their lakes of interstitially contained 
water over the slopes of hills1 where   
the surface rises at the rate of thirty 
feet or more to the mile4 ,so long as   
the deposit of decayed vegetable matter 
which has accumulated in this manner is 
thin1 therefore everywhere penetrated by
 the fibrous roots of the moss1 it may  
continue to cling to its sloping bed2   
but when it attains a considerable      
thickness1 and the roots in the lower   
part decay1 the pulpy mass1 water-laden 
in some time of heavy rain1 break away  
in a vast torrent of thick1 black mud1  
which may inundate the lower lands1     
causing widespread destruction4  ,in    
more southern countries1 other          
water-loving plants lead to the         
formation of climbing bogs4 ,of these1  
the commonest and most effective are the
 species of reeds1 of which our ,indian 
cane is a familiar example4 ,brakes of  

this vegetation1 plentifully mingled    
with other species of aquatic growth1   
form those remarkable climbing bogs     
known as the ,dismal and other swamps1  
which numerously occur along the coast  
line of the ,united ,states from        
southern ,maryland to eastern ,texas4   
,climbing bogs are particularly         
interesting1 not only from the fact that
 they are eminently peculiar effects of 
plant growth1 but because they give us a
 vivid picture of those ancient morasses
 in which grew the plants that formed   
the beds of vegetable matter now        
appearing in the state of coal4 ,each   
such bed of buried swamp material was1  
with rare exceptions1 where the         
accumulation took place in lakes1       
gathered in climbing bogs such as we    
have described4  ,lake bogs occur in all
 parts of the world1 but in their best  
development are limited to relatively   
high latitudes1 and this for the reason 
that the plants which form vegetable    
matter grow most luxuriantly in cool    

climates and in regions where the level 
of the basin is subject to less         
variation than occurs in the alternating
 wet and dry seasons which exist in     
nearly all tropical regions4 ,the       
fittest conditions are found in         
glaciated regions1 where1 as before     
noted1 small lakes are usually very     
abundant4 ,on the shores of one of these
 pools1 of size not so great that the   
waves may attain a considerable height1 
or in the sheltered bay of a larger     
lake1 various aquatic plants1 especially
 the species of pond lilies1 take root  
upon the bottom1 and spread their       
expanded leaves on the surface of the   
water4 ,these flexible-leaved and       
elastic-stemmed plants can endure waves 
which attain no more than a foot or two 
of height1 and by the friction which    
they afford make the swash on the shore 
very slight4 ,in the quiet water1 rushes
 take root1 and still further protect   
the strand1 so that the very delicate   
vegetation of the mosses1 such as the   

,sphagnum1 can fix itself on the shore4 
,as soon as the ,sphagnum mat has begun 
its growth1 the strength given by its   
interlaced fibres enables it to extend  
off from the shore and float upon the   
water4 ,in this way it may rapidly      
enlarge1 if not broken up by the waves1 
so that its front advances into the lake
 at the rate of several inches each     
year4 ,while growing outwardly it       
thickens1 so that the bottom of the mass
 gradually works down toward the floor  
of the basin4 ,at the same time the     
lower part of the sheet1 decaying1      
contributes a shower of soft peat mud to
 the floor of the lake4 ,in this way1   
growing at its edge1 deepening1 and     
contributing to an upgrowth from the    
bottom1 a few centuries may serve       
entirely to fill a deep basin with peaty
 accumulation4 ,in general1 however1 the
 surface of the bog closes over the lake
 before the accumulation has completely 
filled the shoreward portions of the    
area4 ,in these conditions we have what 

is familiarly known as a quaking bog1   
which can be swayed up and down by a    
person who quickly stoops and rises     
while standing on the surface4 ,in this 
state the tough and thick sheet of      
growing plants is sufficient to uphold a
 considerable weight1 but so elastic    
that the underlying water can be thrown 
into waves4 ,long before the bog has    
completely filled the lake with the     
peaty accumulations the growth of trees 
is apt to take place on its surface1    
which often reduces the area to the     
appearance of a very level wet wood4    
,illustration3 ,fig4 #ag4--;,diagram    
showing beginning of peat bog3 ,a1 lake2
 ,b1 lilies and rushes2 ,c1 lake bog2   
,d1 climbing bog4  ,climbing and lake   
bogs in the ,united ,states occupy a    
total area of more than fifty thousand  
square miles4 ,in all ,north ,america   
the total area is probably more than    
twice as great4 ,similar deposits are   
exceedingly common in the ,eurasian     
continent and in southern ,patagonia4   

,it is probable that the total amount of
 these fields in different parts of the 
world exceeds half a million square     
miles4 ,these two groups of fresh-water 
swamps have an interest1 for the reason 
that when reduced to cultivation by     
drainage and by subsequent removal of   
the excess of peaty matter1 by burning  
or by natural decay1 afford very rich   
soil4 ,the fairest fields of northern   
,europe1 particularly in ,great ,britain
 and ,ireland1 have been thus won to    
tillage4 ,in the first centuries of our 
era a large part of ,england--perhaps as
 much as one tenth of the ground now    
tilled in that country--was occupied by 
these lands1 which retained water in    
such measure as to make them unfit for  
tillage1 the greater portion of this    
area being in the condition of thin     
climbing bog4 ,for many centuries much  
of the energy of the people was devoted 
to the reclamation of these valuable    
lands4 ,this task of winning the swamp  
lands to agriculture has been more      

completely accomplished in ,england than
 elsewhere1 but it has gone far on the  
continent of ,europe1 particularly in   
,germany4 ,in the ,united ,states1 owing
 to the fact that lands have been cheap1
 little of this work of swamp-draining  
has as yet been accomplished4 ,it is    
likely that the next great field of     
improvement to be cultivated by the     
enterprising people will be found in    
these excessively humid lands1 from     
which the food-giving resources for the 
support of many million people can be   
won4  ,illustration3 ,fig4              
#ah4--;,diagram showing development of  
swamp3 ,a1 remains of lake2 ,b1 surface 
growth2 c1 peat4  ,the group of marine  
marshes differs in many important       
regards from those which are formed in  
fresh water4 ,where the tide visits any 
coast line1 and in sheltered positions  
along that shore1 a number of plants1   
mostly belonging to the group of        
grasses1 species which have become      
accustomed to having their roots bathed 

by salt water1 begin the formation of a 
spongy mat1 which resembles that        
composed of ,sphagnum1 only it is much  
more solid4 ,this mat of the marine     
marshes soon attains a thickness of a   
foot or more1 the upper or growing      
surface lying in a position where it is 
covered for two or three hours at each  
visit of the tide4 ,growing rapidly     
outward from the shore1 and having a    
strength which enables it to resist in a
 tolerably effective manner waves not   
more than two or three feet high1 this  
accumulation makes head against the sea4
 ,to a certain extent the waves         
undermine the front of the sheet and    
break up masses of it1 which they       
distribute over the shallow bottom below
 the level at which these plants can    
grow4 ,in this deeper water1 also1 other
 marine animals and plants are          
continually developing1 and their       
remains are added to the accumulations  
which are ever shallowing the water1    
thus permitting a further extension of  

the level1 higher-lying marsh4 ,this    
process continues until the growth has  
gone as far as the scouring action of   
the tidal currents will permit4 ,in the 
end the bay1 originally of wide-open    
water1 is only such at high tide4 ,for  
the greater part of the time it appears 
as broad savannas1 whose brilliant green
 gives them the aspect of rare          
fertility4  ,owing to the conditions of 
their growth1 the deposits formed in    
marine marshes contain no distinct peat1
 the nearest approach to that substance 
being the tangle of wirelike roots which
 covers the upper foot or so of the     
accumulation4 ,the greater part of the  
mass is composed of fine silt1 brought  
in by the streams of land water which   
discharge into the basin1 and by the    
remains of animals which dwelt upon the 
bottom or between the stalks of the     
plants that occupy the surface of the   
marshes4 ,these interspaces afford      
admirable shelter to a host of small    
marine forms4 ,the result is1 that the  

tidal marshes1 as well as the           
lower-lying mud flats1 which have been  
occupied by the mat of vegetation1      
afford admirable earth for tillage4     
,unfortunately1 however1 there are two  
disadvantages connected with the        
redemption of such lands4 ,in the first 
place1 it is necessary to exclude the   
sea from the area1 which can only be    
accomplished by considerable engineering
 work2 in the second place1 the         
exclusion of the tide inevitably results
 in the silting up of the passage by    
which the water found its way to the    
sea4 ,as these openings are often used  
for harbours1 the effect arising from   
their destruction is often rather       
serious4 ,nevertheless1 in some parts of
 the world very extensive and most      
fertile tracts of land have thus been   
won from the sea2 a large part of       
,holland and shore-land districts in    
northern ,europe are made up of fields  
which were originally covered by the    
tide4 ,near the mouth of the ,rhine1    

indeed1 the people have found these     
sea-bottom soils so profitable that they
 have gone beyond the zone of the       
marshes1 and have drained considerable  
seas which of old were permanently      
covered1 even at the lowest level of the
 waters4  ,on the coast of ,north       
,america marine marshes have an         
extensive development1 and vary much in 
character4 ,in the ,bay of ,fundy1 where
 the tides have an altitude of fifty    
feet or more1 the energy of their       
currents is such that the marsh mat     
rarely forms4 ,its place1 however1 is   
taken by vast and ever-changing mud     
flats1 the materials of which are swept 
to and fro by the moving waters4 ,the   
people of this region have learned an   
art of a peculiar nature1 by which they 
win broad fields of excellent land from 
the sea4 ,selecting an area of the      
flats1 the surface of which has been    
brought to within a few feet of high    
tide1 they inclose it with a stout      
barrier or dike1 which has openings for 

the free admission of the tidal waters4 
,entering this basin1 the tide1 moving  
with considerable velocity1 bears in    
quantities of sediment4 ,in the basin1  
the motion being arrested1 this sediment
 falls to the bottom1 and serves to     
raise its level4 ,in a few months the   
sheet of sediment is brought near the   
plane of the tidal movement1 then the   
gates are closed at times when the tide 
has attained half of its height1 so that
 the ground within the dike is not      
visited by the sea water1 and can be    
cultivated4  ,illustration3 ,fig4       
#ai4--,map of ,ipswich marshes1         
,massachusetts1 formed behind a barrier 
beach4  ,along the coast of ,new        
,england the ordinary marine marshes    
attain an extensive development in the  
form of broad-grassed savannas4 ,with   
this aspect1 though with a considerable 
change in the plants which they bear1   
the fringe of savannas continues        
southward along the coast to northern   
,florida4 ,in the region about the mouth

 of the ,savannah ,river1 so named from 
the vast extent of the tidal marshes1   
these fields attain their greatest      
development4 ,in central and southern   
,florida1 however1 where the seacoast is
 admirably suited for their development1
 these coastal marshes of the grassy    
type disappear1 their place being taken 
by the peculiar morasses formed by the  
growth of the mangrove tree4  ,in the   
mangrove marshes the tree which gives   
the areas their name covers all the     
field which is visited by the tide4     
,this tree grows with its crown         
supported on stiltlike roots1 at a level
 above high tide4 ,from its horizontal  
branches there grow off roots1 which    
reach downward into the water1 and      
thence to the bottom4 ,the seeds of the 
mangrove are admirably devised so as to 
enable the plant to obtain a foothold on
 the mud flats1 even where they are     
covered at low tide with a depth of two 
or three feet of water4 ,they are       
several inches in length1 and arranged  

with booklets at their lower ends2      
floating near the bottom1 they thus     
catch upon it1 and in a few weeks'      
growth push the shoot to the level of   
the water1 thus affording a foundation  
for a new plantation4 ,in this manner1  
extending the old forests out into the  
shallow water of the bays1 and forming  
new colonies wherever the water is not  
too deep1 these plants rapidly occupy   
all the region which elsewhere would    
appear in the form of savannas4         
,illustration3 ,fig4 #bj4--;,diagram    
showing mode of growth of mangroves4    
,the tidal marshes of ,north ,america1  
which may be in time converted to the   
uses of man1 probably occupy an area    
exceeding twenty thousand square miles4 
,if the work of reclaiming such lands   
from the sea ever attains the advance in
 this country that it has done in       
,holland1 the area added to the dry land
 by engineering devices may amount to as
 much as fifty thousand square miles--a 
territory rather greater than the       

surface of ,kentucky1 and with a        
food-yielding power at least five times 
as great as is afforded by that fertile 
,state4 ,in fact1 these conquests from  
the sea are hereafter to be among the   
great works which will attract the      
energies of mankind4 ,in the arid region
 of the ,cordilleras1 as well as in many
 other countries1 the soil1 though      
destitute of those qualities which make 
it fit for the uses of man1 because of  
the absence of water in sufficient      
amount1 is1 as regards its structure and
 depth1 as well as its mineral contents1
 admirably suited to the needs of       
agriculture4 ,the development of soils  
in desert regions is in almost all cases
 to be accounted for by the former      
existence in the realms they occupy of a
 much greater rainfall than now exists4 
,thus in the ,rocky ,mountain country1  
when the deep soils of the ample valleys
 were formed1 the lakes1 as we have     
before noted1 were no longer dead seas1 
as is at present so generally the case1 

but poured forth great streams to the   
sea4 ,here1 as elsewhere1 we find       
evidence that certain portions of the   
earth which recently had an abundant    
rainfall have now become starved for the
 lack of that supply4 ,all the soils of 
arid regions where the trial has been   
made have proved very fertile when      
subjected to irrigation1 which can often
 be accomplished by storing the waters  
of the brief rainy season or by         
diverting those of rivers which enter   
the deserts from well-watered mountain  
fields4 ,in fact1 the soil of these arid
 realms yields peculiarly ample returns 
to the husbandman1 because of certain   
conditions due to the exceeding dryness 
of the air4 ,this leads to an absence of
 cloudy weather1 so that from the time  
the seed is planted the growth is       
stimulated by uninterrupted and intense 
sunshine4 ,the same dryness of the air  
leads1 as we have seen1 to a rapid      
evaporation from the surface1 by which1 
in a manner before noted1 the dissolved 

mineral matter is brought near the top  
of the soil1 where it can best serve the
 greater part of our crop plants4 ,on   
these accounts an acre of irrigated soil
 can be made to yield a far greater     
return than can be obtained from land of
 like chemical composition in humid     
regions4  ,in many parts of the world1  
particularly in the northern and western
 portions of the ,mississippi ,valley1  
there are widespread areas1 which1      
though moderately well watered1 were in 
their virgin state almost without       
forests4 ,in the prairie region the     
early settlers found the country        
unwooded1 except along the margins of   
the streams4 ,on the borders of the true
 prairies1 however1 they found          
considerable areas of a prevailingly    
forested land1 with here and there a    
tract of prairie4 ,there were several of
 these open fields south of the ,ohio1  
though the country there is in general  
forested2 one of these prairie areas1 in
 the ,green ,river district of          

,kentucky1 was several thousand square  
miles in extent4 ,at first it was       
supposed that the absence of trees in   
the open country of the ,mississippi    
,valley was due to some peculiarity of  
the soil1 but experience shows that     
plantations luxuriantly develop1 and    
that the timber will spread rapidly in  
the natural way4 ,in fact1 if the seeds 
of the trees which have been planted    
since the settlement of the country were
 allowed to develop as they seek to do1 
it would only be a few centuries before 
the region would be forest-clad as far  
west as the rainfall would permit the   
plants to develop4 ,probably the woods  
would attain to near the hundredth      
meridian4  ,in the opinion of the       
writer1 the treeless character of the   
,western plains is mainly to be         
accounted for by the habit which our    
,indians had of burning the herbage of a
 lowly sort each year1 so that the large
 game might obtain better pasturage4 ,it
 is a well-known fact to all those who  

have had to deal with cattle on fields  
which are in the natural state that fire
 betters the pasturage4 ,beginning this 
method of burning in the arid regions to
 the west of the original forests1 the  
natural action of the fire has been     
gradually to destroy these woods4       
,although the older and larger trees1 on
 account of their thick bark and the    
height of their foliage above the       
ground1 escaped destruction1 all the    
smaller and younger members of the      
species were constantly swept away4     
,thus when the old trees died they left 
no succession1 and the country assumed  
its prairie character4 ,that the        
prairies were formed in this manner     
seems to be proved by the testimony     
which we have concerning the open area  
before mentioned as having existed in   
western ,kentucky4 ,it is said that     
around the timberless fields there was a
 wide fringe of old fire-scarred trees1 
with no undergrowth beneath their       
branches1 and that as they died no kind 

of large vegetation took their place4   
,when the ,indians who set these fires  
were driven away1 as was the case in the
 last decade of the last century1 the   
country at once began to resume its     
timbered condition4 ,from the margin and
 from every interior point where the    
trees survived1 their seeds spread so   
that before the open land was all       
subjugated to the plough it was         
necessary in many places to clear away a
 thick growth of the young              
forest-building trees4  ,the soils which
 develop on the lavas and ashes about an
 active volcano afford interesting      
subjects for study1 for the reason that 
they show how far the development of the
 layer which supports vegetation may    
depend upon the character of the rocks  
from which it is derived4 ,where the    
materials ejected from a volcano lie in 
a rainy district1 the process of decay  
which converts the rock into soil is    
commonly very rapid1 a few years of     
exposure to the weather being sufficient

 to bring about the formation of a      
fertile soil4 ,this is due to the fact  
that most lavas1 as well as the         
so-called volcanic ashes1 which are of  
the same material as the lavas1 only    
blown to pieces1 are composed of varied 
minerals1 the most of which are readily 
attacked by the agents of decay4 ,now   
and then1 however1 we find the materials
 ejected from a particular volcano1 or  
even the lavas and ashes of a single    
eruption1 in such a chemical state that 
soils form upon them with exceeding     
slowness4                    99       99
       99       99       99  ,the       
foregoing incomplete considerations make
 it plain that the soil-covering of the 
earth is the result of very delicate    
adjustments1 which determine the rate at
 which the broken-down rocks find their 
path from their original bed places to  
the sea4 ,the admirable way in which    
this movement is controlled is indicated
 by the fact that almost everywhere we  
find a soil-covering deep enough for the

 use of a varied vegetation1 but rarely 
averaging more than a dozen feet in     
depth4 ,only here and there are the     
rocks bare or the earth swathed in a    
profound mass of detritus4 ,this        
indicates how steadfast and measured is 
the march of the rock waste from the    
hills to the sea4 ,unhappily1 man1 when 
by his needs he is forced to till the   
soil1 is compelled to break up this     
ancient and perfect order4 ,he has to   
strip the living mantle from the earth1 
replacing it with growth of those       
species which serve his needs4 ,those   
plants which are most serviceable--which
 are1 indeed1 indispensable in the      
higher civilization1 the grains--require
 for their cultivation that the earth be
 stripped bare and deeply stirred during
 the rainy season1 and thus subjected to
 the most destructive effect of the     
rainfall4 ,the result is1 that in almost
 all grain fields the rate of soil      
destruction vastly surpasses that at    
which the accumulation is being made4   

,we may say1 indeed1 that1 except in    
alluvial plains1 where the soil grows by
 flood-made additions to its upper      
surface1 no field tilled in grain can   
without exceeding care remain usable for
 a century4 ,even though the            
agriculturist returns to the earth all  
the chemical substances which he takes  
away in his crops1 the loss of the soil 
by the washing away of its substance to 
the stream will inevitably reduce the   
region to sterility4  ,it is not        
fanciful to say that the greatest       
misfortune which in a large way man has 
had to meet in his agriculture arises   
from this peculiar stress which grain   
crops put upon the soil4 ,if these      
grains grew upon perennial plants1 in   
the manner of our larger fruits1 the    
problem of man's relation to the soil   
would be much simpler than it is at     
present4 ,he might then manage to till  
the earth without bringing upon it the  
inevitable destruction which he now     
inflicts4 ,as it is1 he should recognise

 that his needs imperil this ancient and
 precious element in the earth's        
structure1 and he should endeavour in   
every possible way to minimize the      
damage which he brings about4 ,this     
result he may accomplish in certain     
simple ways4  ,first1 as regards the    
fertility of the soil1 as distinguished 
from the thickness of the coating1 it   
may be said that modern discoveries     
enable us to see the ways whereby we may
 for an indefinite period avoid the     
debasement of our great heritage1 the   
food-giving earth4 ,we now know in      
various parts of the world extensive and
 practically inexhaustible deposits1    
whence may be obtained the phosphates1  
potash1 soda1 etc41 which we take from  
the soil in our crops4 ,we also have    
learned ways in which the materials     
contained in our sewage may be kept from
 the sea and restored to the fields4 ,in
 fact1 the recent developments of       
agriculture have made it not only easy1 
but in most cases profitable1 to avoid  

this waste of materials which has       
reduced so many regions to poverty4 ,we 
may fairly look forward to the time1 not
 long distant1 when the old progressive 
degradation in the fertility of the soil
 coating will no longer occur4 ,it is   
otherwise with the mass of the soil1    
that body of commingled decayed rock and
 vegetable matter which must possess a  
certain thickness in order to serve its 
needs4 ,as yet no considerable arrest   
has been made in the processes which    
lead to the destruction of this earthy  
mass4 ,in all countries where tillage is
 general the rivers are flowing charged 
with all they can bear away of soil     
material4 ,thus in the valley of the    
,po1 a region where1 if the soil were   
forest-clad1 the down-wearing of the    
surface would probably be at no greater 
rate than one foot in five thousand     
years1 the river bears away the soil    
detritus so rapidly that at the present 
time the downgoing is at the rate of one
 foot in eight hundred years1 and each  

decade sees the soil disappear from     
hillsides which were once fertile1 but  
are now reduced to bare rocks4 ,all     
about the ,mediterranean the traveller  
notes extensive regions which were once 
covered with luxuriant forests1 and were
 afterward the seats of prosperous      
agriculture1 where the soil has utterly 
disappeared1 leaving only the bare      
rocks1 which could not recover its      
natural covering in thousands of years  
of the enforced fallow4  ,within the    
limits of the ,united ,states the       
degradation of the soil1 owing to the   
peculiar conditions of the country1 is  
in many districts going forward with    
startling rapidity4 ,it has been the    
habit of our people--a habit favoured by
 the wide extent of fertile and easily  
acquired frontier ground--recklessly to 
till their farms until the fields were  
exhausted1 and then to abandon them for 
new ground4 ,by shallow ploughing on    
steep hillsides1 by neglect in the      
beginning of those gulches which form in

 such places1 it is easy in the hill    
country of the eastern ,united ,states  
to have the soil washed away within     
twenty years after the protecting       
forests have been destroyed4 ,the writer
 has estimated that in the ,states south
 of the ,ohio and ,james ,rivers more   
than eight thousand square miles of     
originally fertile ground have by       
neglect been brought into a condition   
where it will no longer bear crops of   
any kind1 and over fifteen hundred miles
 of the area have been so worn down to  
the subsoil or the bed rock that it may 
never be profitable to win it again to  
agricultural uses4  ,hitherto1 in our   
,american agriculture1 our people have  
been to a great extent pioneers2 they   
have been compelled to win what they    
could in the cheapest possible way and  
with the rudest implements1 and without 
much regard to the future of those who  
were in subsequent generations to occupy
 the fields which they were conquering  
from the wilderness and the savages4    

,the danger is now that this reckless   
tillage1 in a way justified of old1 may 
be continued and become habitual with   
our people4 ,it is1 indeed1 already a   
fixed habit in many parts of the        
country1 particularly in the ,south1    
where a small farmer expects to wear out
 two or three plantations in the course 
of his natural life4 ,many of them      
manage to ruin from one to two hundred  
acres of land in the course of half a   
century of uninterrupted labour4 ,this  
system deserves the reprobation of all  
good citizens2 it would be well1 indeed1
 if it were possible to do so1 to stamp 
it out by the law4 ,the same principle  
which makes it illegal for a man to burn
 his own dwelling house may fairly be   
applied in restraining him from         
destroying the land which he tills4     
,there are a few simple principles      
which1 if properly applied1 may serve to
 correct this misuse of our ,american   
soil4 ,the careful tiller should note   
that all soils whatever which lie on    

declivities having a slope of more than 
one foot in thirty inevitably and       
rapidly waste when subject to plough    
tillage4 ,this instrument tends to smear
 and consolidate the layer of earth over
 which its heel runs1 so that at a depth
 of a few inches below the surface a    
layer tolerably impervious to water is  
formed4 ,the result is that the porous  
portion of the deposit becomes          
excessively charged with water in times 
of heavy rain1 and moves down the       
hillside in a rapid manner4 ,all such   
steep slopes should be left in their    
wooded state1 or1 if brought into use1  
should be retained as pasture lands4    
,where1 as is often the case with the   
farms in hilly countries1 all the fields
 are steeply inclined1 it is an         
excellent precaution to leave the upper 
part of the slope with a forest         
covering4 ,in this condition not only is
 the excessive flow of surface water    
diminished1 but the moisture which      
creeps down the slope from the wooded   

area tends to keep the lower-lying      
fields in a better state for tillage1   
and promotes the decay of the underlying
 rocks1 and thus adds to the body and   
richness of the earth4  ,on those soils 
which must be tilled1 even where they   
tend to wash away1 the aim should be to 
keep the detritus open to such a depth  
that it may take in as much as possible 
of the rainfall1 yielding the water to  
the streams through the springs4 ,this  
end can generally be accomplished by    
deep ploughing2 it can1 in almost all   
cases1 be attained by under-drainage4   
,the effect of allowing the water to    
penetrate is not only to diminish the   
superficial wearing1 but to maintain the
 process of subsoil and bed-rock decay  
by which the detrital covering is       
naturally renewed4 ,where1 as in many   
parts of the country1 the washing away  
of the soil can not otherwise be        
arrested1 the progress of the           
destruction can be delayed by forming   
with the skilful use of the plough      

ditches of slight declivity leading     
along the hillsides to the natural      
waterways4 ,one of the most satisfactory
 marks of the improvement which is now  
taking place in the agriculture of the  
cotton-yielding ,states of this country 
is to be found in the rapid increase in 
the use of the ditch system here        
mentioned4 ,this system1 combined with  
ploughing in the manner where the earth 
is with each overturning thrown uphill1 
will greatly reduce the destructive     
effect of rainfall on steep-lying       
fields4 ,but the only effective         
protection1 however1 is accomplished by 
carefully terracing the slopes1 so that 
the tilled ground lies in level benches4
 ,this system is extensively followed in
 the thickly settled portions of        
,europe1 but it may be a century before 
it will be much used in this country4   
,the duty of the soil-tiller by the     
earth with which he deals may be briefly
 summed up3 ,he should look upon himself
 as an agent necessarily interfering    

with the operations which naturally form
 and preserve the soil4 ,he should see  
that his work brings two risks2 he may  
impoverish the accumulation of detrital 
material by taking out the plant food   
more rapidly than it is prepared for    
use4 ,this injurious result may be at   
any time reparable by a proper use of   
manures4 ,not so1 however1 with the     
other form of destruction1 which results
 in the actual removal of the soil      
materials4 ,where neglect has brought   
about this disaster1 it can only be     
repaired by leaving the area to recover 
beneath the slowly formed forest        
coating4 ,this process in almost all    
cases requires many thousands of years  
for its accomplishment4 ,the man who has
 wrought such destruction has harmed the
 inheritance of life4                   
,,chapter ,,ix4                         
,,the ,,rocks ,,and ,,their ,,order4    
,in the preceding chapters of this book 
the attention of the student has been   
directed mainly to the operations of    

those natural forces which act upon the 
surface of the earth4 ,incidentally the 
consequences arising from the           
applications of energy to the outer part
 of the planet have been attended to1   
but the main aim has been to set forth  
the work which solar energy1 operating  
in the form of heat1 accomplishes upon  
the lands4 ,we have now to consider one 
of the great results of these actions1  
which is exhibited in the successive    
strata that make up the earth's crust4  
,the most noteworthy effect arising from
 the action of the solar forces on the  
earth and their co-operation with those 
which originate in our sphere is found  
in the destruction of beds or other     
deposits of rock1 and the removal of the
 materials to the floors of water       
basins1 where they are again aggregated 
in strata1 and gradually brought once   
more into a stable condition within the 
earth4 ,this work is accomplished by    
water in its various states1 the action 
being directly affected by gravitation4 

,in the form of steam1 water which has  
been built into rocks and volcanically  
expelled by tensions1 due to the heat   
which it has acquired at great depths   
below the surface1 blows forth great    
quantities of lava1 which is contributed
 to the formation of strata1 either     
directly in the solid form or           
indirectly1 after having been dissolved 
in the sea4 ,acting as waves1 water     
impelled by solar energy transmitted to 
it by the winds beats against the       
shores1 wearing away great quantities of
 rock1 which is dragged off to the      
neighbouring sea bottoms1 there to      
resume the bedded form4 ,moving ice in  
glaciers1 water again applying solar    
energy given to it by its elevation     
above the sea1 most effectively grinds  
away the elevated parts of the crust1   
the dbris being delivered to the ocean4 
,in the rain the same work is done1 and 
even in the wind the power of the sun   
serves to abrade the high-lying rocks1  
making new strata of their fragments4   

,as gravity enters as an element in all 
the movements of divided rock1 the      
tendency of the waste worn from the land
 is to gather on to the bottoms of      
basins which contain water4 ,rarely1 and
 only in a small way1 this process      
results in the accumulation of lake     
deposits2 the greater part of the work  
is done upon the sea floor4 ,when the   
beds are formed in lake basins1 they may
 be accumulated in either of two very   
diverse conditions4 ,they may be formed 
in what are called dead seas1 in which  
case the detrital materials are commonly
 small in amount1 for the reason that   
the inflowing streams are               
inconsiderable2 in such basins there is 
normally a large share of saline        
materials1 which are laid down by the   
evaporation of the water4 ,in ordinary  
lakes the deposits which are formed are 
mostly due to the sediment that the     
rivers import4 ,these materials are     
usually fine-grained1 and the sand or   
pebbles which they contain are          

plentifully mingled with clay4 ,hence   
lake deposits are usually of an         
argillaceous nature4 ,as organic life1  
such as secretes limestone1 is rarely   
developed to any extent in lake basins1 
limy beds are very rarely formed beneath
 those areas of water4 ,where they      
occur1 they are generally due to the    
fact that rivers charged with limy      
matter import such quantities of the    
substance that it is precipitated on the
 bottom4  ,as lake deposits are normally
 formed in basins above the level of the
 sea1 and as the drainage channels of   
the basins are always cutting down1 the 
effect is to leave such strata at a     
considerable height above the sea level1
 where the erosive agents may readily   
attack them4 ,in consequence of this    
condition1 lacustrine beds are rarely   
found of great antiquity2 they generally
 disappear soon after they are formed4  
,where preserved1 their endurance is    
generally to be attributed to the fact  
that the region they occupy has been    

lowered beneath the sea and covered by  
marine strata4  ,the great laboratory in
 which the sedimentary deposits are     
accumulated1 the realm in which at least
 ninety-nine of the hundred parts of    
these materials are laid down1 is the   
oceanic part of the earth4 ,on the      
floors of the seas and oceans we have   
not only the region where the greater   
part of the sedimentation is effected1  
but that in which the work assumes the  
greatest variety4 ,the sea bottoms1 as  
regards the deposits formed upon them1  
are naturally divided into two          
regions--the one in which the dbris from
 the land forms an important part of the
 sediment1 and the other1 where the     
remoteness of the shores deprives the   
sediment of land waste1 or at least of  
enough of that material in any such     
share as can affect the character of the
 deposits4  ,what we may term the       
littoral or shore zone of the sea       
occupies a belt of prevailingly shallow 
water1 varying in width from a few score

 to a few hundred miles4 ,where the     
bottom descends steeply from the coast1 
where there are no strong off-shore     
setting currents1 and where the region  
is not near the mouth of a large river  
which bears a great tide of sediment to 
the sea1 the land waste may not affect  
the bottom for more than a mile or two  
from the shore4 ,where these conditions 
are reversed1 the dbris from the        
air-covered region may be found three or
 four hundred miles from the coast line4
 ,it should also be noted that the      
incessant up-and-down goings of the land
 result in a constant change in the     
position of the coast line1 and         
consequently in the extension of the    
land sediment1 in the course of a few   
geological periods over a far wider     
field of sea bottom than that to which  
they would attain if the shores remained
 steadfast4  ,it is characteristic of   
the sediments deposited within the      
influence of the continental detritus   
that they vary very much in their       

action1 and that this variation takes   
place not only horizontally along the   
shores in the same stratum1 but         
vertically1 in the succession of the    
beds4 ,it also may be traced down the   
slope from the coast line to deep water4
 ,thus where all the dbris comes from   
the action of the waves1 the deposits   
formed from the shore outwardly will    
consist of coarse materials1 such as    
pebbles near the coast1 of sand in the  
deeper and remoter section1 and of finer
 silt in the part of the deposit which  
is farthest out4 ,with each change in   
the level of the coast line the position
 of these belts will necessarily be     
altered4 ,where a great river enters the
 sea1 the changes in the volume of      
sediment which it from time to time     
sends forth1 together with the          
alternations in the position of its     
point of discharge1 led to great local  
complexities in the strata4 ,moreover1  
the turbid water sent forth by the      
stream may1 as in the case of the tide  

from the ,amazon1 be drifted for        
hundreds of miles along the coast line  
or into the open sea4  ,the most        
important variations which occur in the 
deposits of the littoral zone are       
brought about by the formations of rocks
 more or less composed of limestone4    
,everywhere the sea is1 as compared with
 lake waters1 remarkably rich in organic
 life4 ,next the shore1 partly because  
the water is there shallow1 but also    
because of its relative warmth and the  
extent to which it is in motion1 organic
 life1 both that of animals and plants1 
commonly develops in a very luxuriant   
way4 ,only where the bottom is composed 
of drifting sands1 which do not afford a
 foothold for those species which need  
to rest upon the shore1 do we fail to   
find that surface thickly tenanted with 
varied forms4 ,these are arranged       
according to the depth of the bottom4   
,the species of marine plants which are 
attached to fixed objects are limited to
 the depth within which the sunlight    

effectively penetrates the water2 in    
general1 it may be said that they do not
 extend below a depth of one hundred    
feet4 ,the animal forms are distributed1
 according to their kinds1 over the     
floor1 but few species having the       
capacity to endure any great range in   
the pressure of the sea water4 ,only a  
few forms1 indeed1 extend from low tide 
to the depth of a thousand feet4  ,the  
greatest development of organic life1   
the realm in which the largest number of
 species occur1 and where their growth  
is most rapid1 lies within about a      
hundred feet of the low-tide level4     
,here sunlight1 warmth1 and motion in   
the water combine to favour organic     
development4 ,it is in this region that 
coral reefs and other great             
accumulations of limestone1 formed from 
the skeletons of polyps and mollusks1   
most abundantly occur4 ,these deposits  
of a limy nature depend upon a very     
delicate adjustment of the conditions   
which favour the growth of certain      

creatures2 very slight geographic       
changes1 by inducing movements of sand  
or mud1 are apt to interrupt their      
formation1 bringing about a great and   
immediate alteration in the character of
 the deposits4 ,thus it is that where   
geologists find considerable fields of  
rock1 where limestones are intercalated 
with sandstones and deposits of clay1   
they are justified in assuming that the 
strata were laid down near some ancient 
shore4 ,in general1 these coast deposits
 become more and more limy as we go     
toward the tropical realms1 and this for
 the reason that the species which      
secrete large amounts of lime are in    
those regions most abundant and attain  
the most rapid growth4 ,the stony       
polyps1 the most vigorous of the        
limestone makers1 grow in large         
quantities only in the tropical realm1  
or near to it1 where ocean streams of   
great warmth may provide the creatures  
with the conditions of temperature and  
food which they need4  ,as we pass from 

the shore to the deeper sea1 the share  
of land detritus rapidly diminishes     
until1 as before remarked1 at the       
distance of five hundred miles from the 
coast line1 very little of that waste1  
except that from volcanoes1 attains the 
bottom of the sea4 ,by far the larger   
part of the contributions which go to   
the formation of these deep-sea strata  
come from organic remains1 which are    
continually falling upon the sea floor4 
,in part1 this waste is derived from    
creatures which dwell upon the bottom2  
in considerable measure1 however1 it is 
from the dead bodies of those forms     
which live near the surface of the sea1 
and which when dying sink slowly through
 the intermediate realm to the bottom4  
,owing to the absence of sunlight1 the  
prevailingly cold water of the deeper   
seas1 and the lack of vegetation in     
those realms1 the growth of organic     
forms on the deep-sea floor is          
relatively slow4 ,thus it happens that  
each shell or other contribution to the 

sediment lies for some time on the      
bottom before it is buried4 ,while in   
this condition it is apt to be devoured 
by some of the many species which dwell 
on the bottom and subsist from the      
remains of animals and plants which they
 find there4 ,in all cases the          
fossilization of any form depends upon  
the accumulation of sediment before the 
processes of destruction have overtaken 
them1 and among these processes we must 
give the first place to the creatures   
which subsist on shells1 bones1 or other
 substances of like nature which find   
their way to the ocean floor4 ,in the   
absolute darkness1 the still water1 and 
the exceeding cold of the deeper seas1  
animals find difficult conditions for   
development4 ,moreover1 in this deep    
realm there is no native vegetation1    
and1 in general1 but little material of 
this nature descends to the bottom from 
the surface of the sea4 ,the result is1 
the animals have to subsist on the      
remains of other animals which at some  

step in the succession have obtained    
their provender from the plants which   
belong on the surface or in the shallow 
waters of the sea4 ,this limitation of  
the food supply causes the depths of the
 sea to be a realm of continual hunger1 
a region where every particle of organic
 matter is apt to be seized upon by some
 needy creature4  ,in consequence of the
 fact that little organic matter on the 
deeper sea floors escapes being         
devoured1 the most of the material of   
this nature which goes into strata      
enters that state in a finely divided   
condition4 ,in the group of worms       
alone--forms which in a great diversity 
of species inhabit the sea floor--we    
find creatures which are specially      
adapted to digesting the dbris which    
gathers on the sea bottom4 ,wandering   
over this surface1 much in the manner of
 our ordinary earthworms1 these         
creatures devour the mud1 voiding the   
matter from their bodies in a yet more  
perfectly divided form4 ,hence it comes 

about that the limestone beds1 so       
commonly formed beneath the open seas1  
are generally composed of materials     
which show but few and very imperfect   
fossils4 ,studying any series of        
limestone beds1 we commonly find that   
each layer1 in greater or less degree1  
is made up of rather massive materials1 
which evidently came to their place in  
the form of a limy mud4 ,very often this
 lime has crystallized1 and thus has    
lost all trace of its original organic  
structure4  ,one of the conspicuous     
features which may be observed in any   
succession of limestone beds is the     
partings or divisions into layers which 
occur with varied frequency4 ,sometimes 
at vertical intervals of not more than  
one or two inches1 again with spacings  
of a score of feet1 we find divisional  
planes1 which indicate a sudden change  
in the process of rock formation4 ,the  
lime disappears1 and in place of it we  
have a thin layer of very fine detritus1
 which takes on the form of a clay4     

,examining these partings with care1 we 
observe that on the upper surface on the
 limestone the remains of the animal    
which dwelt on the ancient sea floor are
 remarkably well preserved1 they having 
evidently escaped the effect of the     
process which reduced their ancestors1  
whose remains constitute the layer1 to  
mud4 ,furthermore1 we note that the     
shaly layer is not only lacking in lime1
 but commonly contains no trace of      
animals such as might have dwelt on the 
bottom4 ,the fossils it bears are       
usually of species which swam in the    
overlying water and came to the bottom  
after death4 ,following up through the  
layer of shale1 we note that the        
ordinary bottom life gradually          
reappears1 and shortly becomes so       
plentiful that the deposit resumes the  
character which it had before the       
interruption began4 ,often1 however1 we 
note that the assemblage of species     
which dwelt on the given area of sea    
floor has undergone a considerable      

change4 ,forms in existence in the lower
 layer may be lacking in the upper1     
their place being taken by new          
varieties4  ,so far the origin of these 
divisional planes in marine deposits has
 received little attention from         
geologists2 they have1 indeed1 assumed  
that each of these alterations indicates
 some sudden disturbance of the life of 
the sea floors4 ,they have1 however1    
generally assumed that the change was   
due to alterations in the depth of the  
sea or in the run of ocean currents4 ,it
 seems to the writer1 however1 that     
while these divisions may in certain    
cases be due to the above-mentioned and1
 indeed1 to a great variety of causes1  
they are in general best to be explained
 by the action of earthquakes4 ,water   
being an exceedingly elastic substance1 
an earthquake passes through it with    
much greater speed than it traverses the
 rocks which support the ocean floor4   
,the result is that1 when the fluid and 
solid oscillate in the repeated         

swingings which a shock causes1 they do 
not move together1 but rub over each    
other1 the independent movements having 
the swing of from a few inches to a foot
 or two in shocks of considerable       
energy4  ,when the sea bottom and the   
overlying water1 vibrating under the    
impulse of an earthquake shock1 move    
past each other1 the inevitable result  
is the formation of muddy water2 the    
very fine silt of the bottom is shaken  
up into the fluid1 which afterward      
descends as a sheet to its original     
position4 ,it is a well-known fact that 
such muddying of water1 in which species
 accustomed to other conditions dwell1  
inevitably leads to their death by      
covering their breathing organs and     
otherwise disturbing the delicately     
balanced conditions which enable them to
 exist4 ,we find1 in fact1 that most of 
the tenants of the water1 particularly  
the forms which dwell upon the bottom1  
are provided with an array of           
contrivances which enable them to clear 

away from their bodies such small       
quantities of silt as may inconvenience 
them4 ,thus1 in the case of our common  
clam1 the breathing organs are covered  
with vibratory cilia1 which1 acting like
 brooms1 sweep off any foreign matter   
which may come upon their surfaces4     
,moreover1 the creature has a long1     
double1 spoutlike organ1 which it can   
elevate some distance above the bottom1 
through which it draws and discharges   
the water from which it obtains food and
 air4 ,other forms1 such as the         
crinoids1 or sea lilies1 elevate the    
breathing parts on top of tall stems of 
marvellous construction1 which brings   
those vital organs at the level1 it may 
be1 of three or four feet above the zone
 of mud4 ,in consequence of the peculiar
 method of growth1 the crinoids often   
escape the damage done by the           
disturbance of the bottom1 and thus form
 limestone beds of remarkable thickness2
 sometimes1 indeed1 we find these layers
 composed mainly of crinoidal remains1  

which exhibit only slight traces of     
partings such as we have described1     
being essentially united for the depth  
of ten or twenty feet4 ,where the layers
 have been mainly accumulated by        
shellfish1 their average thickness is   
less than half a foot4  ,when we examine
 the partitions between the layers of   
limestone1 we commonly find that1       
however thin1 they generally extend for 
an indefinite distance in every         
direction4 ,the writer has traced some  
of these for miles2 never1 indeed1 has  
he been able to find where they         
disappeared4 ,this fact makes it clear  
that the destruction which took place at
 the stage where these partings were    
formed was widespread2 so far as it was 
due to earthquake shocks1 we may fairly 
believe that in many cases it occurred  
over areas which were to be measured by 
tens of thousands of square miles4      
,indeed1 from what we know of earthquake
 shocks1 it seems likely that the       
devastation may at times have affected  

millions of square miles4  ,another     
class of accidents connected with       
earthquakes may also suddenly disturb   
the mud on the sea bottom4 ,when1 as    
elsewhere noted1 a shock originates     
beneath the sea1 the effect is suddenly 
to elevate the water over the seat of   
the jarring and the regions thereabouts 
to the height of some feet4 ,this       
elevation quickly takes the shape of a  
ringlike wave1 which rolls off in every 
direction from its point of origin4     
,where the sea is deep1 the effect of   
this wave on the bottom may be but      
slight2 but as the undulation attains   
shallower water1 and in proportion to   
the shoaling1 the front of the surge is 
retarded in its advance by the friction 
of the bottom1 while the rear part1     
being in deeper water1 crowds upon the  
advancing line4 ,the action is precisely
 that which has been described as       
occurring in wind-made waves as they    
approach the beach2 but in this         
last-named group of undulations1 because

 of the great width of the swell1 the   
effect of the shallowing is evident in  
much deeper water4 ,it is likely that at
 the depth of a thousand feet the       
passing of one of these vast surges born
 of earthquakes may so stir the mud of  
the sea floor as to bring about a       
widespread destruction of life1 and thus
 give rise to many of the partitions    
between strata4  ,if we examine with the
 microscope the fine-grained silts which
 make up the shaly layers between       
limestones1 we find the materials to be 
mostly of inorganic origin4 ,it is hard 
to trace the origin of the mineral      
matter which it contains2 some of the   
fragments are likely to prove of        
,volcanic origin2 others1 bits of dust  
from meteorites2 yet others1 dust blown 
from the land1 which may1 as we know1 be
 conveyed for any distance across the   
seas4 ,mingled with this sediment of an 
inorganic origin we almost invariably   
find a share of organic waste1 derived  
not from creatures which dwelt upon the 

bottom1 but from those which inhabited  
the higher-lying waters4 ,if1 now1 we   
take a portion of the limestone layer   
which lies above or below the shale     
parting1 and carefully dissolve out with
 acids the limy matter which it         
contains1 we obtain a residuum which in 
general character1 except so far as the 
particles may have been affected by the 
acid1 is exactly like the material which
 forms the claylike partition4 ,we are  
thus readily led to the conclusion that 
on the floors of the deeper seas there  
is constantly descending1 in the form of
 a very slow shower1 a mass of mineral  
detritus4 ,where organic life belonging 
to the species which secrete hard shells
 or skeletons is absent1 this           
accumulation1 proceeding with exceeding 
slowness1 gradually accumulates layers1 
which take on a shaly character4 ,where 
limestone-making animals abound1 they so
 increase the rate of deposition that   
the proportion of the mineral material  
in the growing strata is very much      

reduced2 it may1 indeed1 become as small
 as one per cent of the mass4 ,in this  
case we may say that the deposit of     
limestone grew a hundred times as fast  
as the intervening beds of shale4  ,the 
foregoing considerations make it        
tolerably clear that the sea floor is in
 receipt of two diverse classes of      
sediment--those of a mineral and those  
of an organic origin4 ,the mineral1 or  
inorganic1 materials predominate along  
the shores4 ,they gradually diminish in 
quantity toward the open sea1 where the 
supply is mainly dependent on the       
substances thrown forth from volcanoes1 
on pumice in its massive or its         
comminuted form--i4e41 volcanic dust1   
states of lava in which the material1   
because of the vesicles which it        
contains1 can float for ages before it  
comes to rest on the sea bottom4        
,variations in the volcanic waste       
contributed to the sea floor may        
somewhat affect the quantity of the     
inorganic sediments1 but1 as a whole1   

the downfalling of these fragments is   
probably at a singularly uniform rate4  
,it is otherwise with the contributions 
of sediment arising from organic forms4 
,this varies in a surprising measure4   
,on the coral reefs1 such as form in the
 mid oceans1 the proportion of matter   
which has not come into the accumulation
 through the bodies of animals and      
plants may be as small as one tenth of  
one per cent1 or less4 ,in the deeper   
seas1 it is doubtful whether the rate of
 animal growth is such as to permit the 
formation of any beds which have less   
than one half of their mass made up of  
materials which fell through the water4 
,in certain areas of the open seas the  
upper part of the water is dwelt in by a
 host of creatures1 mostly foraminifera1
 which extract limestone from the water1
 and1 on dying1 send their shells to the
 bottom4 ,thus in the ,north ,atlantic1 
even where the sea floor is of great    
depth beneath the surface1 there is     
constantly accumulating a mass of limy  

matter1 which is forming very massive   
limestone strata1 somewhat resembling   
chalk deposits1 such as abundantly occur
 in ,great ,britain1 in the neighbouring
 parts of ,europe1 in ,texas1 and       
elsewhere4 ,accumulations such as this1 
where the supply is derived from the    
surface of the water1 are not affected  
by the accidents which divide beds made 
on the bottom in the manner before      
described4 ,they may1 therefore1 have   
the singularly continuous character     
which we note in the ,english chalk1    
where1 for the thickness of hundreds of 
feet1 we may have no evident partitions1
 except certain divisions1 which have   
evidently originated long after the beds
 were formed4  ,we have already noted   
the fact that1 while the floors of the  
deeper seas appear to lack mountainous  
elevations1 those arising from the      
folding of strata1 they are plentifully 
scattered over with volcanic cones4 ,we 
may therefore suppose that1 in general1 
the deposits formed on the sea floor are

 to a great extent affected by the      
materials which these vents cast forth4 
,lava streams and showers represent only
 a part of the contributions from       
volcanoes1 which finally find their way 
to the bottom4 ,in larger part1 the     
materials thrown forth are probably     
first dissolved in the water and then   
taken up by the organic species2 only   
after the death of these creatures does 
the waste go to the bottom4 ,as hosts of
 these creatures have no solid skeleton 
to contribute to the sea floor1 such    
mineral matter as they may obtain is    
after their death at once restored to   
the sea4  ,not only does the            
contribution of organic sediment        
diminish in quantity with the depth     
which is attained1 but the deeper parts 
of the ocean bed appear to be in a      
condition where no accumulations of this
 nature are made1 and this for the      
reason that the water dissolves the     
organic matter more rapidly than it is  
laid down4 ,thus in place of limestone1 

which would otherwise form1 we have only
 a claylike residuum1 such as is        
obtained when we dissolve lime rocks in 
acids4 ,this process of solution1 by    
which the limy matter deposited on the  
bottom is taken back into the water1    
goes on everywhere1 but at a rate which 
increases with the depth4 ,this increase
 is due in part to the augmentation of  
pressure1 and in part to the larger     
share of carbonic dioxide which the     
water at great depths holds4 ,the result
 is1 that explorations with the dredge  
seem to indicate that on certain parts  
of the deeper sea floors the rocks are  
undergoing a process of dissolution     
comparable to that which takes place in 
limestone caverns4 ,so considerable is  
the solvent work that a large part of   
the inorganic waste appears to be taken 
up by the waters1 so as to leave the    
bottom essentially without sedimentary  
accumulations4 ,the sea1 in a word1     
appears to be eating into rocks which it
 laid down before the depression        

attained its present great depth4  ,we  
should here note something of the       
conditions which determine the supply of
 food which the marine animals obtain4  
,first of all1 we may recur to the point
 that the ocean waters appear to contain
 something of all the earth materials   
which do not readily decompose when they
 are taken into the state of solution4  
,these mineral substances1 including the
 metals1 are obtained in part from the  
lands1 through the action of the rain   
water and the waves1 but perhaps in     
larger share from the volcanic matter   
which1 in the form of floating lava1    
pumice1 or dust1 is plentifully         
delivered to the sea4 ,except           
doubtfully1 and at most in a very small 
way1 this chemical store of the sea     
water can not be directly taken into the
 structures of animals2 it can only be  
immediately appropriated by the marine  
plants4 ,these forms can only develop in
 that superficial realm of the seas     
which is penetrated by the sunlight1 or 

say within the depth of five hundred    
feet1 mostly within one hundred feet of 
the surface1 about one thirtieth of the 
average1 and about one fiftieth of the  
maximum ocean depth4 ,on this marine    
plant life1 and in a small measure on   
the vegetable matter derived from the   
land1 the marine animals primarily      
depend for their provender4 ,through the
 conditions which bring about the       
formation of ,sargassum seas1 those     
areas of the ocean where seaweeds grow  
afloat1 as well as by the water-logging 
and weighting down of other vegetable   
matter1 some part of the plant remains  
is carried to the sea floor1 even to    
great depths2 but the main dependence of
 the deep-sea forms of animals is upon  
other animal forms1 which themselves may
 have obtained their store from yet     
others4 ,in fact1 in any deep-sea form  
we might find it necessary to trace back
 the food by thousands of steps before  
we found the creature which had access  
to the vegetable matter4 ,it is easy to 

see how such conditions profoundly limit
 the development of organic being in the
 abysm of the ocean4  ,the sedentary    
animals1 or those which are fixed to the
 sea bottom--a group which includes the 
larger part of the marine species--have 
to depend for their sustenance on the   
movement of the water which passes their
 station4 ,if the seas were perfectly   
still1 none of these creatures except   
the most minute could be fed2 therefore 
the currents of the ocean go far by     
their speed to determine the rate at    
which life may flourish4 ,at great      
depths1 as we have seen1 these movements
 are practically limited to that which  
is caused by the slow movement which the
 tide brings about4 ,the amount of this 
motion is proportional to the depth of  
the sea2 in the deeper parts1 it carries
 the water to and fro twice each day for
 the distance of about two hundred and  
fifty feet4 ,in the shallower water this
 motion increases in proportion to the  
shoaling1 and in the regions near the   

shores the currents of the sea which1   
except the massive drift from the poles1
 do not usually touch the bottom1 begin 
to have their influence4 ,where the     
water is less than a hundred feet in    
depth1 each wave contributes to the     
movement1 which attains its maximum near
 the shore1 where every surge sweeps the
 water rapidly to and fro4 ,it is in    
this surge belt1 where the waves are    
broken1 that marine animals are best    
provided with food1 and it is here that 
their growth is most rapid4 ,if the     
student will obtain a pint of water from
 the surf1 he will find that it is      
clouded by fragments of organic matter1 
the quantity in a pound of the fluid    
often amounting to the fiftieth part of 
its weight4 ,he will thus perceive that 
along the shore line1 though the        
provision of victuals is most abundant1 
the store is made from the animals and  
plants which are ground up in the mill4 
,in a word1 while the coast is a place  
of rapid growth1 it is also a region of 

rapid destruction2 only in the case of  
the coral animals1 which associate their
 bodies with a number of myriads in     
large and elaborately organized         
communities1 do we find animals which   
can make such head against the action of
 the waves that they can build great    
deposits in their realm4  ,it should be 
noted that a part of the advantage which
 is afforded to organic life by the     
shore belt is due to the fact that the  
waters are there subjected to a constant
 process of aration by the whipping into
 foam and spray which occurs where the  
waves overturn4  ,it will be interesting
 to the student to note the great number
 of mechanical contrivances which have  
been devised to give security to animals
 and plants which face these difficult  
conditions arising from successive      
violent blows of falling water4 ,among  
these may be briefly noted those of the 
limpets--mollusks which dwell in a      
conical shell1 which faces the water    
with a domelike outside1 and which at   

the moment of the stroke is drawn down  
upon the rock by the strong muscle which
 fastens the creature to its foundation4
 ,the barnacles1 which with their       
wedge-shaped prows cut the water at the 
moment of the stroke1 but open in the   
pauses between the waves1 so that the   
creature may with its branching arms    
grasp at the food which floats about it2
 the nullipores1 forms of seaweed which 
are framed of limestone and cling firmly
 to the rock--afford yet other instances
 of protective adaptations contrived to 
insure the safety of creatures which    
dwell in the field of abundant food     
supply4                    99       99  
99       99       99  ,the facts above  
presented will show the reader that the 
marine sediments are formed under       
conditions which permit a great variety 
in the nature of the materials of which 
they are composed4 ,as soon as the      
deposits are built into rocks and       
covered by later accumulations1 their   
materials enter the laboratory of the   

under earth1 where they are subjected to
 progressive changes4 ,even before they 
have attained a great depth1 through the
 laying down of later deposits upon     
them1 changes begin which serve to alter
 their structure4 ,the fragments of a   
soluble kind begin to be dissolved1 and 
are redeposited1 so that the mass       
commonly becomes much more solid1       
passing from the state of detritus to   
that of more or less solid rock4 ,when  
yet more deeply buried1 and thereby     
brought into a realm of greater warmth1 
or perhaps when penetrated by dikes and 
thereby heated1 these changes go yet    
further4 ,more of the material is       
commonly rearranged by solution and     
redeposition1 so that limestone may be  
converted into crystalline marble1      
granular sandstones into firm masses1   
known as quartzites1 and clays into the 
harder form of slate4 ,where the changes
 go to the extreme point1 rocks         
originally distinctly bedded probably   
may be so taken to pieces and made over 

that all traces of their stratification 
may be destroyed1 all fossils           
obliterated1 and the stone transformed  
into mica schist1 or granite or other   
crystalline rock4 ,it may be injected   
into the overlying strata in the form of
 dikes1 or it may be blown forth into   
the air through volcanoes4 ,involved in 
mountain-folding1 after being more or   
less changed in the manner described1   
the beds may become tangled together    
like the rumpled leaves of a book1 or   
even with the complexity of snarled     
thread4 ,all these changes of condition 
makes it difficult for the geologist to 
unravel the succession of strata so that
 he may know the true order of the      
rocks1 and read from them the story of  
the successive geological periods4 ,this
 task1 though incomplete1 has by the    
labours of many thousand men been so far
 advanced that we are now able to divide
 the record into chapters1 the divisions
 of the geologic ages1 and to give some 
account of the succession of events1    

organic and geographic1 which have      
occurred since life began to write its  
records4                                
,,earthquakes4  ,in ordinary experience 
we seem to behold the greater part of   
the earth which meets our eyes as fixed 
in its position4 ,a better understanding
 shows us that nothing in this world is 
immovable4 ,in the realm of the         
inorganic world the atoms and molecules 
even in solid bodies have to be         
conceived as endowed with ceaseless     
though ordered motions4 ,even when      
matter is built into the solid rock1 it 
is doubtful whether any grain of it ever
 comes really to rest4 ,under the       
strains which arise from the contraction
 of the earth's interior and the        
chemical changes which the rocks        
undergo1 each bit is subject to         
ever-changing thrusts1 which somewhat   
affect its position4 ,if we in any way  
could bring a grain of sand from any    
stratum under a microscope1 so that we  
could perceive its changes of place1 we 

should probably find that it was        
endlessly swaying this way and that1    
with reference to an ideally fixed      
point1 such as the centre of the earth4 
,but even that centre1 whether of       
gravity or of figure1 is probably never 
at rest4  ,earth movements may be       
divided into two groups--those which    
arise from the bodily shifting of       
matter1 which conveys the particles this
 way or that1 or1 as we say1 change     
their place1 and those which merely     
produce vibration1 in which the         
particles1 after their vibratory        
movement1 return to their original      
place4 ,for purposes of illustration the
 first1 or translatory motion1 may be   
compared to that which takes place when 
a bell is carried along upon a          
locomotive or a ship2 and the second1 or
 vibratory movement1 to what takes place
 when the bell is by a blow made to     
ring4 ,it is with these ringing         
movements1 as we may term them1 that we 
find ourselves concerned when we        

undertake the study of earthquakes4  ,it
 is desirable that the reader should    
preface his study of earthquakes by     
noting the great and1 at the same time1 
variable elasticity of rocks4 ,in the   
extreme form this elasticity is very    
well shown when a toy marble1 which is  
made of a close-textured rock1 such as  
that from which it derives its name1 is 
thrown upon a pavement composed of like 
dense material4 ,experiment will show   
that the little sphere can often be made
 to bounce to the height of twenty feet 
without breaking4 ,if1 then1 with the   
same energy the marble is thrown upon a 
brick floor1 the rebound will be very   
much diminished4 ,it is well to consider
 what happens to produce the rebound4   
,when the sphere strikes the floor it   
changes its shape1 becoming shorter in  
the axis at right angles to the point   
which was struck1 and at the same       
instant expanded along the equator of   
that axis4 ,the flattening remains for  
only a small fraction of a second2 the  

sphere vibrates so that it stretches    
along the line on which it previously   
shortened1 and1 as this movement takes  
place with great swiftness1 it may be   
said to propel itself away from the     
floor4 ,at the same time a similar      
movement goes on in the rock of the     
floor1 and1 where the rate of vibration 
is the same1 the two kicks are          
coincident1 and so the sphere is        
impelled violently away from the point  
of contact4 ,where the marble comes in  
contact with brick1 in part because of  
the lesser elasticity of that material1 
due to its rather porous structure1 and 
partly because it does not vibrate at   
the same rate as the marble1 the        
expelling blow is much less strong4     
,all rocks whatever1 even those which   
appear as incoherent sands1 are more or 
less set into vibratory motion whenever 
they are struck by a blow4 ,in the crust
 of the earth various accidents occur   
which may produce that sudden motion    
which we term a blow4 ,when we have     

examined into the origin of these       
impulses1 and the way in which they are 
transmitted through the rocks1 we obtain
 a basis for understanding earthquake   
shocks4 ,the commonest cause of the     
jarrings in the earth is found in the   
formation of fractures1 known as faults4
 ,if the reader has ever been upon a    
frozen lake at a time when the weather  
was growing colder1 and the ice1        
therefore1 was shrinking1 he may have   
noted the rending sound and the slight  
vibration which comes with the formation
 of a crack traversing the sheet of ice4
 ,at such a time he feels a movement    
which is an earthquake1 and which       
represents the simpler form of those    
tremors arising from the sudden rupture 
of fault planes4 ,if he has a mind to   
make the experiment1 he may hang a      
bullet by a thread from a small frame   
which rests upon the ice1 and note that 
as the vibration occurs the little      
pendulum sways to and fro1 thus         
indicating the oscillations of the ice4 

,the same instrument will move in an    
identical manner when affected by a     
quaking in the rocks4  ,where the rocks 
are set in vibration by a rent which is 
formed in them1 the phenomena are more  
complicated1 and often on a vastly      
larger scale than in the simple         
conditions afforded by a sheet of ice4  
,the rocks on either side of the rupture
 generally slide over each other1 and   
the opposing masses are rent in their   
friction upon one another2 the result   
is1 not only the first jar formed by the
 initial fracture1 but a great many     
successive movements from the other     
breakages which occur4 ,again1 in the   
deeper parts of the crust1 the fault    
fissures are often at the moment of     
their formation filled by a violent     
inrush of liquid rock4 ,this1 as it     
swiftly moves along1 tears away masses  
from the walls1 and when it strikes the 
end of the opening delivers a blow which
 may be of great violence4 ,the nature  
of this stroke may be judged by the     

familiar instance where the relatively  
slow-flowing stream from a hydrant pipe 
is suddenly choked by closing the       
stopcock4 ,unless the plumber provides a
 cushion of air to diminish the energy  
of the blow1 it is often strong enough  
to shake the house4 ,again1 when steam  
or other gases are by a sudden          
diminution of pressure enabled to       
expand1 they may deliver a blow which is
 exactly like that caused by the        
explosion of gunpowder1 which1 even when
 it rushes against the soft cushion of  
the air1 may cause a jarring that may be
 felt as well as heard to a great       
distance4 ,such movements very          
frequently occur in the eruptions of    
volcanoes2 they cause a quivering of the
 earth1 which may be felt for a great   
distance from the immediate seat of the 
disturbance4  ,when by any of the sudden
 movements which have been above        
described a jar is applied to the rocks1
 the wave flies through the more or less
 elastic mass until the energy involved 

in it is exhausted4 ,this may not be    
brought about until the motion has      
travelled for the distance of hundreds  
of miles4 ,in the great earthquake of   
#agee1 known as the ,lisbon shock1 the  
records make it seem probable that the  
movement was felt over one eighth part  
of the earth's surface4 ,such great     
disturbances probably bring about a     
motion of the rocks near the point of   
origin1 which may be expressed in       
oscillations having an amplitude of one 
to two feet2 but in the greater number  
of earthquakes the maximum swing        
probably does not exceed the tenth of   
that amount4 ,very sensible shaking1    
even such as may produce considerable   
damage to buildings1 are caused by      
shocks in which the earth vibrates with 
less than an inch of swing4  ,when a    
shock originates1 the wave in the rocks 
due to the compression which the blow   
inflicts runs at a speed varying with   
the elasticity of the substance1 but at 
the rate of about fifteen hundred feet a

 second4 ,the movements of this wave are
 at right angles to the seat of the     
originating disturbance1 so that the    
shock may come to the surface in a line 
forming any angle between the vertical  
and the nearly horizontal4 ,where1 as in
 a volcanic eruption1 the shock         
originates with an explosion1 these     
waves go off in circles4 ,where1        
however1 as is generally the case1 the  
shock originates in a fault plane1 which
 may have a length and depth of many    
miles1 the movement has an elliptical   
form4  ,if the earthquake wave ran      
through a uniform and highly elastic    
substance1 such as glass1 it would move 
everywhere with equal speed1 and1 in the
 case of the greater disturbances1 the  
motion might be felt over the whole     
surface of the earth4 ,but as the motion
 takes place through rocks of varying   
elasticity1 the rate at which it        
journeys is very irregular4 ,moving     
through materials of one density1 and   
with a rate of vibration determined by  

those conditions1 the impulse is with   
difficulty communicated to strata which 
naturally vibrate at another speed4 ,in 
many cases1 as where a shock passing    
through dense crystalline strata        
encounters a mass of soft sandstone1 the
 wave1 in place of going on1 is         
reflected back toward its point of      
origin4 ,these earthquake echoes        
sometimes give rise to very destructive 
movements4 ,it often happens that before
 the original tremors of a shock have   
passed away from a point on the surface 
the reflex movements rush in1 making a  
very irregular motion1 which may be     
compared to that of the waves in a      
cross-sea4  ,the foregoing account of   
earthquake action will serve to prepare 
the reader for an understanding of those
 very curious and important effects     
which these accidents produce in and on 
the earth4 ,below the surface the       
sensible action of earthquake shocks is 
limited4 ,it has often been observed    
that people in mines hardly note a      

swaying which may be very conspicuous to
 those on the surface1 the reason for   
this being that underground1 where the  
rocks are firmly bound together1 all    
those swingings which are due to the    
unsupported position of such objects as 
buildings1 columnar rocks1 trees1 and   
the waters of the earth1 are absent4    
,the effect of the movements which      
earthquakes impress on the under earth  
is mainly due to the fact that in almost
 every part of the crust tensions or    
strains of other kinds are continually  
forming4 ,these may for ages prove      
without effect until the earth is       
jarred1 when motions will suddenly take 
place which in a moment may alter the   
conditions of the rocks throughout a    
wide field4 ,in a word1 a great         
earthquake caused by the formation of an
 extensive fault is likely to produce   
any number of slight dislocations1 each 
of which is in turn shock-making1       
sending its little wave to complicate   
the great oscillation4 ,nor does the    

perturbing effect of these jarring      
movements cease with the fractures which
 they set up and the new strains which  
are in turn developed by the motions    
which they induce4 ,the alterations of  
the rocks which are involved in chemical
 changes are favoured by such motions4  
,it is a familiar experience that a     
vessel of water1 if kept in the state of
 repose1 may have its temperature       
lowered three or four degrees below the 
freezing point without becoming frozen4 
,if the side of the vessel is then      
tapped with the finger1 so as to send a 
slight quake through the mass1 it will  
instantly congeal4 ,molecular           
rearrangements are thus favoured by     
shocks1 and the consequences of those   
which run through the earth are1 from a 
chemical point of view1 probably        
important4  ,the reader may help himself
 to understand something of the         
complicated problem of earth tensions1  
and the corresponding movements of the  
rocks1 by considering certain homely    

illustrations4 ,he may observe how the  
soil cracks as it shrinks in times of   
drought1 the openings closing when it   
rains4 ,in a similar way the frozen     
earth breaks open1 sometimes with a     
shock which is often counted as an      
earthquake4 ,again1 the ashes in a      
sifter or the gravel on a sieve show how
 each shaking may relieve certain       
tensions established by gravity1 while  
they create others which are in turn to 
be released by the next shock4 ,an      
ordinary dwelling house sways and       
strains with the alternations of        
temperature and moisture to which it is 
subjected in the round of climatal      
alterations4 ,now and then we note the  
movements in a cracking sound1 but by   
far the greater part of them escape     
observation4  ,with this sketch of the  
mechanism of earthquake shocks we now   
turn to consider their effects upon the 
surface of the earth4 ,from a geological
 point of view1 the most important      
effect of earthquake shocks is found in 

the movement of rock masses down steep  
slopes1 which is induced by the shaking4
 ,everywhere on the land the agents of  
decay and erosion tend to bring heavy   
masses into position where gravitation  
naturally leads to their downfall1 but  
where they may remain long suspended1   
provided they are not disturbed4 ,thus1 
wherever there are high and steep       
cliffs1 great falls of rock are likely  
to occur when the earthquake movements  
traverse the under earth4 ,in more than 
one instance observers1 so placed that  
they commanded a view of distant        
mountains1 have noticed the downfall of 
precipices in the path of the shock     
before the trembling affected the ground
 on which they stood4 ,in the famous    
earthquake of #aghc1 which devastated   
southern ,italy1 the ,prince of ,scylla 
persuaded his people to take refuge in  
their boats1 hoping that they might     
thereby escape the destruction which    
threatened them on the land4 ,no sooner 
were the unhappy folk on the water than 

the fall of neighbouring cliffs near the
 sea produced a great wave1 which       
overwhelmed the vessels4  ,where the    
soil lies upon steep slopes1 in         
positions in which it has accumulated   
during ages of tranquillity1 a great    
shock is likely to send it down into the
 valleys in vast landslides4 ,thus1 in  
the earthquake of #afib1 the ,blue      
,mountains of ,jamaica were so violently
 shaken that the soil and the forests   
which stood on it were precipitated into
 the river beds1 so that many tree-clad 
summits became fields of bare rock4 ,the
 effect of this action is immensely to  
increase the amount of detritus which   
the streams convey to the sea4 ,after   
the great ,jamaica shock1 above noted1  
the rivers for a while ceased to flow1  
their waters being stored in the masses 
of loose material4 ,then for weeks they 
poured forth torrents of mud and the    
dbris of vegetation--materials which had
 to be swept away as the streams formed 
new channels4  ,in all regions where    

earthquake movements are frequent1 and  
the shock of considerable violence1 the 
trained observer notes that the surfaces
 of bare rock are singularly extensive1 
the fact being that many of these areas1
 where the slope lies at angles of from 
ten to thirty degrees1 which in an      
unshaken region would be thickly        
soil-covered1 are deprived of the       
coating by the downward movement of the 
waste which the disturbances bring      
about4 ,a familiar example of this      
action may be had by watching the       
workmen engaged in sifting sand1 by     
casting the material on a sloping       
grating4 ,the work could not be done but
 for an occasional blow applied to the  
sifter4 ,an arrangement for such a      
jarring motion is commonly found in     
various ore-dressing machines1 where the
 object is to move fragments of matter  
over a sloping surface4  ,even where the
 earth is so level that an earthquake   
shock does not cause a sliding motion of
 the materials1 such as above described1

 other consequences of the shaking may  
readily be noted4 ,as the motion runs   
through the mass1 provided the movement 
be one of considerable violence1        
crevices several feet in width1 and     
sometimes having the length of miles1   
are often formed4 ,in most cases these  
fissures1 opened by one pulsation of the
 shock1 are likely to be closed by the  
return movement1 which occurs the       
instant thereafter4 ,the consequences of
 this action are often singular1 and in 
cases constitute the most frightful     
elements of a shock which the sufferer  
beholds4 ,in the great earthquake of    
#ahaa1 which ravaged the section of the 
,mississippi ,valley between the mouth  
of the ,ohio and ,vicksburg1 these      
crevices were so numerously formed that 
the pioneers protected themselves from  
the danger of being caught in their jaws
 by felling trees so that they lay at   
right angles to the direction in which  
the rents extended1 building on these   
timbers platforms to support their      

temporary dwelling places4 ,the records 
of earthquakes supply many instances in 
which people have been caught in these  
earth fissures1 and in a single case it 
is recorded that a man who disappeared  
into the cavity was in a moment cast    
forth in the rush of waters which in    
this1 as in many other cases1 spouts    
forth as the walls of the opening come  
together4  ,sometimes these rents are   
attended by a dislocation1 which brings 
the earth on one side much higher than  
on the other4 ,the step thus produced   
may be many miles in length1 and may    
have a height of twenty feet or more4   
,it needs no argument to show that we   
have here the top of a fault such as    
produced the shock1 or it may be one of 
a secondary nature1 such as any         
earthquake is likely to bring about in  
the strata which it traverses4 ,in      
certain cases two faults conjoin their  
action1 so that a portion of the surface
 disappears beneath the earth1 entombing
 whatever may have stood on the vanished

 site4 ,thus in the great shock known as
 that of ,lisbon1 which occurred in     
#agee1 the stone quay along the harbour1
 where many thousand people had sought  
refuge from the falling buildings of the
 city1 suddenly sank down with the      
multitude1 and the waters closed over   
it2 no trace of the people or of the    
structure was to be found after the     
shock was over4 ,there is a story to the
 effect that during the same earthquake 
an ,arab village in northern ,africa    
sank down1 the earth on either side     
closing over it1 so that no trace of the
 habitations remained4 ,in both these   
instances the catastrophes are best     
explained by the diagram4               
,illustration3 ,fig4 #ba4--;,diagram    
showing how a portion of the earth's    
surface may be sunk by faulting4 ,fig4  
,a shows the original position2 ,b1 the 
position after faulting2 b b' and c c'  
the planes of the faults2 the arrows the
 direction of the movement4  ,in the    
earthquake of #ahaa the alluvial plains 

on either side of the ,mississippi at   
many points sank down so that arable    
land was converted into lakes2 the area 
of these depressions probably amounted  
to some hundred square miles4 ,the      
writer1 on examining these sunken lands1
 found that the subsidences had occurred
 where the old moats or abandoned       
channels of the great river had been    
filled in with a mixture of decaying    
timber and river silt4 ,when violently  
shaken1 this loose-textured dbris       
naturally settled down1 so that it      
formed a basin occupied by a            
crescent-shaped lake4 ,the same process 
of settling plentifully goes on wherever
 the rocks are still in an uncemented   
state4 ,the result is often the         
production of changes which lead to the 
expulsion of gases4 ,thus1 in the       
,charleston earthquake of #ahhc1 the    
surface over an area of many hundred    
square miles was pitted with small      
craters1 formed by the uprush of water  
impelled by its contained gases4 ,these 

little water volcanoes--for such we may 
call them--sometimes occur to the number
 of a dozen or more on each acre of     
ground in the violently shaken district4
 ,they indicate one result of the       
physical and chemical alterations which 
earthquake shocks bring about4 ,as      
earthquakes increase in violence their  
effect upon the soil becomes continually
 greater1 until in the most violent     
shocks all the loose materials on the   
surface of the earth may be so shaken   
about as to destroy even the boundaries 
of fields4 ,after the famous earthquake 
of ,riobamba1 which occurred on the west
 coast of ,south ,america in #agig1 the 
people of the district in which the town
 of that name was situated were forced  
to redivide their land1 the original    
boundaries having disappeared4          
,fortunately1 shocks of this description
 are exceedingly rare4 ,they occur in   
only a few parts of the world4  ,certain
 effects of earthquakes where the shock 
emerges beneath the sea have been stated

 in the account of volcanic eruptions   
7see page #bii74 ,we may therefore note 
here only certain of the more general   
facts4 ,while passing through the deep  
seas1 this wave may have a height of not
 more than two or three feet and a width
 of some score miles4 ,as it rolls in   
upon the shore the front of the         
undulation is retarded by the friction  
of the bottom in such a measure that its
 speed is diminished1 while the         
following part of the waves1 being less 
checked1 crowds up toward this forward  
part4 ,the result is1 that the surge    
mounts ever higher and higher as it     
draws near the shore1 upon which it may 
roll as a vast wave having the height of
 fifty feet or more and a width quite   
unparalleled by any wave produced from  
wind action4 ,waves of this description 
are most common in the ,pacific ,ocean4 
,although but occasional1 the damage    
which they may inflict is very great4   
,as the movement approaches the shore1  
vessels1 however well anchored1 are     

dragged away to seaward by the great    
back lash of the wave1 a phenomenon     
which may be perceived even in the case 
of the ordinary surf4 ,thus forced to   
seaward1 the crews of the ships may find
 their vessels drawn out for the        
distance of some miles1 until they come 
near the face of the advancing billow4  
,this1 as it approaches the shore1      
straightens up to the wall-fronted form1
 and then topples upon the land4 ,those 
vessels which are not at once crushed   
down by the blow are generally hurled   
far inland by the rush of waters4 ,in   
the great ,jamaica earthquake of #afib a
 ,british man-of-war was borne over the 
tops of certain warehouses and deposited
 at a distance from the shore4  ,owing  
to the fact that water is a highly      
elastic material1 the shocks transmitted
 to it from the bottom are sent onward  
with their energy but little diminished4
 ,while the impulse is very violent1    
these oscillations may prove damaging to
 shipping4 ,the log-books of mariners   

abound in stories of how vessels were   
dismasted or otherwise badly shaken by a
 sudden blow received in the midst of a 
quiet sea4 ,the impression commonly     
conveyed to the sailors is that the     
craft has struck upon a rock4 ,the      
explanation is that an earthquake jar1  
in traversing the water1 has delivered  
its blow to the ship4 ,as the speed of  
this jarring movement is very much      
greater than that of any ordinary wave1 
the blow which it may strike may be most
 destructive4 ,there seems1 indeed1     
little reason to doubt that a portion of
 the vessels which are ever disappearing
 in the wilderness of the ocean are lost
 by the crushing effect of these        
quakings which pass through the waters  
of the deep4  ,we have already spoken of
 the earthquake shock as an oscillation4
 ,it is a quality of all bodies which   
oscillate under the influence of a blow1
 such as originates in earthquake       
shocks1 to swing to and fro1 after the  
manner of the metal in a bell or a      

tuning fork1 in a succession of         
movements1 each less than the preceding1
 until the impulse is worn out1 or      
rather1 we should in strict sense say1  
changed to other forms of energy4 ,the  
result is1 that even in the slightest   
earthquake shock the earth moves not    
once to and fro1 but very many times4   
,in a considerable shock the successive 
diminishing swingings amount to dozens  
before they become so slight as to elude
 perception4 ,although the first swaying
 is the strongest1 and generally the    
most destructive1 the quick to-and-fro  
motions are apt to continue and to      
complete the devastation which the first
 brings about4 ,the vibrations due to   
any one shock take place with great     
rapidity4 ,they may1 indeed1 be compared
 to those movements which we perceive in
 the margin of a large bell when it has 
received a heavy blow from the clapper4 
,the reader has perhaps seen that for a 
moment the rim of the bell vibrates with
 such rapidity that it has a misty      

look--that is1 the motions elude the    
sight4 ,it is easy to see that a shaking
 of this kind is particularly calculated
 to disrupt any bodies which stand free 
in the air and are supported only at    
their base4  ,in what we may call the   
natural architecture of the earth1 the  
pinnacles and obelisks1 such as are     
formed in many high countries1 the      
effect of these shakings is destructive1
 and1 as we have seen1 even the         
firmer-placed objects1 such as the      
strong-walled cliffs and steep slopes of
 earth1 break down under the assaults4  
,it is therefore no matter of surprise  
that the buildings which man erects1    
where they are composed of masonry1     
suffer greatly from these tremblings4   
,in almost all cases human edifices are 
constructed without regard to other     
problems of strength than those which   
may be measured by their weight and the 
resistance to fracture from gravitation 
alone4 ,they are not built with         
expectation of a quaking1 but of a      

firm-set earth4  ,the damage which      
earthquakes do to buildings is in most  
cases due to the fact that they sway    
their walls out of plumb1 so that they  
are no longer in position to support the
 weight which they have to bear4 ,the   
amount of this swaying is naturally very
 much greater than that which the earth 
itself experiences in the movement4 ,a  
building of any height with its walls   
unsupported by neighbouring structures  
may find its roof rocked to and fro     
through an arc which has a length of    
feet1 while its base moves only through 
a length of inches4 ,the reader may see 
an example of this nature if he will    
poise a thin book or a bit of plank a   
foot long on top of a small table2 then 
jarring the table so that it swings     
through a distance of say a quarter of  
an inch1 he will see that the columnar  
object swings at its top through a much 
greater distance1 and is pretty sure to 
be overturned4  ,where a building       
carries a load in its upper parts1 such 

as may be afforded by its heavy roof or 
the stores which it contains1 the effect
 of an earthquake shock such as carries 
the earth to and fro becomes much more  
destructive than it might otherwise be4 
,this weight lags behind when the earth 
slips forward in the first movement of  
the oscillation1 with the effect that   
the walls of the building are pretty    
sure to be thrust so far beyond the     
perpendicular that they give way and are
 carried down by the weight which they  
bore4 ,it has often been remarked in    
earthquake shocks that tall columns1    
even where composed of many blocks1     
survive a shock which overturns lower   
buildings where thin walls support      
several floors1 on each of which is     
accumulated a considerable amount of    
weight4 ,in the case of the column1 the 
strains are even1 and the whole         
structure may rock to and fro without   
toppling over4 ,as the energy of the    
undulations diminish1 it gradually      
regains the quiet state without damage4 

,in the ordinary edifice the irregular  
disposition of the weight does not      
permit the uniform movement which may   
insure safety4 ,thus1 if the city of    
,washington should ever be violently    
shaken1 the great obelisk1              
notwithstanding that it is five hundred 
feet high1 may survive a disturbance    
which would wreck the lower and more    
massive edifices which lie about it4    
,where1 as is fortunately rarely the    
case1 the great shock comes to the earth
 in a vertical direction1 the effect    
upon all movable objects is in the      
highest measure disastrous4 ,in such a  
case buildings are crushed as if by the 
stroke of a giant's hand4 ,the roofs and
 floors are at one stroke thrown to the 
foundations1 and all the parts of the   
walls which are not supported by strong 
masonry continuous from top to bottom   
are broken to pieces4 ,in such cases it 
has been remarked that the bodies of men
 are often thrown considerable          
distances4 ,it is asserted1 indeed1 that

 in the ,riobamba shock they were cast  
upward to the height of more than ninety
 feet4 ,it is related that the solo     
survivor of a congregation which had    
hastened at the outset of the           
disturbance into a church was thrown by 
the greatest and most destructive shock 
upward and through a window the base of 
which was at the height of more than    
twenty feet from the ground4  ,it is    
readily understood that an earthquake   
shock may enter a building in any       
direction between the vertical and the  
horizontal4 ,as the movement exhausts   
itself in passing from the place of its 
origin1 the horizontal shocks are       
usually of least energy4 ,those which   
are accurately vertical are only        
experienced where the edifices are      
placed immediately over the point where 
the motion originates4 ,it follows1     
therefore1 that the destructive work of 
earthquakes is mainly performed in that 
part of the field where the motion is1  
as regards its direction1 between the   

vertical and the horizontal--a position 
in which the edifice is likely to       
receive at once the destructive effect  
arising from the sharp upward thrust of 
the vertical movement and the           
oscillating action of that which is in a
 horizontal direction4 ,against strains 
of this description1 where the movements
 have an amplitude of more than a few   
inches1 no ordinary masonry edifice can 
be made perfectly safe2 the only        
tolerable security is attained where the
 building is of well-framed timber1     
which by its elasticity permits a good  
deal of motion without destructive      
consequences4 ,even such buildings1     
however1 those of the strongest type1   
may be ruined by the greater            
earthquakes4 ,thus1 in the ,mississippi 
,valley earthquake of #ahaa1 the log    
huts of the frontiersmen1 which are     
about as strong as any buildings can be 
made1 were shaken to pieces by the sharp
 and reiterated shocks4  ,it is by no   
means surprising to find that the style 

of architecture adopted in earthquake   
countries differs from that which is    
developed in regions where the earth is 
firm-set4 ,the people generally learn   
that where their buildings must meet the
 trials of earthquakes they have to be  
low and strong1 framed in the manner of 
fortifications1 to withstand the assault
 of this enemy4 ,we observe that ,gothic
 architecture1 where a great weight of  
masonry is carried upon slender columns 
and walls divided by tall windows1      
though it became the dominant style in  
the relatively stable lands of northern 
,europe1 never gained a firm foothold in
 those regions about the ,mediterranean 
which are frequently visited by severe  
convulsions of the earth4 ,there the    
,grecian or the ,romanesque styles1     
which are of a much more massive type1  
retain their places and are the fashions
 to the present day4 ,even this manner  
of building1 though affording a certain 
security against slight tremblings1 is  
not safe in the greater shocks4 ,again  

and again large areas in southern ,italy
 have been almost swept of their        
buildings by the destructive movements  
which occur in that realm4 ,the only    
people who have systematically adapted  
their architectural methods to          
earthquake strains are the ,japanese1   
who in certain districts where such     
risks are to be encountered construct   
their dwellings of wood1 and place them 
upon rollers1 so that they may readily  
move to and fro as the shock passes     
beneath them4 ,in a measure the people  
of ,san ,francisco have also provided   
against this danger by avoiding         
dangerous weights in the upper parts of 
their buildings1 as well as the         
excessive height to which these         
structures are lifted in some of our    
,american towns4  ,earthquakes of       
sensible energy appear to be limited to 
particular parts of the earth's crust4  
,the regions1 indeed1 where within the  
period of human history shocks of       
devastating energy have occurred do not 

include more than one fifteenth part of 
the earth's surface4 ,there is a common 
notion that these movements are most apt
 to happen in volcanic regions4 ,it is1 
indeed1 true that sensible shocks       
commonly attend the explosions from     
great craters1 but the records clearly  
show that these movements are very      
rarely of destructive energy4 ,thus in  
the regions about the base of ,vesuvius 
and of tna1 the two volcanoes of which  
most is known1 the shocks have never    
been productive of extensive disaster4  
,in fact1 the reiterated slight jarrings
 which attend volcanic action appear to 
prevent the formation of those great and
 slowly accumulated strains which in    
their discharge produce the most violent
 tremblings of the earth4 ,the greatest 
and most continuous earthquake          
disturbances of history--that before    
noted in the early days of this century1
 in the ,mississippi ,valley1 where     
shocks of considerable violence         
continued for two years--came about in a

 field very far removed from active     
volcanoes4 ,so1 too1 the disturbances   
beneath the ,atlantic floor which       
originated the shocks that led to the   
destruction of ,lisbon1 and many other  
similar though less violent movements1  
are developed in a field apparently     
remote from living volcanoes4 ,eastern  
,new ,england1 which has been the seat  
of several considerable earthquakes1 is 
about as far away from active vents as  
any place on the habitable globe4 ,we   
may therefore conclude that1 while      
volcanoes necessarily produce shocks    
resulting from the discharge of their   
gases and the intrusion of lava into the
 dikes which are formed about them1 the 
greater part of the important shocks are
 in no wise connected with volcanic     
explosions4  ,with the exception of the 
earthquake in the ,mississippi ,valley1 
all the great shocks of which we have a 
record have occurred in or near regions 
where the rocks have been extensively   
disturbed by mountain-building forces1  

and where the indications lead us to    
believe that dislocations of strata1    
such as are competent to rive the beds  
asunder1 may still be in progress4      
,this1 taken in connection with the fact
 that many of these shocks are attended 
by the formation of fault planes1 which 
appear on the surface1 lead us to the   
conclusion that earthquakes of the      
stronger kind are generally formed by   
the riving of fissures1 which may or may
 not be developed upward to the surface4
 ,this view is supported by many careful
 observations on the effect which       
certain great earthquakes have exercised
 on the buildings which they have       
ravaged4 ,the distinguished observer1   
,mr4 ,charles ,mallet1 who visited the  
seat of the earthquake which1 in #ahed1 
occurred in the province of ,calabria in
 ,italy1 with great labour and skill    
determined the direction in which the   
shock moved through some hundreds of    
edifices on which it left the marks of  
its passage4 ,platting these lines of   

motion1 he found that they were all     
referred to a vertical plane lying at   
the depth of some miles beneath the     
surface1 and extending for a great      
distance in a north and south direction4
 ,this method of inquiry has been       
applied to other fields1 with the result
 that in the case of all the instances  
which have been subjected to this       
inquiry the seat of the shock has been  
traced to such a plane1 which can best  
be accounted for by the supposition of a
 fault4  ,the method pursued by ,mr4    
,mallet in his studies of the origin of 
earthquakes1 and by those who have      
continued his inquiry1 may be briefly   
indicated as follows3 ,examining        
disrupted buildings1 it is easy to      
determine those which have been wrecked 
by a shock that emerged from the earth  
in a vertical direction4 ,in these      
cases1 though tall walls may remain     
standing1 the roofs and floors are      
thrown into the cellars4 ,with a dozen  
such instances the plane of what is     

called the seismic vertical is          
established 7seismos is the ,greek for  
earthquake74 ,then on either side of    
this plane1 which indicates the line but
 not the depth of the disturbance1 other
 observations may be made which give the
 clew to the depth4 ,thus a building may
 be found where the northwest corner at 
its upper part has been thrown off4     
,such a rupture was clearly caused by an
 upward but oblique movement1 which in  
the first half of the oscillation heaved
 the structure upwardly into the        
northwest1 and then in the second half1 
or rebound1 drew the mass of the        
building away from the unsupported      
corner1 allowing that part of the       
masonry to fly off and fall to the      
ground4 ,constructing a line at right   
angles to the plane of the fracture1 it 
will be found to intersect the plane1   
the position of which has been in part  
determined by finding the line where it 
intersects the earth1 or the seismic    
vertical before noted4 ,multiplying such

 observations on either side of the     
last-mentioned line1 the attitude of the
 underground parts of the plane1 as well
 as the depth to which it attained1 can 
be approximately determined4  ,it is    
worth while to consider the extent to   
which earthquake shocks may affect the  
general quality of the people who dwell 
in countries where these disturbances   
occur with such frequency and violence  
as to influence their lives4 ,there can 
be no question that wherever earthquakes
 occur in such a measure as to produce  
widespread terror1 where1 recurring from
 time to time1 they develop in men a    
sense of abiding insecurity1 they become
 potent agents of degradation4 ,all the 
best which men do in creating a         
civilization rests upon a sense of      
confidence that their efforts may be    
accumulated from year to year1 and that 
even after death the work of each man   
may remain as a heritage to his kind4   
,it is likely1 indeed1 that in certain  
realms1 as in southern ,italy1 a part of

 the failure of the people to advance in
 culture is due to their long experience
 of such calamities1 and the natural    
expectation that they will from time to 
time recur4 ,in a similar way the       
,spanish settlements in ,central and    
,south ,america1 which lie mostly in    
lands that are subject to disastrous    
shocks1 may have been retarded by the   
despair1 as well as the loss of property
 and life1 which these accidents have so
 frequently inflicted upon them4 ,it    
will not do1 however1 to attribute too  
much to such terrestrial influences4 ,by
 far the most important element in      
determining the destiny of a people is  
to be found in their native quality1    
that which they owe to their ancestors  
of distant generations4 ,in this        
connection it is well to consider the   
history of the ,icelandic people1 where 
a small folk has for a thousand years   
been exposed to a range and severity of 
trials1 such as earthquakes1 volcanic   
explosions1 and dearth of harvests may  

produce1 and all these in a measure that
 few if any other countries experience4 
,notwithstanding these misfortunes1 the 
,icelanders have developed and          
maintained a civilization which in all  
else1 except its material results1 on   
the average transcends that which has   
been won by any other folk in modern    
times4 ,if a people have the determining
 spirit which leads to high living1 they
 can successfully face calamities far   
greater than those which earthquakes    
inflict4  ,it was long supposed that the
 regions where earthquakes are not      
noticeable by the unaided senses were   
exempt from all such disturbances4 ,the 
observations which seismologists have   
made in recent years point to the       
conclusion that no part of the earth's  
surface is quite exempt from movements  
which1 though not readily perceived1 can
 be made visible by the use of          
appropriate instruments4 ,with an       
apparatus known as the horizontal       
pendulum it is possible to observe      

vibrations which do not exceed in       
amplitude the hundredth part of an inch4
 ,this mechanism consists essentially of
 a slender bar supported near one end by
 two wires1 one from above1 the other   
from below4 ,it may readily be conceived
 that any measurable movement will cause
 the longer end of the rod to sway      
through a considerable arc4 ,wherever   
such a pendulum has been carefully      
observed in any district1 it has been   
found that it indicates the occurrence  
of slight tremors4 ,even certain changes
 of the barometer1 which alter the      
weight of the atmosphere that rests upon
 the earth to the amount indicated by an
 inch in the height of the mercury      
column1 appears in all cases to create  
such tremors4 ,many of these slight     
shocks may be due to the effect of more 
violent quakings1 which have run perhaps
 for thousands of miles from their point
 of origin1 and have thus been reduced  
in the amplitude of their movement4     
,others are probably due to the slight  

motion brought about through the        
chemical changes of the rocks1 which are
 continuously going on4 ,the ease with  
which even small motions are carried to 
a great distance may be judged by the   
fact that when the ground is frozen the 
horizontal pendulum will indicate the   
jarring due to a railway train at the   
distance of a mile or more from the     
track4  ,in connection with the earth   
jarring1 it would be well to note the   
occurrence of another1 though physically
 different1 kind of movement1 which we  
may term earth swayings1 or massive     
movements1 which slowly dislocate the   
vertical1 and doubtless also the        
horizontal1 position of points upon its 
surface4 ,it has more than once been    
remarked that in mountain countries1    
where accurate sights have been taken1  
the heights of points between the       
extremities of a long line appear       
somewhat to vary in the course of a term
 of years4 ,thus at a place in the      
,apennines1 where two buildings         

separated by some miles of distance are 
commonly intervisible over the crest of 
a neighbouring peak1 it has happened    
that a change of level of some one of   
the points has made it impossible to see
 the one edifice from the other4        
,knowing as we do that the line of the  
seacoast is ever-changing1 uprising     
taking place at some points and         
down-sinking at others1 it seems not    
unlikely that these irregular swayings  
are of very common occurrence4          
,moreover1 astronomers are beginning to 
remark the fact that their observatories
 appear not to remain permanently in the
 same position--that is1 they do not    
have exactly the same latitude and      
longitude4 ,certain of these changes    
have recently been explained by the     
discovery of a new and hitherto unnoted 
movement of the polar axis4 ,it is not  
improbable1 however1 that the irregular 
swaying of the earth's crust1 due to the
 folding of strata and to the           
alterations in the volume of rocks which

 are continually going on1 may have some
 share in bringing about these          
dislocations4  ,measured by the         
destruction which was wrought to the    
interests of man1 earthquakes deserve to
 be reckoned among the direst calamities
 of ,nature4 ,since the dawn of history 
the records show us that the destruction
 of life which is to be attributed to   
them is to be counted by the millions4  
,a catalogue of the loss of life in the 
accidents of this description which have
 occurred during the ,christian era has 
led the writer to suppose that probably 
over two million persons have perished  
from these shocks in the last nineteen  
centuries4 ,nevertheless1 as compared   
with other agents of destruction1 such  
as preventable disease1 war1 or famine1 
the loss which has been inflicted by    
earth movements is really trifling1 and 
almost all of it is due to an obstinate 
carelessness in the construction of     
buildings without reference to the risks
 which are known to exist in            

earthquake-ridden countries4  ,although 
all our exact knowledge concerning the  
distribution of earthquakes is limited  
to the imperfect records of two or three
 thousand years1 it is commonly possible
 to measure in a general way the        
liability to such accidents which may   
exist in any country by a careful study 
of the details of its topography4 ,in   
almost every large area the process of  
erosion naturally leaves quantities of  
rock1 either in the form of detached    
columns or as detrital accumulations    
deposited on steep slopes4 ,these       
features are of relatively slow         
formation1 and it is often possible to  
determine that they have been in their  
positions for a time which is to be     
measured by thousands of years4 ,thus1  
on inspecting a country such as ,north  
,america1 where the historic records    
cover but a brief time1 we may on       
inquiry determine which portions of its 
area have long been exempt from powerful
 shocks4 ,where natural obelisks and    

steep taluses abound--features which    
would have disappeared if the region had
 been moved by great shocks--we may be  
sure that the field under inspection has
 for a great period been exempt from    
powerful shaking4 ,judged by this       
standard1 we may safely say that the    
region occupied by the ,appalachian     
,mountains has been exempt from serious 
trouble4 ,so1 too1 the section of the   
,cordilleras lying to the east of what  
is commonly called the ,great ,basin1   
between the ,rocky ,mountains and the   
,sierra ,nevada1 has also enjoyed a long
 reign of peace4 ,in glaciated countries
 the record is naturally less clear than
 in those parts of the world which have 
been subjected to long-continued1 slow  
decay of the rocks4 ,nevertheless1 in   
those fields boulders are often found   
poised in position which they could not 
have maintained if subjected to violent 
shaking4 ,judged by this evidence1 we   
may say that a large part of the        
northern section of this continent1     

particularly the area about the ,great  
,lakes1 has been exempt from            
considerable shocks since the glacier   
passed away4  ,the shores which are     
subject to the visitations of the great 
marine waves1 caused by earthquake      
shocks occurring beneath the bottom of  
the neighbouring ocean1 are so swept by 
those violent inundations that they lose
 many features which are often found    
along coasts that have been exempted    
from such visitations4 ,thus wherever we
 find extensive and delicately moulded  
dunes1 poised stones1 or slender        
pinnacled rocks along a coast1 we may be
 sure that since these features were    
formed the district has not been swept  
by these great waves4  ,illustration3   
,fig4 #bb4--,poised rocks indicating a  
long exemption from strong earthquakes  
in the places where such features occur4
  ,around the northern ,atlantic we     
almost everywhere find the glacial waste
 here and there accumulated near the    
margin of the sea in the complicated    

sculptured outlines which are assumed by
 kame sands and gravels4 ,from a study  
of these features just above the level  
of high tide1 the writer has become     
convinced that the ,north ,atlantic     
district has long been exempt from the  
assaults of other waves than those which
 are produced during heavy storms4 ,at  
the present time the waves formed by    
earthquakes appear to be of destructive 
violence only on the west coast of      
,south ,america1 where they roll in from
 a region of the ,pacific lying to the  
south of the equator and a few hundred  
miles from the shore of the continent1  
which appears to be the seat of         
exceedingly violent shocks4 ,a similar  
field occurs in the ,atlantic between   
the ,lesser ,antilles and the ,spanish  
peninsula1 but no great waves have come 
thence since the time of the ,lisbon    
earthquake4 ,the basin of the ,caribbean
 and the region about ,java appear to be
 also fields where these disturbances   
may be expected1 though in each but one 

wave of this nature has been recorded4  
,therefore we may regard these secondary
 results of a submarine earthquake as   
seldom phenomena4                       
,,duration ,,of ,,geological ,,time4    
,although it is beyond the power of man 
to conceive any such lapses of time as  
have taken place in the history of this 
earth1 it is interesting1 and in certain
 ways profitable1 to determine as near  
as possible in the measure of years the 
duration of the events which are        
recorded in the rocks4 ,some            
astronomers1 basing their conclusions on
 the heat-containing power of matter1   
and on the rate at which energy in this 
form flows from the sun1 have come to   
the conclusion that our planet could not
 have been in independent existence for 
more than about twenty million years4   
,the geologist1 however1 resting his    
conclusions on the records which are the
 subject of his inquiry1 comes on many  
different lines to an opinion which     
traverses that entertained by some      

distinguished astronomers4 ,the ways in 
which the student of the earth arrives  
at this opinion will now be set forth4  
,by noting the amount of sediment       
carried forth to the sea by the rivers1 
the geologist finds that the lands of   
the earth--those1 at least1 which are   
protected by their natural envelopes of 
vegetation--are wearing down at a rate  
which pretty certainly does not exceed  
one foot in about five thousand years1  
or two hundred feet in a million years4 
,discovering at many places on the      
earth's surface deposits which          
originally had a thickness of five      
thousand feet or more1 which have been  
worn down to the depths of thousands of 
feet in a single rather brief section of
 geological time1 the student readily   
finds himself prepared to claim that a  
period of from five to ten million years
 has often been required for the        
accomplishment of but a very small part 
of the changes which he knows to have   
occurred on this earth4  ,as the        

geologist follows down through the      
sections of the stratified rocks1 and   
from the remains of strata determines   
the erosion which has borne away the    
greater part of the thick deposits which
 have been exposed to erosion1 he comes 
upon one of those breaks in the         
succession1 or encounters what is called
 an unconformity1 as when horizontal    
strata lie against those which are      
tilted4 ,in many cases he may observe   
that at this time there was a great     
interval unrepresented by deposits at   
the place where his observations are    
made1 yet a great lapse of time is      
indicated by the fact that a large      
amount of erosion took place in the     
interval between the two sets of beds4  
,putting together the bits of record1   
and assuming that the rate of erosion   
accomplished by the agents which operate
 on the land has always been about the  
same1 the geologist comes to the        
conclusion that the section of the rocks
 from the present day to the lowest     

strata of the ,laurentian represents in 
the time required for their formation   
not less than a hundred million years2  
more likely twice that duration4 ,to    
this argument objection is made by some 
naturalists that the agents of erosion  
may have been more active in the past   
than they are at present4 ,they suggest 
that the rainfall may have been much    
greater or the tides higher than they   
now are4 ,granting all that can be      
claimed on this score1 we note the fact 
that the rate of erosion evidently does 
not increase in anything like a         
proportionate way with the amount of    
rainfall4 ,where a country is protected 
by its natural coating of vegetation1   
the rain is delivered to the streams    
without making any considerable assault 
upon the surface of the earth1 however  
large the fall may be4 ,moreover1 the   
tides have little direct cutting power2 
they can only remove detritus which     
other agents have brought into a        
condition to be borne away4 ,the direct 

cutting power of the tidal movement does
 not seem to be much greater in the ,bay
 of ,fundy1 where the maximum height of 
the waves amounts to fifty feet1 than on
 the southern coast of ,massachusetts1  
where the range is not more than five4  
,so far as the observer can judge1 the  
climatal conditions and the other       
influences which affect the wear of     
rocks have not greatly varied in the    
past from what they are at the present  
day4 ,now and then there have been      
periods of excessive erosion2 again1    
ages in which large fields were in the  
conditions of exceeding drought4 ,it is1
 however1 a fair presumption that these 
periods in a way balance each other1 and
 that the average state was much like   
that which we find at present4  ,if     
after studying the erosive phenomena    
exhibited in the structure of the earth 
the student takes up the study of the   
accumulations of strata1 and endeavours 
to determine the time required for the  
laying down of the sediments1 he finds  

similar evidence of the earth's great   
antiquity4 ,although the process of     
deposition1 which has given us the rocks
 visible in the land masses1 has been   
very much interrupted1 the section which
 is made by grouping the observations   
made in various fields shows that       
something like a maximum thickness of a 
hundred and fifty thousand feet of beds 
has been accumulated in that part of    
geologic time during which strata were  
being laid down in the fields that are  
subjected to our study4 ,although in    
these rocks there are many sets of beds 
which were rapidly formed1 the greater  
part of them have been accumulated with 
exceeding slowness4 ,many fine shales1  
such as those which plentifully occur in
 the ,devonian beds of this country1    
must have required a thousand years or  
more for the deposition of the materials
 that now occupy an inch in depth4 ,in  
those sections a single foot of the rock
 may well represent a period of ten     
thousand years4 ,in many of the         

limestones the rate of accumulation     
could hardly have been more speedy4 ,the
 reckoning has to be rough1 but the     
impression which such studies make upon 
the mind of the unprejudiced observer is
 to the effect that the thirty miles or 
so of sedimentary deposits could not    
have been formed in less than a hundred 
million years4 ,in this reckoning it    
should be noted that no account is taken
 of those great intervals of unrecorded 
time1 such as elapsed between the close 
of the ,laurentian and the beginning of 
the ,cambrian periods4  ,there is a     
third way in which we may seek an       
interpretation of duration from the     
rocks4 ,in each successive stage of the 
earth's history1 in different measure in
 the various ages1 mountains were formed
 which in time1 during their exposure to
 the conditions of the land1 were worn  
down to their roots and covered by      
deposits accumulated during the         
succeeding ages4 ,a score or more of    
these successively constructed series of

 elevations may readily be observed4 ,of
 old1 it was believed that mountain     
ranges were suddenly formed1 but there  
is1 however1 ample evidence to prove    
that these disturbed portions of the    
strata were very gradually dislocated1  
the rate of the mountainous growth      
having been1 in general1 no greater in  
the past than it is at the present day1 
when1 as we know full well1 the         
movements are going on so slowly that   
they escape observation4 ,only here and 
there1 as an attendant on earthquake    
shocks or other related movements of the
 crust1 do we find any trace of the     
upward march which produces these       
elevations4 ,although not a subject for 
exact measurements1 these features of   
mountain growth indicate a vast lapse of
 time1 during which the elevations were 
formed and worn away4  ,yet another and 
very different method by which we may   
obtain some gauge of the depths of the  
past is to be found in the steps which  
have led organic life from its lowest   

and earliest known forms to the present 
state of advancement4 ,taking the       
changes of species which have occurred  
since the beginning of the last ice     
epoch1 we find that the changes which   
have been made in the organic life have 
been very small2 no naturalist who has  
obtained a clear idea of the facts will 
question the statement that they are not
 a thousandth part of the alterations   
which have occurred since the           
,laurentian time4 ,the writer is of the 
opinion that they do not represent the  
ten thousandth part of those vast       
changes4 ,these changes are limited in  
the main to the disappearance of a few  
forms1 and to slight modifications in   
those previously in existence which have
 survived to the present day4 ,so far as
 we can judge1 no considerable step in  
the organic series has taken place in   
this last great period of the earth's   
history1 although it has been a period  
when1 as before noted1 all the          
conditions have combined to induce rapid

 modifications in both animals and      
plants4 ,if1 then1 we can determine the 
duration of this period1 we may obtain a
 gauge of some general value4  ,although
 we can not measure in any accurate way 
the duration of the events which have   
taken place since the last ,glacial     
period began to wane1 a study of the    
facts seems to show that less than a    
hundred thousand years can not well be  
assumed for this interval4 ,some of the 
students who have approached the subject
 are disposed to allow a period of at   
least twice this length as necessary for
 the perspective which the train of     
events exhibits4 ,reckoning on the      
lowest estimate1 and counting the       
organic changes which take place during 
the age as amounting to the thousandth  
part of the organic changes since the   
,laurentian age1 we find ourselves in   
face once again of that inconceivable   
sum which was indicated by the physical 
record4  ,here1 again1 the critics      
assert that there may have been periods 

in the history of the earth when the    
changes of organic life occurred in a   
far swifter manner than in this last    
section of the earth's history4 ,this   
supposition is inadmissible1 for it     
rests on no kind of proof2 it is1       
moreover1 contraindicated by the evident
 fact that the advance in the organic   
series has been more rapid in recent    
time than at any stage of the past4 ,in 
a word1 all the facts with which the    
geologist deals are decidedly against   
the assumption that terrestrial changes 
in the organic or the inorganic world   
ever proceed in a spasmodic manner4     
,here and there1 and from time to time1 
local revolutions of a violent nature   
undoubtedly occur1 but1 so far as we may
 judge from the aspect of the present or
 the records of the past1 these         
accidents are strictly local2 the earth 
has gone forward in its changes much as 
it is now advancing4 ,its revolutions   
have been those of order rather than    
those of accident4  ,the first duty of  

the naturalist is to take ,nature as he 
finds it4 ,he must avoid supposing any  
methods of action which are not clearly 
indicated in the facts that he observes4
 ,the history of his own and of all     
other sciences clearly shows that danger
 is always incurred where suppositions  
as to peculiar methods of action are    
introduced into the interpretation4 ,it 
required many centuries of labour before
 the students of the earth came to adopt
 the principle of explaining the        
problems with which they had to deal by 
the evidence that the earth submitted to
 them4 ,wherever they trusted to their  
imaginations for guidance1 they fell    
into error4 ,those who endeavour to     
abbreviate our conception of geologic   
time by supposing that in the olden days
 the order of events was other than that
 we now behold are going counter to the 
best traditions of the science4         
,although the aspect of the record of   
life since the beginning of the         
,cambrian time indicates a period of at 

least a hundred million years1 it must  
not be supposed that this is the limit  
of the time required for the development
 of the organic series4 ,all the        
important types of animals were already 
in existence in that ancient period with
 the exception of the vertebrates1 the  
remains of which have apparently now    
been traced down to near the ,cambrian  
level4 ,in other words1 at the stage    
where we first find evidence of living  
beings the series to which they belong  
had already climbed very far above the  
level of lifeless matter4 ,few          
naturalists will question the statement 
that half the work of organic advance   
had been accomplished at the beginning  
of the ,cambrian rocks4 ,the writer is  
of the opinion that the development     
which took place before that age must   
have required a much longer period than 
has elapsed from that epoch to the      
present day4 ,we thus come to the       
conclusion that the measurement of      
duration afforded by organic life       

indicates a yet more lengthened claim of
 events1 and demands more time than     
appears to be required for the formation
 of the stratified rocks4  ,the index of
 duration afforded by the organic series
 is probably more trustworthy than that 
which is found in the sedimentary       
strata1 and this for the reason that the
 records of those strata have been      
subjected to numerous and immeasurable  
breaks1 while the development of organic
 life has of necessity been perfectly   
continuous4 ,the one record can at any  
point be broken without interrupting the
 sequences2 the other does not admit of 
any breaches in the continuity4         
,,the ,,moon4  ,set over against the    
earth--related to1 yet contrasted with  
it in many ways--the moon offers a most 
profitable object to the student of     
geology4 ,he should often turn to it for
 those lessons which will be briefly    
noted4  ,in the beginning of their      
mutual history the materials of earth   
and moon doubtless formed one vaporous  

body which had been parted from the     
concentrating mass of the sun in the    
manner noted in the sketch of the       
history of the solar system4 ,after the 
earth-moon body had gathered into a     
nebulous sphere1 it is most likely that 
a ring resembling that still existing   
about ,saturn was formed about the      
earth1 which in time consolidated into  
the satellite4 ,thenceforth the two     
bodies were parted1 except for the      
gravitative attraction which impelled   
them to revolve about their common      
centre of gravity1 and except for the   
light and heat they might exchange with 
one another4  ,the first stages after   
the parting of the spheres of earth and 
moon appear to have been essentially the
 same in each body4 ,concentrating upon 
their centres1 they became in time fluid
 by heat2 further on1 they entered the  
rigid state--in a word1 they froze--at  
least in their outer parts4 ,at this    
point in their existence their histories
 utterly diverge2 or rather1 we may say1

 the development of the earth continued 
in a vast unfolding1 while that of the  
moon appears to have been absolutely    
arrested in ways which we will now      
describe4  ,with the naked eye we see on
 the moon a considerable variation in   
the light of different parts of its     
surface2 we discern that the darker     
patches appear to be rudely circular1   
and that they run together on their     
margins4 ,seeing this little1 the       
ancients fancied that our satellite had 
seas and lands like the earth4 ,the     
first telescopes did not dispel their   
fancies2 even down to the early part of 
this century there were astronomers who 
believed the moon to be habitable2      
indeed1 they thought to find evidence   
that it was the dwelling place of       
intelligent beings who built cities1 and
 who tried to signal their intellectual 
kindred of this planet4 ,when1 however1 
strong glasses were applied to the      
exploration1 these pleasing fancies were
 rudely dispelled4  ,seen with a        

telescope of the better sort1 the moon  
reveals itself to be in large part made 
up of circular depressions1 each        
surrounded by a ringlike wall1 with     
nearly level but rough places between4  
,the largest of these walled areas is   
some four hundred miles in diameter2    
thence they grade down to the smallest  
pits which the glass can disclose1 which
 are probably not over as many feet     
across4 ,the writer1 from a careful     
study of these pits1 has come to the    
conclusion that the wider are the older 
and the smaller the last formed4 ,the   
rude elevations about these pits--some  
of which rise to the height of ten      
thousand feet or more--constitute the   
principal topographic reliefs of the    
lunar surface4 ,besides the pits above  
mentioned1 there are numerous fractures 
in the surface of the plains and        
ringlike ridges2 on the most of these   
the walls have separated1 forming       
trenches not unlike what we find in the 
case of some terrestrial breaks such as 

have been noted about volcanoes and     
elsewhere4 ,it may be that the so-called
 canals of ,mars are of the same nature4
  ,illustration3 ,fig4 #bc4--,lunar     
mountains near the ,gulf of ,iris4  ,the
 most curious feature on the moon's     
surface are the bands of lighter colour1
 which1 radiating from certain of the   
volcanolike pits--those of lesser size  
and probably of latest origin--extend in
 some cases for five hundred miles or   
more across the surface4 ,these light   
bands have never been adequately        
explained4 ,it seems most likely that   
they are stains along the sides of      
cracks1 such as are sometimes observed  
about volcanoes4  ,the eminent          
peculiarity of the moon is that it is   
destitute of any kind of gaseous or     
aqueous envelope4 ,that there is no     
distinct atmosphere is clearly shown by 
the perfectly sharp and sudden way in   
which the light of a star disappears    
when it goes behind the moon and the    
clear lines of the edge of the satellite

 in a solar eclipse4 ,the same evidence 
shows that there is no vapour of water2 
moreover1 a careful search which the    
writer has made shows that the surface  
has none of those continuous down grades
 which mark the work of water flowing   
over the land4 ,nearly all of the       
surface consists of shallow or deep     
pits1 such as could not have been formed
 by water action4 ,we therefore have not
 only to conclude that the moon is      
waterless1 but that it has been in this 
condition ever since the part that is   
turned toward us was shaped4  ,as the   
moon1 except for the slight movement    
termed its libration1 always turns the  
same face to us1 so that we see in all  
only about four sevenths of its surface1
 it has naturally been conjectured that 
the unseen side1 which is probably some 
miles lower than that turned toward us1 
might have a different character from   
that which we behold4 ,there are reasons
 why this is improbable4 ,in the first  
place1 we see on the extreme border of  

the moon1 when the libration turns one  
side the farthest around toward the     
earth1 the edge of a number of the great
 walled pits such as are so plenty on   
the visible area2 it is fair to assume  
that these rings are completed in the   
invisible realm4 ,on this basis we can  
partly map about a third of the hidden  
side4 ,furthermore1 there are certain   
bands of light which1 though appearing  
on the visible side1 evidently converge 
to some points on the other4 ,it is     
reasonable to suppose that1 as all other
 bands radiate from walled pits1 these  
also start from such topographic        
features4 ,in this way certain          
likenesses of the hidden area to that   
which is visible is established1 thus   
making it probable that the whole       
surface of the satellite has the same   
character4  ,clearly as the greater part
 of the moon is revealed to us--so      
clearly1 indeed1 that it is possible to 
map any elevation of its surface that   
attains the height of five hundred      

feet--the interpretation of its features
 in the light of geology is a matter of 
very great difficulty4 ,the main points 
seem to be tolerably clear2 they are as 
follows3 ,the surface of the moon as we 
see it is that which was formed when    
that body1 passing from the state of    
fluidity from heat1 formed a solid      
crust4 ,the pits which we observe on its
 surface are the depressions which were 
formed as the mass gradually ceased to  
boil4 ,the later formed of these        
openings are the smaller1 as would be   
the case in such a slowing down of a    
boiling process4  ,as the diameter of   
the moon is only about one fourth of    
that of the earth1 its bulk is only     
about one sixteenth of that of its      
planet2 consequently1 it must have      
cooled to the point of solidification   
ages before the larger sphere attained  
that state4 ,it is probable that the    
same changeless face that we see looked 
down for millions of years on an earth  
which was still a seething1 fiery mass4 

,in a word1 all that vast history which 
is traceable in the rocks beneath our   
feet--which is in progress in the seas  
and lands and is to endure for an       
inconceivable time to come--has been    
denied our satellite1 for the reason    
that it had no air with which to entrap 
the solar heat and no water to apply the
 solar energy to evolutionary processes4
 ,the heat which comes upon the moon as 
large a share for each equal area as it 
comes upon the earth flies at once away 
from the airless surface1 at most giving
 it a temporary warmth1 but instituting 
no geological work unless it be a little
 movement from the expansion and        
contraction of the rocks4 ,during the   
ages in which the moon has remained thus
 lifeless the earth1 owing to its air   
and water1 has applied a vast amount of 
solar energy to geological work in the  
development and redevelopment of its    
geological features and to the processes
 of organic life4 ,we thus see the      
fundamental importance of the volatile  

envelopes of our sphere1 how absolutely 
they have determined its history4  ,it  
would be interesting to consider the    
causes which led to the absence of air  
and water on the moon1 but this matter  
is one of the most debatable of all that
 relates to that sphere2 we shall       
therefore have to content ourselves with
 the above brief statements as to the   
vast and far-acting effects which have  
arisen from the non-existence of those  
envelopes on our nearest neighbour of   
the heavens4                            
,,methods ,,in ,,studying ,,geology4    
,so far as possible the preceding pages1
 by the method adopted in the           
presentation of facts1 will serve to    
show the student the ways in which he   
may best undertake to trace the order of
 events exhibited in the phenomena of   
the earth4 ,following the plan pursued1 
we shall now consider certain special   
points which need to be noted by those  
who would adopt the methods of the      
geologist4  ,at the outset of his       

studies it may be well for the inquirer 
to note the fact that familiarity with  
the world about him leads the man in all
 cases to a certain neglect and contempt
 of all the familiar presentations of   
,nature4 ,we inevitably forget that     
those points of light in the firmament  
are vast suns1 and we overlook the fact 
that the soil beneath our feet is not   
mere dirt1 but a marvellous structure1  
more complicated in its processes than  
the chemist's laboratory1 from which the
 sustenance of our own and all other    
lives is drawn4 ,we feel our own bodies 
as dear but commonplace possessions1    
though we should understand them as     
inheritances from the inconceivable     
past1 which have come to us through tens
 of thousands of different species and  
hundreds of millions of individual      
ancestors4 ,we must overlook these      
things in our common life4 ,if we could 
take them into account1 each soul would 
carry the universe as an intellectual   
burden4  ,it is1 however1 well from time

 to time to contemplate the truth1 and  
to force ourselves to see that all this 
apparently simple and ordinary medley of
 the world about us is a part of a vast 
procession of events1 coming forth from 
the darkness of the past and moving on  
beyond the light of the present day4    
,even in his professional work the      
naturalist of necessity falls into the  
commonplace way of regarding the facts  
with which he deals4 ,if he be an       
astronomer1 he catalogues the stars with
 little more sense of the immensities   
than the man who keeps a shop takes     
account of his wares4 ,nevertheless1 the
 real profit of all learning is in the  
largeness of the understanding which it 
develops in man4 ,the periods of growth 
in knowledge are those in which the     
mind1 enriched by its store1 enlarges   
its conception while it escapes from    
commonplace ways of thought4 ,with this 
brief mention of what is by far the most
 important principle of guidance which  
the student can follow1 we will turn to 

the questions of method that the student
 need follow in his ordinary work4      
,with almost all students a difficulty  
is encountered which hinders them in    
acquiring any large views as to the     
world about them4 ,this is due to the   
fact that they can not make and retain  
in memory clear pictures of the things  
they see4 ,they remember words rather   
than things--in fact1 the training in   
language1 which is so large a part of an
 education1 tends ever to diminish the  
element of visual memory4 ,the first    
task of the student who would become a  
naturalist is to take his knowledge from
 the thing1 and to remember it by the   
mental picture of the thing4 ,in all    
education in ,nature1 whether the       
student is guided by his own            
understanding or that of the teacher1 a 
first and very continuous aim should be 
to enforce the habit of recalling very  
distinct images of all objects which it 
is desired to remember4 ,to this end the
 student should practise himself by     

looking intently upon a landscape or any
 other object2 then1 turning away1 he   
should try to recall what he has beheld4
 ,after a moment the impression by the  
sight should be repeated1 and the study 
of the memory renewed4 ,the writer knows
 by his own experience that even in     
middle-aged people1 where it is hard to 
breed new habits1 such deliberate       
training can greatly increase the       
capacity of the memory for taking in and
 reproducing images which are deemed of 
importance4 ,practice of this kind      
should form a part of every naturalist's
 daily routine4 ,after a certain time1  
it need not be consciously done4 ,the   
movements of thought and action will1   
indeed1 become as automatic as those    
which the trained fencer makes with his 
foil4  ,along with the habit of         
visualizing memories1 and of storing    
them without the use of words1 the      
student should undertake to enlarge his 
powers of conceiving spaces and         
directions as they exist in the field   

about him4 ,among savages and animals   
below the grade of man1 this            
understanding of spacial relations is   
very clear and strong4 ,it enables the  
primitive man to find his way through   
the trackless forest1 and the carrier   
pigeon to recover his mate and dwelling 
place from the distance of hundreds of  
miles away4 ,in civilized men1 however1 
the habit of the home and street and the
 disuse of the ancient freedom has      
dulled1 and in some instances almost    
destroyed1 all sense of this shape of   
the external world4 ,the best training  
to recover this precious capacity will  
now be set forth4  ,the student should  
begin by drawing a map on a true scale1 
however roughly the work may be done1 of
 those features of the earth about him  
with which he is necessarily most       
familiar4 ,the task may well be begun   
with his own dwelling or his schoolroom4
 ,thence it may be extended so as to    
include the plan of the neighbouring    
streets or fields4 ,at first1 only      

directions and distances should be      
platted4 ,after a time to these         
indications should be added on the map  
lines indicating in a general way       
contours or the lines formed by         
horizontal planes intersecting the area 
subject to delineation4 ,after attaining
 certain rude skill in such work1 the   
student may advantageously make         
excursions to districts which he can see
 only in a hurried way4 ,as he goes1 he 
should endeavour to note on a sketch map
 the positions of the hills and streams 
and the directions of the roads4 ,a year
 of holiday practice in such work will1 
if the tasks occupy somewhere about a   
hundred hours of his time1 serve greatly
 to extend or reawaken what may be      
called the topographic sense1 and enable
 him to place in terms of space the     
observations of ,nature which he may    
make4  ,in his more detailed work the   
student should select some particular   
field for his inquiry4 ,if he be        
specially interested in geologic        

phenomena1 he will best begin by noting 
two classes of facts--those exhibited in
 the rocks as they actually appear in   
the state of repose as shown in the     
outcrops of his neighbourhood1 and those
 shown in the active manifestations of  
geological work1 the decay of the rocks 
and the transportation of their waste1  
or1 if the conditions favour1 the       
complicated phenomena of the seashores4 
,as soon as the student begins to       
observe1 he should begin to make a      
record of his studies4 ,to the novice in
 any science written1 and particularly  
sketched1 notes are of the utmost       
importance4 ,these1 whether in words or 
in drawings1 should be made in face of  
the facts2 they should1 indeed1 be set  
down at the close of an observation1    
though not until the observer feels that
 the object he is studying has yielded  
to him all which it can at that time    
give4 ,it is well to remark that where a
 record is made at the outset of a study
 the student is apt to feel that he is  

in some way pledged to shape all he may 
see to fit that which he has first      
written4 ,in his early experience as a  
teacher1 the writer was accustomed to   
have students compare their work of     
observation and delineation with that   
done by trained men on the same ground4 
,it now seems to him best for the       
beginner at first to avoid all such     
reference of his own work to that of    
others4 ,so great is the need of        
developing independent motive that it is
 better at the outset to make many      
blunders than to secure accuracy by     
trust in a leader4 ,the skilful teacher 
can give fitting words of caution which 
may help a student to find the true way1
 but any reference of his undertakings  
to masterpieces is sure to breed a      
servile habit4 ,therefore such          
comparisons are fitting only after the  
habit of free work has been well formed4
 ,the student who can afford the help of
 a master1 or1 better1 the assistance of
 many1 such as some of our universities 

offer1 should by all means avail himself
 of this resource4 ,more than any other 
science1 geology1 because of the        
complexity of the considerations with   
which it has to deal1 depends upon      
methods of labour which are to a great  
extent traditional1 and which can not1  
indeed1 be well transmitted except in   
the personal way4 ,in the distinctly    
limited sciences1 such as mathematics1  
physics1 or even those which deal with  
organic bodies1 the methods of work can 
be so far set forth in printed          
directions that the student may to a    
great extent acquire sound ways of work 
without the help of a teacher4          
,although there is a vast and important 
literature concerning geology1 the      
greater part of it is of a very special 
nature1 and will convey to the beginner 
no substantial information whatever4 ,it
 is not until he has become familiar    
with the field with which he is enabled 
to deal in the actual way that he can   
transfer experience thus acquired to    

other grounds4 ,therefore beyond the    
pleasing views which he may obtain by   
reading certain general works on the    
science1 the student should at the      
outset of his inquiry limit his work as 
far as possible to his field of         
practice1 using a good text-book1 such  
as ,dana's ,manual of ,geology1 as a    
source of suggestions as to the problems
 which his field may afford4  ,the main 
aim of the student in this1 as in other 
branches of inquiry1 is to gain practice
 in following out the natural series of 
actions4 ,to the primitive man the      
phenomenal world presents itself as a   
mere phantasmagoria1 a vast show in     
which the things seen are only related  
to each other by the fact that they come
 at once into view4 ,the end of science 
is to divine the order of this host1 and
 the ways in which it is marshalled in  
its onward movement and the ends to     
which its march appears to be directed4 
,so far as the student observes well1   
and thus gains a clear notion of        

separated facts1 he is in a fair way to 
gather the data of knowledge which may  
be useful2 but the real value of these  
discernments is not gained until the    
observations go together1 so as to make 
something with a perspective4 ,until the
 store of separate facts is thus        
arranged1 it is merely crude material   
for thought2 it is not in the true      
meaning science1 any more than a store  
of stone and mortar is architecture4    
,when the student has developed an      
appetite for the appreciation of order  
and sources of energy in phenomena1 he  
has passed his novitiate1 and becomes   
one of that happy body of men who not   
only see what is perceived by the mass  
of their fellows1 but are enabled to    
look through those chains of action     
which1 when comprehended1 serve to      
rationalize and ennoble all that the    
senses of man1 aided by the instruments 
which he has devised1 tell us concerning
 the visible world4                     
,,index4      tna1 ,mount1 #cha4        

,agriculture1       ,american1 #cdf2    
in ,england1 winning swamp lands for1   
#cce2       recent developments of1     
#cde4      ,alaska1 changes on the coast
 of1 #if4      ,ants taking food        
underground1 #cai2       work of the1 on
 the soil1 #cah4      ,apsides1         
revolution of the1 #fa1 #fb4            
,arabians1 chemical experiments of the1 
#ac4      ,arches1 natural1 in cavern   
districts1 #beh4      ,artesian wells1  
#beh1 #bei4      ,arts1 advance of      
,italian fine1 #ai4      ,asteroids1    
#ec2       motions of1 about their      
centres and about the sun1 #ec4         
,astronomers1 the solar system and the  
early1 #gi4      ,astronomy1 #ca-hj2    
growth of1 since the time of ,galileo1  
#cc1 #cd2       the first science1 #aj4 
,atmosphere1 #ig-bjf2       along the   
tropical belt1 #ajb2       as a medium  
of communication between different      
regions1 #ii2       deprived of water1  
containing little heat1 #aje2           
beginning of the science of the1 #aag2  

counter-trade movements of the1 #aje2   
envelope of the earth1 #ih2             
expansion of1 in a hollow wall during   
the passage of a storm1 #aad2           
heat-carrying power of the1 #aje2       
heights to which it extends1 #ii2       
in water1 #ii2       movements no direct
 influence on the surface of the earth1 
#abb2       movements of the1 qualified 
by the condition which             it   
encounters1 #aah2       of mountains1   
#ih2       of the seashore1 #ih2        
of the earth1 #ih2       of the sun1    
#gc2       snow as an evidence of1 #fe2 
supplying needs of underground          
creatures1 #cca2       uprushes of1     
#aja1 #ajb2       upward strain of the1 
next the earth1 #ajg2       weight and  
motion of the1 #abj1 #aba4              
,atmospheric circulation of the soil1   
#ccj1 #cca2       envelopes1 #ig4       
,aurora borealis1 #afh4                 
,avalanches1 #baj-bac2       dreaded1 in
 the ,alpine regions1 #bab2       great1
 in the ,swiss ,oberland1 #baa1 #bab2   

rocky1 #age-agg4      ,axis1            
imaginary changes in the earth's1 #ei2  
of the earth's rotation1 #eh2           
polar1 inclined position of1 #eh2       
polar1 nodding movement of the axes1    
#ed2       rotations of the planetary   
spheres on their axes1 #ef4             
,barometer1 causes of changes in the1   
#aag1 #aah4      ,basalts1 #cji4        
,beaches1 #ic1 #adb1 #add2              
boulder1 #adb1 #adc2       pebbly1 #adb2
       sand1 #add4      ,beetles1 work  
of1 on the soil1 #cah1 #cai4            
,belief of the early astronomers about  
the solar system1 #gi4                  
,bergschrund1 the1 #bad4      ,birds and
 mammals contributing to the fertility  
of the soil1 #cai4      ,blanketing1    
#bfi4      ,bogs1       climbing1       
#cca-ccd2       lake1 #cca-ccc2         
peat1 #ccd1 #cce2       quaking1 #ccd4  
,botany1 rapid advance in1 #ad1 #ae4    
,boulders1 #bag1 #bbj4      ,breakers1  
#ace1 #acg1 #aci4      ,bridges1        
natural1 #beg1 #beh4       ,canals of   

,mars1 #fg4      ,caon1 newly formed    
river cutting a1 #aie4      ,cataracts1 
#aic4      ,caves1 #bec-beh1 #bfa2      
architecture of1 #bee-beh2              
hot-water1 #bfa2       mammoth cave1    
#beh2       stalactites and stalagmites 
on the roof and floor of1 #beg4         
,chasms1 #adj1 #ada4      ,chemistry1   
#f1 #ab1 #ad2       advance of1 #ab2    
modern1 evolving from the studies of    
alchemists1 #ac1 #ad4                   
,chromosphere1 #gc4      ,civilization  
of the ,icelanders1 #chd4      ,cliffs1 
sea-beaten1 #acb1 #ada1 #adb4           
,climate1       changes of1 due to      
modifications of the ocean streams1     
#aec2       effect of the ocean on the1 
#adg2       of the ,gulf ,stream1 #adi1 
#aej4      ,clouds1 #aei2               
formation of1 #afb1 #afc2       shape   
of1 #afc2       water of1 usually       
frozen1 #bjg2       cloud-making1 laws  
of1 #afa1 #afb4      ,coast1            
changes on the ,scandinavian1 #if2      
line1 effect of tide on the1 #ade2      

of ,greenland1 #bbf2       of ,new      
,jersey sinking1 #ie2       marine1     
changes in1 #ie4      ,cold in ,siberia1
 #bdc4      ,comets1 #dg1 #ej2          
collisions of1 #ej2       kinship of    
meteorites and1 #dh2       omens of     
calamity to the ancients1 #ej2       the
 great1 of #ahaa1 #di1 #ej4      ,cones4
 ,see under ,,volcanoes4      ,conflict 
between religion and science1 #bj1 #bb2 
between the ,protestant countries and   
the followers of science1 #bj4          
,continental shelves1 #abe4             
,continents and oceans1 #hc2            
changes in position of1 #ia2            
cyclones of the1 #aaa2       forms of1  
#ij2       proofs that they have endured
 for many years1 #ib2       shape of1   
#hd1 #if4      ,coral reefs1 #aec1 #cec4
      ,corona1 realm of the1 #gc4       
,craters4 ,see under ,,volcanoes4       
,crevasse1 a barrier to the explorer1   
#bah4      ,crevice water1 #bej4        
,curds1 #bad4      ,currents1           
coral reefs in ,florida affecting the   

velocity of1 #aec2       equatorial1    
#aej2       of the ,gulf ,stream1       
#adg-adi2       hot and cold1 of the    
sea1 #ajb2       ocean1 #ade2           
oceanic action of trade winds on1 #ade2 
effect on migration of1 #aeg2           
icebergs indicating1 #bdc2              
surface1 history of1 #agb2              
uprushing1 near the equator1 #ajf4      
,cyclones1 #aaa2       cause of1 #aaa2  
of ,north ,america1 #aaa2               
secondary storms of1 #aab4              
,deltas1 #agc1 #ahg4      ,deposits1    
vein1 #bfj1 #bfa4      ,deserts1        
interior1 #aeh4      ,dew1 #aei1 #afj2  
a concomitant of cloudless skies1 #afj1 
and vegetation1 #afj2       formation   
of1 #aei-afa4      ,diablerets1 #agd4   
,diagram of a vein1 #bfj2       showing 
development of swamp1 #cce2       how a 
portion of the earth's surface may be   
sunk by faulting1 #cgd2       growth of 
mangroves1 #cdj2       the effect of the
 position of the fulcrum point          
in the movement of the land masses1 #id4

      ,diameter of our sphere at the    
equator1 #fb2        of the earth1 #hb4 
,dikes1 #aib1 #bic2 #cje-caj2           
abounding in volcanic cones1 #cje2      
cutting through coal1 #cjf2       driven
 upward1 #cjg2       formation of1 #cje1
 #caj2       material of1 #cjg1 #cjh2   
representing movements of softened rock1
 #cji2       their relation to volcanic 
cones1 #cjg2       variations of the    
materials of1 #cjg1 #cjh2               
waterfalls produced by1 #aib2       zone
 of1 #cjf4      ,dismal ,swamp1 #ie1    
#ccc4      ,distances1       general    
idea of1 #bg2       good way to study1  
#bg1 #bh2       training soldiers to    
measure1 #bh4      ,doldrums1 #ajd1     
#aji2       doldrum of the equator1     
#aji2       of the hurricane1 #aji4     
,drainage1 imperfect1 of a country      
affected by glaciers1 #bdb4      ,dunes1
 #abc1 #abd1 #cbe1 #cbf1 #chg2          
moulded1 #chg4      ,duration of        
geological time1 #chi4      ,dust       
accumulations from wind1 in ,china1     

#abb4       ,earth1       a flattened   
sphere1 #hb2       air envelope of the1 
#ih2       amount of heat falling from  
the sun on the1 #da2       antiquity of 
the1 #cia2       atmosphere of the1 #ih2
       attracting power of the1 #abg2   
axis of the rotation of the1 #eh2       
composition of the atmosphere of the1   
#ih2       crust of the1 affected by    
weight1 #ic2       deviation of the path
 of the1 varied1 #fa2       diameter of 
the1 #hb2         of the1 affected by   
loss of heat1 #aca2       difference in 
altitude of the surface of the1 #hc2    
discovery that it was globular1 #ca1    
#cb2       effect of imaginary changes  
in the relations of sun and1 #ei2       
effect of the interior heat of the1     
#cji1 #caj2       effect of the sun on  
the1 #fj1 #fa2       formerly in a fluid
 state1 #hb2       imaginary view of    
the1 from the moon1 #ha2       important
 feature of the surface of the1 #hc2    
jarring caused by faults1 #cfg2         
surface of the1 determined by heat and  

light from the sun1 #eg2       most     
important feature of the surface of the1
 #hc2       motion of the1 affecting the
 direction of trade winds1 #ajc2        
movements1 #cff2       natural          
architecture of the1 #cgg2       no part
 of the1 exempt from movement1 #chd2    
parting of the moon and1 #cif2          
path of the1 around the sun1 #ee1 #ef1  
#ei1 #fj2       revolving from east to  
west1 #ajc2       shrinking of the1 from
 daily escape of heat1 #hi2             
soil-covering of the1 #cdc2       study 
of the1 #ha-if2       swaying1 #che2    
tensions1 problem of1 #cga2             
tremors1 caused by chemical changes in  
the rocks1 #che2       tropical belt of 
the1 #gd2       viewed from the surface 
of the moon1 #caa1 #cab2       water    
store of the1 #abe4      ,earthquakes1  
#bgg1 #bgh1 #bhj1 #cef1 #ceh1 #cgj-chd1 
#chh-cij2       accidents of1 #ceh2     
action of1 #cef2       agents of        
degradation1 #chc1 #chd2       basis of1
 #cfg2       certain limitations to1    

#chj1 #cha2       ,charleston1 of #ahhc1
 #cgd1 #cge2       countries1           
architecture in1 #cha2       echoes1    
#cfi1 #cgj2       damages of1 #cgg1     
#cij2       effect of1         on the   
soil1 #cge2         the surface of the  
earth1 #cga2       formed by riving of  
fissures1 #chb2       great1 occurring  
where rocks have been                   
disturbed by mountain-building1 #cha1   
#chb2       ,herculaneum and ,pompeii   
destroyed by an1 #bgg1 #bhj2            
,italian1 in #aghc1 #cga1 #cgb2         
important1 not connected with volcanic  
explosions1 #cha2       ,jamaica1 in    
#afib1 #cgb1 #cgf2       ,lisbon1 in    
#agee1 #cfh1 #cfi1 #cgc1 #cgd1 #cha2    
maximum swing of1 #cfi2       measuring 
the liability to1 #chf1 #chg2           
mechanism of1 #cgj1 #cga2       method  
of the study of1 followed by ,mr4       
,charles ,mallet1 #chb1 #chc2           
,mississippi1 in #ahaa1 #cgc1 #cgd1     
#chj1 #cha2       movement of the earth 
during1 #cgg2       originating from a  

fault plane1 #cfg1 #cfi1 #cgj2          
originating from the seas1 #ceh1 #cge2  
oscillation of1 #cgf2       poised rocks
 indicating a long exemption from       
strong1 #chh2       ,riobamba1 in #agig1
 #cge2       shocks of1 and their effect
 upon people1 #chc2       the direct    
calamities of ,nature1 #chf2       waves
 of1 #chi4      ,earthworms1 #cag-cai2  
taking food underground1 #cai4          
,eclipses1 record of ancient1 #acj4     
,electrical action in the formation of  
rain and snow1 #afd4      ,elevations of
 seas and lands1 #hc4      ,energy      
indestructible1 #bc4      ,envelope1    
lower1 of the sun1 #gd4      ,equator1  
diameter of our sphere at the1 #fb2     
doldrum of the1 #aji2       updraught   
under the1 #ajb2       uprushing current
 near the1 #ajf4      ,equinoxes1       
precession of the1 #fa1 #fb4            
,eskers1 #bba4      ,expansion of air   
contained in a hollow wall during the   
passage of the storm1 #aad4             
,experiment1 illustrating consolidation 

of disseminated             materials of
 the sun and planets1 #dj4       ,falls4
 ,see ,,waterfalls4      ,fault planes1 
#chb4      ,feldspar1 #cbd4             
,floods1 #ahj1 #aig2       rarity of1 in
 ,new ,england1 #aba2       river1      
frequent east of ,rocky ,mountains1     
#aih4      ,fhns1 #aba4      ,forests1  
salicified1 #abd4      ,fossilization1  
#ced-cef4      ,fulcrum point1 #ie4     
,galactic plane1 #de4      ,galongoon1  
eruption of1 #bid4      ,geological work
 of water1 #afh-bjf4      ,glacial      
action in the valleys of ,switzerland1  
#bbd2       periods1 #fc1 #bdc1 #bdf2   
in the northern hemisphere1 #bdf2       
waste1 #cbd4      ,glaciation1          
effect of1         in ,north ,america1  
#bda2         in ,central ,america1     
#bcd2         ,south ,america1 #bcd4    
,glaciers1 #bjg-bdi2       action of ice
 in forming1 #bcj-bcb2       ,alaskan1  
#baf2       continental1 #bbe1 #bci1    
#bdj2       discharge of1 #bbj2         
exploring1 #bbj2       extensive1 in    

,greenland and ,scandinavia1 #bdd2      
former1 of ,north ,america1 #bcb1 #bcd2 
map of1 and moraines near ,mont ,blanc1 
#bag2       motions of1 #bac2           
retreat of the1 #bbh1 #bcj1 #bce2       
secrets of the under ice of1 #bba2      
speed of a1 #bbd2       study of1 in the
 ,swiss valleys1 #bbb2       testimony  
of the rocks regarding1 #bbh2       when
 covered with winter snows1 #baf2       
valley1 #baf4      ,gombridge1 #ahcj1   
#gd4      ,gravitation1 law of1 #d4     
,greeks' idea of the heavens1 #ca2      
not mechanically inventive1 #bb4        
,gulf ,stream1 current of the1 #adg4    
,heat1       amount of1 daily escaping  
from the earth1 #hi2       amount of1   
falling from the sun on the earth1 #da2 
belief of the ancients regarding1 #db2  
dominating effect on air currents of    
tropical1 #ajd2       energy with which 
it leaves the sun1 #da2       internal1 
of the earth1 #hh1 #hi2         of the  
earth's interior1 #cji1 #caj2       sun1
 effect on the atmosphere of the1 #ajj2 

,prof4 ,newcomb's belief regarding the1 
of the sun1 #eb2       radiation of the 
earth's1 causing winds1 #aja2           
solar1 #da2       tropical1 and air     
currents1 #ajd4      ,hills1 sand1 #abc4
      ,horizontal pendulum1 #chd4       
,horse latitudes1 #ajd4      ,horses1   
#bfa4      ,hurricanes1 #ajg1 #aaj1     
#cag2       commencement of1 #ajg2      
doldrum of1 #aji2       felt near the   
sea1 #aaj2       in the tropics1 #aaj4  
,hypothesis1       nebular1 #cd1 #ce1   
#ci1 #eb1 #ef2       working1 #d1 #e4   
,ice action1       effect of intense1   
#bbb1 #bbc2       in forming glaciers1  
#bcj1 #bcb2       recent studies in     
,greenland of1 #bci2       depth of1 in 
,greenland1 #bbg2       effect of1 on   
river channels1 #aif2       effect of1  
on stream beds1 #aif2       expanding   
when freezing1 #bcg2       epoch1 #ib1  
#ic1 #bdf2       floating1 #bdb2        
made soils rarely fertile1 #bda2        
mass1 greatest1 in ,greenland1 #bbf1    
#bbg2       moulded by pressure1 #bae2  

streams1         continental1 #bbe1     
#bbf2         of the mountains1 #bbe2   
of the ,himalayan ,mountains1 #bcd4     
,icebergs1 #bdb1 #bdc2       indicating 
oceanic currents1 #bdc4      ,iceland1  
volcanic eruptions in1 #big1 #bih4      
,instruments1 first1 astronomical1 #aj1 
#aa4      ,inventions1 mechanical1      
aiding science1 #bb4      ,islands1 #hd1
 #bgb2       continental1 #hd2       in 
the deeper seas made up of volcanic     
ejections1 #bgb2       volcanic1 #bgb4  
,jack-o'-lantern1 #afg4      ,jupiter1  
gaseous wraps of1 #ig2       path of the
 earth affected by1 #ei1 #fj2       the 
largest planet of the sun1 #fi4         
,kames1 #cbe4      ,kant1 ,immanuel1 and
 nebular hypothesis1 #cd4      ,kaolin1 
#cbd4      ,klondike district1 cold in1 
#bdc1 #bdd4      ,krakatoa1             
eruption of1 #bih-cjj2         effect   
of1 on the sea1 #bii2         effect of1
 on the sun1 #cjj4       ,lacolites1    
#cjf4      ,lacustrine beds1 #cea4      
,lagoons1 salt deposits found in1 #bjj4 

,lake basins1       formation of1 #bjj1 
#bja2       bogs1 #cca1 #ccc1 #ccd2     
deposits1 #cej1 #cea4      ,lakes1      
#aii-bjf2       effect of1 on the river 
system1 #bje2       fresh-water1 #ade2  
formed from caverns1 #bjb2       great1 
changing their outlets1 #bje2       of  
extinct volcanoes1 #bjc2       temporary
 features of the land1 #bjc2            
volcanic1 #bjc4      ,lands1            
great1 relatively unchangeable1 #if2    
table1 #ia2       movements resulting in
 change of coast line1 #cea1 #ceb2      
shape of the seas and1 #hc1 #hd2        
accounting for the changes in the       
attitude of the1 #ie2       and water1  
divisions of1 #hd2       dry1 surface   
of1 #he2       general statement as to  
the division of the1 #hc1 #hd2          
surface1 shape of the1 #he2             
triangular forms of great1 #ij4         
,latitudes1 horse1 troublesome to       
mariners1 #ajd4      ,laplace and       
nebular hypothesis1 #cd4      ,lava1    
#bff-bfh1 #bgj1 #bga1 #bib1 #bic1 #bie1 

#bif1 #cjc1 #cjd2       flow of1        
invading a forest1 #bfh2       from     
,vesuvius1 #bic2       of #affi1 #bie1  
#bif2       temperature of1 #bie1 #bif2 
incipient1 #cjd2       outbreaks of1    
#bib1 #cjc2       stream eaves1 #bib1   
#bic4      ,law1 natural1               
,aristotle and1 #c2       of            
gravitation1 #d2       of the           
conservation of energy1 #bc4            
,leaves1 radiation of1 #afj4            
,length of days affected by tidal       
action1 #aca4      ,level surfaces1 #ia4
      ,life1 organic1 evolution of1 #ae1
 #af4      ,light1 belief of the        
ancients regarding1 #db4                
,lightning1 #bd1 #afd-afh2       noise  
from1 #aff2       proceeding from the   
earth to the clouds1 #afe2              
protection of buildings from1 #afe2     
stroke1 wearing-out effect of1 #afe4    
,limestones1 #cec1 #ceg1 #ceh1 #cfj1    
#cfd2       formation of1 #ceg1 #cfj4   
,lisbon1 earthquake of1 #agee1 #cfh1    
#cfi4      ,lowell1 ,mr4 ,percival1     

observations on ,venus1 #fd4      ,lunar
 mountains near the ,gulf of ,iris1     
#cig4       ,mackerel sky1 #ce4         
,mallet1 ,mr4 ,charles1 and the study of
 earthquakes1 #chb1 #chc4      ,man as  
an inventor of tools1 #aj4              
,mangroves1 #cdj2       diagram showing 
mode of growth1 #cdj2       marshes of1 
#cci4      ,map of glaciers and moraines
 near ,mont ,blanc1 #bag2       of      
,ipswich marshes1 #cch4      ,mapping   
with contour lines1 #bg4      ,maps1    
desirable1 for the study of celestial   
geography1 #gg2       geographic sketch1
 #bf1 #bg4      ,marching sands         
jeopardizing agriculture1 #abc4         
,marine animals1 sustenance of1         
#cfa-cfc2       deposits1 #cbe-cbg1     
#cdi1 #cef2       marshes1 #ccf-cdj2    
waves caused by earthquakes1 #chg4      
,mars1 #fe-fg1 #hd1 #ig2       belief   
that it has an atmosphere1 #fe2         
canals of1 #fg2       gaseous wraps of1 
#ig2       more efficient telescopes    
required for the study of1 #fg2         

nearer to the earth than other planets1 
#fe4      ,marshes1       mangrove1     
#cci2       map of ,ipswich1 #cch2      
marine1 #ccf-cdj2       deposits found  
in1 #ccf2       of ,north ,america1     
#ccg2       on the coast of ,new        
,england1 #cci2       phenomena of1     
#afg1 #afh2       tidal1 good earth for 
tillage1 #ccg2       tidal1 of ,north   
,america1 #cdj4      ,mercury1 #ee1 #fc1
 #gh2       nearest to the sun1 #fc2    
time in which it completes the circle of
 its year1 #ee4      ,meteorites1 #dg1  
#dh2       kinship of comets and1 #dh4  
,meteors1 #dg2       falling1 #dg2      
composition of1 #dh2       flashing1    
#ci1 #dj1 #dg2       speed of1 #dg2     
inflamed by friction with air1 #ii4     
,methods in studying geology1 #djj4     
,milky ,way1 #de2       voyage along the
 path of the1 #dd1 #de4      ,mineral   
crusts1 #cbh1 #cbi2       deposits1     
#cjh4      ,moon1 #ch1 #cie-djj2        
absence of air and water on the1 #cii2  
attended by satellites1 #eg2            

attraction which it exercises on the    
earth1 #fb2       curious feature of    
the1 #cig2       destitute of gaseous or
 aqueous envelope1 #cig2       diameter 
of the1 #cii2       imaginary view of   
the earth from the1 #ha2       libration
 of the1 #cih2       made up of circular
 depressions1 #cif1 #cig2               
movements of the1 #gh2       no         
atmosphere in the1 #ig2       parting of
 the earth and1 #cif2       position of 
the1 in relation to the earth1 #fb2     
tidal action and the1 #aca2       tides 
of the1 #abf1 #abg2       why does the  
sun not act in the same manner as the1  
#gh4      ,moraines1 #baf1 #bah1 #bbi1  
#bcj2       map of glaciers and1 near   
,mont ,blanc1 #bag2       movements of  
the1 #baf-bah2       terminal1 #bbh4    
,moulin1 #bai4      ,mount tna1         
#bhh-caj2       lava yielding1 #bij1    
#bic1 #bid2       lava stream caves of1 
#bib1 #bic2       more powerful than    
,vesuvius1 #big2       peculiarities of1
 #bia1 #bib2       size of1 #bhi-bia2   

turning of the torrents of1 #bie4       
,mountain-building1 #ij-ic1 #cjd2       
folding1 #hf1 #hg1 #ij1 #cfe2           
attributed to cooling of the earth1 #hh2
       growth1 #cib2       ,swiss falls1
 #agd2       torrents1 energy of1 #agg4 
,mountains1 #he1 #hf1 #hi1 #ij-ic2      
#agd-agh2       form and structure of1  
#hf2       partly caused by escape of   
heat from the earth1 #hi2       sections
 of1 #hg4      ,mount ,nuova1 formation 
of1 #bhd4      ,mount ,vesuvius1        
#bfc-bhe1 #bhh1 #bhi1 #bic1 #cjb1 #cha2 
description of the eruption of1 in      
,a4,d4 #gi1 #bgg-bhj2       diagrammatic
 sections through1 showing changes in   
the form             of the cone1 #bhc2 
eruption of1 in #ajef1 #bha2       in   
#ahhb-'hc1 #bfd1 #bff2       eruption   
of1 in #ahgb1 #bhb2       eruptions of1 
increased since #afcf1 #bhb2       flow 
of lava from1 #bhe2       likely to     
enter on a period of inaction1 #bhb1    
#bhc2       outbreak of1 in #ahhb-'hc1  
#bfd1 #bff4       ,naples1 prosperity of

 the city1 #bhi4      ,nebular          
hypothesis1 #cd1 #ce1 #ci1 #eb4         
,neptune1 #gj4      ,nv1 the1 #bad2     
no ice-cutting in the region of the1    
#bbd4      ,newcomb's 7,prof47 belief   
regarding the heat of the sun1 #eb4     
,niagara ,falls1 #aia1 #aib1 #bjd2      
cutting back of1 #bjd4      ,north      
,america1       changes in the form of1 
#ia1 #ib2       triangular form of1 #ij4
       ,ocean1       average depth of   
the1 #hi2       climatal effect of the1 
#adg2       currents1 #ade2       effect
 of1 on migration1 #aef2       effect   
of1 on organic life1 #aed2       floor1 
#he1 #ic2       hot and cold currents of
 the1 #ajb2       sinking of the1 #ic1  
#id2       the laboratory of sedimentary
 deposits1 #cea2       depth of the1    
#hi1 #abf4      ,oceanic circulation1   
effect of1 on the temperature1 #aeb4    
,oceans and continents1 #hc4            
,orbit1       alterations of the1 and   
the seasons1 #fj1 #fa2       changing of
 the1 #ei-fc2       shape of the1       

#fa-fc4      ,organic life1 #cae1 #cag1 
#cba1 #ceb1 #cec1 #cfc2       action of1
 on the soil1 #cag1 #cba2               
advantages of the shore belt to1 #cfc2  
development of in the sea1 #ceb1 #cec2  
effect of ocean currents on1 #aed2      
processes of1 in the soil1 #cae2        
decay of1 in the earth1 #cba4           
,orion1 #df4      ,oscillations of the  
shores of the ,bay of ,naples1 #bhg4    
,oxbow of a river1 #ahb1 #ahc4          
,oxbows and cut-off1 #ahb4              
,pebbles1       action of seaweeds on1  
#adc2       action of the waves on1     
#adb1 #add4      ,photosphere1 #gd4     
,plains1 #hf2       alluvial1 #ia1 #agi1
 #ahb1 #ahd-ahf1 #cbe2       history of1
 #ia2       sand1 #cbe4      ,planets1  
#ch2       attended by satellites1 #eg2 
comparative sizes of the1 #fh2          
experiments illustrating consolidation  
of disseminated             materials of
 the sun and1 #dj2       gaseous wraps  
of1 #ig2       important observations by
 the ancients of fixed stars            

and planets1 #dc2       movements of1   
#eg-fa2       outer1 #gh2       table of
 relative masses of sun and1 #gg4       
,plant life in the ,sargassum basins1   
#aef4      ,plants and animals1         
protection of1         by mechanical    
contrivances1 #cfd2         and trees1  
work of the roots of1 on the soil1 #caf1
 #cag2       water-loving1 #aha2        
forming climbing bogs1 #ccb4      ,polar
 axes1 nodding movement of1 #ed4        
,polar snow cap1 #ff4      ,polyps1     
#aee1 #cec4      ,pools1 circular1 #bjc4
      ,prairies1 #cdj1 #cdb4            
,radiation of heat1 #aei4      ,rain1   
#aeb1 #aef1 #afd1 #afh1 #agj1 #cbh1     
#ccj2       circuit of the1 #aef-afh2   
drops1 force of1 #afi1 #agj2            
spheroidal form of1 #agj2               
electrical action in the formation of   
snow and1 #afd2       work of the1 #aga4
      ,realm1 unseen solar1 #ge4        
,reeds1 #ccb4      ,religion1           
conflict between science and1 #bj1 #bb2 
struggle between paganism and1 #ba4     

,rivers and dbris1 #ahc2       changes  
in the course of1 in alluvial plain1    
#ahb2       deposition of1 accelerated  
by tree-planting1 #aha2       great1    
always clear1 #bje2       inundation of 
the ,mississippi1 eating away land1     
#ahb2       muds1 #bbb2       newly     
formed1 cutting a caon1 #aie2       of  
snow-ice1 #baa2       origin of a       
normal1 #agc2       oxbow of a1         
#ahb1ahc2       sinking of1 #aii2       
swinging movement of1 #agi-aha2         
river-valleys1 #aic1 #aid2              
diversity in the form of #ahh-aia4      
,rocks1 #ade2       accidents from      
falling1 #agd2       cut away by        
sandstones1 #ahh2       divided by      
crevices1 #beb2       duration of events
 recorded in1 #chi1 #cij1       ejection
 of1 material1 #caa2       falling of1  
#agd-agf2       formation of1 #bfb1     
#bfc2       from the present day to the 
strata of the ,laurentian1 #cij2        
migration of1 #bia2       poised1       
indicating a long exemption from strong 

earthquakes1 #chh2       rents in1 #beb1
 #bec2       stratification of1 #cdi1   
#cej1 #ceb1 #cfe1 #cij2       testimony 
of the1 in regard to glaciers1 #bbh2    
under volcanoes1 #cjc2       variable   
elasticity of1 #cff2       vibration of1
 #cfg1 #cfh2       rock-waste1 march of 
the1 #cdc2       water1 #bej1 #bfg4     
,rotation of the earth affected by      
tides1 #acj2       of the planetary     
spheres on their axes1 #ef4             
,salicified forests1 #abd4      ,salt   
deposits formed in lagoons1 #bjj2       
found in lakes1 #aii-bjj4      ,sand    
bars1 #ahc2       endurance of1 against 
the waves1 #ade2       hills1 travelling
 of1 #abc2       marching1 #abc2        
silicious stones cutting away rooks1    
#ahh4      ,satellites1 #ec1 #ed2       
motions of1 about their centres and     
about the sun1 #ec1 #ed4      ,saturn1  
#ch1 #ec1 #eg1 #cif2       cloud bands  
of1 #gj2       gaseous wraps of1 #ig2   
path of the earth affected by1 #ei1 #fj4
      ,savages1 primitive1 students of  

,nature1 #a4      ,scandinavia1 changes 
on the coasts of1 #if4      ,science1   
advance of1 due to mechanical           
inventions1 #bb2       astronomy        
beginning with1 #aj2       chemical1    
characteristics of1 #ad2       conflict 
between religion and1 #bj1 #bb2         
conflict between the ,roman faith and1  
#bj2       mechanical inventions as aids
 to1 #bb1 #bc2       modern and ancient1
 #d2       natural1 #e1 #f2       of    
botany in ,aristotle's time1 #ad2       
of physiology1 #ae2       of zology in  
,aristotle's time1 #ad2       resting   
practically on sight1 #aj4              
,scientific development1       historic 
outlines of1 #ag2       tools used in   
measuring and weighing1 as an aid to    
vision1 #ab4      ,sea1       battering 
action of the1 #adj2       coast ever   
changing1 #che1 #chf2       effect of   
volcanic eruptions on the1 #bii2        
floor deposits of the1 affected by      
volcanoes1 #cfj1 #cfa2       in receipt 
of organic and mineral matter1 #cei2    

hot and cold currents of the1 #ajb2     
littoral zone of the1 #cea1 #ceb2       
puss1 #adb2       rich in organic life1 
#ceb1 #cec2       solvent action of the1
 #cfa2       strata1 formation of1 #ced2
       water1 minerals in1 #ahe2        
weeds1 #aee1 #aef4      ,seas1 dead1    
originally living lakes1 #bjj2          
water of1 buoyant1 #aii2                
eventually the seat of salt deposits1   
#aii-bja2       general statement as to 
division of1 #hc1 #hd2       shape of   
the1 #hc1 #hd4      ,seashore1 air of   
the1 #ih4      ,seasons1 changing the   
character of the1 #fa1 #fb4      ,sense 
of hearing1 #i1aj2       of sight1 #aj2 
of smell1 #i1 #aj2       of taste1 #i1  
#aj2       of touch1 #i1 #aj4           
,seracs1 #bad4      ,shocks1 earthquake4
 ,see under ,,earthquakes4      ,shore  
lines1 variation of1 #hc1 #hd4          
,shores1 cliff1 #ach-adb4      ,sink    
holes1 #bjb2       in limestone         
districts1 #bec1 #bed4      ,skaptar1   
eruption of1 #big1 #bih2       lava from

 the eruption of1 #bih4      ,sky1      
mackerel1 #ce4      ,snow1 #bjg-bbe1    
#bdd2       as an evidence of           
atmosphere1 #fe2       blankets1 early  
flowers beginning to blossom under1     
#bjh2       covering1 difference between
 an annual and perennial1 #baj2         
effect of1 on plants1 #bjh2             
electrical action in the formation of   
rain and1 #afd2       flakes1 formation 
of1 #afd2       red1 #baj2       slides1
 #baj2       slides1 phenomena of1 #baj1
 #baa4      ,soil1       alluvial1 #cba1
 #cbb2       atmospheric circulation of1
 #ccj1 #cca2       conditions leading to
 formation of1 #cac1 #cca2              
continuous motion of the1 #cad2         
covering of the earth1 #cdc2       decay
 of the1 #cad1 #cae2       degradation  
of the1 #cdd-cdh2       means for       
correcting1 #cdf-cdh2       destruction 
in grain fields greater than the        
accumulation1 #cdd2       developing on 
lava and ashes an interesting study1    
#cdc2       development of1 in desert   

regions1 #cdj2       effect of animals  
and plants on the1 #cag-cbj2            
effect of earthquakes on the1 #cge2     
fertility of the1 distinguished from the
 coating1 #cdd1 #cde2       fertility   
of1 affected by rain1 #cbg2             
formation of1 #cad-cba2       glacial1  
characteristics of1 #cbd2               
glaciated1 #cbc1 #cbd2       irrigation 
of the1 #cbh-ccj2       local variation 
of1 #cbg2       mineral1 #cba2       of 
arid regions fertile when subjected to  
irrigation1 #cda2       of dust or blown
 sand1 #cba2       of immediate         
derivation1 #cba1 #cbb2       phenomena1
 #cac2       processes of organic life  
in the1 #cae2       variation in1       
#cba-cca2       vegetation protecting   
the1 #caf1 #cag2       washing away of  
the1 #cdf1 #cdg2       winning1 from the
 sea1 #ccg2       work of ants on the1  
#cah2       tiller1 duty of the1 #cdh4  
,solar bodies1       general conditions 
of the1 #fc-ga2       forces1 action of1
 on the earth1 #cdi2       system1 #eb1 

#ef2       independent from the fixed   
stars system1 #dc2       original vapour
 of1 #eb1 #ec2       singular features  
of our1 #fh2       tide1 #abg4          
,spheres1       difference in magnitude 
of1 #ea2       motions of the1 #ej1 #ea2
       planetary1 rotation of1 on their 
axes1 #ef4      ,spots1 sun1 #gb4       
,spouting horn1 #ada4      ,springs1    
formation of small1 #beb4               
,stalactitization1 #bef4                
,stalagmites and stalactites on the roof
 and floor of a cavern1 #beg4           
,stars as dark bodies in the heavens1   
#dg2       discovery of ,fraunhofer and 
others on1 #bc1 #ch2       double1 #ci2 
and tidal action1 #aca2       earliest  
study of1 #aj2       fixed1 important   
observations by the ancients of planets 
and1 #dc2       not isolated suns1 #ch1 
#ci2       variation in the light of1   
#df2       limit of1 seen by the naked  
eye1 #aa2       revolution of one star  
about another1 #df1 #dg2       shooting1
 #dg2       speed of certain1 #ea2      

study of1 #ca-hj2       sudden flashing 
forth of1 due to catastrophe1 #df2      
voyage through the1 #dd1 #de2           
star1 wandering1 #gd4      ,stellar     
realm1 #ca-hj4      ,storms1            
circular1 #aaa2       desert1 #aba1     
#abb2       expansion of air contained  
in a hollow wall during             the 
passage of1 #aad2       great principle 
of1 #aje1 #ajf2       in the ,sahara1   
#aba2       lightning1 more frequent in 
summer1 #afg2       paths of1 #aae2     
secondary1 of cyclones1 #aab2           
spinning1 #aae2       thunder1 #afe-afg2
       whirling1 #ajf1 #abd2            
whirling peculiarity of1 #ajh1 #aji4    
,strabo1 writings of1 #ah4      ,sun1   
atmosphere of the1 #gc2                 
constitution of the1 #gb2       distance
 of the earth from the1 #bi2            
effect from changes in the1 and earth1  
#ei2       envelope of the1 #gc1 #gd1   
#ig2       experiments illustrating     
consolidation of disseminated           
materials of planets and1 #dj2          

finally1 dark and cold1 #db2            
formation of the eight planets of the1  
#ec2       heat leaving the1 #da2       
heat of the1 #gf2       imaginary       
journey from the1 into space1 #dd2      
mass of the1 #gf1 #gg2       path of the
 earth around the1 #ee2       physical  
condition of the1 #ga2       ,prof4     
,newcomb's belief regarding the heat of 
the1 #eb2       spots1 #ge2             
abundant at certain intervals1 #gb2     
difficulty in revealing cause of1 #ge2  
structure of the1 a problem before the  
use of the telescope1 #gb2       table  
of relative masses of1 and planets1 #gg2
       three stages in the history of   
the1 #ga2       tides1 #abf2       why  
does it not act in the same manner as   
the moon8 #gh4      ,surfaces1 level1   
#ij4      ,surf belt1 swayings of the1  
#acg4      ,swamps1       diagram       
showing remains of1 #cce2       ,dismal 
,swamp1 #ie1 #ccc2       drainage of1   
#ccd1 #cce2       fresh-water1 #ccd1    
#cce2       phenomena of1 #afg1 #afh4   

,table-lands1 #ia4      ,table of       
relative masses of sun and planets1 #gg4
      ,telescopes1 #aa1 #ab1 #de2       
first results of1 #gb2       power of1  
#aa2       revelations of1 #de4         
,temperature1       effects of1 produced
 by vibration1 #db2       in the doldrum
 belt1 #aah2       of ,north ,america1  
#aah2       of the ,atlantic ,ocean1    
#aah4      ,tempests1 rate of1 #ii1     
#ajj4      ,thunder1 #aff2       more   
pronounced in the mountains1 #aff4      
,thunderstorms1 #afe1 #aff2             
distribution of1 #aff1 #afg4      ,tidal
 action1       recent studies of1 #aca1 
#acb2       marshes of ,north ,america1 
#cdj4      ,tides1       carving        
channels1 #abi2       effecting the     
earth's rotation1 #acj2       effect of1
 on marine life1 #acj2       height of1 
#abh1 #abi2       moon and sun1 #abf1   
#abg2       normal run of the1 #abg2    
production of1 #aca2       of the trade 
winds1 #aej2       solar1 #abg2         
travelling of1 #abg1 #abh4      ,tillage

 introducing air into the pores of the  
soil1 #cca4      ,tornadoes1 #aab1 #aac1
 #cag2       development of1 #aac2      
effect of1 on buildings1 #aac2          
fiercest in ,north ,america1 #aac2      
length of1 #aae2       resemblance of1  
to hurricanes1 #aae2       upsucking    
action of1 #aad1 #aae4      ,torrents1  
#agg-agi1 #bjd4      ,trade winds4 ,see 
under ,,winds4      ,training in        
language1       diminishing visual      
memory1 #dja2       soldiers to measure 
distances1 #bh2         to measure      
intervals of time1 #bh2       for a     
naturalist1 #be-bi4      ,tunnels1      
natural1 #beg4       ,uranus1 #gj4      
,valley of ,val del ,bove formed from   
disturbances of ,mount tna1 #bid4       
,valleys1       diversity in the form of
 river1 #ahh-aia2       river1 #aic4    
,vapour1 #aef1 #aeg1 #aei1 #afc2        
gravitative attraction of1 #cd1 #ce2    
nebular theory of1 #eb1 #ec2            
original1 of the solar system1 #eb1 #ec4
      ,vegetation1       and dew1 #afj2 

in a measure1 independent of rain1 #afj2
       protecting the soil1 #caf1 #cag4 
,vein1 diagram of a1 #bfj4      ,venus1 
#fd1 #gh2       recent observations of1 
by ,mr4 ,percival ,lowell1 #fd4         
,vesuvian system1 study of the1 #bhe4   
,vesuvius4 ,see ,,mount ,,vesuvius4     
,visualizing memories1 #djb1 #djc4      
,volcanic action1 #bfh-bgf4             
,volcanic eruption of ,a4,d4 #gi1 #bhh2 
important facts concerning1 #bgf-bgi2   
islands1 #bgb2       lava a primary     
feature in1 #bff2       observations of1
 made from a balloon1 #cja2       peaks 
along the floor of the sea1 #bgb1 #bgc2 
possibility of throwing matter beyond   
control of gravitative                  
energy1 #cjj4      ,volcanoes1 #abe1    
#bjc1 #bfc2       abounding on the sea  
floor1 #cjb2       accidents from       
eruptions of1 #bhh2       along the     
,pacific coast1 #bga2       ash showers 
of1 maintaining fertility of the soil1  
#bhi2       distribution of1 #bga2      
eruption of1 #bhf-bid1 #cfh2            

explosions from1 coming from a supposed 
liquid interior             of the      
earth1 #bge2       exporting earth      
material1 #caj2       little water1     
#cge2       ,italian1 considered        
collectively1 #bif1 #big2               
,neapolitan eruptions of and the history
 of civilization1 #bhh2       subsidence
 of the earth after eruption of1 #bhg1  
#bia2       origin of1 #bfc-bgd2        
phenomena of1 #bfc-bfg2       submarine1
 #cja2       travelling of ejections    
from1 #bhg1 #bhh4       ,waters1        
crevice1 #bej2         of the earth1    
#bej1 #bea2       cutting action of1    
#aag1 #aib2       drift1 from the poles1
 #aea2       journey of1 from the       
,arctic ,circle to the tropics1 #aea1   
#aeb2       dynamic value of1 #aga2     
expansion of1 in rocks1 #bgj2           
geological work of1 #afh-bjf2       in  
air1 #ii2       of the clouds usually   
frozen1 #bjg2       pure1 no power for  
cutting rocks1 #bjd2       rock1 #bej1  
#bfc2       sea1 minerals in1 #ahe2     

store of the earth1 #abe2       system  
of1 #abe1 #aef2       tropical1 #aea2   
velocity of the1 under the equator1     
#aej2       wearing away rocks1 #agh1   
#agi2       underground1 carrying       
mineral matter to the sea1 #aic2        
chemical changes of1 leading to changes 
in rock material1 #bfb1 #bfc2           
effect of carbonic-acid gas on1 #bea2   
operations of the1 #abf2       wearing  
away rocks1 #agh1 #agi2       work of1  
#bej4      ,waterfalls1 #ahi-aic2       
cause of1 #aia2       the ,yosemite1    
#aib2       ,niagara1 #aia1 #aib2       
numerous in the torrent district of     
rivers1 #aib2       produced by dikes1  
#aib2       valuable to manufactures1   
#aib1 #aic4      ,waterspouts1 #aae1    
#aaf2       atmospheric cause of1 #aaf2 
firing at1 #aaf2       life of a1 #aaf2 
picturesqueness of1 #aaf2       the     
water of fresh1 #aag4      ,waves1 #abh1
 #abi1 #acb1 #ade2       action of      
friction on1 #ace1 #acf2       break of 
the1 #acf2       endurance of sand      

against the1 #ade2       force of1 #acc1
 #acf1 #aci2       marine1 caused by    
earthquakes1 #chg2       of earthquakes1
 #chi2       peculiar features in the   
action of1 #acg2       size of1 #acg1   
#ach2       stroke of the1 #add2        
surf1 #ace2       tidal height of1 #acb2
       undulations of1 #acb2       wind1
 #acb2       wind influence of1 on the  
sea1 #acd1 #ace2       wind-made1 #abh4 
,ways and means of studying ,nature1 #i4
      ,weeds of the sea1 #aee4          
,well1 artesian1 #beh1 #bei4            
,whirling of fluids and gas1 #cf1 #cg4  
,whirlwinds in ,sahara1 #aba4           
,will-o'-the-wisp1 #afg4      ,winds1   
#aja1 #aaj1 #abb1 #cag2       effect of 
sand1 #abb2       hurricane1 #aaj2      
illustration of how they are produced1  
#aja2       in ,martha's ,vineyard1     
#abj2       of the forests1 work of the1
 #cag2       of tornadoes1 effect of1   
#aac2       on the island of ,jamaica1  
#aai1 #abj2       regimen of the1 #aai2 
variable falling away in the nighttime1 

#ajj2       trade1 #ajb-aje2 #ade1 #adf1
 #aej2       action of1 on ocean        
currents1 #ade3       affected by motion
 of the earth1 #ajc2       belt1 motion 
of the ocean in1 #adf2       flow and   
counter-flow of the1 #aej2       tide of
 the1 #aej2       uniform condition of  
the1 #ajb2       waves1 work of1 #acb1  
#acd1 #ace4      ,witchcraft1 belief of1
 in the early ages1 #ba4       ,zology1 
rapid advance in1 #ad1 #ae4