,a ,,history ,,of ,,science   ,,modern  
,,development ,,of ,,the ,,physical     
,,sciences    ,by ,henry ,smith         
,williams1 ,m4,d41 ,ll4,d4  ,assisted   
,by ,edward ,h4 ,williams1 ,m4,d4  ,in  
,five ,volumes  ,volume ,,iii4          
,,contents    ,,book ,,iii    ,,chapter 
,i4 ,,the ,,successors ,,of ,,newton    
,,in ,,astronomy    ,the work of        
,johannes ,hevelius--,halley and        
,hevelius--,halley's observation   of   
the transit of ,mercury1 and his method 
of determining the parallax of   the    
planets--,halley's observation of       
meteors--,his inability to   explain    
these bodies--,the important work of    
,james ,bradley--,lacaille's            
measurement of the arc of the           
meridian--,the determination of the     
question as to the exact shape of the   
earth--,d',alembert and his   influence 
upon science--,delambre's ,history of   
,astronomy--,the   astronomical work of 
,euler4    ,,chapter ,,ii4 ,,the        
,,progress ,,of ,,modern ,,astronomy    

,the work of ,william ,herschel--,his   
discovery of ,uranus--,his discovery    
that the stars are suns--,his conception
 of the universe--,his deduction   that 
gravitation has caused the grouping of  
the heavenly bodies--,the   nebula1     
hypothesis1--,immanuel ,kant's          
conception of the formation of the      
world--,defects in ,kant's              
conception--,laplace's final solution of
 the   problem--,his explanation in     
detail--,change in the mental attitude  
of the   world since ,bruno--,asteroids 
and satellites--,discoveries of         
,olbersl--,the   mathematical           
calculations of ,adams and              
,leverrier--,the discovery of the       
inner ring of ,saturn--,clerk ,maxwell's
 paper on the stability of ,saturn's    
rings--,helmholtz's conception of the   
action of tidal friction--,professor    
,g4 ,h4 ,darwin's estimate of the       
consequences of tidal action--,comets   
and meteors--,bredichin's cometary      
theory--,the final solution of the      

structure of comets--,newcomb's estimate
 of the amount of cometary dust   swept 
up daily by the earth--,the fixed       
stars--,john ,herschel's studies   of   
double stars--,fraunhofer's perfection  
of the refracting   telescope--,bessel's
 measurement of the parallax of a       
star1--,henderson's                     
measurements--,kirchhoff and ,bunsen's  
perfection of the                       
spectroscope--,wonderful revelations of 
the spectroscope--,lord ,kelvin's       
estimate of the time that will be       
required for the earth to become        
completely cooled--,alvan ,clark's      
discovery of the companion star of      
,sirius--,the advent of the photographic
 film in astronomy--,dr4 ,huggins's     
studies of nebulae--,sir ,norman        
,lockyer's cosmogonic guess1--,croll's  
pre-nebular theory4    ,,chapter ,,iii4 
,,the ,,new ,,science ,,of              
,,paleontology    ,william ,smith and   
fossil shells--,his discovery that      
fossil rocks are   arranged in regular  

systems--,smith's inquiries taken up by 
,cuvier--,his   ,ossements ,fossiles    
containing the first description of     
hairy   elephant--,his contention that  
fossils represent extinct species       
only--,dr4 ,buckland's studies of       
,english fossil-beds--,charles ,lyell   
combats catastrophism1--,elaboration of 
his ideas with reference to   the       
rotation of species--,the establishment 
of the doctrine of                      
uniformitarianism1--,darwin's ,origin of
 ,species--,fossil man--,dr4            
,falconer's visit to the fossil-beds in 
the valley of the                       
,somme--,investigations of ,prestwich   
and ,sir ,john ,evans--,discovery of the
   ,neanderthal skull1--,cuvier's       
rejection of human fossils--,the finding
   of prehistoric carving on ivory--,the
 fossil-beds of ,america--,professor    
,marsh's paper on the fossil horses in  
,america--,the ,warren mastodon1--,the  
,java fossil1 ,pithecanthropus ,erectus4
    ,,chapter ,,iv4 ,,the ,,origin ,,and

 ,,development ,,of ,,modern ,,geology  
,james ,hutton and the study of the     
rocks--,his theory of the earth--,his   
belief in volcanic cataclysms in raising
 and forming the continents--,his       
famous paper before the ,royal ,society 
of ,edinburgh1 #agha---;,his            
conclusions that all strata of the earth
 have their origin at the bottom   of   
the sea---,his deduction that heated and
 expanded matter caused the   elevation 
of land above the                       
sea-level--,indifference at first shown 
this   remarkable paper--,neptunists    
versus ,plutonists--,scrope's classical 
work   on volcanoes--,final acceptance  
of ,hutton's explanation of the origin  
of granites--,lyell and                 
uniformitarianism--,observations on the 
gradual   elevation of the coast-lines  
of ,sweden and ,patagonia--,observations
 on   the enormous amount of land       
erosion constantly taking               
place1--,agassiz   and the glacial      
theory--,perraudin the chamois-hunter1  

and his   explanation of perched        
bowlders--,de ,charpentier's acceptance 
of   ,perraudin's                       
explanation--,agassiz's paper on his    
,alpine studies--,his   conclusion that 
the ,alps were once covered with an     
ice-sheet--,final   acceptance of the   
glacial theory--,the geological         
ages--,the work of   ,murchison and     
,sedgwick--,formation of the ,american  
continents--,past1   present1 and       
future4    ,,chapter ,v4 ,,the ,,new    
,,science ,,of ,,meteorology    ,biot's 
investigations of meteors--,the         
observations of ,brandes and            
,benzenberg on the velocity of falling  
stars--,professor ,olmstead's           
observations on the meteoric shower of  
#ahcc--;,confirmation of ,chladni's     
hypothesis of #agid--,the aurora        
borealis--,franklin's suggestion that   
it is of electrical origin--,its close  
association with terrestrial            
magnetism--,evaporation1                
cloud-formation1 and dew--,dalton's     

demonstration   that water exists in the
 air as an independent gas--,hutton's   
theory of   rain--,luke ,howard's paper 
on clouds--,observations on dew1 by     
,professor   ,wilson and ,mr4 ,six--,dr4
 ,wells's essay on dew--,his            
observations   on several appearances   
connected with dew--,isotherms and ocean
   currents--,humboldt and the-science  
of comparative climatology--,his        
studies of ocean currents--,maury's     
theory that gravity is the cause   of   
ocean currents--,dr4 ,croll on ,climate 
and ,time--,cyclones and                
anti-cyclones1--,dove's studies in      
climatology--,professor ,ferrel's       
mathematical law of the deflection of   
winds--,tyndall's estimate of   the     
amount of heat given off by the         
liberation of a pound of                
vapor--,meteorological observations and 
weather predictions4    ,,chapter ,,vi4 
,,modern ,,theories ,,of ,,heat ,,and   
,,light    ,josiah ,wedgwood and the    
clay pyrometer--,count ,rumford and the 

vibratory   theory of heat--,his        
experiments with boring cannon to       
determine the   nature of heat--,causing
 water to boil by the friction of the   
borer--,his   final determination that  
heat is a form of motion--,thomas ,young
 and the   wave theory of light--,his   
paper on the theory of light and        
colors--,his   exposition of the colors 
of thin plates--,of the colors of thick 
plates1 and of striated                 
surfaces1--,arago and ,fresnel champion 
the wave   theory--opposition to the    
theory by ,biot--,the ,french ,academy's
 tacit   acceptance of the correctness  
of the theory by its admission of       
,fresnel   as a member4    ,,chapter    
,,vii4 ,,the ,,modern ,,development ,,of
 ,,electricity ,,and ,,magnetism        
,galvani and the beginning of modern    
electricity--,the construction of   the 
voltaic pile--,nicholson's and          
,carlisle's discovery that the galvanic 
current decomposes water--,decomposition
 of various substances by ,sir          

,humphry ,davy--,his construction of an 
arc-light--,the deflection of the       
magnetic needle by electricity          
demonstrated by ,oersted--,effect of    
this important discovery--,ampere       
creates the science of                  
electro-dynamics--,joseph ,henry's      
studies of electromagnets--,michael     
,faraday begins his studies of          
electromagnetic induction--,his famous  
paper before the ,royal ,society1 in    
#ahca1 in which he demonstrates         
electro-magnetic induction--,his        
explanation of ,arago's   rotating      
disk--,the search for a satisfactory    
method of storing                       
electricity--,roentgen rays1 or ,x-rays4
    ,,chapter ,,viii4 ,,the             
,,conservation ,,of ,,energy    ,faraday
 narrowly misses the discovery of the   
doctrine of   conservation--,carnot's   
belief that a definite quantity of work 
can be   transformed into a definite    
quantity of heat--,the work of ,james   
,prescott   ,joule--,investigations     

begun by ,dr4 ,mayer--,mayer's paper of 
#ahdb--;,his   statement of the law of  
the conservation of energy--,mayer and  
,helmholtz--,joule's paper of           
#ahdc--;,joule or ,mayer--,lord ,kelvin 
and the   dissipation of energy-,the    
final unification4     ,,chapter ,,ix4  
,,the ,,ether ,,and ,,ponderable        
,,matter    ,james ,clerk-,maxwell's    
conception of ether--,thomas ,young and 
,luminiferous ether1--,young's and      
,fresnel's conception of transverse     
luminiferous undulations--,faraday's    
experiments pointing to the   existence 
of ether--,professor ,lodge's suggestion
 of two ethers--,lord   ,kelvin's       
calculation of the probable density of  
ether--,the vortex theory   of          
atoms--,helmholtz's calculations in     
vortex motions--,professor   ,tait's    
apparatus for creating vortex rings in  
the air---,the ultimate   constitution  
of matter as conceived by               
,boscovich--,davy's speculations   as to
 the changes that occur in the substance

 of matter at different                 
temperatures--,clausius's and ,maxwell's
 investigations of the   kinetic theory 
of gases--,lord ,kelvin's estimate of   
the size of the   molecule--,studies of 
the potential energy of                 
molecules--,action of gases   at low    
temperatures4    ,,appendix    ,a       
,,history ,,of ,,science     ,,book     
,,iii4 ,,modern ,,development ,,of ,,the
 ,,physical ,,sciences  ,with the       
present book we enter the field of the  
distinctively modern4 ,there is no      
precise date at which we take up each of
 the successive stories1 but the main   
sweep of development has to do in each  
case with the nineteenth century4 ,we   
shall see at once that this is a time   
both of rapid progress and of great     
differentiation4 ,we have heard almost  
nothing hitherto of such sciences as    
paleontology1 geology1 and meteorology1 
each of which now demands full          
attention4 ,meantime1 astronomy and what
 the workers of the elder day called    

natural philosophy become wonderfully   
diversified and present numerous phases 
that would have been startling enough to
 the star-gazers and philosophers of the
 earlier epoch4  ,thus1 for example1 in 
the field of astronomy1 ,herschel is    
able1 thanks to his perfected telescope1
 to discover a new planet and then to   
reach out into the depths of space and  
gain such knowledge of stars and nebulae
 as hitherto no one had more than       
dreamed of4 ,then1 in rapid sequence1 a 
whole coterie of hitherto unsuspected   
minor planets is discovered1 stellar    
distances are measured1 some members of 
the starry galaxy are timed in their    
flight1 the direction of movement of the
 solar system itself is investigated1   
the spectroscope reveals the chemical   
composition even of suns that are       
unthinkably distant1 and a tangible     
theory is grasped of the universal cycle
 which includes the birth and death of  
worlds4  ,similarly the new studies of  
the earth's surface reveal secrets of   

planetary formation hitherto quite      
inscrutable4 ,it becomes known that the 
strata of the earth's surface have been 
forming throughout untold ages1 and that
 successive populations differing       
utterly from one another have peopled   
the earth in different geological       
epochs4 ,the entire point of view of    
thoughtful men becomes changed in       
contemplating the history of the world  
in which we live--albeit the newest     
thought harks back to some extent to    
those days when the inspired thinkers of
 early ,greece dreamed out the wonderful
 theories with which our earlier        
chapters have made our readers familiar4
  ,in the region of natural philosophy  
progress is no less pronounced and no   
less striking4 ,it suffices here1       
however1 by way of anticipation1 simply 
to name the greatest generalization of  
the century in physical science--the    
doctrine of the conservation of energy4 
,i4 ,,the ,,successors ,,of ,,newton    
,,in ,,astronomy   ,,hevelius ,,and     

,,halley  ,,strangely enough1 the decade
 immediately following ,newton was one  
of comparative barrenness in scientific 
progress1 the early years of the        
eighteenth century not being as         
productive of great astronomers as the  
later years of the seventeenth1 or1 for 
that matter1 as the later years of the  
eighteenth century itself4 ,several of  
the prominent astronomers of the later  
seventeenth century lived on into the   
opening years of the following century1 
however1 and the younger generation soon
 developed a coterie of astronomers1    
among whom ,euler1 ,lagrange1 ,laplace1 
and ,herschel1 as we shall see1 were to 
accomplish great things in this field   
before the century closed4  ,one of the 
great seventeenth-century astronomers1  
who died just before the close of the   
century1 was ,johannes ,hevelius        
7#afaa-afhg71 of ,dantzig1 who advanced 
astronomy by his accurate description of
 the face and the spots of the moon4    
,but he is remembered also for having   

retarded progress by his influence in   
refusing to use telescopic sights in his
 observations1 preferring until his     
death the plain sights long before      
discarded by most other astronomers4    
,the advantages of these telescope      
sights have been discussed under the    
article treating of ,robert ,hooke1 but 
no such advantages were ever recognized 
by ,hevelius4 ,so great was ,hevelius's 
reputation as an astronomer that his    
refusal to recognize the advantage of   
the telescope sights caused many        
astronomers to hesitate before accepting
 them as superior to the plain2 and even
 the famous ,halley1 of whom we shall   
speak further in a moment1 was          
sufficiently in doubt over the matter to
 pay the aged astronomer a visit to test
 his skill in using the old-style       
sights4 ,side by side1 ,hevelius and    
,halley made their observations1        
,hevelius with his old instrument and   
,halley with the new4 ,the results      
showed slightly in the younger man's    

favor1 but not enough to make it an     
entirely convincing demonstration4 ,the 
explanation of this1 however1 did not   
lie in the lack of superiority of the   
telescopic instrument1 but rather in the
 marvellous skill of the aged ,hevelius1
 whose dexterity almost compensated for 
the defect of his instrument4 ,what he  
might have accomplished could he have   
been induced to adopt the telescope can 
only be surmised4  ,halley himself was  
by no means a tyro in matters           
astronomical at that time4 ,as the only 
son of a wealthy soap-boiler living near
 ,london1 he had been given a liberal   
education1 and even before leaving      
college made such novel scientific      
observations as that of the change in   
the variation of the compass4 ,at       
nineteen years of age he discovered a   
new method of determining the elements  
of the planetary orbits which was a     
distinct improvement over the old4 ,the 
year following he sailed for the ,island
 of ,st1 ,helena to make observations of

 the heavens in the southern hemisphere4
  ,it was while in ,st4 ,helena that    
,halley made his famous observation of  
the transit of ,mercury over the sun's  
disk1 this observation being connected1 
indirectly at least1 with his discovery 
of a method of determining the parallax 
of the planets4 ,by parallax is meant   
the apparent change in the position of  
an object1 due really to a change in the
 position of the observer4 ,thus1 if we 
imagine two astronomers making          
observations of the sun from opposite   
sides of the earth at the same time1 it 
is obvious that to these observers the  
sun will appear to be at two different  
points in the sky4 ,half the angle      
measuring this difference would be known
 as the sun's parallax4 ,this would     
depend1 then1 upon the distance of the  
earth from the sun and the length of the
 earth's radius4 ,since the actual      
length of this radius has been          
determined1 the parallax of any heavenly
 body enables the astronomer to         

determine its exact distance4  ,the     
parallaxes can be determined equally    
well1 however1 if two observers are     
separated by exactly known distances1   
several hundreds or thousands of miles  
apart4 ,in the case of a transit of     
,venus across the sun's disk1 for       
example1 an observer at ,new ,york notes
 the image of the planet moving across  
the sun's disk1 and notes also the exact
 time of this observation4 ,in the same 
manner an observer at ,london makes     
similar observations4 ,knowing the      
distance between ,new ,york and ,london1
 and the different time of the passage1 
it is thus possible to calculate the    
difference of the parallaxes of the sun 
and a planet crossing its disk4 ,the    
idea of thus determining the parallax of
 the planets originated1 or at least was
 developed1 by ,halley1 and from this   
phenomenon he thought it possible to    
conclude the dimensions of all the      
planetary orbits4 ,as we shall see      
further on1 his views were found to be  

correct by later astronomers4  ,in #agba
 ,halley succeeded ,flamsteed as        
astronomer royal at the ,greenwich      
,observatory4 ,although sixty-four years
 of age at that time his activity in    
astronomy continued unabated for another
 score of years4 ,at ,greenwich he      
undertook some tedious observations of  
the moon1 and during those observations 
was first to detect the acceleration of 
mean motion4 ,he was unable to explain  
this1 however1 and it remained for      
,laplace in the closing years of the    
century to do so1 as we shall see later4
  ,halley's book1 the ,synopsis         
,astronomiae ,cometicae1 is one of the  
most valuable additions to astronomical 
literature since the time of ,kepler4   
,he was first to attempt the calculation
 of the orbit of a comet1 having revived
 the ancient opinion that comets belong 
to the solar system1 moving in eccentric
 orbits round the sun1 and his          
calculation of the orbit of the comet of
 #afhb led him to predict correctly the 

return of that comet in #ageh4 ,halley's
 ,study of ,meteors4  ,like other       
astronomers of his time he was greatly  
puzzled over the well-known phenomena of
 shooting-stars1 or meteors1 making many
 observations himself1 and examining    
carefully the observations of other     
astronomers4 ,in #agad he gave his views
 as to the origin and composition of    
these mysterious visitors in the earth's
 atmosphere4 ,as this subject will be   
again referred to in a later chapter1   
,halley's views1 representing the most  
advanced views of his age1 are of       
interest4  ,the theory of the air       
seemeth at present1 he says1 to be      
perfectly well understood1 and the      
differing densities thereof at all      
altitudes2 for supposing the same air to
 occupy spaces reciprocally proportional
 to the quantity of the superior or     
incumbent air1 ,i have elsewhere proved 
that at forty miles high the air is     
rarer than at the surface of the earth  
at three thousand times2 and that the   

utmost height of the atmosphere1 which  
reflects light in the ,crepusculum1 is  
not fully forty-five miles1             
notwithstanding which 'tis still        
manifest that some sort of vapors1 and  
those in no small quantity1 arise nearly
 to that height4 ,an instance of this   
may be given in the great light the     
society had an account of 7vide         
,transact4 ,sep41 #afgf7 from ,dr4      
,wallis1 which was seen in very distant 
counties almost over all the south part 
of ,england4 ,of which though the doctor
 could not get so particular a relation 
as was requisite to determine the height
 thereof1 yet from the distant places it
 was seen in1 it could not but be very  
many miles high4  ,so likewise that     
meteor which was seen in #agjh1 on the  
#cast of ,july1 between nine and ten    
o'clock at night1 was evidently between 
forty and fifty miles perpendicularly   
high1 and as near as ,i can gather1 over
 ,shereness and the buoy on the ,nore4  
,for it was seen at ,london moving      

horizontally from east by north to east 
by south at least fifty degrees high1   
and at ,redgrove1 in ,suffolk1 on the   
,yarmouth road1 about twenty miles from 
the east coast of ,england1 and at least
 forty miles to the eastward of ,london1
 it appeared a little to the westward of
 the south1 suppose south by west1 and  
was seen about thirty degrees high1     
sliding obliquely downward4 ,i was shown
 in both places the situation thereof1  
which was as described1 but could wish  
some person skilled in astronomical     
matters bad seen it1 that we might      
pronounce concerning its height with    
more certainty4 ,yet1 as it is1 we may  
securely conclude that it was not many  
more miles westerly than ,redgrove1     
which1 as ,i said before1 is about forty
 miles more easterly than ,london4      
,suppose it1 therefore1 where           
perpendicular1 to have been thirty-five 
miles east from ,london1 and by the     
altitude it appeared at in              
,london--viz41 fifty degrees1 its       

tangent will be forty-two miles1 for the
 height of the meteor above the surface 
of the earth2 which also is rather of   
the least1 because the altitude of the  
place shown me is rather more than less 
than fifty degrees2 and the like may be 
concluded from the altitude it appeared 
in at ,redgrove1 near seventy miles     
distant4 ,though at this very great     
distance1 it appeared to move with an   
incredible velocity1 darting1 in a very 
few seconds of time1 for about twelve   
degrees of a great circle from north to 
south1 being very bright at its first   
appearance2 and it died away at the east
 of its course1 leaving for some time a 
pale whiteness in the place1 with some  
remains of it in the track where it had 
gone2 but no hissing sound as it passed1
 or bounce of an explosion were heard4  
,it may deserve the honorable society's 
thoughts1 how so great a quantity of    
vapor should be raised to the top of the
 atmosphere1 and there collected1 so as 
upon its ascension or otherwise         

illumination1 to give a light to a      
circle of above one hundred miles       
diameter1 not much inferior to the light
 of the moon2 so as one might see to    
take a pin from the ground in the       
otherwise dark night4 ',tis hard to     
conceive what sort of exhalations should
 rise from the earth1 either by the     
action of the sun or subterranean heat1 
so as to surmount the extreme cold and  
rareness of the air in those upper      
regions3 but the fact is indisputable1  
and therefore requires a solution4      
,from this much of the paper it appears 
that there was a general belief that    
this burning mass was heated vapor      
thrown off from the earth in some       
mysterious manner1 yet this is          
unsatisfactory to ,halley1 for after    
citing various other meteors that have  
appeared within his knowledge1 he goes  
on to say3  ,what sort of substance it  
must be1 that could be so impelled and  
ignited at the same time2 there being no
 ,vulcano or other ,spiraculum of       

subterraneous fire in the northeast     
parts of the world1 that we ever yet    
heard of1 from whence it might be       
projected4  ,i have much considered this
 appearance1 and think it one of the    
hardest things to account for that ,i   
have yet met with in the phenomena of   
meteors1 and ,i am induced to think that
 it must be some collection of matter   
formed in the aether1 as it were1 by    
some fortuitous concourse of atoms1 and 
that the earth met with it as it passed 
along in its orb1 then but newly formed1
 and before it had conceived any great  
impetus of descent towards the sun4 ,for
 the direction of it was exactly        
opposite to that of the earth1 which    
made an angle with the meridian at that 
time of sixty-seven gr41 that is1 its   
course was from west southwest to east  
northeast1 wherefore the meteor seemed  
to move the contrary way4 ,and besides  
falling into the power of the earth's   
gravity1 and losing its motion from the 
opposition of the medium1 it seems that 

it descended towards the earth1 and was 
extinguished in the ,tyrrhene ,sea1 to  
the west southwest of ,leghorn4 ,the    
great blow being heard upon its first   
immersion into the water1 and the       
rattling like the driving of a cart over
 stones being what succeeded upon its   
quenching2 something like this is always
 heard upon quenching a very hot iron in
 water4 ,these facts being past dispute1
 ,i would be glad to have the opinion of
 the learned thereon1 and what objection
 can be reasonably made against the     
above hypothesis1 which ,i humbly submit
 to their censure47#a7  ,these few      
paragraphs1 coming as they do from a    
leading eighteenth-century astronomer1  
convey more clearly than any comment the
 actual state of the meteorological     
learning at that time4 ,that this ball  
of fire1 rushing at a greater velocity  
than the swiftest cannon-ball1 was      
simply a mass of heated rock passing    
through our atmosphere1 did not occur to
 him1 or at least was not credited4 ,nor

 is this surprising when we reflect that
 at that time universal gravitation had 
been but recently discovered2 heat had  
not as yet been recognized as simply a  
form of motion2 and thunder and         
lightning were unexplained mysteries1   
not to be explained for another         
three-quarters of a century4 ,in the    
chapter on meteorology we shall see how 
the solution of this mystery that       
puzzled ,halley and his associates all  
their lives was finally attained4       
,,bradley ,,and ,,the ,,aberration ,,of 
,,light  ,halley was succeeded as       
astronomer royal by a man whose useful  
additions to the science were not to be 
recognized or appreciated fully until   
brought to light by the ,prussian       
astronomer ,bessel early in the         
nineteenth century4 ,this was ,dr4      
,james ,bradley1 an ecclesiastic1 who   
ranks as one of the most eminent        
astronomers of the eighteenth century4  
,his most remarkable discovery was the  
explanation of a peculiar motion of the 

pole-star1 first observed1 but not      
explained1 by ,picard a century before4 
,for many years a satisfactory          
explanation was sought unsuccessfully by
 ,bradley and his fellow-astronomers1   
but at last he was able to demonstrate  
that the stary ,draconis1 on which he   
was making his observations1 described1 
or appeared to describe1 a small        
ellipse4 ,if this observation was       
correct1 it afforded a means of         
computing the aberration of any star at 
all times4 ,the explanation of the      
physical cause of this aberration1 as   
,bradley thought1 and afterwards        
demonstrated1 was the result of the     
combination of the motion of light with 
the annual motion of the earth4 ,bradley
 first formulated this theory in #agbh1 
but it was not until #agdh--twenty years
 of continuous struggle and observation 
by him--that he was prepared to         
communicate the results of his efforts  
to the ,royal ,society4 ,this remarkable
 paper is thought by the ,frenchman1    

,delambre1 to entitle its author to a   
place in science beside such astronomers
 as ,hipparcbus and ,kepler4  ,bradley's
 studies led him to discover also the   
libratory motion of the earth's axis4   
,as this appearance of ,draconis        
indicated a diminution of the           
inclination of the earth's axis to the  
plane of the ecliptic1 he says2 and as  
several astronomers have supposed ,,that
 inclination to diminish regularly2 if  
this phenomenon depended upon such a    
cause1 and amounted to #ah in nine      
years1 the obliquity of the ecliptic    
would1 at that rate1 alter a whole      
minute in thirty years2 which is much   
faster than any observations1 before    
made1 would allow4 ,i had reason1       
therefore1 to think that some part of   
this motion at the least1 if not the    
whole1 was owing to the moon's action   
upon the equatorial parts of the earth2 
which1 ,i conceived1 might cause a      
libratory motion of the earth's axis4   
,but as ,i was unable to judge1 from    

only nine years observations1 whether   
the axis would entirely recover the same
 position that it had in the year #agbg1
 ,i found it necessary to continue my   
observations through a whole period of  
the moon's nodes2 at the end of which ,i
 had the satisfaction to see1 that the  
stars1 returned into the same position  
again2 as if there had been no          
alteration at all in the inclination of 
the earth's axis2 which fully convinced 
me that ,i had guessed rightly as to the
 cause of the phenomena4 ,this          
circumstance proves likewise1 that if   
there be a gradual diminution of the    
obliquity of the ecliptic1 it does not  
arise only from an alteration in the    
position of the earth's axis1 but rather
 from some change in the plane of the   
ecliptic itself2 because the stars1 at  
the end of the period of the moon's     
nodes1 appeared in the same places1 with
 respect to the equator1 as they ought  
to have done1 if the earth's axis had   
retained the same inclination to an     

invariable plane47#b7   ,,french        
,,astronomers  ,meanwhile1 astronomers  
across the channel were by no means     
idle4 ,in ,france several successful    
observers were making many additions to 
the already long list of observations of
 the first astronomer of the ,royal     
,observatory of ,paris1 ,dominic        
,cassini 7#afbe-agab71 whose reputation 
among his contemporaries was much       
greater than among succeeding           
generations of astronomers4 ,perhaps the
 most deserving of these successors was 
,nicolas ,louis de ,lacaille            
7#agac-agfb71 a theologian who had been 
educated at the expense of the ,duke of 
,bourbon1 and who1 soon after completing
 his clerical studies1 came under the   
patronage of ,cassini1 whose attention  
had been called to the young man's      
interest in the sciences4 ,one of       
,lacaille's first under-takings was the 
remeasuring of the ,french are of the   
meridian1 which had been incorrectly    
measured by his patron in #afhd4 ,this  

was begun in #agci1 and occupied him for
 two years before successfully          
completed4 ,as a reward1 however1 he was
 admitted to the academy and appointed  
mathematical professor in ,mazarin      
,college4  ,in #agea he went to the     
,cape of ,good ,hope for the purpose of 
determining the sun's parallax by       
observations of the parallaxes of ,mars 
and ,venus1 and incidentally to make    
observations on the other southern      
hemisphere stars4 ,the results of this  
undertaking were most successful1 and   
were given in his ,coelum australe      
stelligerum1 etc41 published in #agfc4  
,in this he shows that in the course of 
a single year he had observed some ten  
thousand stars1 and computed the places 
of one thousand nine hundred and        
forty-two of them1 measured a degree of 
the meridian1 and made many observations
 of the moon--productive industry seldom
 equalled in a single year in any field4
 ,these observations were of great      
service to the astronomers1 as they     

afforded the opportunity of comparing   
the stars of the southern hemisphere    
with those of the northern1 which were  
being observed simultaneously by        
,lelande at ,berlin4  ,lacaille's       
observations followed closely upon the  
determination of an absorbing question  
which occupied the attention of the     
astronomers in the early part of the    
century4 ,this question was as to the   
shape of the earth--whether it was      
actually flattened at the poles4 ,to    
settle this question once for all the   
,academy of ,sciences decided to make   
the actual measurement of the length of 
two degrees1 one as near the pole as    
possible1 the other at the equator4     
,accordingly1 three astronomers1 ,godin1
 ,bouguer1 and ,la ,condamine1 made the 
journey to a spot on the equator in     
,peru1 while four astronomers1 ,camus1  
,clairaut1 ,maupertuis1 and ,lemonnier1 
made a voyage to a place selected in    
,lapland4 ,the result of these          
expeditions was the determination that  

the globe is oblately spheroidal4  ,a   
great contemporary and fellow-countryman
 of ,lacaille was ,jean ,le ,rond       
d',alembert 7#agag-aghc71 who1 although 
not primarily an astronomer1 did so much
 with his mathematical calculations to  
aid that science that his name is       
closely connected with its progress     
during the eighteenth century4          
,d',alembert1 who became one of the     
best-known men of science of his day1   
and whose services were eagerly sought  
by the rulers of ,europe1 began life as 
a foundling1 having been exposed in one 
of the markets of ,paris4 ,the sickly   
infant was adopted and cared for in the 
family of a poor glazier1 and treated as
 a member of the family4 ,in later      
years1 however1 after the foundling had 
become famous throughout ,europe1 his   
mother1 ,madame ,tencin1 sent for him1  
and acknowledged her relationship4 ,it  
is more than likely that the great      
philosopher believed her story1 but if  
so he did not allow her the satisfaction

 of knowing his belief1 declaring always
 that ,madame ,tencin could not be      
nearer than a step-mother to him1 since 
his mother was the wife of the glazier4 
,d',alembert did much for the cause of  
science by his example as well as by his
 discoveries4 ,by living a plain but    
honest life1 declining magnificent      
offers of positions from royal patrons1 
at the same time refusing to grovel     
before nobility1 he set a worthy example
 to other philosophers whose cringing   
and pusillanimous attitude towards      
persons of wealth or position had       
hitherto earned them the contempt of the
 upper classes4  ,his direct additions  
to astronomy are several1 among others  
the determination of the mutation of the
 axis of the earth4 ,he also determined 
the ratio of the attractive forces of   
the sun and moon1 which he found to be  
about as seven to three4 ,from this he  
reached the conclusion that the earth   
must be seventy times greater than the  
moon4 ,the first two volumes of his     

,researches on the ,systems of the      
,world1 published in #aged1 are largely 
devoted to mathematical and astronomical
 problems1 many of them of little       
importance now1 but of great interest to
 astronomers at that time4  ,another    
great contemporary of ,d',alembert1     
whose name is closely associated and    
frequently confounded with his1 was     
,jean ,baptiste ,joseph ,delambre       
7#agdi-ahbb74 ,more fortunate in birth  
as also in his educational advantages1  
,delambre as a youth began his studies  
under the celebrated poet ,delille4     
,later he was obliged to struggle       
against poverty1 supporting himself for 
a time by making translations from      
,latin1 ,greek1 ,italian1 and ,english1 
and acting as tutor in private families4
 ,the turning-point of his fortune came 
when the attention of ,lalande was      
called to the young man by his          
remarkable memory1 and ,lalande soon    
showed his admiration by giving         
,delambre certain difficult astronomical

 problems to solve4 ,by performing these
 tasks successfully his future as an    
astronomer became assured4 ,at that time
 the planet ,uranus had just been       
discovered by ,herschel1 and the        
,academy of ,sciences offered as the    
subject for one of its prizes the       
determination of the planet's orbit4    
,delambre made this determination and   
won the prize--a feat that brought him  
at once into prominence4  ,by his       
writings he probably did as much towards
 perfecting modern astronomy as any one 
man4 ,his ,history of ,astronomy is not 
merely a narrative of progress of       
astronomy but a complete abstract of all
 the celebrated works written on the    
subject4 ,thus he became famous as an   
historian as well as an astronomer4     
,,leonard ,,euler  ,still another       
contemporary of ,d',alembert and        
,delambre1 and somewhat older than      
either of them1 was ,leonard ,euler     
7#agjg-aghc71 of ,basel1 whose fame as a
 philosopher equals that of either of   

the great ,frenchmen4 ,he is of         
particular interest here in his capacity
 of astronomer1 but astronomy was only  
one of the many fields of science in    
which he shone4 ,surely something out of
 the ordinary was to be expected of the 
man who could repeat the ,a,eneid of    
,virgil from the beginning to the end   
without hesitation1 and indicate the    
first and last line of every page of the
 edition which he used4 ,something was  
expected1 and he fulfilled these        
expectations4  ,in early life he devoted
 himself to the study of theology and   
the ,oriental languages1 at the request 
of his father1 but his love of          
mathematics proved too strong1 and1 with
 his father's consent1 he finally gave  
up his classical studies and turned to  
his favorite study1 geometry4 ,in #agbg 
he was invited by ,catharine ,i4 to     
reside in ,st4 ,petersburg1 and on      
accepting this invitation he was made an
 associate of the ,academy of ,sciences4
 ,a little later he was made professor  

of physics1 and in #agcc professor of   
mathematics4 ,in #agce he solved a      
problem in three days which some of the 
eminent mathematicians would not        
undertake under several months4 ,in     
#agda ,frederick the ,great invited him 
to ,berlin1 where he soon became a      
member of the ,academy of ,sciences and 
professor of mathematics2 but in #agff  
he returned to ,st4 ,petersburg4        
,towards the close of his life he became
 virtually blind1 being obliged to      
dictate his thoughts1 sometimes to      
persons entirely ignorant of the subject
 in hand4 ,nevertheless1 his remarkable 
memory1 still further heightened by his 
blindness1 enabled him to carry out the 
elaborate computations frequently       
involved4  ,euler's first memoir1       
transmitted to the ,academy of ,sciences
 of ,paris in #agdg1 was on the         
planetary perturbations4 ,this memoir   
carried off the prize that had been     
offered for the analytical theory of the
 motions of ,jupiter and ,saturn4 ,other

 memoirs followed1 one in #agdi and     
another in #agej1 with further          
expansions of the same subject4 ,as some
 slight errors were found in these1 such
 as a mistake in some of the formulae   
expressing the secular and periodic     
inequalities1 the academy proposed the  
same subject for the prize of #ageb4    
,euler again competed1 and won this     
prize also4 ,the contents of this memoir
 laid the foundation for the subsequent 
demonstration of the permanent stability
 of the planetary system by ,laplace and
 ,lagrange4  ,it was ,euler also who    
demonstrated that within certain fixed  
limits the eccentricities and places of 
the aphelia of ,saturn and ,jupiter are 
subject to constant variation1 and he   
calculated that after a lapse of about  
thirty thousand years the elements of   
the orbits of these two planets recover 
their original values4     ,,ii4 ,,the  
,,progress ,,of ,,modern ,,astronomy    
,a ,,new epoch in astronomy begins with 
the work of ,william ,herschel1 the     

,hanoverian1 whom ,england made hers by 
adoption4 ,he was a man with a positive 
genius for sidereal discovery4 ,at first
 a mere amateur in astronomy1 he        
snatched time from his duties as        
music-teacher to grind him a telescopic 
mirror1 and began gazing at the stars4  
,not content with his first telescope1  
he made another and another1 and he had 
such genius for the work that he soon   
possessed a better instrument than was  
ever made before4 ,his patience in      
grinding the curved reflective surface  
was monumental4 ,sometimes for sixteen  
hours together he must walk steadily    
about the mirror1 polishing it1 without 
once removing his hands4 ,meantime his  
sister1 always his chief lieutenant1    
cheered him with her presence1 and from 
time to time put food into his mouth4   
,the telescope completed1 the astronomer
 turned night into day1 and from sunset 
to sunrise1 year in and year out1 swept 
the heavens unceasingly1 unless         
prevented by clouds or the brightness of

 the moon4 ,his sister sat always at his
 side1 recording his observations4 ,they
 were in the open air1 perched high at  
the mouth of the reflector1 and         
sometimes it was so cold that the ink   
froze in the bottle in ,caroline        
,herschel's hand2 but the two           
enthusiasts hardly noticed a thing so   
common-place as terrestrial weather4    
,they were living in distant worlds4    
,the results8 ,what could they be8 ,such
 enthusiasm would move mountains4 ,but1 
after all1 the moving of mountains seems
 a liliputian task compared with what   
,herschel really did with those         
wonderful telescopes4 ,he moved worlds1 
stars1 a universe--even1 if you please1 
a galaxy of universes2 at least he      
proved that they move1 which seems      
scarcely less wonderful2 and he expanded
 the cosmos1 as man conceives it1 to    
thousands of times the dimensions it had
 before4 ,as a mere beginning1 he       
doubled the diameter of the solar system
 by observing the great outlying planet 

which we now call ,uranus1 but which he 
christened ,georgium ,sidus1 in honor of
 his sovereign1 and which his ,french   
contemporaries1 not relishing that name1
 preferred to call ,herschel4  ,this    
discovery was but a trifle compared with
 what ,herschel did later on1 but it    
gave him world-wide reputation none the 
less4 ,comets and moons aside1 this was 
the first addition to the solar system  
that had been made within historic      
times1 and it created a veritable furor 
of popular interest and enthusiasm4     
,incidentally ,king ,george was         
flattered at having a world named after 
him1 and he smiled on the astronomer1   
and came with his court to have a look  
at his namesake4 ,the inspection was    
highly satisfactory2 and presently the  
royal favor enabled the astronomer to   
escape the thraldom of teaching music   
and to devote his entire time to the    
more congenial task of star-gazing4     
,thus relieved from the burden of       
mundane embarrassments1 he turned with  

fresh enthusiasm to the skies1 and his  
discoveries followed one another in     
bewildering profusion4 ,he found various
 hitherto unseen moons of our sister    
planets2 he made special studies of     
,saturn1 and proved that this planet1   
with its rings1 revolves on its axis2 he
 scanned the spots on the sun1 and      
suggested that they influence the       
weather of our earth2 in short1 he      
extended the entire field of solar      
astronomy4 ,but very soon this field    
became too small for him1 and his most  
important researches carried him out    
into the regions of space compared with 
which the span of our solar system is a 
mere point4 ,with his perfected         
telescopes he entered abysmal vistas    
which no human eve ever penetrated      
before1 which no human mind had hitherto
 more than vaguely imagined4 ,he tells  
us that his forty-foot reflector will   
bring him light from a distance of at   
least eleven and three-fourths millions 
of millions of millions of miles--light 

which left its source two million years 
ago4 ,the smallest stars visible to the 
unaided eye are those of the sixth      
magnitude2 this telescope1 he thinks1   
has power to reveal stars of the #acdb;d
 magnitude4  ,but what did ,herschel    
learn regarding these awful depths of   
space and the stars that people them8   
,that was what the world wished to know4
 ,copernicus1 ,galileo1 ,kepler1 had    
given us a solar system1 but the stars  
had been a mystery4 ,what says the great
 reflector--are the stars points of     
light1 as the ancients taught1 and as   
more than one philosopher of the        
eighteenth century has still contended1 
or are they suns1 as others hold8       
,herschel answers1 they are suns1 each  
and every one of all the millions--suns1
 many of them1 larger than the one that 
is the centre of our tiny system4 ,not  
only so1 but they are moving suns4      
,instead of being fixed in space1 as has
 been thought1 they are whirling in     
gigantic orbits about some common       

centre4 ,is our sun that centre8 ,far   
from it4 ,our sun is only a star like   
all the rest1 circling on with its      
attendant satellites--our giant sun a   
star1 no different from myriad other    
stars1 not even so large as some2 a mere
 insignificant spark of matter in an    
infinite shower of sparks4  ,nor is this
 all4 ,looking beyond the few thousand  
stars that are visible to the naked eye1
 ,herschel sees series after series of  
more distant stars1 marshalled in       
galaxies of millions2 but at last he    
reaches a distance beyond which the     
galaxies no longer increase4 ,and       
yet--so he thinks--he has not reached   
the limits of his vision4 ,what then8   
,he has come to the bounds of the       
sidereal system--seen to the confines of
 the universe4 ,he believes that he can 
outline this system1 this universe1 and 
prove that it has the shape of an       
irregular globe1 oblately flattened to  
almost disklike proportions1 and divided
 at one edge--a bifurcation that is     

revealed even to the naked eye in the   
forking of the ,milky ,way4  ,this1     
then1 is our universe as ,herschel      
conceives it--a vast galaxy of suns1    
held to one centre1 revolving1 poised in
 space4 ,but even here those marvellous 
telescopes do not pause4 ,far1 far out  
beyond the confines of our universe1 so 
far that the awful span of our own      
system might serve as a unit of measure1
 are revealed other systems1 other      
universes1 like our own1 each composed1 
as he thinks1 of myriads of suns1       
clustered like our galaxy into an       
isolated system--mere islands of matter 
in an infinite ocean of space4 ,so      
distant from our universe are these now 
universes of ,herschel's discovery that 
their light reaches us only as a dim1   
nebulous glow1 in most cases invisible  
to the unaided eye4 ,about a hundred of 
these nebulae were known when ,herschel 
began his studies4 ,before the close of 
the century he had discovered about two 
thousand more of them1 and many of these

 had been resolved by his largest       
telescopes into clusters of stars4 ,he  
believed that the farthest of these     
nebulae that he could see was at least  
three hundred thousand times as distant 
from us as the nearest fixed star4 ,yet 
that nearest star--so more recent       
studies prove--is so remote that its    
light1 travelling one hundred and eighty
 thousand miles a second1 requires three
 and one-half years to reach our planet4
  ,as if to give the finishing touches  
to this novel scheme of cosmology1      
,herschel1 though in the main very      
little given to unsustained theorizing1 
allows himself the privilege of one     
belief that he cannot call upon his     
telescope to substantiate4 ,he thinks   
that all the myriad suns of his         
numberless systems are instinct with    
life in the human sense4 ,giordano      
,bruno and a long line of his followers 
had held that some of our sister planets
 may be inhabited1 but ,herschel extends
 the thought to include the moon1 the   

sun1 the stars--all the heavenly bodies4
 ,he believes that he can demonstrate   
the habitability of our own sun1 and1   
reasoning from analogy1 he is firmly    
convinced that all the suns of all the  
systems are well supplied with          
inhabitants4 ,in this1 as in some other 
inferences1 ,herschel is misled by the  
faulty physics of his time4 ,future     
generations1 working with perfected     
instruments1 may not sustain him all    
along the line of his observations1     
even1 let alone his inferences4 ,but how
 one's egotism shrivels and shrinks as  
one grasps the import of his sweeping   
thoughts6  ,continuing his observations 
of the innumerable nebulae1 ,herschel is
 led presently to another curious       
speculative inference4 ,he notes that   
some star groups are much more thickly  
clustered than others1 and he is led to 
infer that such varied clustering tells 
of varying ages of the different        
nebulae4 ,he thinks that at first all   
space may have been evenly sprinkled    

with the stars and that the grouping has
 resulted from the action of            
gravitation4  ,that the ,milky ,way is a
 most extensive stratum of stars of     
various sizes admits no longer of       
lasting doubt1 he declares1 and that our
 sun is actually one of the heavenly    
bodies belonging to it is as evident4 ,i
 have now viewed and gauged this shining
 zone in almost every direction and find
 it composed of stars whose number444   
constantly increases and decreases in   
proportion to its apparent brightness to
 the naked eye4  ,let us suppose        
numberless stars of various sizes1      
scattered over an indefinite portion of 
space in such a manner as to be almost  
equally distributed throughout the      
whole4 ,the laws of attraction which no 
doubt extend to the remotest regions of 
the fixed stars will operate in such a  
manner as most probably to produce the  
following effects3  ,in the first case1 
since we have supposed the stars to be  
of various sizes1 it will happen that a 

star1 being considerably larger than its
 neighboring ones1 will attract them    
more than they will be attracted by     
others that are immediately around them2
 by which means they will be1 in time1  
as it were1 condensed about a centre1   
or1 in other words1 form themselves into
 a cluster of stars of almost a globular
 figure1 more or less regular according 
to the size and distance of the         
surrounding stars4444  ,the next case1  
which will also happen almost as        
frequently as the former1 is where a few
 stars1 though not superior in size to  
the rest1 may chance to be rather nearer
 one another than the surrounding       
ones1444 and this construction admits of
 the utmost variety of shapes4444  ,from
 the composition and repeated           
conjunction of both the foregoing       
formations1 a third may be derived when 
many large stars1 or combined small     
ones1 are spread in long1 extended1     
regular1 or crooked rows1 streaks1 or   
branches2 for they will also draw the   

surrounding stars1 so as to produce     
figures of condensed stars curiously    
similar to the former which gave rise to
 these condensations4  ,we may likewise 
admit still more extensive combinations2
 when1 at the same time that a cluster  
of stars is forming at the one part of  
space1 there may be another collection  
in a different but perhaps not          
far-distant quarter1 which may occasion 
a mutual approach towards their own     
centre of gravity4  ,in the last place1 
as a natural conclusion of the former   
cases1 there will be formed great       
cavities or vacancies by the retreating 
of the stars towards the various centres
 which attract them47#a7   ,looking     
forward1 it appears that the time must  
come when all the suns of a system will 
be drawn together and destroyed by      
impact at a common centre4 ,already1 it 
seems to ,herschel1 the thickest        
clusters have outlived their usefulness 
and are verging towards their doom4     
,but again1 other nebulae present an    

appearance suggestive of an opposite    
condition4 ,they are not resolvable into
 stars1 but present an almost uniform   
appearance throughout1 and are hence    
believed to be composed of a shining    
fluid1 which in some instances is seen  
to be condensed at the centre into a    
glowing mass4 ,in such a nebula         
,herschel thinks he sees a sun in       
process of formation4   ,,the ,,nebular 
,,hypothesis ,,of ,,kant  ,taken        
together1 these two conceptions outline 
a majestic cycle of world formation and 
world destruction--a broad scheme of    
cosmogony1 such as had been vaguely     
adumbrated two centuries before by      
,kepler and in more recent times by     
,wright and ,swedenborg4 ,this so-called
 nebular hypothesis assumes that in the 
beginning all space was uniformly filled
 with cosmic matter in a state of       
nebular or fire-mist diffusion1 formless
 and void4 ,it pictures the             
condensation--coagulation1 if you       
will--of portions of this mass to form  

segregated masses1 and the ultimate     
development out of these masses of the  
sidereal bodies that we see4  ,perhaps  
the first elaborate exposition of this  
idea was that given by the great ,german
 philosopher ,immanuel ,kant 7born at   
,konigsberg in #agbd1 died in #ahjd71   
known to every one as the author of the 
,critique of ,pure ,reason4 ,let us     
learn from his own words how the        
imaginative philosopher conceived the   
world to have come into existence4  ,i  
assume1 says ,kant1 that all the        
material of which the globes belonging  
to our solar system--all the planets and
 comets--consist1 at the beginning of   
all things was decomposed into its      
primary elements1 and filled the whole  
space of the universe in which the      
bodies formed out of it now revolve4    
,this state of nature1 when viewed in   
and by itself without any reference to a
 system1 seems to be the very simplest  
that can follow upon nothing4 ,at that  
time nothing has yet been formed4 ,the  

construction of heavenly bodies at a    
distance from one another1 their        
distances regulated by their attraction1
 their form arising out of the          
equilibrium of their collected matter1  
exhibit a later state4444 ,in a region  
of space filled in this manner1 a       
universal repose could last only a      
moment4 ,the elements have essential    
forces with which to put each other in  
motion1 and thus are themselves a source
 of life4 ,matter immediately begins to 
strive to fashion itself4 ,the scattered
 elements of a denser kind1 by means of 
their attraction1 gather from a sphere  
around them all the matter of less      
specific gravity2 again1 these elements 
themselves1 together with the material  
which they have united with them1       
collect in those points where the       
particles of a still denser kind are    
found2 these in like manner join still  
denser particles1 and so on4 ,if we     
follow in imagination this process by   
which nature fashions itself into form  

through the whole extent of chaos1 we   
easily perceive that all the results of 
the process would consist in the        
formation of divers masses which1 when  
their formation was complete1 would by  
the equality of their attraction be at  
rest and be forever unmoved4  ,but      
nature has other forces in store which  
are specially exerted when matter is    
decomposed into fine particles4 ,they   
are those forces by which these         
particles repel one another1 and which1 
by their conflict with attractions1     
bring forth that movement which is1 as  
it were1 the lasting life of nature4    
,this force of repulsion is manifested  
in the elasticity of vapors1 the        
effluences of strong-smelling bodies1   
and the diffusion of all spirituous     
matters4 ,this force is an uncontestable
 phenomenon of matter4 ,it is by it that
 the elements1 which may be falling to  
the point attracting them1 are turned   
sideways promiscuously from their       
movement in a straight line2 and their  

perpendicular fall thereby issues in    
circular movements1 which encompass the 
centre towards which they were falling4 
,in order to make the formation of the  
world more distinctly conceivable1 we   
will limit our view by withdrawing it   
from the infinite universe of nature and
 directing it to a particular system1 as
 the one which belongs to our sun4      
,having considered the generation of    
this system1 we shall be able to advance
 to a similar consideration of the      
origin of the great world-systems1 and  
thus to embrace the infinitude of the   
whole creation in one conception4  ,from
 what has been said1 it will appear that
 if a point is situated in a very large 
space where the attraction of the       
elements there situated acts more       
strongly than elsewhere1 then the matter
 of the elementary particles scattered  
throughout the whole region will fall to
 that point4 ,the first effect of this  
general fall is the formation of a body 
at this centre of attraction1 which1 so 

to speak1 grows from an infinitely small
 nucleus by rapid strides2 and in the   
proportion in which this mass increases1
 it also draws with greater force the   
surrounding particles to unite with it4 
,when the mass of this central body has 
grown so great that the velocity with   
which it draws the particles to itself  
with great distances is bent sideways by
 the feeble degree of repulsion with    
which they impede one another1 and when 
it issues in lateral movements which are
 capable by means of the centrifugal    
force of encompassing the central body  
in an orbit1 then there are produced    
whirls or vortices of particles1 each of
 which by itself describes a curved line
 by the composition of the attracting   
force and the force of revolution that  
had been bent sideways4 ,these kinds of 
orbits all intersect one another1 for   
which their great dispersion in this    
space gives place4 ,yet these movements 
are in many ways in conflict with one   
another1 and they naturally tend to     

bring one another to a uniformity--that 
is1 into a state in which one movement  
is as little obstructive to the other as
 possible4 ,this happens in two ways3   
first by the particles limiting one     
another's movement till they all advance
 in one direction2 and1 secondly1 in    
this way1 that the particles limit their
 vertical movements in virtue of which  
they are approaching the centre of      
attraction1 till they all move          
horizontally--i4 e41 in parallel circles
 round the sun as their centre1 no      
longer intercept one another1 and by the
 centrifugal force becoming equal with  
the falling force they keep themselves  
constantly in free circular orbits at   
the distance at which they move4 ,the   
result1 finally1 is that only those     
particles continue to move in this      
region of space which have acquired by  
their fall a velocity1 and through the  
resistance of the other particles a     
direction1 by which they can continue to
 maintain a ,,free ,,circular           

,,movement4444  ,the view of the        
formation of the planets in this system 
has the advantage over every other      
possible theory in holding that the     
origin of the movements1 and the        
position of the orbits in arising at    
that same point of time--nay1 more1 in  
showing that even the deviations from   
the greatest possible exactness in their
 determinations1 as well as the         
accordances themselves1 become clear at 
a glance4 ,the planets are formed out of
 particles which1 at the distance at    
which they move1 have exact movements in
 circular orbits2 and therefore the     
masses composed out of them will        
continue the same movements and at the  
same rate and in the same direction47#b7
   ,it must be admitted that this       
explanation leaves a good deal to be    
desired4 ,it is the explanation of a    
metaphysician rather than that of an    
experimental scientist4 ,such phrases as
 matter immediately begins to strive to 
fashion itself1 for example1 have no    

place in the reasoning of inductive     
science4 ,nevertheless1 the hypothesis  
of ,kant is a remarkable conception2 it 
attempts to explain along rational lines
 something which hitherto had for the   
most part been considered altogether    
inexplicable4  ,but there are various   
questions that at once suggest          
themselves which the ,kantian theory    
leaves unanswered4 ,how happens it1 for 
example1 that the cosmic mass which gave
 birth to our solar system was divided  
into several planetary bodies instead of
 remaining a single mass8 ,were the     
planets struck from the sun by the      
chance impact of comets1 as ,buffon has 
suggested8 or thrown out by explosive   
volcanic action1 in accordance with the 
theory of ,dr4 ,darwin8 or do they owe  
their origin to some unknown law8 ,in   
any event1 how chanced it that all were 
projected in nearly the same plane as we
 now find them8   ,,laplace ,,and ,,the 
,,nebular ,,hypothesis  ,it remained for
 a mathematical astronomer to solve     

these puzzles4 ,the man of all others   
competent to take the subject in hand   
was the ,french astronomer ,laplace4    
,for a quarter of a century he had      
devoted his transcendent mathematical   
abilities to the solution of problems of
 motion of the heavenly bodies4 ,working
 in friendly rivalry with his countryman
 ,lagrange1 his only peer among the     
mathematicians of the age1 he had taken 
up and solved one by one the problems   
that ,newton left obscure4 ,largely     
through the efforts of these two men the
 last lingering doubts as to the        
solidarity of the ,newtonian hypothesis 
of universal gravitation had been       
removed4 ,the share of ,lagrange was    
hardly less than that of his co-worker2 
but ,laplace will longer be remembered1 
because he ultimately brought his       
completed labors into a system1 and1    
incorporating with them the labors of   
his contemporaries1 produced in the     
,mecanique ,celeste the undisputed      
mathematical monument of the century1 a 

fitting complement to the ,principia of 
,newton1 which it supplements and in a  
sense completes4  ,in the closing years 
of the eighteenth century ,laplace took 
up the nebular hypothesis of cosmogony1 
to which we have just referred1 and gave
 it definite proportions2 in fact1 made 
it so thoroughly his own that posterity 
will always link it with his name4      
,discarding the crude notions of        
cometary impact and volcanic eruption1  
,laplace filled up the gaps in the      
hypothesis with the aid of well-known   
laws of gravitation and motion4 ,he     
assumed that the primitive mass of      
cosmic matter which was destined to form
 our solar system was revolving on its  
axis even at a time when it was still   
nebular in character1 and filled all    
space to a distance far beyond the      
present limits of the system4 ,as this  
vaporous mass contracted through loss of
 heat1 it revolved more and more        
swiftly1 and from time to time1 through 
balance of forces at its periphery1     

rings of its substance were whirled off 
and left revolving there1 subsequently  
to become condensed into planets1 and in
 their turn whirl off minor rings that  
became moons4 ,the main body of the     
original mass remains in the present as 
the still contracting and rotating body 
which we call the sun4  ,let us allow   
,laplace to explain all this in detail3 
,in order to explain the prime movements
 of the planetary system1 he says1 there
 are the five following phenomena3 ,the 
movement of the planets in the same     
direction and very nearly in the same   
plane2 the movement of the satellites in
 the same direction as that of the      
planets2 the rotation of these different
 bodies and the sun in the same         
direction as their revolution1 and in   
nearly the same plane2 the slight       
eccentricity of the orbits of the       
planets and of the satellites2 and1     
finally1 the great eccentricity of the  
orbits of the comets1 as if their       
inclinations had been left to chance4   

,buffon is the only man ,i know who1    
since the discovery of the true system  
of the world1 has endeavored to show the
 origin of the planets and their        
satellites4 ,he supposes that a comet1  
in falling into the sun1 drove from it a
 mass of matter which was reassembled at
 a distance in the form of various      
globes more or less large1 and more or  
less removed from the sun1 and that     
these globes1 becoming opaque and solid1
 are now the planets and their          
satellites4  ,this hypothesis satisfies 
the first of the five preceding         
phenomena2 for it is clear that all the 
bodies thus formed would move very      
nearly in the plane which passed through
 the centre of the sun1 and in the      
direction of the torrent of matter which
 was produced2 but the four other       
phenomena appear to be inexplicable to  
me by this means4 ,indeed1 the absolute 
movement of the molecules of a planet   
ought then to be in the direction of the
 movement of its centre of gravity2 but 

it does not at all follow that the      
motion of the rotation of the planets   
should be in the same direction4 ,thus  
the earth should rotate from east to    
west1 but nevertheless the absolute     
movement of its molecules should be from
 east to west2 and this ought also to   
apply to the movement of the revolution 
of the satellites1 in which the         
direction1 according to the hypothesis  
which he offers1 is not necessarily the 
same as that of the progressive movement
 of the planets4  ,a phenomenon not only
 very difficult to explain under this   
hypothesis1 but one which is even       
contrary to it1 is the slight           
eccentricity of the planetary orbits4   
,we know1 by the theory of central      
forces1 that if a body moves in a closed
 orbit around the sun and touches it1 it
 also always comes back to that point at
 every revolution2 whence it follows    
that if the planets were originally     
detached from the sun1 they would touch 
it at each return towards it1 and their 

orbits1 far from being circular1 would  
be very eccentric4 ,it is true that a   
mass of matter driven from the sun      
cannot be exactly compared to a globe   
which touches its surface1 for the      
impulse which the particles of this mass
 receive from one another and the       
reciprocal attractions which they exert 
among themselves1 could1 in changing the
 direction of their movements1 remove   
their perihelions from the sun2 but     
their orbits would be always most       
eccentric1 or at least they would not   
have slight eccentricities except by the
 most extraordinary chance4 ,thus we    
cannot see1 according to the hypothesis 
of ,buffon1 why the orbits of more than 
a hundred comets already observed are so
 elliptical4 ,this hypothesis is        
therefore very far from satisfying the  
preceding phenomena4 ,let us see if it  
is possible to trace them back to their 
true cause4  ,whatever may be its       
ultimate nature1 seeing that it has     
caused or modified the movements of the 

planets1 it is necessary that this cause
 should embrace every body1 and1 in view
 of the enormous distances which        
separate them1 it could only have been a
 fluid of immense extent4 ,in order to  
have given them an almost circular      
movement in the same direction around   
the sun1 it is necessary that this fluid
 should have enveloped the sun as in an 
atmosphere4 ,the consideration of the   
planetary movements leads us then to    
think that1 on account of excessive     
heat1 the atmosphere of the sun         
originally extended beyond the orbits of
 all the planets1 and that it was       
successively contracted to its present  
limits4  ,in the primitive condition in 
which we suppose the sun to have been1  
it resembled a nebula such as the       
telescope shows is composed of a nucleus
 more or less brilliant1 surrounded by a
 nebulosity which1 on condensing itself 
towards the centre1 forms a star4 ,if it
 is conceived by analogy that all the   
stars were formed in this manner1 it is 

possible to imagine their previous      
condition of nebulosity1 itself preceded
 by other states in which the nebulous  
matter was still more diffused1 the     
nucleus being less and less luminous4   
,by going back as far as possible1 we   
thus arrive at a nebulosity so diffused 
that its existence could hardly be      
suspected4  ,for a long time the        
peculiar disposition of certain stars1  
visible to the unaided eye1 has struck  
philosophical observers4 ,mitchell has  
already remarked how little probable it 
is that the stars in the ,pleiades1 for 
example1 could have been contracted into
 the small space which encloses them by 
the fortuity of chance alone1 and he has
 concluded that this group of stars1 and
 similar groups which the skies present 
to us1 are the necessary result of the  
condensation of a nebula1 with several  
nuclei1 and it is evident that a nebula1
 by continually contracting1 towards    
these various nuclei1 at length would   
form a group of stars similar to the    

,pleiades4 ,the condensation of a nebula
 with two nuclei would form a system of 
stars close together1 turning one upon  
the other1 such as those double stars of
 which we already know the respective   
movements4  ,but how did the solar      
atmosphere determine the movements of   
the rotation and revolution of the      
planets and satellites8 ,if these bodies
 had penetrated very deeply into this   
atmosphere1 its resistance would have   
caused them to fall into the sun4 ,we   
can therefore conjecture that the       
planets were formed at their successive 
limits by the condensation of a zone of 
vapors which the sun1 on cooling1 left  
behind1 in the plane of his equator4    
,let us recall the results which we have
 given in a preceding chapter4 ,the     
atmosphere of the sun could not have    
extended indefinitely4 ,its limit was   
the point where the centrifugal force   
due to its movement of rotation balanced
 its weight4 ,but in proportion as the  
cooling contracted the atmosphere1 and  

those molecules which were near to them 
condensed upon the surface of the body1 
the movement of the rotation increased2 
for1 on account of the ,law of ,areas1  
the sum of the areas described by the   
vector of each molecule of the sun and  
its atmosphere and projected in the     
plane of the equator being always the   
same1 the rotation should increase when 
these molecules approach the centre of  
the sun4 ,the centrifugal force due to  
this movement becoming thus larger1 the 
point where the weight is equal to it is
 nearer the sun4 ,supposing1 then1 as it
 is natural to admit1 that the          
atmosphere extended at some period to   
its very limits1 it should1 on cooling1 
leave molecules behind at this limit and
 at limits successively occasioned by   
the increased rotation of the sun4 ,the 
abandoned molecules would continue to   
revolve around this body1 since their   
centrifugal force was balanced by their 
weight4 ,but this equilibrium not       
arising in regard to the atmospheric    

molecules parallel to the solar equator1
 the latter1 on account of their weight1
 approached the atmosphere as they      
condensed1 and did not cease to belong  
to it until by this motion they came    
upon the equator4  ,let us consider now 
the zones of vapor successively left    
behind4 ,these zones ought1 according to
 appearance1 by the condensation and    
mutual attraction of their molecules1 to
 form various concentric rings of vapor 
revolving around the sun4 ,the mutual   
gravitational friction of each ring     
would accelerate some and retard others1
 until they had all acquired the same   
angular velocity4 ,thus the actual      
velocity of the molecules most removed  
from the sun would be the greatest4 ,the
 following cause would also operate to  
bring about this difference of speed4   
,the molecules farthest from the sun1   
and which by the effects of cooling and 
condensation approached one another to  
form the outer part of the ring1 would  
have always described areas proportional

 to the time since the central force by 
which they were controlled has been     
constantly directed towards this body4  
,but this constancy of areas            
necessitates an increase of velocity    
proportional to the distance4 ,it is    
thus seen that the same cause would     
diminish the velocity of the molecules  
which form the inner part of the ring4  
,if all the molecules of the ring of    
vapor continued to condense without     
disuniting1 they would at length form a 
ring either solid or fluid4 ,but this   
formation would necessitate such a      
regularity in every part of the ring1   
and in its cooling1 that this phenomenon
 is extremely rare2 and the solar system
 affords us1 indeed1 but one            
example--namely1 in the ring of ,saturn4
 ,in nearly every case the ring of vapor
 was broken into several masses1 each   
moving at similar velocities1 and       
continuing to rotate at the same        
distance around the sun4 ,these masses  
would take a spheroid form with a       

rotatory movement in the direction of   
the revolution1 because their inner     
molecules had less velocity than the    
outer4 ,thus were formed so many planets
 in a condition of vapor4 ,but if one of
 them were powerful enough to reunite   
successively by its attraction all the  
others around its centre of gravity1 the
 ring of vapor would be thus transformed
 into a single spheroidical mass of     
vapor revolving around the sun with a   
rotation in the direction of its        
revolution4 ,the latter case has been   
that which is the most common1 but      
nevertheless the solar system affords us
 an instance of the first case in the   
four small planets which move between   
,jupiter and ,mars2 at least1 if we do  
not suppose1 as does ,m4 ,olbers1 that  
they originally formed a single planet  
which a mighty explosion broke up into  
several portions each moving at         
different velocities4  ,according to our
 hypothesis1 the comets are strangers to
 our planetary system4 ,in considering  

them1 as we have done1 as minute        
nebulosities1 wandering from solar      
system to solar system1 and formed by   
the condensation of the nebulous matter 
everywhere existent in profusion in the 
universe1 we see that when they come    
into that part of the heavens where the 
sun is all-powerful1 he forces them to  
describe orbits either elliptical or    
hyperbolic1 their paths being equally   
possible in all directions1 and at all  
inclinations of the ecliptic1           
conformably to what has been observed4  
,thus the condensation of nebulous      
matter1 by which we have at first       
explained the motions of the rotation   
and revolution of the planets and their 
satellites in the same direction1 and in
 nearly approximate planes1 explains    
also why the movements of the comets    
escape this general law47#c7   ,the     
nebular hypothesis thus given detailed  
completion by ,laplace is a worthy      
complement of the grand cosmologic      
scheme of ,herschel4 ,whether true or   

false1 the two conceptions stand as the 
final contributions of the eighteenth   
century to the history of man's         
ceaseless efforts to solve the mysteries
 of cosmic origin and cosmic structure4 
,the world listened eagerly and without 
prejudice to the new doctrines2 and that
 attitude tells of a marvellous         
intellectual growth of our race4 ,mark  
the transition4 ,in the year #afjj1     
,bruno was burned at the stake for      
teaching that our earth is not the      
centre of the universe4 ,in #agjj1      
,newton was pronounced impious and      
heretical by a large school of          
philosophers for declaring that the     
force which holds the planets in their  
orbits is universal gravitation4 ,in    
#ahjj1 ,laplace and ,herschel are       
honored for teaching that gravitation   
built up the system which it still      
controls2 that our universe is but a    
minor nebula1 our sun but a minor star1 
our earth a mere atom of matter1 our    
race only one of myriad races peopling  

an infinity of worlds4 ,doctrines which 
but the span of two human lives before  
would have brought their enunciators to 
the stake were now pronounced not       
impious1 but sublime4   ,,asteroids     
,,and ,,satellites  ,the first day of   
the nineteenth century was fittingly    
signalized by the discovery of a new    
world4 ,on the evening of ,january #a1  
#ahja1 an ,italian astronomer1 ,piazzi1 
observed an apparent star of about the  
eighth magnitude 7hence1 of course1     
quite invisible to the unaided eye71    
which later on was seen to have moved1  
and was thus shown to be vastly nearer  
the earth than any true star4 ,he at    
first supposed1 as ,herschel had done   
when he first saw ,uranus1 that the     
unfamiliar body was a comet2 but later  
observation proved it a tiny planet1    
occupying a position in space between   
,mars and ,jupiter4 ,it was christened  
,ceres1 after the tutelary goddess of   
,sicily4  ,though unpremeditated1 this  
discovery was not unexpected1 for       

astronomers had long surmised the       
existence of a planet in the wide gap   
between ,mars and ,jupiter4 ,indeed1    
they were even preparing to make        
concerted search for it1 despite the    
protests of philosophers1 who argued    
that the planets could not possibly     
exceed the magic number seven1 when     
,piazzi forestalled their efforts4 ,but 
a surprise came with the sequel2 for the
 very next year ,dr4 ,olbers1 the       
wonderful physician-astronomer of       
,bremen1 while following up the course  
of ,ceres1 happened on another tiny     
moving star1 similarly located1 which   
soon revealed itself as planetary4 ,thus
 two planets were found where only one  
was expected4  ,the existence of the    
supernumerary was a puzzle1 but ,olbers 
solved it for the moment by suggesting  
that ,ceres and ,pallas1 as he called   
his captive1 might be fragments of a    
quondam planet1 shattered by internal   
explosion or by the impact of a comet4  
,other similar fragments1 he ventured to

 predict1 would be found when searched  
for4 ,william ,herschel sanctioned this 
theory1 and suggested the name asteroids
 for the tiny planets4 ,the explosion   
theory was supported by the discovery of
 another asteroid1 by ,harding1 of      
,lilienthal1 in #ahjd1 and it seemed    
clinched when ,olbers himself found a   
fourth in #ahjg4 ,the new-comers were   
named ,juno and ,vesta respectively4    
,there the case rested till #ahde1 when 
a ,prussian amateur astronomer named    
,hencke found another asteroid1 after   
long searching1 and opened a new epoch  
of discovery4 ,from then on the finding 
of asteroids became a commonplace4      
,latterly1 with the aid of photography1 
the list has been extended to above four
 hundred1 and as yet there seems no     
dearth in the supply1 though doubtless  
all the larger members have been        
revealed4 ,even these are but a few     
hundreds of miles in diameter1 while the
 smaller ones are too tiny for          
measurement4 ,the combined bulk of these

 minor planets is believed to be but a  
fraction of that of the earth4          
,olbers's explosion theory1 long        
accepted by astronomers1 has been proven
 open to fatal objections4 ,the minor   
planets are now believed to represent a 
ring of cosmical matter1 cast off from  
the solar nebula like the rings that    
went to form the major planets1 but     
prevented from becoming aggregated into 
a single body by the perturbing mass of 
,jupiter4   ,the ,discovery of ,neptune 
,as we have seen1 the discovery of the  
first asteroid confirmed a conjecture2  
the other important planetary discovery 
of the nineteenth century fulfilled a   
prediction4 ,neptune was found through  
scientific prophecy4 ,no one suspected  
the existence of a trans-,uranian planet
 till ,uranus itself1 by hair-breadth   
departures from its predicted orbit1    
gave out the secret4 ,no one saw the    
disturbing planet till the pencil of the
 mathematician1 with almost occult      
divination1 had pointed out its place in

 the heavens4 ,the general predication  
of a trans-,uranian planet was made by  
,bessel1 the great ,konigsberg          
astronomer1 in #ahdj2 the analysis that 
revealed its exact location was         
undertaken1 half a decade later1 by two 
independent workers--,john ,couch       
,adams1 just graduated senior wrangler  
at ,cambridge1 ,england1 and ,u4 ,j4 ,j4
 ,leverrier1 the leading ,french        
mathematician of his generation4        
,adams's calculation was first begun and
 first completed4 ,but it had one       
radical defect--it was the work of a    
young and untried man4 ,so it found     
lodgment in a pigeon-hole of the desk of
 ,england's ,astronomer ,royal1 and an  
opportunity was lost which ,english     
astronomers have never ceased to mourn4 
,had the search been made1 an actual    
planet would have been seen shining     
there1 close to the spot where the      
pencil of the mathematician had placed  
its hypothetical counterpart4 ,but the  
search was not made1 and while the      

prophecy of ,adams gathered dust in that
 regrettable pigeon-hole1 ,leverrier's  
calculation was coming on1 his tentative
 results meeting full encouragement from
 ,arago and other ,french savants4 ,at  
last the laborious calculations proved  
satisfactory1 and1 confident of the     
result1 ,leverrier sent to the ,berlin  
observatory1 requesting that search be  
made for the disturber of ,uranus in a  
particular spot of the heavens4 ,dr4    
,galle received the request ,september  
#bc1 #ahdf4 ,that very night he turned  
his telescope to the indicated region1  
and there1 within a single degree of the
 suggested spot1 he saw a seeming star1 
invisible to the unaided eye1 which     
proved to be the long-sought planet1    
henceforth to be known as ,neptune4 ,to 
the average mind1 which finds something 
altogether mystifying about abstract    
mathematics1 this was a feat savoring of
 the miraculous4  ,stimulated by this   
success1 ,leverrier calculated an orbit 
for an interior planet from             

perturbations of ,mercury1 but though   
prematurely christened ,vulcan1 this    
hypothetical nursling of the sun still  
haunts the realm of the undiscovered1   
along with certain equally hypothetical 
trans-,neptunian planets whose existence
 has been suggested by residual         
perturbations of ,uranus1 and by the    
movements of comets4 ,no other veritable
 additions of the sun's planetary family
 have been made in our century1 beyond  
the finding of seven small moons1 which 
chiefly attest the advance in telescopic
 powers4 ,of these1 the tiny attendants 
of our ,martian neighbor1 discovered by 
,professor ,hall with the great         
,washington refractor1 are of greatest  
interest1 because of their small size   
and extremely rapid flight4 ,one of them
 is poised only six thousand miles from 
,mars1 and whirls about him almost four 
times as fast as he revolves1 seeming   
thus1 as viewed by the ,martian1 to rise
 in the west and set in the east1 and   
making the month only one-fourth as long

 as the day4   ,the ,rings of ,saturn   
,the discovery of the inner or crape    
ring of ,saturn1 made simultaneously in 
#ahej by ,william ,c4 ,bond1 at the     
,harvard observatory1 in ,america1 and  
the ,rev4 ,w4 ,r4 ,dawes in ,england1   
was another interesting optical         
achievement2 but our most important     
advances in knowledge of ,saturn's      
unique system are due to the            
mathematician4 ,laplace1 like his       
predecessors1 supposed these rings to be
 solid1 and explained their stability as
 due to certain irregularities of       
contour which ,herschel bad pointed out4
 ,but about #ahea ,professor ,peirce1 of
 ,harvard1 showed the untenability of   
this conclusion1 proving that were the  
rings such as ,laplace thought them they
 must fall of their own weight4 ,then   
,professor ,j4 ,clerk-,maxwell1 of      
,cambridge1 took the matter in hand1 and
 his analysis reduced the puzzling rings
 to a cloud of meteoric particles--a    
shower of brickbats--each fragment of   

which circulates exactly as if it were  
an independent planet1 though of course 
perturbed and jostled more or less by   
its fellows4 ,mutual perturbations1 and 
the disturbing pulls of ,saturn's       
orthodox satellites1 as investigated by 
,maxwell1 explain nearly all the        
phenomena of the rings in a manner      
highly satisfactory4  ,after elaborate  
mathematical calculations covering many 
pages of his paper entitled ,on the     
,stability of ,saturn's ,rings1 he      
summarizes his deductions as follows3   
,let us now gather together the         
conclusions we have been able to draw   
from the mathematical theory of various 
kinds of conceivable rings4  ,we found  
that the stability of the motion of a   
solid ring depended on so delicate an   
adjustment1 and at the same time so     
unsymmetrical a distribution of mass1   
that even if the exact conditions were  
fulfilled1 it could scarcely last long1 
and1 if it did1 the immense             
preponderance of one side of the ring   

would be easily observed1 contrary to   
experience4 ,these considerations1 with 
others derived from the mechanical      
structure of so vast a body1 compel us  
to abandon any theory of solid rings4   
,we next examined the motion of a ring  
of equal satellites1 and found that if  
the mass of the planet is sufficient1   
any disturbances produced in the        
arrangement of the ring will be         
propagated around it in the form of     
waves1 and will not introduce dangerous 
confusion4 ,if the satellites are       
unequal1 the propagations of the waves  
will no longer be regular1 but          
disturbances of the ring will in this1  
as in the former case1 produce only     
waves1 and not growing confusion4       
,supposing the ring to consist1 not of a
 single row of large satellites1 but a  
cloud of evenly distributed unconnected 
particles1 we found that such a cloud   
must have a very small density in order 
to be permanent1 and that this is       
inconsistent with its outer and inner   

parts moving with the same angular      
velocity4 ,supposing the ring to be     
fluid and continuous1 we found that it  
will be necessarily broken up into small
 portions4  ,we conclude1 therefore1    
that the rings must consist of          
disconnected particles2 these must be   
either solid or liquid1 but they must be
 independent4 ,the entire system of     
rings must1 therefore1 consist either of
 a series of many concentric rings each 
moving with its own velocity and having 
its own system of waves1 or else of a   
confused multitude of revolving         
particles not arranged in rings and     
continually coming into collision with  
one another4  ,taking the first case1 we
 found that in an indefinite number of  
possible cases the mutual perturbations 
of two rings1 stable in themselves1     
might mount up in time to a destructive 
magnitude1 and that such cases must     
continually occur in an extensive system
 like that of ,saturn1 the only         
retarding cause being the irregularity  

of the rings4  ,the result of           
long-continued disturbance was found to 
be the spreading-out of the rings in    
breadth1 the outer rings pressing       
outward1 while the inner rings press    
inward4  ,the final result1 therefore1  
of the mechanical theory is that the    
only system of rings which can exist is 
one composed of an indefinite number of 
unconnected particles1 revolving around 
the planet with different velocities1   
according to their respective distances4
 ,these particles may be arranged in    
series of narrow rings1 or they may move
 through one another irregularly4 ,in   
the first case the destruction of the   
system will be very slow1 in the second 
case it will be more rapid1 but there   
may be a tendency towards arrangement in
 narrow rings which may retard the      
process4  ,we are not able to ascertain 
by observation the constitution of the  
two outer divisions of the system of    
rings1 but the inner ring is certainly  
transparent1 for the limb of ,saturn has

 been observed through it4 ,it is also  
certain that though the space occupied  
by the ring is transparent1 it is not   
through the material parts of it that   
the limb of ,saturn is seen1 for his    
limb was observed without distortion2   
which shows that there was no           
refraction1 and1 therefore1 that the    
rays did not pass through a medium at   
all1 but between the solar or liquid    
particles of which the ring is composed4
 ,here1 then1 we have an optical        
argument in favor of the theory of      
independent particles as the material of
 the rings4 ,the two outer rings may be 
of the same nature1 but not so          
exceedingly rare that a ray of light can
 pass through their whole thickness     
without encountering one of the         
particles4  ,finally1 the two outer     
rings have been observed for two hundred
 years1 and it appears1 from the careful
 analysis of all the observations of ,m4
 ,struve1 that the second ring is       
broader than when first observed1 and   

that its inner edge is nearer the planet
 than formerly4 ,the inner ring also is 
suspected to be approaching the planet  
ever since its discovery in #ahej4      
,these appearances seem to indicate the 
same slow progress of the rings towards 
separation which we found to be the     
result of theory1 and the remark that   
the inner edge of the inner ring is more
 distinct seems to indicate that the    
approach towards the planet is less     
rapid near the edge1 as we had reason to
 conjecture4 ,as to the apparent        
unchangeableness of the exterior        
diameter of the outer ring1 we must     
remember that the outer rings are       
certainly far more dense than the inner 
one1 and that a small change in the     
outer rings must balance a great change 
in the inner one4 ,it is possible1      
however1 that some of the observed      
changes may be due to the existence of a
 resisting medium4 ,if the changes      
already suspected should be confirmed by
 repeated observations with the same    

instruments1 it will be worth while to  
investigate more carefully whether      
,saturn's rings are permanent or        
transitory elements of the solar system1
 and whether in that part of the heavens
 we see celestial immutability or       
terrestrial corruption and generation1  
and the old order giving place to the   
new before our eyes47#d7   ,studies of  
the ,moon  ,but perhaps the most        
interesting accomplishments of          
mathematical astronomy--from a mundane  
standpoint1 at any rate--are those that 
refer to the earth's own satellite4     
,that seemingly staid body was long ago 
discovered to have a propensity to gain 
a little on the earth1 appearing at     
eclipses an infinitesimal moment ahead  
of time4 ,astronomers were sorely       
puzzled by this act of insubordination2 
but at last ,laplace and ,lagrange      
explained it as due to an oscillatory   
change in the earth's orbit1 thus fully 
exonerating the moon1 and seeming to    
demonstrate the absolute stability of   

our planetary system1 which the moon's  
misbehavior had appeared to threaten4   
,this highly satisfactory conclusion was
 an orthodox belief of celestial        
mechanics until #ahec1 when ,professor  
,adams of ,neptunian fame1 with whom    
complex analyses were a pastime1        
reviewed ,laplace's calculation1 and    
discovered an error which1 when         
corrected1 left about half the moon's   
acceleration unaccounted for4 ,this was 
a momentous discrepancy1 which at first 
no one could explain4 ,but presently    
,professor ,helmholtz1 the great ,german
 physicist1 suggested that a key might  
be found in tidal friction1 which1      
acting as a perpetual brake on the      
earth's rotation1 and affecting not     
merely the waters but the entire        
substance of our planet1 must in the    
long sweep of time have changed its rate
 of rotation4 ,thus the seeming         
acceleration of the moon might be       
accounted for as actual retardation of  
the earth's rotation--a lengthening of  

the day instead of a shortening of the  
month4  ,again the earth was shown to be
 at fault1 but this time the moon could 
not be exonerated1 while the estimated  
stability of our system1 instead of     
being re-established1 was quite upset4  
,for the tidal retardation is not an    
oscillatory change which will presently 
correct itself1 like the orbital wobble1
 but a perpetual change1 acting always  
in one direction4 ,unless fully         
counteracted by some opposing reaction1 
therefore 7as it seems not to be71 the  
effect must be cumulative1 the ultimate 
consequences disastrous4 ,the exact     
character of these consequences was     
first estimated by ,professor ,g4 ,h4   
,darwin in #ahgi4 ,he showed that tidal 
friction1 in retarding the earth1 must  
also push the moon out from the parent  
planet on a spiral orbit4 ,plainly1     
then1 the moon must formerly have been  
nearer the earth than at present4 ,at   
some very remote period it must have    
actually touched the earth2 must1 in    

other words1 have been thrown off from  
the then plastic mass of the earth1 as a
 polyp buds out from its parent polyp4  
,at that time the earth was spinning    
about in a day of from two to four      
hours4  ,now the day has been lengthened
 to twenty-four hours1 and the moon has 
been thrust out to a distance of a      
quarter-million miles2 but the end is   
not yet4 ,the same progress of events   
must continue1 till1 at some remote     
period in the future1 the day has come  
to equal the month1 lunar tidal action  
has ceased1 and one face of the earth   
looks out always at the moon with that  
same fixed stare which even now the moon
 has been brought to assume towards her 
parent orb4 ,should we choose to take   
even greater liberties with the future1 
it may be made to appear 7though some   
astronomers dissent from this           
prediction7 that1 as solar tidal action 
still continues1 the day must finally   
exceed the month1 and lengthen out      
little by little towards coincidence    

with the year2 and that the moon        
meantime must pause in its outward      
flight1 and come swinging back on a     
descending spiral1 until finally1 after 
the lapse of untold aeons1 it ploughs   
and ricochets along the surface of the  
earth1 and plunges to catastrophic      
destruction4  ,but even though          
imagination pause far short of this     
direful culmination1 it still is clear  
that modern calculations1 based on      
inexorable tidal friction1 suffice to   
revolutionize the views formerly current
 as to the stability of the planetary   
system4 ,the eighteenth-century         
mathematician looked upon this system as
 a vast celestial machine which had been
 in existence about six thousand years1 
and which was destined to run on        
forever4 ,the analyst of to-day computes
 both the past and the future of this   
system in millions instead of thousands 
of years1 yet feels well assured that   
the solar system offers no contradiction
 to those laws of growth and decay which

 seem everywhere to represent the       
immutable order of nature4   ,,comets   
,,and ,,meteors  ,until the             
mathematician ferreted out the secret1  
it surely never could have been         
suspected by any one that the earth's   
serene attendant1       ,that orbed     
maiden1 with white fire laden1          
,whom mortals call the moon1  could be  
plotting injury to her parent orb4 ,but 
there is another inhabitant of the skies
 whose purposes have not been similarly 
free from popular suspicion4 ,needless  
to say ,i refer to the black sheep of   
the sidereal family1 that celestial     
vagabond the comet4  ,time out of mind  
these wanderers have been supposed to   
presage war1 famine1 pestilence1 perhaps
 the destruction of the world4 ,and     
little wonder4 ,here is a body which    
comes flashing out of boundless space   
into our system1 shooting out a         
pyrotechnic tail some hundreds of       
millions of miles in length2 whirling1  
perhaps1 through the very atmosphere of 

the sun at a speed of three or four     
hundred miles a second2 then darting off
 on a hyperbolic orbit that forbids it  
ever to return1 or an elliptical one    
that cannot be closed for hundreds or   
thousands of years2 the tail meantime   
pointing always away from the sun1 and  
fading to nothingness as the weird      
voyager recedes into the spatial void   
whence it came4 ,not many times need the
 advent of such an apparition coincide  
with the outbreak of a pestilence or the
 death of a ,caesar to stamp the race of
 comets as an ominous clan in the minds 
of all superstitious generations4  ,it  
is true1 a hard blow was struck at the  
prestige of these alleged supernatural  
agents when ,newton proved that the     
great comet of #afhj obeyed ,kepler's   
laws in its flight about the sun2 and an
 even harder one when the same visitant 
came back in #ageh1 obedient to         
,halley's prediction1 after its         
three-quarters of a century of voyaging 
but in the abyss of space4 ,proved thus 

to bow to natural law1 the celestial    
messenger could no longer fully1 sustain
 its role4 ,but long-standing notoriety 
cannot be lived down in a day1 and the  
comet1 though proved a natural object1  
was still regarded as a very menacing   
one for another hundred years or so4 ,it
 remained for the nineteenth century to 
completely unmask the pretender and show
 how egregiously our forebears had been 
deceived4  ,the unmasking began early in
 the century1 when ,dr4 ,olbers1 then   
the highest authority on the subject1   
expressed the opinion that the          
spectacular tail1 which had all along   
been the comet's chief stock-in-trade as
 an earth-threatener1 is in reality     
composed of the most filmy vapors1      
repelled from the cometary body by the  
sun1 presumably through electrical      
action1 with a velocity comparable to   
that of light4 ,this luminous suggestion
 was held more or less in abeyance for  
half a century4 ,then it was elaborated 
by ,zollner1 and particularly by        

,bredichin1 of the ,moscow observatory1 
into what has since been regarded as the
 most plausible of cometary theories4   
,it is held that comets and the sun are 
similarly electrified1 and hence        
mutually repulsive4 ,gravitation vastly 
outmatches this repulsion in the body of
 the comet1 but yields to it in the case
 of gases1 because electrical force     
varies with the surface1 while          
gravitation varies only with the mass4  
,from study of atomic weights and       
estimates of the velocity of thrust of  
cometary tails1 ,bredichin concluded    
that the chief components of the various
 kinds of tails are hydrogen1           
hydrocarbons1 and the vapor of iron2 and
 spectroscopic analysis goes far towards
 sustaining these assumptions4  ,but1   
theories aside1 the unsubstantialness of
 the comet's tail has been put to a     
conclusive test4 ,twice during the      
nineteenth century the earth has        
actually plunged directly through one of
 these threatening appendages--in #ahai1

 and again in #ahfa1 once being immersed
 to a depth of some three hundred       
thousand miles in its substance4 ,yet   
nothing dreadful happened to us4 ,there 
was a peculiar glow in the atmosphere1  
so the more imaginative observers       
thought1 and that was all4 ,after such  
fiascos the cometary train could never  
again pose as a world-destroyer4  ,but  
the full measure of the comet's         
humiliation is not yet told4 ,the       
pyrotechnic tail1 composed as it is of  
portions of the comet's actual          
substance1 is tribute paid the sun1 and 
can never be recovered4 ,should the     
obeisance to the sun be many times      
repeated1 the train-forming material    
will be exhausted1 and the comet's      
chiefest glory will have departed4 ,such
 a fate has actually befallen a         
multitude of comets which ,jupiter and  
the other outlying planets have dragged 
into our system and helped the sun to   
hold captive here4 ,many of these       
tailless comets were known to the       

eighteenth-century astronomers1 but no  
one at that time suspected the true     
meaning of their condition4 ,it was not 
even known how closely some of them are 
enchained until the ,german astronomer  
,encke1 in #ahbb1 showed that one which 
he had rediscovered1 and which has since
 borne his name1 was moving in an orbit 
so contracted that it must complete its 
circuit in about three and a half years4
 ,shortly afterwards another comet1     
revolving in a period of about six      
years1 was discovered by ,biela1 and    
given his name4 ,only two more of these 
short-period comets were discovered     
during the first half of last century1  
but latterly they have been shown to be 
a numerous family4 ,nearly twenty are   
known which the giant ,jupiter holds so 
close that the utmost reach of their    
elliptical tether does not let them go  
beyond the orbit of ,saturn4 ,these     
aforetime wanderers have adapted        
themselves wonderfully to planetary     
customs1 for all of them revolve in the 

same direction with the planets1 and in 
planes not wide of the ecliptic4        
,checked in their proud hyperbolic      
sweep1 made captive in a planetary net1 
deprived of their trains1 these quondam 
free-lances of the heavens are now mere 
shadows of their former selves4         
,considered as to mere bulk1 they are   
very substantial shadows1 their extent  
being measured in hundreds of thousands 
of miles2 but their actual mass is so   
slight that they are quite at the mercy 
of the gravitation pulls of their       
captors4 ,and worse is in store for     
them4 ,so persistently do sun and       
planets tug at them that they are doomed
 presently to be torn into shreds4      
,such a fate has already overtaken one  
of them1 under the very eyes of the     
astronomers1 within the relatively short
 period during which these ill-fated    
comets have been observed4 ,in #ahcb    
,biela's comet passed quite near the    
earth1 as astronomers measure distance1 
and in doing so created a panic on our  

planet4 ,it did no greater harm than    
that1 of course1 and passed on its way  
as usual4 ,the very next time it came   
within telescopic hail it was seen to   
have broken into two fragments4 ,six    
years later these fragments were        
separated by many millions of miles2 and
 in #aheb1 when the comet was due again1
 astronomers looked for it in vain4 ,it 
had been completely shattered4  ,what   
had become of the fragments8 ,at that   
time no one positively knew4 ,but the   
question was to be answered presently4  
,it chanced that just at this period    
astronomers were paying much attention  
to a class of bodies which they had     
hitherto somewhat neglected1 the        
familiar shooting-stars1 or meteors4    
,the studies of ,professor ,newton1 of  
,yale1 and ,professor ,adams1 of        
,cambridge1 with particular reference to
 the great meteor-shower of ,november1  
#ahff1 which ,professor ,newton had     
predicted and shown to be recurrent at  
intervals of thirty-three years1 showed 

that meteors are not mere sporadic      
swarms of matter flying at random1 but  
exist in isolated swarms1 and sweep     
about the sun in regular elliptical     
orbits4  ,presently it was shown by the 
,italian astronomer ,schiaparelli that  
one of these meteor swarms moves in the 
orbit of a previously observed comet1   
and other coincidences of the kind were 
soon forthcoming4 ,the conviction grew  
that meteor swarms are really the debris
 of comets2 and this conviction became a
 practical certainty when1 in ,november1
 #ahgb1 the earth crossed the orbit of  
the ill-starred ,biela1 and a shower of 
meteors came whizzing into our          
atmosphere in lieu of the lost comet4   
,and so at last the full secret was out4
 ,the awe-inspiring comet1 instead of   
being the planetary body it had all     
along been regarded1 is really nothing  
more nor less than a great aggregation  
of meteoric particles1 which have become
 clustered together out in space        
somewhere1 and which by jostling one    

another or through electrical action    
become luminous4 ,so widely are the     
individual particles separated that the 
cometary body as a whole has been       
estimated to be thousands of times less 
dense than the earth's atmosphere at    
sea-level4 ,hence the ease with which   
the comet may be dismembered and its    
particles strung out into streaming     
swarms4  ,so thickly is the space we    
traverse strewn with this cometary dust 
that the earth sweeps up1 according to  
,professor ,newcomb's estimate1 a       
million tons of it each day4 ,each      
individual particle1 perhaps no larger  
than a millet seed1 becomes a           
shooting-star1 or meteor1 as it burns to
 vapor in the earth's upper atmosphere4 
,and if one tiny planet sweeps up such  
masses of this cosmic matter1 the amount
 of it in the entire stretch of our     
system must be beyond all estimate4     
,what a story it tells of the myriads of
 cometary victims that have fallen prey 
to the sun since first he stretched his 

planetary net across the heavens6       
,,the ,,fixed ,,stars  ,when ,biela's   
comet gave the inhabitants of the earth 
such a fright in #ahcb1 it really did   
not come within fifty millions of miles 
of us4 ,even the great comet through    
whose filmy tail the earth passed in    
#ahfa was itself fourteen millions of   
miles away4 ,the ordinary mind1 schooled
 to measure space by the tiny stretches 
of a pygmy planet1 cannot grasp the     
import of such distances2 yet these are 
mere units of measure compared with the 
vast stretches of sidereal space4 ,were 
the comet which hurtles past us at a    
speed of1 say1 a hundred miles a second 
to continue its mad flight unchecked    
straight into the void of space1 it must
 fly on its frigid way eight thousand   
years before it could reach the very    
nearest of our neighbor stars2 and even 
then it would have penetrated but a mere
 arm's-length into the vistas where lie 
the dozen or so of sidereal residents   
that are next beyond4 ,even to the      

trained mind such distances are only    
vaguely imaginable4 ,yet the astronomer 
of our century has reached out across   
this unthinkable void and brought back  
many a secret which our predecessors    
thought forever beyond human grasp4  ,a 
tentative assault upon this stronghold  
of the stars was being made by ,herschel
 at the beginning of the century4 ,in   
#ahjb that greatest of observing        
astronomers announced to the ,royal     
,society his discovery that certain     
double stars had changed their relative 
positions towards one another since he  
first carefully charted them twenty     
years before4 ,hitherto it had been     
supposed that double stars were mere    
optical effects4 ,now it became clear   
that some of them1 at any rate1 are true
 binary systems1 linked together        
presumably by gravitation and revolving 
about one another4 ,halley had shown1   
three-quarters of a century before1 that
 the stars have an actual or proper     
motion in space2 ,herschel himself had  

proved that the sun shares this motion  
with the other stars4 ,here was another 
shift of place1 hitherto quite          
unsuspected1 to be reckoned with by the 
astronomer in fathoming sidereal        
secrets4   ,double ,stars  ,when ,john  
,herschel1 the only son and the worthy  
successor of the great astronomer1 began
 star-gazing in earnest1 after          
graduating senior wrangler at           
,cambridge1 and making two or three     
tentative professional starts in other  
directions to which his versatile genius
 impelled him1 his first extended work  
was the observation of his father's     
double stars4 ,his studies1 in which at 
first he had the collaboration of ,mr4  
,james ,south1 brought to light scores  
of hitherto unrecognized pairs1 and gave
 fresh data for the calculation of the  
orbits of those longer known4 ,so also  
did the independent researches of ,f4   
,g4 ,w4 ,struve1 the enthusiastic       
observer of the famous ,russian         
observatory at the university of        

,dorpat1 and subsequently at ,pulkowa4  
,utilizing data gathered by these       
observers1 ,m4 ,savary1 of ,paris1      
showed1 in #ahbg1 that the observed     
elliptical orbits of the double stars   
are explicable by the ordinary laws of  
gravitation1 thus confirming the        
assumption that ,newton's laws apply to 
these sidereal bodies4 ,henceforth there
 could be no reason to doubt that the   
same force which holds terrestrial      
objects on our globe pulls at each and  
every particle of matter throughout the 
visible universe4  ,the pioneer         
explorers of the double stars early     
found that the systems into which the   
stars are linked are by no means        
confined to single pairs4 ,often three  
or four stars are found thus closely    
connected into gravitation systems2     
indeed1 there are all gradations between
 binary systems and great clusters      
containing hundreds or even thousands of
 members4 ,it is known1 for example1    
that the familiar cluster of the        

,pleiades is not merely an optical      
grouping1 as was formerly supposed1 but 
an actual federation of associated      
stars1 some two thousand five hundred in
 number1 only a few of which are visible
 to the unaided eve4 ,and the more      
carefully the motions of the stars are  
studied1 the more evident it becomes    
that widely separated stars are linked  
together into infinitely complex        
systems1 as yet but little understood4  
,at the same time1 all instrumental     
advances tend to resolve more and more  
seemingly single stars into close pairs 
and minor clusters4 ,the two ,herschels 
between them discovered some thousands  
of these close multiple systems2 ,struve
 and others increased the list to above 
ten thousand2 and ,mr4 ,s4 ,w4 ,burnham1
 of late years the most enthusiastic and
 successful of double-star pursuers1    
added a thousand new discoveries while  
he was still an amateur in astronomy1   
and by profession the stenographer of a 
,chicago court4 ,clearly the actual     

number of multiple stars is beyond all  
present estimate4  ,the elder           
,herschel's early studies of double     
stars were undertaken in the hope that  
these objects might aid him in          
ascertaining the actual distance of a   
star1 through measurement of its annual 
parallax--that is to say1 of the angle  
which the diameter of the earth's orbit 
would subtend as seen from the star4    
,the expectation was not fulfilled4 ,the
 apparent shift of position of a star as
 viewed from opposite sides of the      
earth's orbit1 from which the parallax  
might be estimated1 is so extremely     
minute that it proved utterly           
inappreciable1 even to the almost       
preternaturally acute vision of         
,herschel1 with the aid of any          
instrumental means then at command4 ,so 
the problem of star distance allured and
 eluded him to the end1 and he died in  
#ahbb without seeing it even in prospect
 of solution4 ,his estimate of the      
minimum distance of the nearest star1   

based though it was on the fallacious   
test of apparent brilliancy1 was a      
singularly sagacious one1 but it was at 
best a scientific guess1 not a          
scientific measurement4   ,the ,distance
 of the ,stars  ,just about this time1  
however1 a great optician came to the   
aid of the astronomers4 ,joseph         
,fraunhofer perfected the refracting    
telescope1 as ,herschel had perfected   
the reflector1 and invented a           
wonderfully accurate heliometer1 or     
sun-measurer4 ,with the aid of these    
instruments the old and almost          
infinitely difficult problem of star    
distance was solved4 ,in #ahch ,bessel  
announced from the ,konigsberg          
observatory that he had succeeded1 after
 months of effort1 in detecting and     
measuring the parallax of a star4       
,similar claims had been made often     
enough before1 always to prove          
fallacious when put to further test2 but
 this time the announcement carried the 
authority of one of the greatest        

astronomers of the age1 and scepticism  
was silenced4  ,nor did ,bessel's       
achievement long await corroboration4   
,indeed1 as so often happens in fields  
of discovery1 two other workers had     
almost simultaneously solved the same   
problem--,struve at ,pulkowa1 where the 
great ,russian observatory1 which so    
long held the palm over all others1 had 
now been established2 and ,thomas       
,henderson1 then working at the ,cape of
 ,good ,hope1 but afterwards the        
,astronomer ,royal of ,scotland4        
,henderson's observations had actual    
precedence in point of time1 but        
,bessel's measurements were so much more
 numerous and authoritative that he has 
been uniformly considered as deserving  
the chief credit of the discovery1 which
 priority of publication secured him4   
,by an odd chance1 the star on which    
,henderson's observations were made1 and
 consequently the first star the        
parallax of which was ever measured1 is 
our nearest neighbor in sidereal space1 

being1 indeed1 some ten billions of     
miles nearer than the one next beyond4  
,yet even this nearest star is more than
 two hundred thousand times as remote   
from us as the sun4 ,the sun's light    
flashes to the earth in eight minutes1  
and to ,neptune in about three and a    
half hours1 but it requires three and a 
half years to signal ,alpha ,centauri4  
,and as for the great majority of the   
stars1 had they been blotted out of     
existence before the ,christian era1 we 
of to-day should still receive their    
light and seem to see them just as we   
do4 ,when we look up to the sky1 we     
study ancient history2 we do not see the
 stars as they ,,are1 but as they ,,were
 years1 centuries1 even millennia ago4  
,the information derived from the       
parallax of a star by no means halts    
with the disclosure of the distance of  
that body4 ,distance known1 the proper  
motion of the star1 hitherto only to be 
reckoned as so many seconds of arc1 may 
readily be translated into actual speed 

of progress2 relative brightness becomes
 absolute lustre1 as compared with the  
sun2 and in the case of the double stars
 the absolute mass of the components may
 be computed from the laws of           
gravitation4 ,it is found that stars    
differ enormously among themselves in   
all these regards4 ,as to speed1 some1  
like our sun1 barely creep through      
space--compassing ten or twenty miles a 
second1 it is true1 yet even at that    
rate only passing through the equivalent
 of their own diameter in a day4 ,at the
 other extreme1 among measured stars1 is
 one that moves two hundred miles a     
second2 yet even this flying star1 as   
seen from the earth1 seems to change its
 place by only about three and a half   
lunar diameters in a thousand years4 ,in
 brightness1 some stars yield to the    
sun1 while others surpass him as the    
arc-light surpasses a candle4 ,arcturus1
 the brightest measured star1 shines    
like two hundred suns2 and even this    
giant orb is dim beside those other     

stars which are so distant that their   
parallax cannot be measured1 yet which  
greet our eyes at first magnitude4 ,as  
to actual bulk1 of which apparent lustre
 furnishes no adequate test1 some stars 
are smaller than the sun1 while others  
exceed him hundreds or perhaps thousands
 of times4 ,yet one and all1 so distant 
are they1 remain mere disklike points of
 light before the utmost powers of the  
modern telescope4   ,revelations of the 
,spectroscope  ,all this seems wonderful
 enough1 but even greater things were in
 store4 ,in #ahei the spectroscope came 
upon the scene1 perfected by ,kirchhoff 
and ,bunsen1 along lines pointed out by 
,fraunhofer almost half a century       
before4 ,that marvellous instrument1 by 
revealing the telltale lines sprinkled  
across a prismatic spectrum1 discloses  
the chemical nature and physical        
condition of any substance whose light  
is submitted to it1 telling its story   
equally well1 provided the light be     
strong enough1 whether the luminous     

substance be near or far--in the same   
room or at the confines of space4       
,clearly such an instrument must prove a
 veritable magic wand in the hands of   
the astronomer4  ,very soon eager       
astronomers all over the world were     
putting the spectroscope to the test4   
,kirchhoff himself led the way1 and     
,donati and ,father ,secchi in ,italy1  
,huggins and ,miller in ,england1 and   
,rutherfurd in ,america1 were the chief 
of his immediate followers4 ,the results
 exceeded the dreams of the most        
visionary4 ,at the very outset1 in      
#ahfj1 it was shown that such common    
terrestrial substances as sodium1 iron1 
calcium1 magnesium1 nickel1 barium1     
copper1 and zinc exist in the form of   
glowing vapors in the sun1 and very soon
 the stars gave up a corresponding      
secret4 ,since then the work of solar   
and sidereal analysis has gone on       
steadily in the hands of a multitude of 
workers 7prominent among whom1 in this  
country1 are ,professor ,young of       

,princeton1 ,professor ,langley of      
,washington1 and ,professor ,pickering  
of ,harvard71 and more than half the    
known terrestrial elements have been    
definitely located in the sun1 while    
fresh discoveries are in prospect4  ,it 
is true the sun also contains some      
seeming elements that are unknown on the
 earth1 but this is no matter for       
surprise4 ,the modern chemist makes no  
claim for his elements except that they 
have thus far resisted all human efforts
 to dissociate them2 it would be nothing
 strange if some of them1 when subjected
 to the crucible of the sun1 which is   
seen to vaporize iron1 nickel1 silicon1 
should fail to withstand the test4 ,but 
again1 chemistry has by no means        
exhausted the resources of the earth's  
supply of raw material1 and the         
substance which sends its message from a
 star may exist undiscovered in the dust
 we tread or in the air we breathe4 ,in 
the year #ahie two new terrestrial      
elements were discovered2 but one of    

these had for years been known to the   
astronomer as a solar and suspected as a
 stellar element1 and named helium      
because of its abundance in the sun4    
,the spectroscope had reached out       
millions of miles into space and brought
 back this new element1 and it took the 
chemist a score of years to discover    
that he had all along had samples of the
 same substance unrecognized in his     
sublunary laboratory4 ,there is hardly a
 more picturesque fact than that in the 
entire history of science4  ,but the    
identity in substance of earth and sun  
and stars was not more clearly shown    
than the diversity of their existing    
physical conditions4 ,it was seen that  
sun and stars1 far from being the cool1 
earthlike1 habitable bodies that        
,herschel thought them 7surrounded by   
glowing clouds1 and protected from undue
 heat by other clouds71 are in truth    
seething caldrons of fiery liquid1 or   
gas made viscid by condensation1 with   
lurid envelopes of belching flames4 ,it 

was soon made clear1 also1 particularly 
by the studies of ,rutherfurd and of    
,secchi1 that stars differ among        
themselves in exact constitution or     
condition4 ,there are white or ,sirian  
stars1 whose spectrum revels in the     
lines of hydrogen2 yellow or solar stars
 7our sun being the type71 showing      
various metallic vapors2 and sundry red 
stars1 with banded spectra indicative of
 carbon compounds2 besides the purely   
gaseous stars of more recent discovery1 
which ,professor ,pickering had         
specially studied4 ,zollner's famous    
interpretation of these diversities1 as 
indicative of varying stages of cooling1
 has been called in question as to the  
exact sequence it postulates1 but the   
general proposition that stars exist    
under widely varying conditions of      
temperature is hardly in dispute4  ,the 
assumption that different star types    
mark varying stages of cooling has the  
further support of modern physics1 which
 has been unable to demonstrate any way 

in which the sun's radiated energy may  
be restored1 or otherwise made          
perpetual1 since meteoric impact has    
been shown to be--under existing        
conditions1 at any rate--inadequate4 ,in
 accordance with the theory of          
,helmholtz1 the chief supply of solar   
energy is held to be contraction of the 
solar mass itself2 and plainly this must
 have its limits4 ,therefore1 unless    
some means as yet unrecognized is       
restoring the lost energy to the stellar
 bodies1 each of them must gradually    
lose its lustre1 and come to a condition
 of solidification1 seeming sterility1  
and frigid darkness4 ,in the case of our
 own particular star1 according to the  
estimate of ,lord ,kelvin1 such a       
culmination appears likely to occur     
within a period of five or six million  
years4   ,the ,astronomy of the         
,invisible  ,but by far the strongest   
support of such a forecast as this is   
furnished by those stellar bodies which 
even now appear to have cooled to the   

final stage of star development and     
ceased to shine4 ,of this class examples
 in miniature are furnished by the earth
 and the smaller of its companion       
planets4 ,but there are larger bodies of
 the same type out in stellar           
space--veritable dark stars--invisible1 
of course1 yet nowadays clearly         
recognized4  ,the opening up of this    
astronomy of the invisible is another of
 the great achievements of the          
nineteenth century1 and again it is     
,bessel to whom the honor of discovery  
is due4 ,while testing his stars for    
parallax2 that astute observer was led  
to infer1 from certain unexplained      
aberrations of motion1 that various     
stars1 ,sirius himself among the number1
 are accompanied by invisible           
companions1 and in #ahdj he definitely  
predicated the existence of such dark   
stars4 ,the correctness of the inference
 was shown twenty years later1 when     
,alvan ,clark1 ,jr41 the ,american      
optician1 while testing a new lens1     

discovered the companion of ,sirius1    
which proved thus to be faintly         
luminous4 ,since then the existence of  
other and quite invisible star          
companions has been proved              
incontestably1 not merely by renewed    
telescopic observations1 but by the     
curious testimony of the ubiquitous     
spectroscope4  ,one of the most         
surprising accomplishments of that      
instrument is the power to record the   
flight of a luminous object directly in 
the line of vision4 ,if the luminous    
body approaches swiftly1 its ,fraunhofer
 lines are shifted from their normal    
position towards the violet end of the  
spectrum2 if it recedes1 the lines shift
 in the opposite direction4 ,the actual 
motion of stars whose distance is       
unknown may be measured in this way4    
,but in certain cases the light lines   
are seen to oscillate on the spectrum at
 regular intervals4 ,obviously the star 
sending such light is alternately       
approaching and receding1 and the       

inference that it is revolving about a  
companion is unavoidable4 ,from this    
extraordinary test the orbital distance1
 relative mass1 and actual speed of     
revolution of the absolutely invisible  
body may be determined4 ,thus the       
spectroscope1 which deals only with     
light1 makes paradoxical excursions into
 the realm of the invisible4 ,what      
secrets may the stars hope to conceal   
when questioned by an instrument of such
 necromantic power8  ,but the           
spectroscope is not alone in this       
audacious assault upon the strongholds  
of nature4 ,it has a worthy companion   
and assistant in the photographic film1 
whose efficient aid has been invoked by 
the astronomer even more recently4      
,pioneer work in celestial photography  
was1 indeed1 done by ,arago in ,france  
and by the elder ,draper in ,america in 
#ahci1 but the results then achieved    
were only tentative1 and it was not till
 forty years later that the method      
assumed really important proportions4   

,in #ahhj1 ,dr4 ,henry ,draper1 at      
,hastings-on-the-,hudson1 made the first
 successful photograph of a nebula4     
,soon after1 ,dr4 ,david ,gill1 at the  
,cape observatory1 made fine photographs
 of a comet1 and the flecks of starlight
 on his plates first suggested the      
possibilities of this method in charting
 the heavens4  ,since then star-charting
 with the film has come virtually to    
supersede the old method4 ,a concerted  
effort is being made by astronomers in  
various parts of the world to make a    
complete chart of the heavens1 and      
before the close of our century this    
work will be accomplished1 some fifty or
 sixty millions of visible stars being  
placed on record with a degree of       
accuracy hitherto unapproachable4       
,moreover1 other millions of stars are  
brought to light by the negative1 which 
are too distant or dim to be visible    
with any telescopic powers yet          
attained--a fact which wholly discredits
 all previous inferences as to the      

limits of our sidereal system4 ,hence1  
notwithstanding the wonderful           
instrumental advances of the nineteenth 
century1 knowledge of the exact form and
 extent of our universe seems more      
unattainable than it seemed a century   
ago4   ,the ,structure of ,nebulae  ,yet
 the new instruments1 while leaving so  
much untold1 have revealed some vastly  
important secrets of cosmic structure4  
,in particular1 they have set at rest   
the long-standing doubts as to the real 
structure and position of the mysterious
 nebulae--those lazy masses1 only two or
 three of them visible to the unaided   
eye1 which the telescope reveals in     
almost limitless abundance1 scattered   
everywhere among the stars1 but grouped 
in particular about the poles of the    
stellar stream or disk which we call the
 ,milky ,way4  ,herschel's later view1  
which held that some at least of the    
nebulae are composed of a shining fluid1
 in process of condensation to form     
stars1 was generally accepted for almost

 half a century4 ,but in #ahdd1 when    
,lord ,rosse's great six-foot           
reflector--the largest telescope ever   
yet constructed--was turned on the      
nebulae1 it made this hypothesis seem   
very doubtful4 ,just as ,galileo's first
 lens had resolved the ,milky ,way into 
stars1 just as ,herschel had resolved   
nebulae that resisted all instruments   
but his own1 so ,lord ,rosse's even     
greater reflector resolved others that  
would not yield to ,herschel's largest  
mirror4 ,it seemed a fair inference that
 with sufficient power1 perhaps some day
 to be attained1 all nebulae would      
yield1 hence that all are in reality    
what ,herschel had at first thought     
them--vastly distant island universes1  
composed of aggregations of stars1      
comparable to our own galactic system4  
,but the inference was wrong2 for when  
the spectroscope was first applied to a 
nebula in #ahfd1 by ,dr4 ,huggins1 it   
clearly showed the spectrum not of      
discrete stars1 but of a great mass of  

glowing gases1 hydrogen among others4   
,more extended studies showed1 it is    
true1 that some nebulae give the        
continuous spectrum of solids or        
liquids1 but the different types        
intermingle and grade into one another4 
,also1 the closest affinity is shown    
between nebulae and stars4 ,some nebulae
 are found to contain stars1 singly or  
in groups1 in their actual midst2       
certain condensed planetary nebulae are 
scarcely to be distinguished from stars 
of the gaseous type2 and recently the   
photographic film has shown the presence
 of nebulous matter about stars that to 
telescopic vision differ in no respect  
from the generality of their fellows in 
the galaxy4 ,the familiar stars of the  
,pleiades cluster1 for example1 appear  
on the negative immersed in a hazy blur 
of light4 ,all in all1 the accumulated  
impressions of the photographic film    
reveal a prodigality of nebulous matter 
in the stellar system not hitherto even 
conjectured4  ,and so1 of course1 all   

question of island universes vanishes1  
and the nebulae are relegated to their  
true position as component parts of the 
one stellar system--the one             
universe--that is open to present human 
inspection4 ,and these vast clouds of   
world-stuff have been found by          
,professor ,keeler1 of the ,lick        
observatory1 to be floating through     
space at the starlike speed of from ten 
to thirty-eight miles per second4  ,the 
linking of nebulae with stars1 so       
clearly evidenced by all these modern   
observations1 is1 after all1 only the   
scientific corroboration of what the    
elder ,herschel's later theories        
affirmed4 ,but the nebulae have other   
affinities not until recently suspected2
 for the spectra of some of them are    
practically identical with the spectra  
of certain comets4 ,the conclusion seems
 warranted that comets are in point of  
fact minor nebulae that are drawn into  
our system2 or1 putting it otherwise1   
that the telescopic nebulae are simply  

gigantic distant comets4   ,lockyer's   
,meteoric ,hypothesis  ,following up the
 surprising clews thus suggested1 ,sir  
,norman ,lockyer1 of ,london1 has in    
recent years elaborated what is perhaps 
the most comprehensive cosmogonic guess 
that has ever been attempted4 ,his      
theory1 known as the meteoric           
hypothesis1 probably bears the same     
relation to the speculative thought of  
our time that the nebular hypothesis of 
,laplace bore to that of the eighteenth 
century4 ,outlined in a few words1 it is
 an attempt to explain all the major    
phenomena of the universe as due1       
directly or indirectly1 to the          
gravitational impact of such meteoric   
particles1 or specks of cosmic dust1 as 
comets are composed of4 ,nebulae are    
vast cometary clouds1 with particles    
more or less widely separated1 giving   
off gases through meteoric collisions1  
internal or external1 and perhaps       
glowing also with electrical or         
phosphorescent light4 ,gravity          

eventually brings the nebular particles 
into closer aggregations1 and increased 
collisions finally vaporize the entire  
mass1 forming planetary nebulae and     
gaseous stars4 ,continued condensation  
may make the stellar mass hotter and    
more luminous for a time1 but eventually
 leads to its liquefaction1 and ultimate
 consolidation--the aforetime nebulae   
becoming in the end a dark or planetary 
star4  ,the exact correlation which     
,lockyer attempts to point out between  
successive stages of meteoric           
condensation and the various types of   
observed stellar bodies does not meet   
with unanimous acceptance4 ,mr4         
,ranyard1 for example1 suggests that the
 visible nebulae may not be nascent     
stars1 but emanations from stars1 and   
that the true pre-stellar nebulae are   
invisible until condensed to stellar    
proportions4 ,but such details aside1   
the broad general hypothesis that all   
the bodies of the universe are1 so to   
speak1 of a single species--that nebulae

 7including comets71 stars of all types1
 and planets1 are but varying stages in 
the life history of a single race or    
type of cosmic organisms--is accepted by
 the dominant thought of our time as    
having the highest warrant of scientific
 probability4  ,all this1 clearly1 is   
but an amplification of that nebular    
hypothesis which1 long before the       
spectroscope gave us warrant to         
accurately judge our sidereal neighbors1
 had boldly imagined the development of 
stars out of nebulae and of planets out 
of stars4 ,but ,lockyer's hypothesis    
does not stop with this4 ,having traced 
the developmental process from the      
nebular to the dark star1 it sees no    
cause to abandon this dark star to its  
fate by assuming1 as the original       
speculation assumed1 that this is a     
culminating and final stage of cosmic   
existence4 ,for the dark star1 though   
its molecular activities have come to   
relative stability and impotence1 still 
retains the enormous potentialities of  

molar motion2 and clearly1 where motion 
is1 stasis is not4 ,sooner or later1 in 
its ceaseless flight through space1 the 
dark star must collide with some other  
stellar body1 as ,dr4 ,croll imagines of
 the dark bodies which his pre-nebular  
theory postulates4 ,such collision may  
be long delayed2 the dark star may be   
drawn in comet-like circuit about       
thousands of other stellar masses1 and  
be hurtled on thousands of diverse      
parabolic or elliptical orbits1 before  
it chances to collide--but that matters 
not3 billions are the units in the      
arithmetic of eternity1 and sooner or   
later1 we can hardly doubt1 a collision 
must occur4 ,then without question the  
mutual impact must shatter both         
colliding bodies into vapor1 or vapor   
combined with meteoric fragments2 in    
short1 into a veritable nebula1 the     
matrix of future worlds4 ,thus the dark 
star1 which is the last term of one     
series of cosmic changes1 becomes the   
first term of another series--at once a 

post-nebular and a pre-nebular          
condition2 and the nebular hypothesis1  
thus amplified1 ceases to be a mere     
linear scale1 and is rounded out to     
connote an unending series of cosmic    
cycles1 more nearly satisfying the      
imagination4  ,in this extended view1   
nebulae and luminous stars are but the  
infantile and adolescent stages of the  
life history of the cosmic individual2  
the dark star1 its adult stage1 or time 
of true virility4 ,or we may think of   
the shrunken dark star as the germ-cell1
 the pollen-grain1 of the cosmic        
organism4 ,reduced in size1 as becomes a
 germ-cell1 to a mere fraction of the   
nebular body from which it sprang1 it   
yet retains within its seemingly        
non-vital body all the potentialities of
 the original organism1 and requires    
only to blend with a fellow-cell to     
bring a new generation into being4 ,thus
 may the cosmic race1 whose aggregate   
census makes up the stellar universe1 be
 perpetuated--individual solar systems1 

such as ours1 being born1 and growing   
old1 and dying to live again in their   
descendants1 while the universe as a    
whole maintains its unified integrity   
throughout all these internal           
mutations--passing on1 it may be1 by    
infinitesimal stages1 to a culmination  
hopelessly beyond human comprehension4  
,,iii4 ,,the ,,new ,,science ,,of       
,,paleontology   ,,william ,,smith ,,and
 ,,fossil ,,shells  ,ever since         
,leonardo da ,vinci first recognized the
 true character of fossils1 there had   
been here and there a man who realized  
that the earth's rocky crust is one     
gigantic mausoleum4 ,here and there a   
dilettante had filled his cabinets with 
relics from this monster crypt2 here and
 there a philosopher had pondered over  
them--questioning whether perchance they
 had once been alive1 or whether they   
were not mere abortive souvenirs of that
 time when the fertile matrix of the    
earth was supposed to have              
teemed at a birth      ,innumerous      

living creatures1 perfect forms1        
,limbed and full grown4  ,some few of   
these philosophers--as ,robert ,hooke   
and ,steno in the seventeenth century1  
and ,moro1 ,leibnitz1 ,buffon1          
,whitehurst1 ,werner1 ,hutton1 and      
others in the eighteenth--had vaguely   
conceived the importance of fossils as  
records of the earth's ancient history1 
but the wisest of them no more suspected
 the full import of the story written in
 the rocks than the average stroller in 
a modern museum suspects the meaning of 
the hieroglyphs on the case of a mummy4 
,it was not that the rudiments of this  
story are so very hard to               
decipher--though in truth they are hard 
enough--but rather that the men who made
 the attempt had all along viewed the   
subject through an atmosphere of        
preconception1 which gave a distorted   
image4 ,before this image could be      
corrected it was necessary that a man   
should appear who could see without     
prejudice1 and apply sound common-sense 

to what he saw4 ,and such a man did     
appear towards the close of the century1
 in the person of ,william ,smith1 the  
,english surveyor4 ,he was a self-taught
 man1 and perhaps the more independent  
for that1 and he had the gift1 besides  
his sharp eyes and receptive mind1 of a 
most tenacious memory4 ,by exercising   
these faculties1 rare as they are       
homely1 he led the way to a science     
which was destined1 in its later        
developments1 to shake the structure of 
established thought to its foundations4 
,little enough did ,william ,smith      
suspect1 however1 that any such dire    
consequences were to come of his act    
when he first began noticing the fossil 
shells that here and there are to be    
found in the stratified rocks and soils 
of the regions over which his surveyor's
 duties led him4 ,nor1 indeed1 was there
 anything of such apparent revolutionary
 character in the facts which he        
unearthed2 yet in their implications    
these facts were the most disconcerting 

of any that had been revealed since the 
days of ,copernicus and ,galileo4 ,in   
its bald essence1 ,smith's discovery was
 simply this3 that the fossils in the   
rocks1 instead of being scattered       
haphazard1 are arranged in regular      
systems1 so that any given stratum of   
rock is labelled by its fossil          
population2 and that the order of       
succession of such groups of fossils is 
always the same in any vertical series  
of strata in which they occur4 ,that is 
to say1 if fossil ,a underlies fossil ,b
 in any given region1 it never overlies 
it in any other series2 though a kind of
 fossils found in one set of strata may 
be quite omitted in another4 ,moreover1 
a fossil once having disappeared never  
reappears in any later stratum4  ,from  
these novel facts ,smith drew the       
commonsense inference that the earth had
 had successive populations of          
creatures1 each of which in its turn had
 become extinct4 ,he partially verified 
this inference by comparing the fossil  

shells with existing species of similar 
orders1 and found that such as occur in 
older strata of the rocks had no        
counterparts among living species4 ,but1
 on the whole1 being eminently a        
practical man1 ,smith troubled himself  
but little about the inferences that    
might be drawn from his facts4 ,he was  
chiefly concerned in using the key he   
had discovered as an aid to the         
construction of the first geological map
 of ,england ever attempted1 and he left
 to others the untangling of any snarls 
of thought that might seem to arise from
 his discovery of the succession of     
varying forms of life on the globe4  ,he
 disseminated his views far and wide1   
however1 in the course of his           
journeyings--quite disregarding the fact
 that peripatetics went out of fashion  
when the printing-press came in--and by 
the beginning of the nineteenth century 
he had begun to have a following among  
the geologists of ,england4 ,it must not
 for a moment be supposed1 however1 that

 his contention regarding the succession
 of strata met with immediate or general
 acceptance4 ,on the contrary1 it was   
most bitterly antagonized4 ,for a long  
generation after the discovery was made1
 the generality of men1 prone as always 
to strain at gnats and swallow camels1  
preferred to believe that the fossils1  
instead of being deposited in successive
 ages1 had been swept all at once into  
their present positions by the current  
of a mighty flood--and that flood1      
needless to say1 the ,noachian deluge4  
,just how the numberless successive     
strata could have been laid down in     
orderly sequence to the depth of several
 miles in one such fell cataclysm was   
indeed puzzling1 especially after it    
came to be admitted that the heaviest   
fossils were not found always at the    
bottom2 but to doubt that this had been 
done in some way was rank heresy in the 
early days of the nineteenth century4   
,,cuvier ,,and ,,fossil ,,vertebrates   
,but once discovered1 ,william ,smith's 

unique facts as to the succession of    
forms in the rocks would not down4      
,there was one most vital point1        
however1 regarding which the inferences 
that seem to follow from these facts    
needed verification--the question1      
namely1 whether the disappearance of a  
fauna from the register in the rocks    
really implies the extinction of that   
fauna4 ,everything really depended upon 
the answer to that question1 and none   
but an accomplished naturalist could    
answer it with authority4 ,fortunately1 
the most authoritative naturalist of the
 time1 ,george ,cuvier1 took the        
question in hand--not1 indeed1 with the 
idea of verifying any suggestion of     
,smith's1 but in the course of his own  
original studies--at the very beginning 
of the century1 when ,smith's views were
 attracting general attention4  ,cuvier 
and ,smith were exact contemporaries1   
both men having been born in #agfi1 that
 fertile year which gave the world also 
,chateaubriand1 ,von ,humboldt1         

,wellington1 and ,napoleon4 ,but the    
,french naturalist was of very different
 antecedents from the ,english surveyor4
 ,he was brilliantly educated1 had early
 gained recognition as a scientist1 and 
while yet a young man had come to be    
known as the foremost comparative       
anatomist of his time4 ,it was the      
anatomical studies that led him into the
 realm of fossils4 ,some bones dug out  
of the rocks by workmen in a quarry were
 brought to his notice1 and at once his 
trained eye told him that they were     
different from anything he had seen     
before4 ,hitherto such bones1 when not  
entirely ignored1 had been for the most 
part ascribed to giants of former days1 
or even to fallen angels4 ,cuvier soon  
showed that neither giants nor angels   
were in question1 but elephants of an   
unrecognized species4 ,continuing his   
studies1 particularly with material     
gathered from gypsum beds near ,paris1  
he had accumulated1 by the beginning of 
the nineteenth century1 bones of about  

twenty-five species of animals that he  
believed to be different from any now   
living on the globe4  ,the fame of these
 studies went abroad1 and presently     
fossil bones poured in from all sides1  
and ,cuvier's conviction that extinct   
forms of animals are represented among  
the fossils was sustained by the        
evidence of many strange and anomalous  
forms1 some of them of gigantic size4   
,in #ahaf the famous ,ossements         
,fossiles1 describing these novel       
objects1 was published1 and vertebrate  
paleontology became a science4 ,among   
other things of great popular interest  
the book contained the first            
authoritative description of the hairy  
elephant1 named by ,cuvier the mammoth1 
the remains of which bad been found     
embedded in a mass of ice in ,siberia in
 #ahjb1 so wonderfully preserved that   
the dogs of the ,tungusian fishermen    
actually ate its flesh4 ,bones of the   
same species had been found in ,siberia 
several years before by the naturalist  

,pallas1 who had also found the carcass 
of a rhinoceros there1 frozen in a      
mud-bank2 but no one then suspected that
 these were members of an extinct       
population--they were supposed to be    
merely transported relics of the flood4 
,cuvier1 on the other hand1 asserted    
that these and the other creatures he   
described had lived and died in the     
region where their remains were found1  
and that most of them have no living    
representatives upon the globe4 ,this1  
to be sure1 was nothing more than       
,william ,smith had tried all along to  
establish regarding lower forms of life2
 but flesh and blood monsters appeal to 
the imagination in a way quite beyond   
the power of mere shells2 so the        
announcement of ,cuvier's discoveries   
aroused the interest of the entire      
world1 and the ,ossements ,fossiles was 
accorded a popular reception seldom     
given a work of technical science--a    
reception in which the enthusiastic     
approval of progressive geologists was  

mingled with the bitter protests of the 
conservatives4   ,naturalists certainly 
have neither explored all the           
continents1 said ,cuvier1 nor do they as
 yet even know all the quadrupeds of    
those parts which have been explored4   
,new species of this class are          
discovered from time to time2 and those 
who have not examined with attention all
 the circumstances belonging to these   
discoveries may allege also that the    
unknown quadrupeds1 whose fossil bones  
have been found in the strata of the    
earth1 have hitherto remained concealed 
in some islands not yet discovered by   
navigators1 or in some of the vast      
deserts which occupy the middle of      
,africa1 ,asia1 the two ,americas1 and  
,new ,holland4  ,but if we carefully    
attend to the kind of quadrupeds that   
have been recently discovered1 and to   
the circumstances of their discovery1 we
 shall easily perceive that there is    
very little chance indeed of our ever   
finding alive those which have only been

 seen in a fossil state4  ,islands of   
moderate size1 and at a considerable    
distance from the large continents1 have
 very few quadrupeds4 ,these must have  
been carried to them from other         
countries4 ,cook and ,bougainville found
 no other quadrupeds besides hogs and   
dogs in the ,south ,sea ,islands2 and   
the largest quadruped of the ,west      
,india ,islands1 when first discovered1 
was the agouti1 a species of the cavy1  
an animal apparently between the rat and
 the rabbit4  ,it is true that the great
 continents1 as ,asia1 ,africa1 the two 
,americas1 and ,new ,holland1 have large
 quadrupeds1 and1 generally speaking1   
contain species common to each2         
insomuch1 that upon discovering         
countries which are isolated from the   
rest of the world1 the animals they     
contain of the class of quadruped were  
found entirely different from those     
which existed in other countries4 ,thus1
 when the ,spaniards first penetrated   
into ,south ,america1 they did not find 

it to contain a single quadruped exactly
 the same with those of ,europe1 ,asia1 
and ,africa4 ,the puma1 the jaguar1 the 
tapir1 the capybara1 the llama1 or      
glama1 and vicuna1 and the whole tribe  
of sapajous1 were to them entirely new  
animals1 of which they had not the      
smallest idea4444  ,if there still      
remained any great continent to be      
discovered1 we might perhaps expect to  
be made acquainted with new species of  
large quadrupeds1 among which some might
 be found more or less similar to those 
of which we find the exuviae in the     
bowels of the earth4 ,but it is merely  
sufficient to glance the eye over the   
maps of the world and observe the       
innumerable directions in which         
navigators have traversed the ocean1 in 
order to be satisfied that there does   
not remain any large land to be         
discovered1 unless it may be situated   
towards the ,antarctic ,pole1 where     
eternal ice necessarily forbids the     
existence of animal life47#a7  ,cuvier  

then points out that the ancients were  
well acquainted with practically all the
 animals on the continents of ,europe1  
,asia1 and ,africa now known to         
scientists4 ,he finds little grounds1   
therefore1 for belief in the theory that
 at one time there were monstrous       
animals on the earth which it was       
necessary to destroy in order that the  
present fauna and men might flourish4   
,after reviewing these theories and     
beliefs in detail1 he takes up his      
,inquiry ,respecting the ,fabulous      
,animals of the ,ancients4 ,it is easy1 
he says1 to reply to the foregoing      
objections1 by examining the            
descriptions that are left us by the    
ancients of those unknown animals1 and  
by inquiring into their origins4 ,now   
that the greater number of these animals
 have an origin1 the descriptions given 
of them bear the most unequivocal marks2
 as in almost all of them we see merely 
the different parts of known animals    
united by an unbridled imagination1 and 

in contradiction to every established   
law of nature47#b7  ,having shown how   
the fabulous monsters of ancient times  
and of foreign nations1 such as the     
,chinese1 were simply products of the   
imagination1 having no prototypes in    
nature1 ,cuvier takes up the            
consideration of the difficulty of      
distinguishing the fossil bones of      
quadrupeds4  ,we shall have occasion to 
revert to this part of ,cuvier's paper  
in another connection4 ,here it suffices
 to pass at once to the final conclusion
 that the fossil bones in question are  
the remains of an extinct fauna1 the    
like of which has no present-day        
representation on the earth4 ,whatever  
its implications1 this conclusion now   
seemed to ,cuvier to be fully           
established4  ,in ,england the interest 
thus aroused was sent to fever-heat in  
#ahba by the discovery of abundant beds 
of fossil bones in the                  
stalagmite-covered floor of a cave at   
,kirkdale1 ,yorkshire which went to show

 that ,england1 too1 had once had her   
share of gigantic beasts4 ,dr4          
,buckland1 the incumbent of the chair of
 geology at ,oxford1 and the most       
authoritative ,english geologist of his 
day1 took these finds in hand and showed
 that the bones belonged to a number of 
species1 including such alien forms as  
elephants1 rhinoceroses1 hippopotami1   
and hyenas4 ,he maintained that all of  
these creatures had actually lived in   
,britain1 and that the caves in which   
their bones were found had been the dens
 of hyenas4  ,the claim was hotly       
disputed1 as a matter of course4 ,as    
late as #ahbg books were published      
denouncing ,buckland1 doctor of divinity
 though he was1 as one who had joined in
 an unhallowed cause1 and reiterating   
the old cry that the fossils were only  
remains of tropical species washed      
thither by the deluge4 ,that they were  
found in solid rocks or in caves offered
 no difficulty1 at least not to the     
fertile imagination of ,granville ,penn1

 the leader of the conservatives1 who   
clung to the old idea of ,woodward and  
,cattcut that the deluge had dissolved  
the entire crust of the earth to a      
paste1 into which the relics now called 
fossils had settled4 ,the caves1 said   
,mr4 ,penn1 are merely the result of    
gases given off by the carcasses during 
decomposition--great air-bubbles1 so to 
speak1 in the pasty mass1 becoming      
caverns when the waters receded and the 
paste hardened to rocky consistency4    
,but these and such-like fanciful views 
were doomed even in the day of their    
utterance4 ,already in #ahbc other      
gigantic creatures1 christened          
ichthyosaurus and plesiosaurus by       
,conybeare1 had been found in deeper    
strata of ,british rocks2 and these1 as 
well as other monsters whose remains    
were unearthed in various parts of the  
world1 bore such strange forms that even
 the most sceptical could scarcely hope 
to find their counterparts among living 
creatures4 ,cuvier's contention that all

 the larger vertebrates of the existing 
age are known to naturalists was borne  
out by recent explorations1 and there   
seemed no refuge from the conclusion    
that the fossil records tell of         
populations actually extinct4 ,but if   
this were admitted1 then ,smith's view  
that there have been successive         
rotations of population could no longer 
be denied4 ,nor could it be in doubt    
that the successive faunas1 whose       
individual remains have been preserved  
in myriads1 representing extinct species
 by thousands and tens of thousands1    
must have required vast periods of time 
for the production and growth of their  
countless generations4  ,as these facts 
came to be generally known1 and as it   
came to be understood in addition that  
the very matrix of the rock in which    
fossils are imbedded is in many cases   
one gigantic fossil1 composed of the    
remains of microscopic forms of life1   
common-sense1 which1 after all1 is the  
final tribunal1 came to the aid of      

belabored science4 ,it was conceded that
 the only tenable interpretation of the 
record in the rocks is that numerous    
populations of creatures1 distinct from 
one another and from present forms1 have
 risen and passed away2 and that the    
geologic ages in which these creatures  
lived were of inconceivable length4 ,the
 rank and file came thus1 with the aid  
of fossil records1 to realize the import
 of an idea which ,james ,hutton1 and   
here and there another thinker1 had     
conceived with the swift intuition of   
genius long before the science of       
paleontology came into existence4 ,the  
,huttonian proposition that time is long
 had been abundantly established1 and by
 about the close of the first third of  
the last century geologists had begun to
 speak of ages and untold aeons of time 
with a familiarity which their          
predecessors had reserved for days and  
decades4   ,,charles ,,lyell ,,combats  
,,catastrophism  ,and now a new question
 pressed for solution4 ,if the earth has

 been inhabited by successive           
populations of beings now extinct1 how  
have all these creatures been destroyed8
 ,that question1 however1 seemed to     
present no difficulties4 ,it was        
answered out of hand by the application 
of an old idea4 ,all down the centuries1
 whatever their varying phases of       
cosmogonic thought1 there had been ever 
present the idea that past times were   
not as recent times2 that in remote     
epochs the earth had been the scene of  
awful catastrophes that have no parallel
 in these degenerate days4 ,naturally   
enough1 this thought1 embalmed in every 
cosmogonic speculation of whatever      
origin1 was appealed to in explanation  
of the destruction of these hitherto    
unimagined hosts1 which now1 thanks to  
science1 rose from their abysmal slumber
 as incontestable1 but also as silent   
and as thought-provocative1 as ,sphinx  
or pyramid4 ,these ancient hosts1 it was
 said1 have been exterminated at        
intervals of odd millions of years by   

the recurrence of catastrophes of which 
the ,mosaic deluge is the latest1 but   
perhaps not the last4  ,this explanation
 had fullest warrant of scientific      
authority4 ,cuvier had prefaced his     
classical work with a speculative       
disquisition whose very title 7,discours
 sur les ,revolutions du ,globe7 is     
ominous of catastrophism1 and whose text
 fully sustains the augury4 ,and        
,buckland1 ,cuvier's foremost follower  
across the ,channel1 had gone even      
beyond the master1 naming the work in   
which he described the ,kirkdale        
fossils1 ,reliquiae ,diluvianae1 or     
,proofs of a ,universal ,deluge4  ,both 
these authorities supposed the creatures
 whose remains they studied to have     
perished suddenly in the mighty flood   
whose awful current1 as they supposed1  
gouged out the modern valleys and hurled
 great blocks of granite broadcast over 
the land4 ,and they invoked similar     
floods for the extermination of previous
 populations4  ,it is true these        

scientific citations had met with only  
qualified approval at the time of their 
utterance1 because then the conservative
 majority of mankind did not concede    
that there had been a plurality of      
populations or revolutions2 but now that
 the belief in past geologic ages had   
ceased to be a heresy1 the recurring    
catastrophes of the great               
paleontologists were accepted with      
acclaim4 ,for the moment science and    
tradition were at one1 and there was a  
truce to controversy1 except indeed in  
those outlying skirmish-lines of thought
 whither news from headquarters does not
 permeate till it has become ancient    
history at its source4  ,the truce1     
however1 was not for long4 ,hardly had  
contemporary thought begun to adjust    
itself to the conception of past ages of
 incomprehensible extent1 each          
terminated by a catastrophe of the      
,noachian type1 when a man appeared who 
made the utterly bewildering assertion  
that the geological record1 instead of  

proving numerous catastrophic           
revolutions in the earth's past history1
 gives no warrant to the pretensions of 
any universal catastrophe whatever1 near
 or remote4  ,this iconoclast was       
,charles ,lyell1 the ,scotchman1 who was
 soon to be famous as the greatest      
geologist of his time4 ,as a young man  
he had become imbued with the force of  
the ,huttonian proposition1 that present
 causes are one with those that produced
 the past changes of the globe1 and he  
carried that idea to what he conceived  
to be its logical conclusion4 ,to his   
mind this excluded the thought of       
catastrophic changes in either inorganic
 or organic worlds4  ,but to deny       
catastrophism was to suggest a          
revolution in current thought4 ,needless
 to say1 such revolution could not be   
effected without a long contest4 ,for a 
score of years the matter was argued pro
 and con41 often with most unscientific 
ardor4 ,a mere outline of the           
controversy would fill a volume2 yet the

 essential facts with which ,lyell at   
last established his proposition1 in its
 bearings on the organic world1 may be  
epitomized in a few words4 ,the evidence
 which seems to tell of past revolutions
 is the apparently sudden change of     
fossils from one stratum to another of  
the rocks4 ,but ,lyell showed that this 
change is not always complete4 ,some    
species live on from one alleged epoch  
into the next4 ,by no means all the     
contemporaries of the mammoth are       
extinct1 and numerous marine forms      
vastly more ancient still have living   
representatives4  ,moreover1 the blanks 
between strata in any particular        
vertical series are amply filled in with
 records in the form of thick strata in 
some geographically distant series4 ,for
 example1 in some regions ,silurian     
rocks are directly overlaid by the coal 
measures2 but elsewhere this sudden     
break is filled in with the ,devonian   
rocks that tell of a great age of       
fishes4 ,so commonly are breaks in the  

strata in one region filled up in       
another that we are forced to conclude  
that the record shown by any single     
vertical series is of but local         
significance--telling1 perhaps1 of a    
time when that particular sea-bed       
oscillated above the water-line1 and so 
ceased to receive sediment until some   
future age when it had oscillated back  
again4 ,but if this be the real         
significance of the seemingly sudden    
change from stratum to stratum1 then the
 whole case for catastrophism is        
hopelessly lost2 for such breaks in the 
strata furnish the only suggestion      
geology can offer of sudden and         
catastrophic changes of wide extent4    
,let us see how ,lyell elaborates these 
ideas1 particularly with reference to   
the rotation of species47#b7  ,i have   
deduced as a corollary1 he says1 that   
the species existing at any particular  
period must1 in the course of ages1     
become extinct1 one after the other4    
',they must die out1' to borrow an      

emphatic expression from ,buffon1       
'because ,time fights against them4' ,if
 the views which ,i have taken are just1
 there will be no difficulty in         
explaining why the habitations of so    
many species are now restrained within  
exceeding narrow limits4 ,every local   
revolution tends to circumscribe the    
range of some species1 while it enlarges
 that of others2 and if we are led to   
infer that new species originate in one 
spot only1 each must require time to    
diffuse itself over a wide area4 ,it    
will follow1 therefore1 from the        
adoption of our hypothesis that the     
recent origin of some species and the   
high antiquity of others are equally    
consistent with the general fact of     
their limited distribution1 some being  
local because they have not existed long
 enough to admit of their wide          
dissemination2 others1 because          
circumstances in the animate or         
inanimate world have occurred to        
restrict the range within which they may

 once have obtained4444  ,if the reader 
should infer1 from the facts laid before
 him1 that the successive extinction of 
animals and plants may be part of the   
constant and regular course of nature1  
he will naturally inquire whether there 
are any means provided for the repair of
 these losses8 ,is it possible as a part
 of the economy of our system that the  
habitable globe should to a certain     
extent become depopulated1 both in the  
ocean and on the land1 or that the      
variety of species should diminish until
 some new era arrives when a new and    
extraordinary effort of creative energy 
is to be displayed8 ,or is it possible  
that new species can be called into     
being from time to time1 and yet that so
 astonishing a phenomenon can escape the
 naturalist8  ,in the first place1 it is
 obviously more easy to prove that a    
species once numerously represented in a
 given district has ceased to be than   
that some other which did not pre-exist 
had made its appearance--assuming       

always1 for reasons before stated1 that 
single stocks only of each animal and   
plant are originally created1 and that  
individuals of new species did not      
suddenly start up in many different     
places at once4  ,so imperfect has the  
science of natural history remained down
 to our own times that1 within the      
memory of persons now living1 the       
numbers of known animals and plants have
 doubled1 or even quadrupled1 in many   
classes4 ,new and often conspicuous     
species are annually discovered in parts
 of the old continent long inhabited by 
the most civilized nations4 ,conscious1 
therefore1 of the limited extent of our 
information1 we always infer1 when such 
discoveries are made1 that the beings in
 question bad previously eluded our     
research1 or had at least existed       
elsewhere1 and only migrated at a recent
 period into the territories where we   
now find them4  ,what kind of proofs1   
therefore1 could we reasonably expect to
 find of the origin at a particular     

period of a new species8  ,perhaps1 it  
may be said in reply1 that within the   
last two or three centuries some forest 
tree or new quadruped might have been   
observed to appear suddenly in those    
parts of ,england or ,france which had  
been most thoroughly investigated--that 
naturalists might have been able to show
 that no such being inhabited any other 
region of the globe1 and that there was 
no tradition of anything similar having 
been observed in the district where it  
had made its appearance4  ,now1 although
 this objection may seem plausible1 yet 
its force will be found to depend       
entirely on the rate of fluctuation     
which we suppose to prevail in the      
animal world1 and on the proportions    
which such conspicuous subjects of the  
animal and vegetable kingdoms bear to   
those which are less known and escape   
our observation4 ,there are perhaps more
 than a million species of plants and   
animals1 exclusive of the microscopic   
and infusory animalcules1 now inhabiting

 the terraqueous globe1 so that if only 
one of these were to become extinct     
annually1 and one new one were to be    
every year called into being1 much more 
than a million of years might be        
required to bring about a complete      
revolution of organic life4  ,i am not  
hazarding at present any hypothesis as  
to the probable rate of change1 but none
 will deny that when the annual birth   
and the annual death of one species on  
the globe is proposed as a mere         
speculation1 this1 at least1 is to      
imagine no slight degree of instability 
in the animate creation4 ,if we divide  
the surface of the earth into twenty    
regions of equal area1 one of these     
might comprehend a space of land and    
water about equal in dimensions to      
,europe1 and might contain a twentieth  
part of the million of species which may
 be assumed to exist in the animal      
kingdom4 ,in this region one species    
only could1 according to the rate of    
mortality before assumed1 perish in     

twenty years1 or only five out of fifty 
thousand in the course of a century4    
,but as a considerable portion of the   
whole world belongs to the aquatic      
classes1 with which we have a very      
imperfect acquaintance1 we must exclude 
them from our consideration1 and1 if    
they constitute half of the entire      
number1 then one species only might be  
lost in forty years among the           
terrestrial tribes4 ,now the mammalia1  
whether terrestrial or aquatic1 bear so 
small a proportion to other classes of  
animals1 forming less1 perhaps1 than a  
thousandth part of a whole1 that1 if the
 longevity of species in the different  
orders were equal1 a vast period must   
elapse before it would come to the turn 
of this conspicuous class to lose one of
 their number4 ,if one species only of  
the whole animal kingdom died out in    
forty years1 no more than one mammifer  
might disappear in forty thousand years1
 in a region of the dimensions of       
,europe4  ,it is easy1 therefore1 to see

 that in a small portion of such an     
area1 in countries1 for example1 of the 
size of ,england and ,france1 periods of
 much greater duration must elapse      
before it would be possible to          
authenticate the first appearance of one
 of the larger plants or animals1       
assuming the annual birth and death of  
one species to be the rate of           
vicissitude in the animal creation      
throughout the world47#c7   ,in a word1 
then1 said ,lyell1 it becomes clear that
 the numberless species that have been  
exterminated in the past have died out  
one by one1 just as individuals of a    
species die1 not in vast shoals2 if     
whole populations have passed away1 it  
has been not by instantaneous           
extermination1 but by the elimination of
 a species now here1 now there1 much as 
one generation succeeds another in the  
life history of any single species4 ,the
 causes which have brought about such   
gradual exterminations1 and in the long 
lapse of ages have resulted in rotations

 of population1 are the same natural    
causes that are still in operation4     
,species have died out in the past as   
they are dying out in the present1 under
 influence of changed surroundings1 such
 as altered climate1 or the migration   
into their territory of more masterful  
species4 ,past and present causes are   
one--natural law is changeless and      
eternal4  ,such was the essence of the  
,huttonian doctrine1 which ,lyell       
adopted and extended1 and with which his
 name will always be associated4        
,largely through his efforts1 though of 
course not without the aid of many other
 workers after a time1 this idea--the   
doctrine of uniformitarianism1 it came  
to be called--became the accepted dogma 
of the geologic world not long after the
 middle of the nineteenth century4 ,the 
catastrophists1 after clinging madly to 
their phantom for a generation1 at last 
capitulated without terms3 the old      
heresy became the new orthodoxy1 and the
 way was paved for a fresh controversy4 

,,the ,,origin ,,of ,,species  ,the     
fresh controversy followed quite as a   
matter of course4 ,for the idea of      
catastrophism had not concerned the     
destruction of species merely1 but their
 introduction as well4 ,if whole faunas 
had been extirpated suddenly1 new faunas
 had presumably been introduced with    
equal suddenness by special creation2   
but if species die out gradually1 the   
introduction of new species may be      
presumed to be correspondingly gradual4 
,then may not the new species of a later
 geological epoch be the modified lineal
 descendants of the extinct population  
of an earlier epoch8  ,the idea that    
such might be the case was not new4 ,it 
had been suggested when fossils first   
began to attract conspicuous attention2 
and such sagacious thinkers as ,buffon  
and ,kant and ,goethe and ,erasmus      
,darwin had been disposed to accept it  
in the closing days of the eighteenth   
century4 ,then1 in #ahji1 it had been   
contended for by one of the early       

workers in systematic                   
paleontology--,jean ,baptiste ,lamarck1 
who had studied the fossil shells about 
,paris while ,cuvier studied the        
vertebrates1 and who had been led by    
these studies to conclude that there had
 been not merely a rotation but a       
progression of life on the globe4 ,he   
found the fossil shells--the fossils of 
invertebrates1 as he himself had        
christened them--in deeper strata than  
,cuvier's vertebrates2 and he believed  
that there had been long ages when no   
higher forms than these were in         
existence1 and that in successive ages  
fishes1 and then reptiles1 had been the 
highest of animate creatures1 before    
mammals1 including man1 appeared4       
,looking beyond the pale of his bare    
facts1 as genius sometimes will1 he had 
insisted that these progressive         
populations had developed one from      
another1 under influence of changed     
surroundings1 in unbroken series4  ,of  
course such a thought as this was       

hopelessly misplaced in a generation    
that doubted the existence of extinct   
species1 and hardly less so in the      
generation that accepted catastrophism2 
but it had been kept alive by here and  
there an advocate like ,geoffrey        
,saint-,hilaire1 and now the banishment 
of catastrophism opened the way for its 
more respectful consideration4          
,respectful consideration was given it  
by ,lyell in each recurring edition of  
his ,principles1 but such consideration 
led to its unqualified rejection4 ,in   
its place ,lyell put forward a modified 
hypothesis of special creation4 ,he     
assumed that from time to time1 as the  
extirpation of a species had left room1 
so to speak1 for a new species1 such new
 species had been created de novo2 and  
he supposed that such intermittent1     
spasmodic impulses of creation manifest 
themselves nowadays quite as frequently 
as at any time in the past4 ,he did not 
say in so many words that no one need be
 surprised to-day were he to see a new  

species of deer1 for example1 come up   
out of the ground before him1 pawing to 
get free1 like ,milton's lion1 but his  
theory implied as much4 ,and that       
theory1 let it be noted1 was not the    
theory of ,lyell alone1 but of nearly   
all his associates in the geologic      
world4 ,there is perhaps no other fact  
that will bring home to one so vividly  
the advance in thought of our own       
generation as the recollection that so  
crude1 so almost unthinkable a          
conception could have been the current  
doctrine of science less than half a    
century ago4  ,this theory of special   
creation1 moreover1 excluded the current
 doctrine of uniformitarianism as night 
excludes day1 though most thinkers of   
the time did not seem to be aware of the
 incompatibility of the two ideas4 ,it  
may be doubted whether even ,lyell      
himself fully realized it4 ,if he did1  
he saw no escape from the dilemma1 for  
it seemed to him that the record in the 
rocks clearly disproved the alternative 

,lamarckian hypothesis4 ,and almost with
 one accord the paleontologists of the  
time sustained the verdict4 ,owen1      
,agassiz1 ,falconer1 ,barrande1 ,pictet1
 ,forbes1 repudiated the idea as        
unqualifiedly as their great predecessor
 ,cuvier had done in the earlier        
generation4 ,some of them did1 indeed1  
come to believe that there is evidence  
of a progressive development of life in 
the successive ages1 but no such graded 
series of fossils had been discovered as
 would give countenance to the idea that
 one species had ever been transformed  
into another4 ,and to nearly every one  
this objection seemed insuperable4  ,but
 in #ahei appeared a book which1 though 
not dealing primarily with paleontology1
 yet contained a chapter that revealed  
the geological record in an altogether  
new light4 ,the book was ,charles       
,darwin's ,origin of ,species1 the      
chapter that wonderful citation of the  
,imperfections of the ,geological       
,record4 ,in this epoch-making chapter  

,darwin shows what conditions must      
prevail in any given place in order that
 fossils shall be formed1 how unusual   
such conditions are1 and how probable it
 is that fossils once imbedded in       
sediment of a sea-bed will be destroyed 
by metamorphosis of the rocks1 or by    
denudation when the strata are raised   
above the water-level4 ,add to this the 
fact that only small territories of the 
earth have been explored geologically1  
he says1 and it becomes clear that the  
paleontological record as we now possess
 it shows but a mere fragment of the    
past history of organisms on the earth4 
,it is a history imperfectly kept and   
written in a changing dialect4 ,of this 
history we possess the last volume      
alone1 relating only to two or three    
countries4 ,of this volume only here and
 there a short chapter has been         
preserved1 and of each page only here   
and there a few lines4 ,for a           
paleontologist to dogmatize from such a 
record would be as rash1 he thinks1 as  

for a naturalist to land for five       
minutes on a barren point of ,australia 
and then discuss the number and range of
 its productions4  ,this citation of    
observations1 which when once pointed   
out seemed almost self-evident1 came as 
a revelation to the geological world4   
,in the clarified view now possible old 
facts took on a new meaning4 ,it was    
recalled that ,cuvier had been obliged  
to establish a new order for some of the
 first fossil creatures he examined1 and
 that ,buckland had noted that the      
nondescript forms were intermediate in  
structure between allied existing       
orders4 ,more recently such intermediate
 forms had been discovered over and     
over2 so that1 to name but one example1 
,owen had been able1 with the aid of    
extinct species1 to dissolve by         
gradations the apparently wide interval 
between the pig and the camel4 ,owen1   
moreover1 had been led to speak         
repeatedly of the generalized forms of  
extinct animals1 and ,agassiz had called

 them synthetic or prophetic types1     
these terms clearly implying that such  
forms are in fact intermediate or       
connecting links4 ,darwin himself had   
shown some years before that the fossil 
animals of any continent are closely    
related to the existing animals of that 
continent--edentates predominating1 for 
example1 in ,south ,america1 and        
marsupials in ,australia4 ,many         
observers had noted that recent strata  
everywhere show a fossil fauna more     
nearly like the existing one than do    
more ancient strata2 and that fossils   
from any two consecutive strata are far 
more closely related to each other than 
are the fossils of two remote           
formations1 the fauna of each geological
 formation being1 indeed1 in a wide     
view1 intermediate between preceding and
 succeeding faunas4  ,so suggestive were
 all these observations that ,lyell1 the
 admitted leader of the geological      
world1 after reading ,darwin's          
citations1 felt able to drop his own    

crass explanation of the introduction of
 species and adopt the transmutation    
hypothesis1 thus rounding out the       
doctrine of uniformitarianism to the    
full proportions in which ,lamarck had  
conceived it half a century before4 ,not
 all paleontologists could follow him at
 once1 of course2 the proof was not yet 
sufficiently demonstrative for that2 but
 all were shaken in the seeming security
 of their former position1 which is     
always a necessary stage in the progress
 of thought4 ,and popular interest in   
the matter was raised to white heat in a
 twinkling4  ,so1 for the third time in 
this first century of its existence1    
paleontology was called upon to play a  
leading role in a controversy whose     
interest extended far beyond the bounds 
of staid truth-seeking science4 ,and the
 controversy waged over the age of the  
earth had not been more bitter1 that    
over catastrophism not more acrimonious1
 than that which now raged over the     
question of the transmutation of        

species4 ,the question had implications 
far beyond the bounds of paleontology1  
of course4 ,the main evidence yet       
presented had been drawn from quite     
other fields1 but by common consent the 
record in the rocks might furnish a     
crucial test of the truth or falsity of 
the hypothesis4 ,he who rejects this    
view of the imperfections of the        
geological record1 said ,darwin1 will   
rightly reject the whole theory4  ,with 
something more than mere scientific     
zeal1 therefore1 paleontologists turned 
anew to the records in the rocks1 to    
inquire what evidence in proof or       
refutation might be found in unread     
pages of the great stone book4 ,and1 as 
might have been expected1 many minds    
being thus prepared to receive new      
evidence1 such evidence was not long    
withheld4   ,,fossil ,,man  ,indeed1 at 
the moment of ,darwin's writing a new   
and very instructive chapter of the     
geologic record was being presented to  
the public--a chapter which for the     

first time brought man into the story4  
,in #ahei ,dr4 ,falconer1 the           
distinguished ,british paleontologist1  
made a visit to ,abbeville1 in the      
valley of the ,somme1 incited by reports
 that for a decade before bad been sent 
out from there by ,m4 ,boucher de       
,perthes4 ,these reports had to do with 
the alleged finding of flint implements1
 clearly the work of man1 in undisturbed
 gravel-beds1 in the midst of fossil    
remains of the mammoth and other extinct
 animals4 ,what ,falconer saw there and 
what came of his visit may best be told 
in his own words3  ,in ,september of    
#ahef ,i made the acquaintance of my    
distinguished friend ,m4 ,boucher de    
,perthes1 wrote ,dr4 ,falconer1 on the  
introduction of ,m4 ,desnoyers at       
,paris1 when he presented to me the     
earlier volume of his ,antiquites       
celtiques1 etc41 with which ,i thus     
became acquainted for the first time4 ,i
 was then fresh from the examination of 
the ,indian fossil remains of the valley

 of the ,jumna2 and the antiquity of the
 human race being a subject of interest 
to both1 we conversed freely about it1  
each from a different point of view4 ,m4
 de ,perthes invited me to visit        
,abbeville1 in order to examine his     
antediluvian collection1 fossil and     
geological1 gleaned from the valley of  
the ,somme4 ,this ,i was unable to      
accomplish then1 but ,i reserved it for 
a future occasion4  ,in ,october1 #ahef1
 having determined to proceed to        
,sicily1 ,i arranged by correspondence  
with ,m4 ,boucher de ,perthes to visit  
,abbeville on my journey through        
,france4 ,i was at the time in constant 
communication with ,mr4 ,prestwich about
 the proofs of the antiquity of the     
human race yielded by the ,broxham      
,cave1 in which he took a lively        
interest2 and ,i engaged to communicate 
to him the opinions at which ,i should  
arrive1 after my examination of the     
,abbeville collection4 ,m4 de ,perthes  
gave me the freest access to his        

materials1 with unreserved explanations 
of all the facts of the case that had   
come under his observation2 and having  
considered his ,menchecourt ,section1   
taken with such scrupulous care1 and    
identified the molars of elephas        
primigenius1 which he had exhumed with  
his own hands deep in that section1     
along with flint weapons1 presenting the
 same character as some of those found  
in the ,broxham ,cave1 ,i arrived at the
 conviction that they were of           
contemporaneous age1 although ,i was not
 prepared to go along with ,m4 de       
,perthes in all his inferences regarding
 the hieroglyphics and in an industrial 
interpretation of the various other     
objects which he had met with47#d7      
,that ,dr4 ,falconer was much impressed 
by the collection of ,m4 de ,perthes is 
shown in a communication which he sent  
at once to his friend ,prestwich3  ,i   
have been richly rewarded1 he exclaims4 
,his collection of wrought flint        
implements1 and of the objects of every 

description associated with them1 far   
exceeds everything ,i expected to have  
seen1 especially from a single locality4
 ,he has made great additions1 since the
 publication of his first volume1 in the
 second1 which ,i now have by me4 ,he   
showed me flint hatchets which ,,he     
,,had ,,dug ,,up with his own hands1    
mixed ,,indiscriminately with molars of 
elephas primigenius4 ,i examined and    
identified plates of the molars and the 
flint objects which were got along with 
them4 ,abbeville is an out-of-the-way   
place1 very little visited2 and the     
,french savants who meet him in ,paris  
laugh at ,monsieur de ,perthes and his  
researches4 ,but after devoting the     
greater part of a day to his vast       
collection1 ,i am perfectly satisfied   
that there is a great deal of fair      
presumptive evidence in favor of many of
 his speculations regarding the remote  
antiquity of these industrial objects   
and their association with animals now  
extinct4 ,m4 ,boucher's hotel is1 from  

the ground floor to garret1 a continued 
museum1 filled with pictures1 mediaeval 
art1 and ,gaulish antiquities1 including
 antediluvian flint-knives1             
fossil-bones1 etc4 ,if1 during next     
summer1 you should happen to be paying a
 visit to ,france1 let me strongly      
recommend you to come to ,abbeville4 ,i 
am sure you would be richly             
rewarded47#e7   ,this letter aroused the
 interest of the ,english geologists1   
and in the spring of #ahei ,prestwich   
and ,mr4 7afterwards ,sir ,john7 ,evans 
made a visit to ,abbeville to see the   
specimens and examine at first hand the 
evidences as pointed out by ,dr4        
,falconer4 ,the evidence yielded by the 
valley of the ,somme1 continues         
,falconer1 in speaking of this visit1   
was gone into with the scrupulous care  
and severe and exhaustive analysis which
 are characteristic of ,mr4 ,prestwich's
 researches4 ,the conclusions to which  
he was conducted were communicated to   
the ,royal ,society on ,may #ab1 #ahei1 

in his celebrated memoir1 read on ,may  
#bfth and published in the              
,philosophical ,transactions of #ahfj1  
which1 in addition to researches made in
 the valley of the ,somme1 contained an 
account of similar phenomena presented  
by the valley of the ,waveney1 near     
,hoxne1 in ,suffolk4 ,mr4 ,evans        
communicated to the ,society of         
,antiquaries a memoir on the character  
and geological position of the ',flint  
,implements in the ,drift1' which       
appeared in the ,archaeologia for #ahfj4
 ,the results arrived at by ,mr4        
,prestwich were expressed as follows3   
,first4 ,that the flint implements are  
the result of design and the work of    
man4  ,second4 ,that they are found in  
beds of gravel1 sand1 and clay1 which   
have never been artificially disturbed4 
,third4 ,that they occur associated with
 the remains of land1 fresh-water1 and  
marine testacea1 of species now living1 
and most of them still common in the    
same neighborhood1 and also with the    

remains of various mammalia--a few      
species now living1 but more of extinct 
forms4  ,fourth4 ,that the period at    
which their entombment took place was   
subsequent to the bowlder-clay period1  
and to that extent post-glacial2 and    
also that it was among the latest in    
geological time--one apparently anterior
 to the surface assuming its present    
form1 so far as it regards some of the  
minor features47#f7   ,these reports    
brought the subject of the very         
significant human fossils at ,abbeville 
prominently before the public2 whereas  
the publications of the original        
discoverer1 ,boucher de ,perthes1       
bearing date of #ahdg1 had been         
altogether ignored4 ,a new aspect was   
thus given to the current controversy4  
,as ,dr4 ,falconer remarked1 geology was
 now passing through the same ordeal    
that astronomy passed in the age of     
,galileo4 ,but the times were changed   
since the day when the author of the    
,dialogues was humbled before the       

,congregation of the ,index1 and now no 
,index ,librorum ,prohibitorum could    
avail to hide from eager human eyes such
 pages of the geologic story as ,nature 
herself had spared4 ,eager searchers    
were turning the leaves with renewed    
zeal everywhere1 and with no small      
measure of success4 ,in particular1     
interest attached just at this time to a
 human skull which ,dr4 ,fuhlrott had   
discovered in a cave at ,neanderthal two
 or three years before--a cranium which 
has ever since been famous as the       
,neanderthal skull1 the type specimen of
 what modern zoologists are disposed to 
regard as a distinct species of man1    
,homo neanderthalensis4 ,like others of 
the same type since discovered at ,spy1 
it is singularly simian in              
character--low-arched1 with receding    
forehead and enormous1 protuberant      
eyebrows4 ,when it was first exhibited  
to the scientists at ,berlin by ,dr4    
,fuhlrott1 in #aheg1 its human character
 was doubted by some of the witnesses2  

of that1 however1 there is no present   
question4  ,this interesting find served
 to recall with fresh significance some 
observations that had been made in      
,france and ,belgium a long generation  
earlier1 but whose bearings had hitherto
 been ignored4 ,in #ahbf ,,mm4 ,tournal 
and ,christol had made independent      
discoveries of what they believed to be 
human fossils in the caves of the south 
of ,france2 and in #ahbg ,dr4           
,schmerling had found in the cave of    
,engis1 in ,westphalia1 fossil bones of 
even greater significance4 ,schmerling's
 explorations had been made with the    
utmost care1 and patience4 ,at ,engis he
 had found human bones1 including       
skulls1 intermingled with those of      
extinct mammals of the mammoth period in
 a way that left no doubt in his mind   
that all dated from the same geological 
epoch4 ,he bad published a full account 
of his discoveries in an elaborate      
monograph issued in #ahcc4  ,but at that
 time1 as it chanced1 human fossils were

 under a ban as effectual as any ever   
pronounced by canonical index1 though of
 far different origin4 ,the oracular    
voice of ,cuvier had declared against   
the authenticity of all human fossils4  
,some of the bones brought him for      
examination the great anatomist had     
pettishly pitched out of the window1    
declaring them fit only for a cemetery1 
and that had settled the matter for a   
generation3 the evidence gathered by    
lesser workers could avail nothing      
against the decision rendered at the    
,delphi of ,science4 ,but no ban1       
scientific or canonical1 can longer     
resist the germinative power of a fact1 
and so now1 after three decades of      
suppression1 the truth which ,cuvier had
 buried beneath the weight of his       
ridicule burst its bonds1 and fossil man
 stood revealed1 if not as a            
flesh-and-blood1 at least as a skeletal 
entity4  ,the reception now accorded our
 prehistoric ancestor by the progressive
 portion of the scientific world        

amounted to an ovation2 but the         
unscientific masses1 on the other hand1 
notwithstanding their usual fondness for
 tracing remote genealogies1 still gave 
the men of ,engis and ,neanderthal the  
cold shoulder4 ,nor were all of the     
geologists quite agreed that the        
contemporaneity of these human fossils  
with the animals whose remains had been 
mingled with them had been fully        
established4 ,the bare possibility that 
the bones of man and of animals that    
long preceded him had been swept        
together into the eaves in successive   
ages1 and in some mysterious way        
intermingled there1 was clung to by the 
conservatives as a last refuge4 ,but    
even this small measure of security was 
soon to be denied them1 for in #ahfe two
 associated workers1 ,m4 ,edouard       
,lartet and ,mr4 ,henry ,christy1 in    
exploring the caves of ,dordogne1       
unearthed a bit of evidence against     
which no such objection could be urged4 
,this momentous exhibit was a bit of    

ivory1 a fragment of the tusk of a      
mammoth1 on which was scratched a rude  
but unmistakable outline portrait of the
 mammoth itself4 ,if all the evidence as
 to man's antiquity before presented was
 suggestive merely1 here at last was    
demonstration2 for the cave-dwelling man
 could not well have drawn the picture  
of the mammoth unless he had seen that  
animal1 and to admit that man and the   
mammoth had been contemporaries was to  
concede the entire case4 ,so soon1      
therefore1 as the full import of this   
most instructive work of art came to be 
realized1 scepticism as to man's        
antiquity was silenced for all time to  
come4  ,in the generation that has      
elapsed since the first drawing of the  
cave-dweller artist was discovered1     
evidences of the wide-spread existence  
of man in an early epoch have multiplied
 indefinitely1 and to-day the           
paleontologist traces the history of our
 race back beyond the iron and bronze   
ages1 through a neolithic or            

polished-stone age1 to a paleolithic or 
rough-stone age1 with confidence born of
 unequivocal knowledge4 ,and he looks   
confidently to the future explorer of   
the earth's fossil records to extend the
 history back into vastly more remote   
epochs1 for it is little doubted that   
paleolithic man1 the most ancient of our
 recognized progenitors1 is a modern    
compared to those generations that      
represented the real childhood of our   
race4   ,,the ,,fossil-,,beds ,,of      
,,america  ,coincidently with the       
discovery of these highly suggestive    
pages of the geologic story1 other still
 more instructive chapters were being   
brought to light in ,america4 ,it was   
found that in the ,rocky ,mountain      
region1 in strata found in ancient lake 
beds1 records of the tertiary period1 or
 age of mammals1 had been made and      
preserved with fulness not approached in
 any other region hitherto geologically 
explored4 ,these records were made known
 mainly by ,professors ,joseph ,leidy1  

,o4 ,c4 ,marsh1 and ,e4 ,d4 ,cope1      
working independently1 and more recently
 by numerous younger paleontologists4   
,the profusion of vertebrate remains    
thus brought to light quite beggars all 
previous exhibits in point of mere      
numbers4 ,professor ,marsh1 for example1
 who was first in the field1 found three
 hundred new tertiary species between   
the years #ahgj and #ahgf4 ,meanwhile1  
in cretaceous strata1 he unearthed      
remains of about two hundred birds with 
teeth1 six hundred pterodactyls1 or     
flying dragons1 some with a spread of   
wings of twenty-five feet1 and one      
thousand five hundred mosasaurs of the  
sea-serpent type1 some of them sixty    
feet or more in length4 ,in a single bed
 of ,jurassic rock1 not larger than a   
good-sized lecture-room1 he found the   
remains of one hundred and sixty        
individuals of mammals1 representing    
twenty species and nine genera2 while   
beds of the same age have yielded three 
hundred reptiles1 varying from the size 

of a rabbit to sixty or eighty feet in  
length4  ,but the chief interest of     
these fossils from the ,west is not     
their number but their nature2 for among
 them are numerous illustrations of just
 such intermediate types of organisms as
 must have existed in the past if the   
succession of life on the globe has been
 an unbroken lineal succession4 ,here   
are reptiles with bat-like wings1 and   
others with bird-like pelves and legs   
adapted for bipedal locomotion4 ,here   
are birds with teeth1 and other         
reptilian characters4 ,in short1 what   
with reptilian birds and birdlike       
reptiles1 the gap between modern        
reptiles and birds is quite bridged     
over4 ,in a similar way1 various diverse
 mammalian forms1 as the tapir1 the     
rhinoceros1 and the horse1 are linked   
together by fossil progenitors4 ,and1   
most important of all1 ,professor ,marsh
 has discovered a series of mammalian   
remains1 occurring in successive        
geological epochs1 which are held to    

represent beyond cavil the actual line  
of descent of the modern horse2 tracing 
the lineage of our one-toed species back
 through two and three toed forms1 to an
 ancestor in the eocene or early        
tertiary that had four functional toes  
and the rudiment of a fifth4 ,this      
discovery is too interesting and too    
important not to be detailed at length  
in the words of the discoverer4   ,marsh
 ,describes the ,fossil ,horse  ,it is a
 well-known fact1 says ,professor       
,marsh1 that the ,spanish discoverers of
 ,america discovered no horses on this  
continent1 and that the modern horse    
7,equus caballus1 ,linn47 was           
subsequently introduced from the ,old   
,world4 ,it is1 however1 not so         
generally known that these animals had  
formerly been abundant here1 and that   
long before1 in tertiary time1 near     
relatives of the horse1 and probably his
 ancestors1 existed in the far ,west in 
countless numbers and in a marvellous   
variety of forms4 ,the remains of equine

 mammals1 now known from the tertiary   
and quaternary deposits of this country1
 already represent more than double the 
number of genera and species hitherto   
found in the strata of the eastern      
hemisphere1 and hence afford most       
important aid in tracing out the        
genealogy of the horses still existing4 
,the animals of this group which lived  
in ,america during the three diversions 
of the tertiary period were especially  
numerous in the ,rocky ,mountain        
regions1 and their remains are well     
preserved in the old lake basins which  
then covered so much of that country4   
,the most ancient of these lakes--which 
extended over a considerable part of the
 present territories of ,wyoming and    
,utah--remained so long in eocene times 
that the mud and sand1 slowly deposited 
in it1 accumulated to more than a mile  
in vertical thickness4 ,in these        
deposits vast numbers of tropical       
animals were entombed1 and here the     
oldest equine remains occur1 four       

species of which have been described4   
,these belong to the genus ,orohippus   
7,marsh71 and are all of a diminutive   
size1 hardly bigger than a fox4 ,the    
skeletons of these animals resemble that
 of the horse in many respects1 much    
more indeed than any other existing     
species1 but1 instead of the single toe 
on each foot1 so characteristic of all  
modern equines1 the various species of  
,orohippus had four toes before and     
three behind1 all of which reached the  
ground4 ,the skull1 too1 was            
proportionately shorter1 and the orbit  
was not enclosed behind by a bridge of  
bone4 ,there were fifty four teeth in   
all1 and the premolars were larger than 
the molars4 ,the crowns of these teeth  
were very short4 ,the canine teeth were 
developed in both sexes1 and the        
incisors did not have the mark which    
indicates the age of the modern horse4  
,the radius and ulna were separate1 and 
the latter was entire through the whole 
length4 ,the tibia and fibula were      

distinct4 ,in the forefoot all the      
digits except the pollex1 or first1 were
 well developed4 ,the third digit is the
 largest1 and its close resemblance to  
that of the horse is clearly marked4    
,the terminal phalanx1 or coffin-bone1  
has a shallow median bone in front1 as  
in many species of this group in the    
later tertiary4 ,the fourth digit       
exceeds the second in size1 and the     
second is much the shortest of all4 ,its
 metacarpal bone is considerably curved 
outward4 ,in the hind-foot of this genus
 there are but three digits4 ,the fourth
 metatarsal is much larger than the     
second4  ,the larger number of equine   
mammals now known from the tertiary     
deposits of this country1 and their     
regular distributions through the       
subdivisions of this formation1 afford a
 good opportunity to ascertain the      
probable descent of the modern horse4   
,the ,american representative of the    
latter is the extinct ,equus fraternus  
7,leidy71 a species almost1 if not      

wholly1 identical with the ,old ,world  
,equus caballus 7,linnaeus71 to which   
our recent horse belongs4 ,huxley has   
traced successfully the later genealogy 
of the horse through ,european extinct  
forms1 but the line in ,america was     
probably a more direct one1 and the     
record is more complete4 ,taking1 then1 
as the extreme of a series1 ,orohippus  
agilis 7,marsh71 from the eocene1 and   
,equus fraternus 7,leidy71 from the     
quaternary1 intermediate forms may be   
intercalated with considerable certainty
 from thirty or more well-marked species
 that lived in the intervening periods4 
,the natural line of descent would seem 
to be through the following genera3     
,orohippus1 of the eocene2 ,miohippus   
and ,anchitherium1 of the miocene2      
,anchippus1 ,hipparion1 ,protohippus1   
,phohippus1 of the pliocene2 and ,equus1
 quaternary and recent4  ,the most      
marked changes undergone by the         
successive equine genera are as follows3
 ,first1 increase in size2 second1      

increase in speed1 through concentration
 of limb bones2 third1 elongation of    
head and neck1 and modifications of     
skull4 ,the eocene ,orohippus was the   
size of a fox4 ,miohippus and           
,anchitherium1 from the miocene1 were   
about as large as a sheep4 ,hipparion   
and ,pliohippus1 of the pliocene1       
equalled the ass in height2 while the   
size of the quaternary ,equus was fully 
up to that of a modern horse4  ,the     
increase of speed was equally well      
marked1 and was a direct result of the  
gradual formation of the limbs4 ,the    
latter were slowly concentrated by the  
reduction of their lateral elements and 
enlargement of the axial bone1 until the
 force exerted by each limb came to act 
directly through its axis in the line of
 motion4 ,this concentration is well    
seen--e4g41 in the fore-limb4 ,there    
was1 first1 a change in the scapula and 
humerus1 especially in the latter1 which
 facilitated motion in one line only2   
second1 an expansion of the radius and  

reduction of the ulna1 until the former 
alone remained entire and effective2    
third1 a shortening of all the carpal   
bones and enlargement of the median     
ones1 insuring a firmer wrist2 fourth1  
an increase of size of the third digit1 
at the expense of those of each side1   
until the former alone supported the    
limb4  ,such is1 in brief1 a general    
outline of the more marked changes that 
seemed to have produced in ,america the 
highly specialized modern ,equus from   
his diminutive four-toed predecessor1   
the eocene ,orohippus4 ,the line of     
descent appears to have been direct1 and
 the remains now known supply every     
important intermediate form4 ,it is1 of 
course1 impossible to say with certainty
 through which of the three-toed genera 
of the pliocene that lived together the 
succession came4 ,it is not impossible  
that the latter species1 which appear   
generically identical1 are the          
descendants of more distinct pliocene   
types1 as the persistent tendency in all

 the earlier forms was in the same      
direction4 ,considering the remarkable  
development of the group through the    
tertiary period1 and its existence even 
later1 it seems very strange that none  
of the species should have survived1 and
 that we are indebted for our present   
horse to the ,old ,world47#g7           
,,paleontology ,,of ,,evolution  ,these 
and such-like revelations have come to  
light in our own time--are1 indeed1     
still being disclosed4 ,needless to say1
 no index of any sort now attempts to   
conceal them2 yet something has been    
accomplished towards the same end by the
 publication of the discoveries in      
,smithsonian bulletins and in technical 
memoirs of government surveys4          
,fortunately1 however1 the results have 
been rescued from that partial oblivion 
by such interpreters as ,professors     
,huxley and ,cope1 so the unscientific  
public has been allowed to gain at least
 an inkling of the wonderful progress of
 paleontology in our generation4  ,the  

writings of ,huxley in particular       
epitomize the record4 ,in #ahfb he      
admitted candidly that the              
paleontological record as then known1 so
 far as it bears on the doctrine of     
progressive development1 negatives that 
doctrine4 ,in #ahgj he was able to      
soften somewhat the ,brutus-like        
severity of his former verdict1 and to  
assert that the results of recent       
researches seem to leave a clear balance
 in favor of the doctrine of the        
evolution of living forms one from      
another4 ,six years later1 when         
reviewing the work of ,marsh in ,america
 and of ,gaudry in ,pikermi1 he declared
 that1 on the evidence of paleontology1 
the evolution of many existing forms of 
animal life from their predecessors is  
no longer an hypothesis1 but an         
historical fact4 ,in #ahha he asserted  
that the evidence gathered in the       
previous decade had been so unequivocal 
that1 had the transmutation hypothesis  
not existed1 the paleontologist would   

have had to invent it4  ,since then the 
delvers after fossils have piled proof  
on proof in bewildering profusion4 ,the 
fossil-beds in the bad lands of western 
,america seem inexhaustible4 ,and in the
 ,connecticut ,river ,valley near       
relatives of the great reptiles which   
,professor ,marsh and others have found 
in such profusion in the ,west left     
their tracks on the mud-flats--since    
turned to sandstone2 and a few skeletons
 also have been found4 ,the bodies of a 
race of great reptiles that were the    
lords of creation of their day have been
 dissipated to their elements1 while the
 chance indentations of their feet as   
they raced along the shores1 mere       
footprints on the sands1 have been      
preserved among the most imperishable of
 the memory-tablets of the world4  ,of  
the other vertebrate fossils that have  
been found in the eastern portions of   
,america1 among the most abundant and   
interesting are the skeletons of        
mastodons4 ,of these one of the largest 

and most complete is that which was     
unearthed in the bed of a drained lake  
near ,newburg1 ,new ,york1 in #ahde4    
,this specimen was larger than the      
existing elephants1 and had tusks eleven
 feet in length4 ,it was mounted and    
described by ,dr4 ,john ,c4 ,warren1 of 
,boston1 and has been famous for half a 
century as the ,warren mastodon4  ,but  
to the student of racial development as 
recorded by the fossils all these       
sporadic finds have but incidental      
interest as compared with the rich      
,western fossil-beds to which we have   
already referred4 ,from records here    
unearthed1 the racial evolution of many 
mammals has in the past few years been  
made out in greater or less detail4     
,professor ,cope has traced the ancestry
 of the camels 7which1 like the         
rhinoceroses1 hippopotami1 and sundry   
other forms now spoken of as ,old       
,world1 seem to have had their origin   
here7 with much completeness4  ,a       
lemuroid form of mammal1 believed to be 

of the type from which man has          
descended1 has also been found in these 
beds4 ,it is thought that the           
descendants of this creature1 and of the
 other ,old-,world forms above referred 
to1 found their way to ,asia1 probably1 
as suggested by ,professor ,marsh1      
across a bridge at ,bering ,strait1 to  
continue their evolution on the other   
hemisphere1 becoming extinct in the land
 of their nativity4 ,the ape-man fossil 
found in the tertiary strata of the     
island of ,java in #ahia by the ,dutch  
surgeon ,dr4 ,eugene ,dubois1 and named 
,pithecanthropus erectus1 may have been 
a direct descendant of the ,american    
tribe of primitive lemurs1 though this  
is only a conjecture4  ,not all the     
strange beasts which have left their    
remains in our bad lands are represented
 by living descendants4 ,the            
titanotheres1 or brontotheridae1 for    
example1 a gigantic tribe1 offshoots of 
the same stock which produced the horse 
and rhinoceros1 represented the         

culmination of a line of descent4 ,they 
developed rapidly in a geological sense1
 and flourished about the middle of the 
tertiary period2 then1 to use ,agassiz's
 phrase1 time fought against them4 ,the 
story of their evolution has been worked
 out by ,professors ,leidy1 ,marsh1     
,cope1 and ,h4 ,f4 ,osborne4  ,a recent 
bit of paleontological evidence bearing 
on the question of the introduction of  
species is that presented by ,dr4 ,j4   
,l4 ,wortman in connection with the     
fossil lineage of the edentates4 ,it was
 suggested by ,marsh1 in #ahgg1 that    
these creatures1 whose modern           
representatives are all ,south          
,american1 originated in ,north ,america
 long before the two continents had any 
land connection4 ,the stages of         
degeneration by which these animals     
gradually lost the enamel from their    
teeth1 coming finally to the unique     
condition of their modern descendants of
 the sloth tribe1 are illustrated by    
strikingly graded specimens now         

preserved in the ,american ,museum of   
,natural ,history1 as shown by ,dr4     
,wortman4  ,all these and a multitude of
 other recent observations that cannot  
be even outlined here tell the same     
story4 ,with one accord paleontologists 
of our time regard the question of the  
introduction of new species as solved4  
,as ,professor ,marsh has said1 to doubt
 evolution today is to doubt science2   
and science is only another name for    
truth4  ,thus the third great battle    
over the meaning of the fossil records  
has come to a conclusion4 ,again there  
is a truce to controversy1 and it may   
seem to the casual observer that the    
present stand of the science of fossils 
is final and impregnable4 ,but does this
 really mean that a full synopsis of the
 story of paleontology has been told8   
,or do we only await the coming of the  
twentieth-century ,lamarck or ,darwin1  
who shall attack the fortified knowledge
 of to-day with the batteries of a new  
generalization8     ,,iv4 ,,the ,,origin

 ,,and ,,development ,,of ,,modern      
,,geology   ,,james ,,hutton  ,one might
 naturally suppose that the science of  
the earth which lies at man's feet would
 at least have kept pace with the       
science of the distant stars4 ,but      
perhaps the very obviousness of the     
phenomena delayed the study of the crust
 of the earth4 ,it is the unattainable  
that allures and mystifies and enchants 
the developing mind4 ,the proverbial    
child spurns its toys and cries for the 
moon4  ,so in those closing days of the 
eighteenth century1 when astronomers had
 gone so far towards explaining the     
mysteries of the distant portions of the
 universe1 we find a chaos of opinion   
regarding the structure and formation of
 the earth4 ,guesses were not wanting to
 explain the formation of the world1 it 
is true1 but1 with one or two           
exceptions1 these are bizarre indeed4   
,one theory supposed the earth to have  
been at first a solid mass of ice1 which
 became animated only after a comet had 

dashed against it4 ,other theories      
conceived the original globe as a mass  
of water1 over which floated vapors     
containing the solid elements1 which in 
due time were precipitated as a crust   
upon the waters4 ,in a word1 the various
 schemes supposed the original mass to  
have been ice1 or water1 or a           
conglomerate of water and solids1       
according to the random fancies of the  
theorists2 and the final separation into
 land and water was conceived to have   
taken place in all the ways which fancy1
 quite unchecked by any tenable data1   
could invent4  ,whatever important      
changes in the general character of the 
surface of the globe were conceived to  
have taken place since its creation were
 generally associated with the ,mosaic3 
deluge1 and the theories which attempted
 to explain this catastrophe were quite 
on a par with those which dealt with a  
remoter period of the earth's history4  
,some speculators1 holding that the     
interior of the globe is a great abyss  

of waters1 conceived that the crust had 
dropped into this chasm and had thus    
been inundated4 ,others held that the   
earth had originally revolved on a      
vertical axis1 and that the sudden      
change to its present position bad      
caused the catastrophic shifting of its 
oceans4 ,but perhaps the favorite theory
 was that which supposed a comet to have
 wandered near the earth1 and in        
whirling about it to have carried the   
waters1 through gravitation1 in a vast  
tide over the continents4  ,thus blindly
 groped the majority of                 
eighteenth-century philosophers in their
 attempts to study what we now term     
geology4 ,deluded by the old deductive  
methods1 they founded not a science1 but
 the ghost of a science1 as immaterial  
and as unlike anything in nature as any 
other phantom that could be conjured    
from the depths of the speculative      
imagination4 ,and all the while the     
beckoning earth lay beneath the feet of 
these visionaries2 but their eyes were  

fixed in air4  ,at last1 however1 there 
came a man who had the penetration to   
see that the phantom science of geology 
needed before all else a body corporeal1
 and who took to himself the task of    
supplying it4 ,this was ,dr4 ,james     
,hutton1 of ,edinburgh1 physician1      
farmer1 and manufacturing               
chemist--patient1 enthusiastic1         
level-headed devotee of science4        
,inspired by his love of chemistry to   
study the character of rocks and soils1 
,hutton had not gone far before the     
earth stood revealed to him in a new    
light4 ,he saw1 what generations of     
predecessors had blindly refused to see1
 that the face of nature everywhere1    
instead of being rigid and immutable1 is
 perennially plastic1 and year by year  
is undergoing metamorphic changes4 ,the 
solidest rocks are day by day           
disintegrated slowly1 but none the less 
surely1 by wind and rain and frost1 by  
mechanical attrition and chemical       
decomposition1 to form the pulverized   

earth and clay4 ,this soil is being     
swept away by perennial showers1 and    
carried off to the oceans4 ,the oceans  
themselves beat on their shores1 and eat
 insidiously into the structure of sands
 and rocks4 ,everywhere1 slowly but     
surely1 the surface of the land is being
 worn away2 its substance is being      
carried to burial in the seas4  ,should 
this denudation continue long enough1   
thinks ,hutton1 the entire surface of   
the continents must be worn away4       
,should it be continued ,,long ,,enough6
 ,and with that thought there flashes on
 his mind an inspiring conception--the  
idea that solar time is long1           
indefinitely long4 ,that seems a simple 
enough thought--almost a truism--to the 
twentieth-century mind2 but it required 
genius to conceive it in the eighteenth4
 ,hutton pondered it1 grasped its full  
import1 and made it the basis of his    
hypothesis1 his theory of the earth4    
,,modern ,,geology  ,the hypothesis is  
this--that the observed changes of the  

surface of the earth1 continued through 
indefinite lapses of time1 must result  
in conveying all the land at last to the
 sea2 in wearing continents away till   
the oceans overflow them4 ,what then8   
,why1 as the continents wear down1 the  
oceans are filling up4 ,along their     
bottoms the detritus of wasted          
continents is deposited in strata1      
together with the bodies of marine      
animals and vegetables4 ,why might not  
this debris solidify to form layers of  
rocks--the basis of new continents8 ,why
 not1 indeed8  ,but have we any proof   
that such formation of rocks in an      
ocean-bed has1 in fact1 occurred8 ,to be
 sure we have4 ,it is furnished by every
 bed of limestone1 every outcropping    
fragment of fossil-bearing rock1 every  
stratified cliff4 ,how else than through
 such formation in an ocean-bed came    
these rocks to be stratified8 ,how else 
came they to contain the shells of once 
living organisms imbedded in their      
depths8 ,the ancients1 finding fossil   

shells imbedded in the rocks1 explained 
them as mere freaks of nature and the   
stars4 ,less superstitious generations  
had repudiated this explanation1 but had
 failed to give a tenable solution of   
the mystery4 ,to ,hutton it is a mystery
 no longer4 ,to him it seems clear that 
the basis of the present continents was 
laid in ancient sea-beds1 formed of the 
detritus of continents yet more ancient4
  ,but two links are still wanting to   
complete the chain of ,hutton's         
hypothesis4 ,through what agency has the
 ooze of the ocean-bed been transformed 
into solid rock8 and through what agency
 has this rock been lifted above the    
surface of the water to form new        
continents8 ,hutton looks about him for 
a clew1 and soon he finds it4           
,everywhere about us there are          
outcropping rocks that are not          
stratified1 but which give evidence to  
the observant eye of having once been in
 a molten state4 ,different minerals are
 mixed together2 pebbles are scattered  

through masses of rock like plums in a  
pudding2 irregular crevices in otherwise
 solid masses of rock--so-called        
veinings--are seen to be filled with    
equally solid granite of a different    
variety1 which can have gotten there in 
no conceivable way1 so ,hutton thinks1  
but by running in while molten1 as      
liquid metal is run into the moulds of  
the founder4 ,even the stratified rocks1
 though they seemingly have not been    
melted1 give evidence in some instances 
of having been subjected to the action  
of heat4 ,marble1 for example1 is       
clearly nothing but calcined limestone4 
,with such evidence before him1 ,hutton 
is at no loss to complete his           
hypothesis4 ,the agency which has       
solidified the ocean-beds1 he says1 is  
subterranean heat4 ,the same agency1    
acting excessively1 has produced        
volcanic cataclysms1 upheaving          
ocean-beds to form continents4 ,the     
rugged and uneven surfaces of mountains1
 the tilted and broken character of     

stratified rocks everywhere1 are the    
standing witnesses of these gigantic    
upheavals4  ,and with this the imagined 
cycle is complete4 ,the continents1 worn
 away and carried to the sea by the     
action of the elements1 have been made  
over into rocks again in the ocean-beds1
 and then raised once more into         
continents4 ,and this massive cycle1 ,in
 ,hutton's scheme1 is supposed to have  
occurred not once only1 but over and    
over again1 times without number4 ,in   
this unique view ours is indeed a world 
without beginning and without end2 its  
continents have been making and unmaking
 in endless series since time began4    
,hutton formulated his hypothesis while 
yet a young man1 not long after the     
middle of the century4 ,he first gave it
 publicity in #agha1 in a paper before  
the ,royal ,society of ,edinburgh3  ,a  
solid body of land could not have       
answered the purpose of a habitable     
world1 said ,hutton1 for a soil is      
necessary to the growth of plants1 and a

 soil is nothing but the material       
collected from the destruction of the   
solid land4 ,therefore the surface of   
this land inhabited by man1 and covered 
by plants and animals1 is made by nature
 to decay1 in dissolving from that hard 
and compact state in which it is found2 
and this soil is necessarily washed away
 by the continual circulation of the    
water running from the summits of the   
mountains towards the general receptacle
 of that fluid4  ,the heights of our    
land are thus levelled with our shores1 
our fertile plains are formed from the  
ruins of the mountains2 and those       
travelling materials are still pursued  
by the moving water1 and propelled along
 the inclined surface of the earth4     
,these movable materials1 delivered into
 the sea1 cannot1 for a long            
continuance1 rest upon the shore1 for by
 the agitation of the winds1 the tides1 
and the currents every movable thing is 
carried farther and farther along the   
shelving bottom of the sea1 towards the 

unfathomable regions of the ocean4  ,if 
the vegetable soil is thus constantly   
removed from the surface of the land1   
and if its place is then to be supplied 
from the dissolution of the solid earth 
as here represented1 we may perceive an 
end to this beautiful machine2 an end   
arising from no error in its            
constitution as a world1 but from that  
destructibility of its land which is so 
necessary in the system of the globe1 in
 the economy of life and vegetation4    
,the immense time necessarily required  
for the total destruction of the land   
must not be opposed to that view of     
future events which is indicated by the 
surest facts and most approved          
principles4 ,time1 which measures       
everything in our idea1 and is often    
deficient to our schemes1 is to nature  
endless and as nothing2 it cannot limit 
that by which alone it has existence2   
and as the natural course of time1 which
 to us seems infinite1 cannot be bounded
 by any operation that may have an end1 

the progress of things upon this globe  
that in the course of nature cannot be  
limited by time must proceed in a       
continual succession4 ,we are1          
therefore1 to consider as inevitable the
 destruction of our land1 so far as     
effected by those operations which are  
necessary in the purpose of the globe1  
considered as a habitable world1 and so 
far as we have not examined any other   
part of the economy of nature1 in which 
other operations and a different        
intention might appear4  ,we have now   
considered the globe of this earth as a 
machine1 constructed upon chemical as   
well as mechanical principles1 by which 
its different parts are all adapted1 in 
form1 in quality1 and quantity1 to a    
certain end--an end attained with       
certainty of success1 and an end from   
which we may perceive wisdom in         
contemplating the means employed4  ,but 
is this world to be considered thus     
merely as a machine1 to last no longer  
than its parts retain their present     

position1 their proper forms and        
qualities8 ,or may it not be also       
considered as an organized body such as 
has a constitution1 in which the        
necessary decay of the machine is       
naturally repaired in the exertion of   
those productive powers by which it has 
been formed8  ,this is the view in which
 we are now to examine the globe2 to see
 if there be1 in the constitution of the
 world1 a reproductive operation by     
which a ruined constitution may be again
 repaired and a duration of stability   
thus procured to the machine considered 
as a world containing plants and        
animals4  ,if no such reproductive      
power1 or reforming operation1 after due
 inquiry1 is to be found in the         
constitution of this world1 we should   
have reason to conclude that the system 
of this earth has either been           
intentionally made imperfect or has not 
been the work of infinite power and     
wisdom47#a7   ,this1 then1 was the      
important question to be answered--the  

question of the constitution of the     
globe4 ,to accomplish this1 it was      
necessary1 first of all1 to examine     
without prejudice the material already  
in hand1 adding such new discoveries    
from time to time as might be made1 but 
always applying to the whole unvarying  
scientific principles and inductive     
methods of reasoning4  ,if we are to    
take the written history of man for the 
rule by which we should judge of the    
time when the species first began1 said 
,hutton1 that period would be but little
 removed from the present state of      
things4 ,the ,mosaic history places this
 beginning of man at no great distance2 
and there has not been found1 in natural
 history1 any document by which high    
antiquity might be attributed to the    
human race4 ,but this is not the case   
with regard to the inferior species of  
animals1 particularly those which       
inhabit the ocean and its shores4 ,we   
find in natural history monuments which 
prove that those animals had long       

existed2 and we thus procure a measure  
for the computation of a period of time 
extremely remote1 though far from being 
precisely ascertained4  ,in examining   
things present1 we have data from which 
to reason with regard to what has been2 
and from what actually has been we have 
data for concluding with regard to that 
which is to happen hereafter4           
,therefore1 upon the supposition that   
the operations of nature are equable and
 steady1 we find1 in natural            
appearances1 means for concluding a     
certain portion of time to have         
necessarily elapsed in the production of
 those events of which we see the       
effects4  ,it is thus that1 in finding  
the relics of sea animals of every kind 
in the solid body of our earth1 a       
natural history of those animals is     
formed1 which includes a certain portion
 of time2 and for the ascertaining this 
portion of time we must again have      
recourse to the regular operations of   
this world4 ,we shall thus arrive at    

facts which indicate a period to which  
no other species of chronology is able  
to remount4  ,we find the marks of      
marine animals in the most solid parts  
of the earth1 consequently those solid  
parts have been formed after the ocean  
was inhabited by those animals which are
 proper to that fluid medium4 ,if1      
therefore1 we knew the natural history  
of these solid parts1 and could trace   
the operations of the globe by which    
they have been formed1 we would have    
some means for computing the time       
through which those species of animals  
have continued to live4 ,but how shall  
we describe a process which nobody has  
seen performed and of which no written  
history gives any account8 ,this is only
 to be investigated1 first1 in examining
 the nature of those solid bodies the   
history of which we want to know2 and1  
secondly1 in examining the natural      
operations of the globe1 in order to see
 if there now exist such operations as1 
from the nature of the solid bodies1    

appear to have been necessary for their 
formation4  ,there are few beds of      
marble or limestone in which may not be 
found some of those objects which       
indicate the marine object of the mass4 
,if1 for example1 in a mass of marble   
taken from a quarry upon the top of the 
,alps or ,andes there shall be found one
 cockle-shell or piece of coral1 it must
 be concluded that this bed of stone has
 been originally formed at the bottom of
 the sea1 as much as another bed which  
is evidently composed almost altogether 
of cockle-shells and coral4 ,if one bed 
of limestone is thus found to have been 
of marine origin1 every concomitant bed 
of the same kind must be also concluded 
to have been formed in the same manner4 
,in those calcareous strata1 which are  
evidently of marine origin1 there are   
many parts which are of sparry          
structure--that is to say1 the original 
texture of those beds in such places has
 been dissolved1 and a new structure has
 been assumed which is peculiar to a    

certain state of the calcareous earth4  
,this change is produced by             
crystallization1 in consequence of a    
previous state of fluidity1 which has so
 disposed the concerting parts as to    
allow them to assume a regular shape and
 structure proper to that substance4 ,a 
body whose external form has been       
modified by this process is called a    
,,crystal2 one whose internal           
arrangement of parts is determined by it
 is said to be of a ,,sparry            
,,structure1 and this is known from its 
fracture4  ,there are1 in all the       
regions of the earth1 huge masses of    
calcareous matter in that crystalline   
form or sparry state in which1 perhaps1 
no vestige can be found of any organized
 body1 nor any indication that such     
calcareous matter has belonged to       
animals2 but as in other masses this    
sparry structure or crystalline state is
 evidently assumed by the marine        
calcareous substances in operations     
which are natural to the globe1 and     

which are necessary to the consolidation
 of the strata1 it does not appear that 
the sparry masses in which no figured   
body is formed have been originally     
different from other masses1 which1     
being only crystallized in part1 and in 
part still retaining their original     
form1 have ample evidence of their      
marine origin4  ,we are led1 in this    
manner1 to conclude that all the strata 
of the earth1 not only those consisting 
of such calcareous masses1 but others   
superincumbent upon these1 have had     
their origin at the bottom of the sea4  
,the general amount of our reasoning is 
this1 that nine-tenths1 perhaps1 or     
ninety-nine-hundredths1 of this earth1  
so far as we see1 have been formed by   
natural operations of the globe in      
collecting loose materials and          
depositing them at the bottom of the    
sea2 consolidating those collections in 
various degrees1 and either elevating   
those consolidated masses above the     
level on which they were formed or      

lowering the level of that sea4  ,let us
 now consider how far the other         
proposition of strata being elevated by 
the power of heat above the level of the
 sea may be confirmed from the          
examination of natural appearances4 ,the
 strata formed at the bottom of the     
ocean are necessarily horizontal in     
their position1 or nearly so1 and       
continuous in their horizontal direction
 or extent4 ,they may be changed and    
gradually assume the nature of each     
other1 so far as concerns the materials 
of which they are formed1 but there     
cannot be any sudden change1 fracture1  
or displacement naturally in the body of
 a stratum4 ,but if the strata are      
cemented by the heat of fusion1 and     
erected with an expansive power acting  
below1 we may expect to find every      
species of fracture1 dislocation1 and   
contortion in those bodies and every    
degree of departure from a horizontal   
towards a vertical position4  ,the      
strata of the globe are actually found  

in every possible position3 for from    
horizontal they are frequently found    
vertical2 from continuous they are      
broken and separated in every possible  
direction2 and from a plane they are    
bent and doubled4 ,it is impossible that
 they could have originally been formed1
 by the known laws of nature1 in their  
present state and position2 and the     
power that has been necessarily required
 for their change has not been inferior 
to that which might have been required  
for their elevation from the place in   
which they have been formed47#b7   ,from
 all this1 therefore1 ,hutton reached   
the conclusion that the elevation of the
 bodies of land above the water on the  
earth's surface had been effected by the
 same force which had acted in          
consolidating the strata and giving them
 stability4 ,this force he conceived to 
be exerted by the expansion of heated   
matter4  ,we have1 he said1 been now    
supposing that the beginning of our     
present earth had been laid in the      

bottom of the ocean1 at the completion  
of the former land1 but this was only   
for the sake of distinctness4 ,the just 
view is this1 that when the former land 
of the globe had been complete1 so as to
 begin to waste and be impaired by the  
encroachment of the sea1 the present    
land began to appear above the surface  
of the ocean4 ,in this manner we suppose
 a due proportion to be always preserved
 of land and water upon the surface of  
the globe1 for the purpose of a         
habitable world such as this which we   
possess4 ,we thus also allow time and   
opportunity for the translation of      
animals and plants to occupy the earth4 
,but if the earth on which we live began
 to appear in the ocean at the time when
 the ,,last began to be resolved1 it    
could not be from the materials of the  
continent immediately preceding this    
which we examine that the present earth 
has been constructed2 for the bottom of 
the ocean must have been filled with    
materials before land could be made to  

appear above its surface4  ,let us      
suppose that the continent which is to  
succeed our land is at present beginning
 to appear above the water in the middle
 of the ,pacific ,ocean2 it must be     
evident that the materials of this great
 body1 which is formed and ready to be  
brought forth1 must have been collected 
from the destruction of an earth which  
does not now appear4 ,consequently1 in  
this true statement of the case there is
 necessarily required the destruction of
 an animal and vegetable earth prior to 
the former land2 and the materials of   
that earth which is first in our account
 must have been collected at the bottom 
of the ocean1 and begun to be concocted 
for the production of the present earth1
 when the land immediately preceding the
 present had arrived at its full extent4
  ,we have now got to the end of our    
reasoning2 we have no data further to   
conclude immediately from that which    
actually is2 but we have got enough2 we 
have the satisfaction to find that in   

nature there are wisdom1 system1 and    
consistency4 ,for having in the natural 
history of the earth seen a succession  
of worlds1 we may from this conclude    
that there is a system in nature2 in    
like manner as1 from seeing revolutions 
of the planets1 it is concluded that    
there is a system by which they are     
intended to continue those revolutions4 
,but if the succession of worlds is     
established in the system of nature1 it 
is in vain to look for anything higher  
in the origin of the earth4 ,the result1
 therefore1 of our present inquiry is   
that we find no vestige of a            
beginning--no prospect of an end4       
,altogether remarkable as this paper    
seems in the light of later knowledge1  
neither friend nor foe deigned to notice
 it at the moment4 ,it was not published
 in book form until the last decade of  
the century1 when ,hutton had lived with
 and worked over his theory for almost  
fifty years4 ,then it caught the eye of 
the world4 ,a school of followers       

expounded the ,huttonian doctrines2 a   
rival school under ,werner in ,germany  
opposed some details of the hypothesis1 
and the educated world as a whole viewed
 the disputants askance4 ,the very      
novelty of the new views forbade their  
immediate acceptance4 ,bitter attacks   
were made upon the heresies1 and that   
was meant to be a soberly tempered      
judgment which in #ahjj pronounced      
,hutton's theories not only hostile to  
sacred history1 but equally hostile to  
the principles of probability1 to the   
results of the ablest observations on   
the mineral kingdom1 and to the dictates
 of rational philosophy4 ,and all this  
because ,hutton's theory presupposed the
 earth to have been in existence more   
than six thousand years4  ,thus it      
appears that though the thoughts of men 
had widened1 in those closing days of   
the eighteenth century1 to include the  
stars1 they had not as yet expanded to  
receive the most patent records that are
 written everywhere on the surface of   

the earth4 ,before ,hutton's views could
 be accepted1 his pivotal conception    
that time is long must be established by
 convincing proofs4 ,the evidence was   
being gathered by ,william ,smith1      
,cuvier1 and other devotees of the      
budding science of paleontology in the  
last days of the century1 but their     
labors were not brought to completion   
till a subsequent epoch4   ,,neptunists 
,,versus ,,plutonists  ,in the mean     
time1 ,james ,hutton's theory that      
continents wear away and are replaced by
 volcanic upheaval gained comparatively 
few adherents4 ,even the lucid          
,illustrations of the ,huttonian        
,theory1 which ,playfair1 the pupil and 
friend of the great ,scotchman1         
published in #ahjb1 did not at once     
prove convincing4 ,the world had become 
enamoured of the rival theory of        
,hutton's famous contemporary1 ,werner  
of ,saxony--the theory which taught that
 in the beginning all the solids of the 
earth's present crust were dissolved in 

the heated waters of a universal sea4   
,werner affirmed that all rocks1 of     
whatever character1 had been formed by  
precipitation from this sea as the      
waters cooled2 that even veins have     
originated in this way2 and that        
mountains are gigantic crystals1 not    
upheaved masses4 ,in a word1 he         
practically ignored volcanic action1 and
 denied in toto the theory of           
metamorphosis of rocks through the      
agency of heat4  ,the followers of      
,werner came to be known as ,neptunists2
 the ,huttonians as ,plutonists4 ,the   
history of geology during the first     
quarter of the nineteenth century is    
mainly a recital of the intemperate     
controversy between these opposing      
schools2 though it should not be        
forgotten that1 meantime1 the members of
 the ,geological ,society of ,london    
were making an effort to hunt for facts 
and avoid compromising theories4 ,fact  
and theory1 however1 were too closely   
linked to be thus divorced4  ,the brunt 

of the controversy settled about the    
unstratified rocks--granites and their  
allies--which the ,plutonists claimed as
 of igneous origin4 ,this contention had
 the theoretical support of the nebular 
hypothesis1 then gaining ground1 which  
supposed the earth to be a cooling      
globe4 ,the ,plutonists laid great      
stress1 too1 on the observed fact that  
the temperature of the earth increases  
at a pretty constant ratio as descent   
towards its centre is made in mines4    
,but in particular they appealed to the 
phenomena of volcanoes4  ,the evidence  
from this source was gathered and       
elaborated by ,mr4 ,g4 ,poulett ,scrope1
 secretary of the ,geological ,society  
of ,england1 who1 in #ahbc1 published a 
classical work on volcanoes in which he 
claimed that volcanic mountains1        
including some of the highest-known     
peaks1 are merely accumulated masses of 
lava belched forth from a crevice in the
 earth's crust4  ,supposing the globe to
 have had any irregular shape when      

detached from the sun1 said ,scrope1 the
 vaporization of its surface1 and1 of   
course1 of its projecting angles1       
together with its rotatory motion on its
 axis and the liquefaction of its outer 
envelope1 would necessarily occasion its
 actual figure of an oblate spheroid4   
,as the process of expansion proceeded  
in depth1 the original granitic beds    
were first partially disaggregated1 next
 disintegrated1 and more or less        
liquefied1 the crystals being merged in 
the elastic vehicle produced by the     
vaporization of the water contained     
between the laminae4  ,where this fluid 
was produced in abundance by great      
dilatation--that is1 in the outer and   
highly disintegrated strata1 the        
superior specific gravity of the        
crystals forced it to ooze upward1 and  
thus a great quantity of aqueous vapor  
was produced on the surface of the      
globe4 ,as this elastic fluid rose into 
outer space1 its continually increasing 
expansion must have proportionately     

lowered its temperature2 and1 in        
consequence1 a part was recondensed into
 water and sank back towards the more   
solid surface of the globe4  ,and in    
this manner1 for a certain time1 a      
violent reciprocation of atmospheric    
phenomena must have continued--torrents 
of vapor rising outwardly1 while equally
 tremendous torrents of condensed vapor1
 or rain1 fell towards the earth4 ,the  
accumulation of the latter on the yet   
unstable and unconsolidated surface of  
the globe constituted the primeval      
ocean4 ,the surface of this ocean was   
exposed to continued vaporization owing 
to intense heat2 but this process1      
abstracting caloric from the stratum of 
the water below1 by partially cooling   
it1 tended to preserve the remainder in 
a liquid form4 ,the ocean will have     
contained1 both in solution and         
suspension1 many of the matters carried 
upward from the granitic bed in which   
the vapors from whose condensation it   
proceeded were produced1 and which they 

had traversed in their rise4 ,the       
dissolved matters will have been silex1 
carbonates1 and sulphates of lime1 and  
those other mineral substances which    
water at an intense temperature and     
under such circumstances was enabled to 
hold in solution4 ,the suspended        
substances will have been all the       
lighter and finer particles of the upper
 beds where the disintegration had been 
extreme2 and particularly their mica1   
which1 owing to the tenuity of its      
plate-shaped crystals1 would be most    
readily carried up by the ascending     
fluid1 and will have remained longest in
 suspension4  ,but as the torrents of   
vapor1 holding these various matters in 
solution and suspension1 were forced    
upward1 the greater part of the         
disintegrated crystals by degrees       
subsided2 those of felspar and quartz   
first1 the mica being1 as observed      
above1 from the form of its plates1 of  
peculiar buoyancy1 and therefore held   
longest in suspension4  ,the crystals of

 felspar and quartz as they subsided1   
together with a small proportion of     
mica1 would naturally arrange themselves
 so as to have their longest dimensions 
more or less parallel to the surface on 
which they rest2 and this parallelism   
would be subsequently increased1 as we  
shall see hereafter1 by the pressure of 
these beds sustained between the weight 
of the supported column of matter and   
the expansive force beneath them4 ,these
 beds ,i conceive1 when consolidated1 to
 constitute the gneiss formation4  ,the 
farther the process of expansion        
proceeded in depth1 the more was the    
column of liquid matter lengthened1     
which1 gravitating towards the centre of
 the globe1 tended to check any further 
expansion4 ,it is1 therefore1 obvious   
that after the globe settled into its   
actual orbit1 and thenceforward lost    
little of its enveloping matter1 the    
whole of which began from that moment to
 gravitate towards its centre1 the      
progress of expansion inwardly would    

continually increase in rapidity2 and a 
moment must have at length arrived hen  
the forces of expansion and repression  
had reached an equilibrium and the      
process was stopped from progressing    
farther inwardly by the great pressure  
of the gravitating column of liquid4    
,this column may be considered as       
consisting of different strata1 though  
the passage from one extremity of       
complete solidity to the other of       
complete expansion1 in reality1 must    
have been perfectly gradual4 ,the lowest
 stratum1 immediately above the extreme 
limit of expansion1 will have been      
granite barely ,,disaggregated1 and     
rendered imperfectly liquid by the      
partial vaporization of its contained   
water4  ,the second stratum was granite 
,,disintegrated2 aqueous vapor1 having  
been produced in such abundance as to be
 enabled to rise upward1 partially      
disintegrating the crystals of felspar  
and mica1 and superficially dissolving  
those of quartz4 ,this mass would       

reconsolidate into granite1 though of a 
smaller grain than the preceding rock4  
,the third stratum was so disintegrated 
that a greater part of the mica had been
 carried up by the escaping vapor ,,in  
,,suspension1 and that of quartz in     
solution2 the felspar crystals1 with the
 remaining quartz and mica1 ,,subsiding 
by their specific gravity and arranging 
themselves in horizontal planes4  ,the  
consolidation of this stratum produced  
the gneiss formation4  ,the fourth zone 
will have been composed of the ocean of 
turbid and heated water1 holding mica1  
etc41 in suspension1 and quartz1        
carbonate of lime1 etc41 in solution1   
and continually traversed by            
reciprocating bodies of heated water    
rising from below1 and of cold fluid    
sinking from the surface1 by reason of  
their specific gravities4  ,the         
disturbance thus occasioned will have   
long retarded the deposition of the     
suspended particles4 ,but this must by  
degrees have taken place1 the quartz    

grains and the larger and coarser plates
 of mica subsiding first and the finest 
last4  ,but the fragments of quartz and 
mica were not deposited alone2 a great  
proportion of the quartz held in        
,,solution must have been precipitated  
at the same time as the water cooled1   
and therefore by degrees lost its       
faculty of so much in solution4 ,thus   
was gradually produced the formation of 
mica-schist1 the mica imperfectly       
recrystallizing or being merely         
aggregated together in horizontal       
plates1 between which the quartz either 
spread itself generally in minute grains
 or unified into crystalline nuclei4 ,on
 other spots1 instead of silex1         
carbonate of lime was precipitated1     
together with more or less of the       
nucaceous sediment1 and gave rise to    
saccharoidal limestones4 ,at a later    
period1 when the ocean was yet further  
cooled down1 rock-salt and sulphate of  
lime were locally precipitated in a     
similar mode4  ,the fifth stratum was   

aeriform1 and consisted in great part of
 aqueous vapors2 the remainder being a  
compound of other elastic fluids        
7permanent gases7 which had been formed 
probably from the volatilization of some
 of the substances contained in the     
primitive granite and carried upward    
with the aqueous vapor from below4      
,these gases will have been either mixed
 together or otherwise disposed1        
according to their different specific   
gravities or chemical affinities1 and   
this stratum constituted the atmosphere 
or aerial envelope of the globe4  ,when1
 in this manner1 the general and        
positive expansion of the globe1        
occasioned by the sudden reduction of   
outward pressure1 had ceased 7in        
consequence of the ,,repressive ,,force1
 consisting of the weight of its fluid  
envelope1 having reached an equilibrium 
with the ,,expansive ,,force1 consisting
 of the caloric of the heated nucleus71 
the rapid superficial evaporation of the
 ocean continued2 and1 by gradually     

reducing its temperature1 occasioned the
 precipitation of a proportionate       
quantity of the minerals it held in     
solution1 particularly its silex4 ,these
 substances falling to the bottom1      
accompanied by a large proportion of the
 matters held in solution1 particularly 
the mica1 in consequence of the greater 
comparative tranquillity of the ocean1  
agglomerated these into more or less    
compact beds of rock 7the mica-schist   
formation71 producing the first crust or
 solid envelope of the globe4 ,upon     
this1 other stratified rocks1 composed  
sometimes of a mixture1 sometimes of an 
alternation of precipitations1          
sediments1 and occasionally of          
conglomerates1 were by degrees          
deposited1 giving rise to the           
,,transition formations4  ,beneath this 
crust a new process now commenced4 ,the 
outer zones of crystalline matter having
 been suddenly refrigerated by the rapid
 vaporization and partial escape of the 
water they contained1 abstracted caloric

 from the intensely heated nucleus of   
the globe4 ,these crystalline zones were
 of unequal density1 the expansion they 
had suffered diminishing from above     
downward4  ,their expansive force was1  
however1 equal at all points1 their     
temperature everywhere bearing an       
inverse ratio to their density4 ,but    
when by the accession of caloric from   
the inner and unliquefied nucleus the   
temperature1 and consequently the       
expansive force of the lower strata of  
dilated crystalline matter1 was         
augmented1 it acted upon the upper and  
more liquefied strata4 ,these being     
prevented from yielding ,,outwardly by  
the tenacity and weight of the solid    
involucrum of precipitated and          
sedimental deposits which overspread    
them1 sustained a pressure out of       
proportion to their expansive force1 and
 were in consequence proportionately    
condensed1 and by the continuance of the
 process1 where the overlying strata    
were sufficiently resistant1 finally    

consolidated4  ,this process of         
consolidation must have progressed from 
above downward1 with the increase of the
 expansive force in the lower strata1   
commencing from the upper surface1      
which1 its temperature being lowest1    
offered the least resistance to the     
force of compression4  ,by this process 
the upper zone of crystalline matter1   
which had intumesced so far as to allow 
of the escape of its aqueous vapor and  
of much of its mica and quartz1 was     
resolidified1 the component crystals    
arranging themselves in planes          
perpendicular to the direction of the   
pressure by which the mass was          
consolidated--that is1 to the radius of 
the globe4 ,the gneiss formation1 as    
already observed1 was the result4  ,the 
inferior zone of barely disintegrated   
granite1 from which only a part of the  
steam and quartz and none of the mica   
had escaped1 reconsolidated in a        
confused or granitoidal manner2 but     
exhibits marks of the process it had    

undergone in its broken crystals of     
felspar and mica1 its rounded and       
superficially dissolved grains of       
quartz1 its imbedded fragments 7broken  
from the more solid parts of the mass1  
as it rose1 and enveloped by the softer 
parts71 its concretionary nodules and   
new minerals1 etc4  ,beneath this1 the  
granite which had been simply           
disintegrated was again solidified1 and 
returned in all respects to its former  
condition4 ,the temperature1 however1   
and with it the expansive force of the  
inferior zone1 was continually on the   
increase1 the caloric of the interior of
 the globe still endeavoring to put     
itself in equilibrio by passing off     
towards the less-intensely heated crust4
  ,this continually increasing expansive
 force must at length have overcome the 
resistance opposed by the tenacity and  
weight of the overlying consolidated    
strata4 ,it is reasonable to suppose    
that this result took place             
contemporaneously1 or nearly so1 on many

 spots1 wherever accidental             
circumstances in the texture or         
composition of the oceanic deposits led 
them to yield more readily2 and in this 
manner were produced those original     
fissures in the primeval crust of the   
earth through some of which 7fissures of
 elevation7 were intruded portions of   
interior crystalline zones in a solid or
 nearly solid state1 together with more 
or less of the intumescent granite1 in  
the manner above described2 while others
 7fissures of eruption7 gave rise to    
extravasations of the heated crystalline
 matter1 in the form of lavas--that is1 
still further liquefied by the greater  
comparative reduction of the pressure   
they endured47#c7   ,the ,neptunists    
stoutly contended for the aqueous origin
 of volcanic as of other mountains4 ,but
 the facts were with ,scrope1 and as    
time went on it came to be admitted that
 not merely volcanoes1 but many trap    
formations not taking the form of       
craters1 had been made by the obtrusion 

of molten rock through fissures in      
overlying strata4 ,such1 for example1 to
 cite familiar illustrations1 are ,mount
 ,holyoke1 in ,massachusetts1 and the   
well-known formation of the ,palisades  
along the ,hudson4  ,but to admit the   
,plutonic origin of such widespread     
formations was practically to abandon   
the ,neptunian hypothesis4 ,so gradually
 the ,huttonian explanation of the      
origin of granites and other igneous    
rocks1 whether massed or in veins1 came 
to be accepted4 ,most geologists then   
came to think of the earth as a molten  
mass1 on which the crust rests as a mere
 film4 ,some1 indeed1 with ,lyell1      
preferred to believe that the molten    
areas exist only as lakes in a solid    
crust1 heated to melting1 perhaps1 by   
electrical or chemical action1 as ,davy 
suggested4 ,more recently a popular     
theory attempts to reconcile geological 
facts with the claim of the physicists1 
that the earth's entire mass is at least
 as rigid as steel1 by supposing that a 

molten film rests between the observed  
solid crust and the alleged solid       
nucleus4 ,but be that as it may1 the    
theory that subterranean heat has been  
instrumental in determining the         
condition of primary rocks1 and in      
producing many other phenomena of the   
earth's crust1 has never been in dispute
 since the long controversy between the 
,neptunists and the ,plutonists led to  
its establishment4   ,,lyell ,,and      
,,uniformitarianism  ,if molten matter  
exists beneath the crust of the earth1  
it must contract in cooling1 and in so  
doing it must disturb the level of the  
portion of the crust already solidified4
 ,so a plausible explanation of the     
upheaval of continents and mountains was
 supplied by the ,plutonian theory1 as  
,hutton had from the first alleged4 ,but
 now an important difference of opinion 
arose as to the exact rationale of such 
upheavals4 ,hutton himself1 and         
practically every one else who accepted 
his theory1 had supposed that there are 

long periods of relative repose1 during 
which the level of the crust is         
undisturbed1 followed by short periods  
of active stress1 when continents are   
thrown up with volcanic suddenness1 as  
by the throes of a gigantic earthquake4 
,but now came ,charles ,lyell with his  
famous extension of the uniformitarian  
doctrine1 claiming that past changes of 
the earth's surface have been like      
present changes in degree as well as in 
kind4 ,the making of continents and     
mountains1 he said1 is going on as      
rapidly to-day as at any time in the    
past4 ,there have been no gigantic      
cataclysmic upheavals at any time1 but  
all changes in level of the strata as a 
whole have been gradual1 by slow        
oscillation1 or at most by repeated     
earthquake shocks such as are still     
often experienced4  ,in support of this 
very startling contention ,lyell        
gathered a mass of evidence of the      
recent changes in level of continental  
areas4 ,he corroborated by personal     

inspection the claim which had been made
 by ,playfair in #ahjb1 and by ,von     
,buch in #ahjg1 that the coast-line of  
,sweden is rising at the rate of from a 
few inches to several feet in a century4
 ,he cited ,darwin's observations going 
to prove that ,patagonia is similarly   
rising1 and ,pingel's claim that        
,greenland is slowly sinking4 ,proof as 
to sudden changes of level of several   
feet1 over large areas1 due to          
earthquakes1 was brought forward in     
abundance4 ,cumulative evidence left it 
no longer open to question that such    
oscillatory changes of level1 either    
upward or downward1 are quite the rule1 
and it could not be denied that these   
observed changes1 if continued long     
enough in one direction1 would produce  
the highest elevations4 ,the possibility
 that the making of even the highest    
ranges of mountains had been            
accomplished without exaggerated        
catastrophic action came to be freely   
admitted4  ,it became clear that the    

supposedly stable-land surfaces are in  
reality much more variable than the     
surface of the shifting sea2 that       
continental masses1 seemingly so fixed1 
are really rising and falling in billows
 thousands of feet in height1 ages      
instead of moments being consumed in the
 sweep between crest and hollow4  ,these
 slow oscillations of land surfaces     
being understood1 many geological       
enigmas were made clear--such as the    
alternation of marine and fresh-water   
formations in a vertical series1 which  
,cuvier and ,brongniart had observed    
near ,paris2 or the sandwiching of      
layers of coal1 of subaerial formation1 
between layers of subaqueous clay or    
sandstone1 which may be observed        
everywhere in the coal measures4 ,in    
particular1 the extreme thickness of the
 sedimentary strata as a whole1 many    
times exceeding the depth of the deepest
 known sea1 was for the first time      
explicable when it was understood that  
such strata had formed in slowly sinking

 ocean-beds4  ,all doubt as to the mode 
of origin of stratified rocks being thus
 removed1 the way was opened for a more 
favorable consideration of that other   
,huttonian doctrine of the extremely    
slow denudation of land surfaces4 ,the  
enormous amount of land erosion will be 
patent to any one who uses his eyes     
intelligently in a mountain district4   
,it will be evident in any region where 
the strata are tilted--as1 for example1 
the ,alleghanies--that great folds of   
strata which must once have risen miles 
in height have in many cases been worn  
entirely away1 so that now a valley     
marks the location of the former        
eminence4 ,where the strata are level1  
as in the case of the mountains of      
,sicily1 the ,scotch ,highlands1 and the
 familiar ,catskills1 the evidence of   
denudation is1 if possible1 even more   
marked2 for here it is clear that       
elevation and valley have been carved by
 the elements out of land that rose from
 the sea as level plateaus4  ,but that  

this herculean labor of land-sculpturing
 could have been accomplished by the    
slow action of wind and frost and shower
 was an idea few men could grasp within 
the first half-century after ,hutton    
propounded it2 nor did it begin to gain 
general currency until ,lyell's crusade 
against catastrophism1 begun about      
#ahcj1 had for a quarter of a century   
accustomed geologists to the thought of 
slow1 continuous changes producing final
 results of colossal proportions4 ,and  
even long after that it was combated by 
such men as ,murchison1                 
,director-,general of the ,geological   
,survey of ,great ,britain1 then        
accounted the foremost field-geologist  
of his time1 who continued to believe   
that the existing valleys owe their main
 features to subterranean forces of     
upheaval4 ,even ,murchison1 however1    
made some recession from the belief of  
the ,continental authorities1 ,elie de  
,beaumont and ,leopold von ,buch1 who   
contended that the mountains had sprung 

up like veritable jacks-in-the-box4 ,von
 ,buch1 whom his friend and fellow-pupil
 ,von ,humboldt considered the foremost 
geologist of the time1 died in #ahec1   
still firm in his early faith that the  
erratic bowlders found high on the ,jura
 had been hurled there1 like            
cannon-balls1 across the valley of      
,geneva by the sudden upheaval of a     
neighboring mountain-range4   ,,agassiz 
,,and ,,the ,,glacial ,,theory  ,the    
bowlders whose presence on the crags of 
the ,jura the old ,gerinan accounted for
 in a manner so theatrical had long been
 a source of contention among           
geologists4 ,they are found not merely  
on the ,jura1 but on numberless other   
mountains in all north-temperate        
latitudes1 and often far out in the open
 country1 as many a farmer who has      
broken his plough against them might    
testify4 ,the early geologists accounted
 for them1 as for nearly everything     
else1 with their supposititious ,deluge4
 ,brongniart and ,cuvier and ,buckland  

and their contemporaries appeared to    
have no difficulty in conceiving that   
masses of granite weighing hundreds of  
tons had been swept by this current     
scores or hundreds of miles from their  
source4 ,but1 of course1 the            
uniformitarian faith permitted no such  
explanation1 nor could it countenance   
the projection idea2 so ,lyell was bound
 to find some other means of            
transportation for the puzzling         
erratics4  ,the only available medium   
was ice1 but1 fortunately1 this one     
seemed quite sufficient4 ,icebergs1 said
 ,lyell1 are observed to carry all      
manner of debris1 and deposit it in the 
sea-bottoms4 ,present land surfaces have
 often been submerged beneath the sea4  
,during the latest of these submergences
 icebergs deposited the bowlders now    
scattered here and there over the land4 
,nothing could be simpler or more       
clearly uniformitarian4 ,and even the   
catastrophists1 though they met ,lyell  
amicably on almost no other theoretical 

ground1 were inclined to admit the      
plausibility of his theory of erratics4 
,indeed1 of all ,lyell's nonconformist  
doctrines1 this seemed the one most     
likely to meet with general acceptance4 
,yet1 even as this iceberg theory loomed
 large and larger before the geological 
world1 observations were making in a    
different field that were destined to   
show its fallacy4 ,as early as #ahae a  
sharp-eyed chamois-hunter of the ,alps1 
,perraudin by name1 had noted the       
existence of the erratics1 and1 unlike  
most of his companion hunters1 had      
puzzled his head as to how the bowlders 
got where he saw them4 ,he knew nothing 
of submerged continents or of icebergs1 
still less of upheaving mountains2 and  
though he doubtless had heard of the    
,flood1 he had no experience of heavy   
rocks floating like corks in water4     
,moreover1 he had never observed stones 
rolling uphill and perching themselves  
on mountain-tops1 and he was a good     
enough uniformitarian 7though he would  

have been puzzled indeed had any one    
told him so7 to disbelieve that stones  
in past times had disported themselves  
differently in this regard from stones  
of the present4 ,yet there the stones   
are4 ,how did they get there8  ,the     
mountaineer thought that he could answer
 that question4 ,he saw about him those 
gigantic serpent-like streams of ice    
called glaciers1 from their far         
fountains slow rolling on1 carrying with
 them blocks of granite and other debris
 to form moraine deposits4 ,if these    
glaciers had once been much more        
extensive than they now are1 they might 
have carried the bowlders and left them 
where we find them4 ,on the other hand1 
no other natural agency within the      
sphere of the chamois-hunter's knowledge
 could have accomplished this1 ergo the 
glaciers must once have been more       
extensive4 ,perraudin would probably    
have said that common-sense drove him to
 this conclusion2 but be that as it may1
 he had conceived one of the few truly  

original and novel ideas of which the   
nineteenth century can boast4           
,perraudin announced his idea to the    
greatest scientist in his little        
world--,jean de ,charpentier1 director  
of the mines at ,bex1 a skilled         
geologist who had been a fellow-pupil of
 ,von ,buch and ,von ,humboldt under    
,werner at the ,freiberg ,school of     
,mines4 ,charpentier laughed at the     
mountaineer's grotesque idea1 and       
thought no more about it4 ,and ten years
 elapsed before ,perraudin could find   
any one who treated his notion with     
greater respect4 ,then he found a       
listener in ,m4 ,venetz1 a civil        
engineer1 who read a paper on the novel 
glacial theory before a local society in
 #ahbc4 ,this brought the matter once   
more to the attention of ,de            
,charpentier1 who now felt that there   
might be something in it worth          
investigation4  ,a survey of the field  
in the light of the new theory soon     
convinced ,charpentier that the         

chamois-hunter had all along been right4
 ,he became an enthusiastic supporter of
 the idea that the ,alps had once been  
imbedded in a mass of ice1 and in #ahcf 
he brought the notion to the attention  
of ,louis ,agassiz1 who was spending the
 summer in the ,alps4 ,agassiz was      
sceptical at first1 but soon became a   
convert4  ,in #ahdj ,agassiz published a
 paper in which the results of his      
,alpine studies were elaborated4  ,let  
us consider1 he says1 those more        
considerable changes to which glaciers  
are subject1 or rather1 the immense     
extent which they had in the prehistoric
 period4 ,this former immense extension1
 greater than any that tradition has    
preserved1 is proved1 in the case of    
nearly every valley in the ,alps1 by    
facts which are both many and well      
established4 ,the study of these facts  
is even easy if the student is looking  
out for them1 and if he will seize the  
least indication of their presence2 and1
 if it were a long time before they were

 observed and connected with glacial    
action1 it is because the evidences are 
often isolated and occur at places more 
or less removed from the glacier which  
originated them4 ,if it be true that it 
is the prerogative of the scientific    
observer to group in the field of his   
mental vision those facts which appear  
to be without connection to the vulgar  
herd1 it is1 above all1 in such a case  
as this that he is called upon to do so4
 ,i have often compared these feeble    
effects1 produced by the glacial action 
of former ages1 with the appearance of  
the markings upon a lithographic stone1 
prepared for the purpose of             
preservation1 and upon which one cannot 
see the lines of the draughtsman's work 
unless it is known beforehand where and 
how to search for them4  ,the fact of   
the former existence of glaciers which  
have now disappeared is proved by the   
survival of the various phenomena which 
always accompany them1 and which        
continue to exist even after the ice has

 melted4 ,these phenomena are as        
follows3  #a4 ,moraines4--,the          
disposition and composition of moraines 
enable them to be always recognized1    
even when they are no longer adjacent to
 a glacier nor immediately surround its 
lower extremities4 ,i may remark that   
lateral and terminal moraines alone     
enable us to recognize with certainty   
the limits of glacial extension1 because
 they can be easily distinguished from  
the dikes and irregularly distributed   
stones carried down by the ,alpine      
torrents1 ,the lateral moraines         
deposited upon the sides of valleys are 
rarely affected by the larger torrents1 
but they are1 however1 often cut by the 
small streams which fall down the side  
of a mountain1 and which1 by interfering
 with their continuity1 make them so    
much more difficult to recognize4  #b4  
,the ,perched ,bowlders4--,it often     
happens that glaciers encounter         
projecting points of rock1 the sides of 
which become rounded1 and around which  

funnel-like cavities are formed with    
more or less profundity4 ,when glaciers 
diminish and retire1 the blocks which   
have fallen into these funnels often    
remain perched upon the top of the      
projecting rocky point within it1 in    
such a state of equilibrium that any    
idea of a current of water as the cause 
of their transportation is completely   
inadmissible on account of their        
position4 ,when such points of rock     
project above the surface of the glacier
 or appear as a more considerable islet 
in the midst of its mass 7such as is the
 case in the ,jardin of the ,mer de     
,glace1 above ,montavert71 such         
projections become surrounded on all    
sides by stones which ultimately form a 
sort of crown around the summit whenever
 the glaciers decrease or retire        
completely4 ,water currents never       
produce anything like this2 but1 on the 
contrary1 whenever a stream breaks      
itself against a projecting rock1 the   
stones which it carries down are turned 

aside and form a more or less regular   
trail4 ,never1 under such circumstances1
 can the stones remain either at the top
 or at the sides of the rock1 for1 if   
such a thing were possible1 the rapidity
 of the current would be accelerated by 
the increased resistance1 and the moving
 bowlders would be carried beyond the   
obstruction before they were finally    
deposited4  #c4 ,the polished and       
striated rocks1 such as have been       
described in ,chapter ,,xiv41 afford yet
 further evidence of the presence of a  
glacier2 for1 as has been said already1 
neither a current nor the action of     
waves upon an extensive beach produces  
such effects4 ,the general direction of 
the channels and furrows indicates the  
direction of the general movement of the
 glacier1 and the streaks which vary    
more or less from this direction are    
produced by the local effects of        
oscillation and retreat1 as we shall    
presently see4  #d4 ,the ,lapiaz1 or    
,lapiz1 which the inhabitants of ,german

 ,switzerland call ,karrenfelder1 cannot
 always be distinguished from erosions1 
because1 both produced as they are by   
water1 they do not differ in their      
exterior characteristics1 but only in   
their positions4 ,erosions due to       
torrents are always found in places more
 or less depressed1 and never occur upon
 large inclined surfaces4 ,the ,lapiaz1 
on the contrary1 are frequently found   
upon the projecting parts of the sides  
of valleys in places where it is not    
possible to suppose that water has ever 
formed a current4 ,some geologists1 in  
their embarrassment to explain these    
phenomena1 have supposed that they were 
due to the infiltration of acidulated   
water1 but this hypothesis is purely    
gratuitous4  ,we will now describe the  
remains of these various phenomena as   
they are found in the ,alps outside the 
actual glacial limits1 in order to prove
 that at a certain epoch glaciers were  
much larger than they are to-day4  ,the 
ancient moraines1 situated as they are  

at a great distance from those of the   
present day1 are nowhere so distinct or 
so frequent as in ,valais1 where ,,mm4  
,venetz and ,j4 de ,charpentier noticed 
them for the first time2 but as their   
observations are as yet unpublished1 and
 they themselves gave me the            
information1 it would be an             
appropriation of their discovery if ,i  
were to describe them here in detail4 ,i
 will limit myself to say that there can
 be found traces1 more or less distinct1
 of ancient terminal moraines in the    
form of vaulted dikes at the foot of    
every glacier1 at a distance of a few   
minutes' walk1 a quarter of an hour1 a  
half-hour1 an hour1 and even of several 
leagues from their present extremities4 
,these traces become less distinct in   
proportion to their distance from the   
glacier1 and1 since they are also often 
traversed by torrents1 they are not as  
continuous as the moraines which are    
nearer to the glaciers4 ,the farther    
these ancient moraines are removed from 

the termination of a glacier1 the higher
 up they reach upon the sides of the    
valley1 which proves to us that the     
thickness of the glacier must have been 
greater when its size was larger4 ,at   
the same time1 their number indicates so
 many stopping-places in the retreat of 
the glacier1 or so many extreme limits  
of its extension--limits which were     
never reached again after it had        
retired4 ,i insist upon this point1     
because if it is true that all these    
moraines demonstrate a larger extent of 
the glacier1 they also prove that their 
retreat into their present boundaries1  
far from having been catastrophic1 was  
marked on the contrary by periods of    
repose more or less frequent1 which     
caused the formation of a series of     
concentric moraines which even now      
indicate their retrogression4  ,the     
remains of longitudinal moraines are    
less frequent1 less distinct1 and more  
difficult to investigate1 because1      
indicating as they do the levels to     

which the edges of the glacier reached  
at different epochs1 it is generally    
necessary to look for them above the    
line of the paths along the escarpments 
of the valleys1 and hence it is not     
always possible to follow them along a  
valley4 ,often1 also1 the sides of a    
valley which enclosed a glacier are so  
steep that it is only here and there    
that the stones have remained in place4 
,they are1 nevertheless1 very distinct  
in the lower part of the valley of the  
,rhone1 between ,martigny and the ,lake 
of ,geneva1 where several parallel      
ridges can be observed1 one above the   
other1 at a height of one thousand1 one 
thousand two hundred1 and even one      
thousand five hundred feet above the    
,rhone4 ,it is between ,st4 ,maurice and
 the cascade of ,pissevache1 close to   
the hamlet of ,chaux-,fleurie1 that they
 are most accessible1 for at this place 
the sides of the valley at different    
levels ascend in little terraces1 upon  
which the moraines have been preserved4 

,they are also very distinct above the  
,bains de ,lavey1 and above the village 
of ,monthey at the entrance of the ,val 
d',illiers1 where the sides of the      
valley are less inclined than in many   
other places4  ,the perched bowlders    
which are found in the ,alpine valleys1 
at considerable distances from the      
glaciers1 occupy at times positions so  
extraordinary that they excite in a high
 degree the curiosity of those who see  
them4 ,for instance1 when one sees an   
angular stone perched upon the top of an
 isolated pyramid1 or resting in some   
way in a very steep locality1 the first 
inquiry of the mind is1 ,when and how   
have these stones been placed in such   
positions1 where the least shock would  
seem to turn them over8 ,but this       
phenomenon is not in the least          
astonishing when it is seen to occur    
also within the limits of actual        
glaciers1 and it is recalled by what    
circumstances it is occasioned4  ,the   
most curious examples of perched stones 

which can be cited are those which      
command the northern part of the cascade
 of ,pissevache1 close to               
,chaux-,fleurie1 and those above the    
,bains de ,lavey1 close to the village  
of ,morcles2 and those1 even more       
curious1 which ,i have seen in the      
valley of ,st4 ,nicolas and ,oberhasli4 
,at ,kirchet1 near ,meiringen1 can be   
seen some very remarkable crowns of     
bowlders around several domes of rock   
which appear to have been projected     
above the surface of the glacier which  
surrounded them4 ,something very similar
 can be seen around the top of the rock 
of ,st4 ,triphon4  ,the extraordinary   
phenomenon of perched stones could not  
escape the observing eye of ,de         
,saussure1 who noticed several at       
,saleve1 of which he described the      
positions in the following manner3 ',one
 sees1' said he1 'upon the slope of an  
inclined meadow1 two of these great     
bowlders of granite1 elevated one upon  
the other1 above the grass at a height  

of two or three feet1 upon a base of    
limestone rock on which both rest4 ,this
 base is a continuation of the          
horizontal strata of the mountain1 and  
is even united with it visibly on its   
lower face1 being cut perpendicularly   
upon the other sides1 and is not larger 
than the stone which it supports4' ,but 
seeing that the entire mountain is      
composed of the same limestone1 ,de     
,saussure naturally concluded that it   
would be absurd to think that it was    
elevated precisely and only beneath the 
blocks of granite4 ,but1 on the other   
hand1 since he did not know the manner  
in which these perched stones are       
deposited in our days by glacial action1
 he had recourse to another explanation3
 ,he supposes that the rock was worn    
away around its base by the continual   
erosion of water and air1 while the     
portion of the rock which served as the 
base for the granite had been protected 
by it4 ,this explanation1 although very 
ingenious1 could no longer be admitted  

after the researches of ,m4 ,elie de    
,beaumont had proved that the action of 
atmospheric agencies was not by a good  
deal so destructive as was theretofore  
supposed4 ,de ,saussure speaks also of a
 detached bowlder1 situated upon the    
opposite side of the ,tete-,noire1      
'which is1' he says1 'of so great a size
 that one is tempted to believe that it 
was formed in the place it occupies2 and
 it is called ,barme russe1 because it  
is worn away beneath in the form of a   
cave which can afford accommodation for 
more than thirty persons at a time47#d7 
,but the implications of the theory of  
glaciers extend1 so ,agassiz has come to
 believe1 far beyond the ,alps4 ,if the 
,alps had been covered with an ice      
sheet1 so had many other regions of the 
northern hemisphere4 ,casting abroad for
 evidences of glacial action1 ,agassiz  
found them everywhere in the form of    
transported erratics1 scratched and     
polished outcropping rocks1 and         
moraine-like deposits4 ,finally1 he     

became convinced that the ice sheet that
 covered the ,alps had spread over the  
whole of the higher latitudes of the    
northern hemisphere1 forming an ice cap 
over the globe4 ,thus the common-sense  
induction of the chamois-hunter         
blossomed in the mind of ,agassiz into  
the conception of a universal ice age4  
,in #ahcg ,agassiz had introduced his   
theory to the world1 in a paper read at 
,neuchatel1 and three years later he    
published his famous ,etudes sur les    
,glaciers1 from which we have just      
quoted4 ,never did idea make a more     
profound disturbance in the scientific  
world4 ,von ,buch treated it with       
alternate ridicule1 contempt1 and rage2 
,murchison opposed it with customary    
vigor2 even ,lyell1 whose most          
remarkable mental endowment was an      
unfailing receptiveness to new truths1  
could not at once discard his iceberg   
theory in favor of the new claimant4    
,dr4 ,buckland1 however1 after ,agassiz 
had shown him evidence of former glacial

 action in his own ,scotland1 became a  
convert--the more readily1 perhaps1 as  
it seemed to him to oppose the          
uniformitarian idea4 ,gradually others  
fell in line1 and after the usual       
imbittered controversy and the          
inevitable full generation of probation1
 the idea of an ice age took its place  
among the accepted tenets of geology4   
,all manner of moot points still        
demanded attention--the cause of the ice
 age1 the exact extent of the ice sheet1
 the precise manner in which it produced
 its effects1 and the exact nature of   
these effects2 and not all of these have
 even yet been determined4 ,but1 details
 aside1 the ice age now has full        
recognition from geologists as an       
historical period4 ,there may have been 
many ice ages1 as ,dr4 ,croll contends2 
there was surely one2 and the conception
 of such a period is one of the very few
 ideas of our century that no previous  
century had even so much as faintly     
adumbrated4   ,,the ,,geological ,,ages 

,but1 for that matter1 the entire       
subject of historical geology is one    
that had but the barest beginning before
 our century4 ,until the paleontologist 
found out the key to the earth's        
chronology1 no one--not even            
,hutton--could have any definite idea as
 to the true story of the earth's past4 
,the only conspicuous attempt to        
classify the strata was that made by    
,werner1 who divided the rocks into     
three systems1 based on their supposed  
order of deposition1 and called primary1
 transition1 and secondary4  ,though    
,werner's observations were confined to 
the small province of ,saxony1 he did   
not hesitate to affirm that all over the
 world the succession of strata would be
 found the same as there1 the concentric
 layers1 according to this conception1  
being arranged about the earth with the 
regularity of layers on an onion4 ,but  
in this ,werner was as mistaken as in   
his theoretical explanation of the      
origin of the primary rocks4 ,it        

required but little observation to show 
that the exact succession of strata is  
never precisely the same in any widely  
separated regions4 ,nevertheless1 there 
was a germ of truth in ,werner's system4
 ,it contained the idea1 however        
faultily interpreted1 of a chronological
 succession of strata2 and it furnished 
a working outline for the observers who 
were to make out the true story of      
geological development4 ,but the correct
 interpretation of the observed facts   
could only be made after the ,huttonian 
view as to the origin of strata had     
gained complete acceptance4  ,when      
,william ,smith1 having found the true  
key to this story1 attempted to apply   
it1 the territory with which he had to  
deal chanced to be one where the surface
 rocks are of that later series which   
,werner termed secondary4 ,he made      
numerous subdivisions within this       
system1 based mainly on the fossils4    
,meantime it was found that1 judged by  
the fossils1 the strata that ,brongniart

 and ,cuvier studied near ,paris were of
 a still more recent period 7presumed at
 first to be due to the latest deluge71 
which came to be spoken of as tertiary4 
,it was in these beds1 some of which    
seemed to have been formed in           
fresh-water lakes1 that many of the     
strange mammals which ,cuvier first     
described were found4  ,but the         
transition rocks1 underlying the        
secondary system that ,smith studied1   
were still practically unexplored when1 
along in the thirties1 they were taken  
in hand by ,roderick ,impey ,murchison1 
the reformed fox-hunter and ex-captain1 
who had turned geologist to such notable
 advantage1 and ,adam ,sedgwick1 the    
brilliant ,woodwardian professor at     
,cambridge4  ,working together1 these   
two friends classified the  transition  
rocks into chronological groups1 since  
familiar to every one in the larger     
outlines as the ,silurian system 7age of
 invertebrates7 and the ,devonian system
 7age of fishes7--names derived         

respectively from the country of the    
ancient ,silures1 in ,wales and         
,devonshire1 ,england4 ,it was          
subsequently discovered that these      
systems of strata1 which crop out from  
beneath newer rocks in restricted areas 
in ,britain1 are spread out into broad1 
undisturbed sheets over thousands of    
miles in continental ,europe and in     
,america4 ,later on ,murchison studied  
them in ,russia1 and described them1    
conjointly with ,verneuil and ,von      
,kerserling1 in a ponderous and         
classical work4 ,in ,america they were  
studied by ,hall1 ,newberry1 ,whitney1  
,dana1 ,whitfield1 and other pioneer    
geologists1 who all but anticipated     
their ,english contemporaries4  ,the    
rocks that are of still older formation 
than those studied by ,murchison and    
,sedgwick 7corresponding in location to 
the primary rocks of ,werner's          
conception7 are the surface feature of  
vast areas in ,canada1 and were first   
prominently studied there by ,william   

,i4 ,logan1 of the ,canadian ,government
 ,survey1 as early as #ahdf1 and later  
on by ,sir ,william ,dawson4 ,these     
rocks--comprising the ,laurentian       
system--were formerly supposed to       
represent parts of the original crust of
 the earth1 formed on first cooling from
 a molten state2 but they are now more  
generally regarded as once-stratified   
deposits metamorphosed by the action of 
heat4  ,whether primitive or            
metamorphic1 however1 these ,canadian   
rocks1 and analogous ones beneath the   
fossiliferous strata of other countries1
 are the oldest portions of the earth's 
crust of which geology has any present  
knowledge4 ,mountains of this formation1
 as the ,adirondacks and the ,storm     
,king range1 overlooking the ,hudson    
near ,west ,point1 are the patriarchs of
 their kind1 beside which ,alleghanies  
and ,sierra ,nevadas are recent         
upstarts1 and ,rockies1 ,alps1 and      
,andes are mere parvenus of yesterday4  
,the ,laurentian rocks were at first    

spoken of as representing ,azoic time2  
but in #ahdf ,dawson found a formation  
deep in their midst which was believed  
to b e the fossil relic of a very low   
form of life1 and after that it became  
customary to speak of the system as     
,eozoic4 ,still more recently the title 
of ,dawson's supposed fossil to rank as 
such has been questioned1 and ,dana's   
suggestion that the early rocks be      
termed merely ,archman has met with     
general favor4 ,murchison and           
,sedgwick's ,silurian1 ,devonian1 and   
,carboniferous groups 7the ages of      
invertebrates1 of fishes1 and of coal   
plants1 respectively7 are together      
spoken of as representing ,paleozoic    
time4 ,william ,smith's system of       
strata1 next above these1 once called   
secondary1 represents ,mesozoic time1 or
 the age of reptiles4 ,still higher1 or 
more recent1 are ,cuvier and            
,brongniart's tertiary rocks1           
representing the age of mammals4        
,lastly1 the most recent formations1    

dating back1 however1 to a period far   
enough from recent in any but a         
geological sense1 are classed as        
quaternary1 representing the age of man4
  ,it must not be supposed1 however1    
that the successive ages of the         
geologist are shut off from one another 
in any such arbitrary way as this verbal
 classification might seem to suggest4  
,in point of fact1 these ages have no   
better warrant for existence than have  
the centuries and the weeks of every-day
 computation4 ,they are convenient1 and 
they may even stand for local divisions 
in the strata1 but they are bounded by  
no actual gaps in the sweep of          
terrestrial events4  ,moreover1 it must 
be understood that the ages of different
 continents1 though described under the 
same name1 are not necessarily of exact 
contemporaneity4 ,there is no sure test 
available by which it could be shown    
that the ,devonian age1 for instance1 as
 outlined in the strata of ,europe1 did 
not begin millions of years earlier or  

later than the period whose records are 
said to represent the ,devonian age in  
,america4 ,in attempting to decide such 
details as this1 mineralogical data fail
 us utterly4 ,even in rocks of adjoining
 regions identity of structure is no    
proof of contemporaneous origin2 for the
 veritable substance of the rock of one 
age is ground up to build the rocks of  
subsequent ages4 ,furthermore1 in seas  
where conditions change but little the  
same form of rock may be made age after 
age4 ,it is believed that chalk-beds    
still forming in some of our present    
seas may form one continuous mass dating
 back to earliest geologic ages4 ,on the
 other hand1 rocks different in         
character maybe formed at the same time 
in regions not far apart--say a         
sandstone along shore1 a coral limestone
 farther seaward1 and a chalk-bed       
beyond4 ,this continuous stratum1 broken
 in the process of upheaval1 might seem 
the record of three different epochs4   
,paleontology1 of course1 supplies far  

better chronological tests1 but even    
these have their limitations4 ,there has
 been no time since rocks now in        
existence were formed1 if ever1 when the
 earth had a uniform climate and a      
single undiversified fauna over its     
entire land surface1 as the early       
paleontologists supposed4 ,speaking     
broadly1 the same general stages have   
attended the evolution of organic forms 
everywhere1 but there is nothing to show
 that equal periods of time witnessed   
corresponding changes in diverse        
regions1 but quite the contrary4 ,to    
cite but a single illustration1 the     
marsupial order1 which is the dominant  
mammalian type of the living fauna of   
,australia to-day1 existed in ,europe   
and died out there in the tertiary age4 
,hence a future geologist might think   
the ,australia of to-day contemporaneous
 with a period in ,europe which in      
reality antedated it by perhaps millions
 of years4  ,all these puzzling features
 unite to render the subject of         

historical geology anything but the     
simple matter the fathers of the science
 esteemed it4 ,no one would now attempt 
to trace the exact sequence of formation
 of all the mountains of the globe1 as  
,elie de ,beaumont did a half-century   
ago4 ,even within the limits of a single
 continent1 the geologist must proceed  
with much caution in attempting to      
chronicle the order in which its various
 parts rose from the matrix of the sea4 
,the key to this story is found in the  
identification of the strata that are   
the surface feature in each territory4  
,if ,devonian rocks are at the surface  
in any given region1 for example1 it    
would appear that this region became a  
land surface in the ,devonian age1 or   
just afterwards4 ,but a moment's        
consideration shows that there is an    
element of uncertainty about this1 due  
to the steady denudation that all land  
surfaces undergo4 ,the ,devonian rocks  
may lie at the surface simply because   
the thousands of feet of carboniferous  

strata that once lay above them have    
been worn away4 ,all that the cautious  
geologist dare assert1 therefore1 is    
that the region in question did not     
become permanent land surface earlier   
than the ,devonian age4  ,but to know   
even this is much--sufficient1 indeed1  
to establish the chronological order of 
elevation1 if not its exact period1 for 
all parts of any continent that have    
been geologically                       
explored--understanding always that     
there must be no scrupling about a      
latitude of a few millions or perhaps   
tens of millions of years here and      
there4  ,regarding our own continent1   
for example1 we learn through the       
researches of a multitude of workers    
that in the early day it was a mere     
archipelago4 ,its chief island--the     
backbone of the future continent--was a 
great ,v-shaped area surrounding what is
 now ,hudson ,bay1 an area built tip1   
perhaps1 through denudation of a yet    
more ancient polar continent1 whose     

existence is only conjectured4 ,to the  
southeast an island that is now the     
,adirondack ,mountains1 and another that
 is now the ,jersey ,highlands rose     
above the waste of waters1 and far to   
the south stretched probably a line of  
islands now represented by the ,blue    
,ridge ,mountains4 ,far off to the      
westward another line of islands        
foreshadowed our present ,pacific       
border4 ,a few minor islands in the     
interior completed the archipelago4     
,from this bare skeleton the continent  
grew1 partly by the deposit of sediment 
from the denudation of the original     
islands 7which once towered miles1      
perhaps1 where now they rise thousands  
of feet71 but largely also by the       
deposit of organic remains1 especially  
in the interior sea1 which teemed with  
life4 ,in the ,silurian ages1           
invertebrates--brachiopods and crinoids 
and cephalopods--were the dominant      
types4 ,but very early--no one knows    
just when--there came fishes of many    

strange forms1 some of the early ones   
enclosed in turtle-like shells4 ,later  
yet1 large spaces within the interior   
sea having risen to the surface1 great  
marshes or forests of strange types of  
vegetation grew and deposited their     
remains to form coal-beds4 ,many times  
over such forests were formed1 only to  
be destroyed by the oscillations of the 
land surface4 ,all told1 the strata of  
this ,paleozoic period aggregate several
 miles in thickness1 and the time       
consumed in their formation stands to   
all later time up to the present1       
according to ,professor ,dana's         
estimate1 as three to one4  ,towards the
 close of this ,paleozoic era the       
,appalachian ,mountains were slowly     
upheaved in great convoluted folds1 some
 of them probably reaching three or four
 miles above the sea-level1 though the  
tooth of time has since gnawed them down
 to comparatively puny limits4 ,the     
continental areas thus enlarged were    
peopled during the ensuing ,mesozoic    

time with multitudes of strange         
reptiles1 many of them gigantic in size4
 ,the waters1 too1 still teeming with   
invertebrates and fishes1 had their     
quota of reptilian monsters2 and in the 
air were flying reptiles1 some of which 
measured twenty-five feet from tip to   
tip of their batlike wings4 ,during this
 era the ,sierra ,nevada ,mountains     
rose4 ,near the eastern border of the   
forming continent the strata were       
perhaps now too thick and stiff to bend 
into mountain folds1 for they were rent 
into great fissures1 letting out floods 
of molten lava1 remnants of which are   
still in evidence after ages of         
denudation1 as the ,palisades along the 
,hudson1 and such elevations as ,mount  
,holyoke in western ,massachusetts4     
,still there remained a vast interior   
sea1 which later on1 in the tertiary    
age1 was to be divided by the slow      
uprising of the land1 which only        
yesterday--that is to say1 a million1 or
 three or five or ten million1 years    

ago--became the ,rocky ,mountains4 ,high
 and erect these young mountains stand  
to this day1 their sharp angles and     
rocky contours vouching for their youth1
 in strange contrast with the shrunken  
forms of the old ,adirondacks1 ,green   
,mountains1 and ,appalachians1 whose    
lowered heads and rounded shoulders     
attest the weight of ages4 ,in the vast 
lakes which still remained on either    
side of the ,rocky range1 tertiary      
strata were slowly formed to the        
ultimate depth of two or three miles1   
enclosing here and there those          
vertebrate remains which were to be     
exposed again to view by denudation when
 the land rose still higher1 and then1  
in our own time1 to tell so wonderful a 
story to the paleontologist4  ,finally1 
the interior seas were filled1 and the  
shore lines of the continent assumed    
nearly their present outline4  ,then    
came the long winter of the glacial     
epoch--perhaps of a succession of       
glacial epochs4 ,the ice sheet extended 

southward to about the fortieth         
parallel1 driving some animals before   
it1 and destroying those that were      
unable to migrate4 ,at its fulness1 the 
great ice mass lay almost a mile in     
depth over ,new ,england1 as attested by
 the scratched and polished rock        
surfaces and deposited erratics in the  
,white ,mountains4 ,such a mass presses 
down with a weight of about one hundred 
and twenty-five tons to the square foot1
 according to ,dr4 ,croll's estimate4   
,it crushed and ground everything       
beneath it more or less1 and in some    
regions planed off hilly surfaces into  
prairies4 ,creeping slowly forward1 it  
carried all manner of debris with it4   
,when it melted away its terminal       
moraine built up the nucleus of the land
 masses now known as ,long ,island and  
,staten ,island2 other of its deposits  
formed the drumlins about ,boston famous
 as ,bunker and ,breed's hills2 and it  
left a long1 irregular line of ridges of
 till or bowlder clay and scattered     

erratics clear across the country at    
about the latitude of ,new ,york city4  
,as the ice sheet slowly receded it left
 minor moraines all along its course4   
,sometimes its deposits dammed up river 
courses or inequalities in the surface1 
to form the lakes which everywhere      
abound over ,northern territories4 ,some
 glacialists even hold the view first   
suggested by ,ramsey1 of the ,british   
,geological ,survey1 that the great     
glacial sheets scooped out the basins of
 many lakes1 including the system that  
feeds the ,st4 ,lawrence4 ,at all       
events1 it left traces of its presence  
all along the line of its retreat1 and  
its remnants exist to this day as       
mountain glaciers and the polar ice cap4
 ,indeed1 we live on the border of the  
last glacial epoch1 for with the closing
 of this period the long geologic past  
merges into the present4   ,,past1      
,,present1 ,,and ,,future  ,and the     
present1 no less than the past1 is a    
time of change4 ,this is the thought    

which ,james ,hutton conceived more than
 a century ago1 but which his           
contemporaries and successors were so   
very slow to appreciate4 ,now1 however1 
it has become axiomatic--one can hardly 
realize that it was ever doubted4 ,every
 new scientific truth1 says ,agassiz1   
must pass through three stages--first1  
men say it is not true2 then they       
declare it hostile to religion2 finally1
 they assert that every one has known it
 always4 ,hutton's truth that natural   
law is changeless and eternal has       
reached this final stage4 ,nowhere now  
could you find a scientist who would    
dispute the truth of that text which    
,lyell1 quoting from ,playfair's        
,illustrations of the ,huttonian        
,theory1 printed on the title-page of   
his ,principles3 ,amid all the          
revolutions of the globe the economy of 
,nature has been uniform1 and her laws  
are the only things that have resisted  
the general movement4 ,the rivers and   
the rocks1 the seas and the continents1 

have been changed in all their parts2   
but the laws which direct those changes1
 and the rules to which they are        
subject1 have remained invariably the   
same4  ,but1 on the other hand1 ,hutton 
and ,playfair1 and in particular ,lyell1
 drew inferences from this principle    
which the modern physicist can by no    
means admit4 ,to them it implied that   
the changes on the surface of the earth 
have always been the same in degree as  
well as in kind1 and must so continue   
while present forces hold their sway4   
,in other words1 they thought of the    
world as a great perpetual-motion       
machine4 ,but the modern physicist1     
given truer mechanical insight by the   
doctrines of the conservation and the   
dissipation of energy1 will have none of
 that4 ,lord ,kelvin1 in particular1 has
 urged that in the periods of our       
earth's in fancy and adolescence its    
developmental changes must have been1   
like those of any other infant organism1
 vastly more rapid and pronounced than  

those of a later day2 and to every clear
 thinker this truth also must now seem  
axiomatic4  ,whoever thinks of the earth
 as a cooling globe can hardly doubt    
that its crust1 when thinner1 may have  
heaved under strain of the moon's tidal 
pull--whether or not that body was      
nearer--into great billows1 daily rising
 and falling1 like waves of the present 
seas vastly magnified4  ,under stress of
 that same lateral pressure from        
contraction which now produces the slow 
depression of the ,jersey coast1 the    
slow rise of ,sweden1 the occasional    
belching of an insignificant volcano1   
the jetting of a geyser1 or the         
trembling of an earthquake1 once large  
areas were rent in twain1 and vast      
floods of lava flowed over thousands of 
square miles of the earth's surface1    
perhaps1 at a single jet2 and1 for aught
 we know to the contrary1 gigantic      
mountains may have heaped up their      
contorted heads in cataclysms as        
spasmodic as even the most ardent       

catastrophist of the elder day of       
geology could have imagined4  ,the      
atmosphere of that early day1 filled    
with vast volumes of carbon1 oxygen1 and
 other chemicals that have since been   
stored in beds of coal1 limestone1 and  
granites1 may have worn down the rocks  
on the one hand and built up organic    
forms on the other1 with a rapidity that
 would now seem hardly conceivable4     
,and yet while all these anomalous      
things went on1 the same laws held sway 
that now are operative2 and a true      
doctrine of uniformitarianism would make
 no unwonted concession in conceding    
them all--though most of the imbittered 
geological controversies of the middle  
of the nineteenth century were due to   
the failure of both parties to realize  
that simple fact4  ,and as of the past  
and present1 so of the future4 ,the same
 forces will continue to operate2 and   
under operation of these unchanging     
forces each day will differ from every  
one that has preceded it4 ,if it be     

true1 as every physicist believes1 that 
the earth is a cooling globe1 then1     
whatever its present stage of           
refrigeration1 the time must come when  
its surface contour will assume a       
rigidity of level not yet attained4     
,then1 just as surely1 the slow action  
of the elements will continue to wear   
away the land surfaces1 particle by     
particle1 and transport them to the     
ocean1 as it does to-day1 until1        
compensation no longer being afforded by
 the upheaval of the continents1 the    
last foot of dry land will sink for the 
last time beneath the water1 the last   
mountain-peak melting away1 and our     
globe1 lapsing like any other organism  
into its second childhood1 will be on   
the surface--as presumably it was before
 the first continent rose--one vast     
waste of waters4 ,as puny man conceives 
time and things1 an awful cycle will    
have lapsed2 in the sweep of the cosmic 
life1 a pulse-beat will have throbbed4  
,v4 ,,the ,,new ,,science ,,of          

,,meteorology   ,,meteorites  ,an       
astonishing miracle has just occurred in
 our district1 wrote ,m4 ,marais1 a     
worthy if undistinguished citizen of    
,france1 from his home at ,l',aigle1    
under date of the #acth ,floreal1 year  
#aa--;a date which outside of ,france   
would be interpreted as meaning ,may #c1
 #ahjc4 ,this miracle was the appearance
 of a fireball in broad                 
daylight--perhaps it was wildfire1 says 
the naive chronicle--which hung over the
 meadow1 being seen by many people1 and 
then exploded with a loud sound1        
scattering thousands of stony fragments 
over the surface of a territory some    
miles in extent4  ,such a miracle could 
not have been announced at a more       
opportune time4 ,for some years the     
scientific world had been agog over the 
question whether such a form of         
lightning as that reported--appearing in
 a clear sky1 and hurling literal       
thunderbolts--had real existence4 ,such 
cases had been reported often enough1 it

 is true4 ,the thunderbolts themselves  
were exhibited as sacred relics before  
many an altar1 and those who doubted    
their authenticity had been chided as   
having an evil heart of unbelief4 ,but  
scientific scepticism had questioned the
 evidence1 and late in the eighteenth   
century a consensus of opinion in the   
,french ,academy had declined to admit  
that such stones had been conveyed to   
the earth by lightning1 let alone any   
more miraculous agency4  ,in #ahjb1     
however1 ,edward ,howard had read a     
paper before the ,royal ,society in     
which1 after reviewing the evidence     
recently put forward1 he had reached the
 conclusion that the fall of stones from
 the sky1 sometimes or always           
accompanied by lightning1 must be       
admitted as an actual phenomenon1       
however inexplicable4 ,so now1 when the 
great stone-fall at ,l',aigle was       
announced1 the ,french ,academy made    
haste to send the brilliant young       
physicist ,jean ,baptiste ,biot to      

investigate it1 that the matter might1  
if possible1 be set finally at rest4    
,the investigation was in all respects  
successful1 and ,biot's report          
transferred the stony or metallic       
lightning-bolt--the aerolite or         
meteorite--from the realm of tradition  
and conjecture to that of accepted      
science4  ,but how explain this strange 
phenomenon8 ,at once speculation was    
rife4 ,one theory contended that the    
stony masses had not actually fallen1   
but had been formed from the earth by   
the action of the lightning2 but this   
contention was early abandoned4 ,the    
chemists were disposed to believe that  
the aerolites had been formed by the    
combination of elements floating in the 
upper atmosphere4 ,geologists1 on the   
other hand1 thought them of terrestrial 
origin1 urging that they might have been
 thrown up by volcanoes4 ,the           
astronomers1 as represented by ,olbers  
and ,laplace1 modified this theory by   
suggesting that the stones might1       

indeed1 have been cast out by volcanoes1
 but by volcanoes situated not on the   
earth1 but on the moon4  ,and one       
speculator of the time took a step even 
more daring1 urging that the aerolites  
were neither of telluric nor selenitic  
origin1 nor yet children of the sun1 as 
the old ,greeks had1 many of them1      
contended1 but that they are visitants  
from the depths of cosmic space4 ,this  
bold speculator was the distinguished   
,german physicist ,ernst ,f4 ,f4        
,chladni1 a man of no small repute in   
his day4 ,as early as #agid he urged his
 cosmical theory of meteorites1 when the
 very existence of meteorites was denied
 by most scientists4 ,and he did more3  
he declared his belief that these       
falling stones were really one in origin
 and kind with those flashing meteors of
 the upper atmosphere which are familiar
 everywhere as shooting-stars4  ,each of
 these coruscating meteors1 he affirmed1
 must tell of the ignition of a bit of  
cosmic matter entering the earth's      

atmosphere4 ,such wandering bits of     
matter might be the fragments of        
shattered worlds1 or1 as ,chladni       
thought more probable1 merely           
aggregations of world stuff never       
hitherto connected with any large       
planetary mass4  ,naturally enough1 so  
unique a view met with very scant favor4
 ,astronomers at that time saw little to
 justify it2 and the non-scientific     
world rejected it with fervor as being  
atheistic and heretical1 because its    
acceptance would seem to imply that the 
universe is not a perfect mechanism4    
,some light was thrown on the moot point
 presently by the observations of       
,brandes and ,benzenberg1 which tended  
to show that falling-stars travel at an 
actual speed of from fifteen to ninety  
miles a second4 ,this observation tended
 to discredit the selenitic theory1     
since an object1 in order to acquire    
such speed in falling merely from the   
moon1 must have been projected with an  
initial velocity not conceivably to be  

given by any lunar volcanic impulse4    
,moreover1 there was a growing          
conviction that there are no active     
volcanoes on the moon1 and other        
considerations of the same tenor led to 
the complete abandonment of the         
selenitic theory4  ,but the theory of   
telluric origin of aerolites was by no  
means so easily disposed of4 ,this was  
an epoch when electrical phenomena were 
exciting unbounded and universal        
interest1 and there was a not unnatural 
tendency to appeal to electricity in    
explanation of every obscure phenomenon2
 and in this case the seeming similarity
 between a lightning flash and the flash
 of an aerolite lent color to the       
explanation4 ,so we find ,thomas        
,forster1 a meteorologist of repute1    
still adhering to the atmospheric theory
 of formation of aerolites in his book  
published in #ahbc2 and1 indeed1 the    
prevailing opinion of the time seemed   
divided between various telluric        
theories1 to the neglect of any cosmical

 theory whatever4  ,but in #ahcc        
occurred a phenomenon which set the     
matter finally at rest4 ,a great        
meteoric shower occurred in ,november of
 that year1 and in observing it         
,professor ,denison ,olmstead1 of ,yale1
 noted that all the stars of the shower 
appeared to come from a single centre or
 vanishing-point in the heavens1 and    
that this centre shifted its position   
with the stars1 and hence was not       
telluric4 ,the full significance of this
 observation was at once recognized by  
astronomers2 it demonstrated beyond all 
cavil the cosmical origin of the        
shooting-stars4 ,some conservative      
meteorologists kept up the argument for 
the telluric origin for some decades to 
come1 as a matter of course--such a band
 trails always in the rear of progress4 
,but even these doubters were silenced  
when the great shower of shooting-stars 
appeared again in #ahff1 as predicted by
 ,olbers and ,newton1 radiating from the
 same point of the heavens as before4   

,since then the spectroscope has added  
its confirmatory evidence as to the     
identity of meteorite and shooting-star1
 and1 moreover1 has linked these        
atmospheric meteors with such distant   
cosmic residents as comets and nebulae4 
,thus it appears that ,chladni's daring 
hypothesis of #agid has been more than  
verified1 and that the fragments of     
matter dissociated from planetary       
connection--which be postulated and was 
declared atheistic for postulating--have
 been shown to be billions of times more
 numerous than any larger cosmic bodies 
of which we have cognizance--so widely  
does the existing universe differ from  
man's preconceived notions as to what it
 should be4  ,thus also the miracle of  
the falling stone1 against which the    
scientific scepticism of yesterday      
presented an evil heart of unbelief1    
turns out to be the most natural        
phenomena1 inasmuch as it is repeated in
 our atmosphere some millions of times  
each day4   ,,the ,,aurora ,,borealis   

,if fire-balls were thought miraculous  
and portentous in days of yore1 what    
interpretation must needs have been put 
upon that vastly more picturesque       
phenomenon1 the aurora8 ,through all the
 city1 says the ,book of ,maccabees1 for
 the space of almost forty days1 there  
were seen horsemen running in the air1  
in cloth of gold1 armed with lances1    
like a band of soldiers3 and troops of  
horsemen in array encountering and      
running one against another1 with       
shaking of shields and multitude of     
pikes1 and drawing of swords1 and       
casting of darts1 and glittering of     
golden ornaments and harness4 ,dire     
omens these2 and hardly less ominous the
 aurora seemed to all succeeding        
generations that observed it down well  
into the eighteenth century--as witness 
the popular excitement in ,england in   
#agaf over the brilliant aurora of that 
year1 which became famous through       
,halley's description4  ,but after      
#ageb1 when ,franklin dethroned the     

lightning1 all spectacular meteors came 
to be regarded as natural phenomena1 the
 aurora among the rest4 ,franklin       
explained the aurora--which was seen    
commonly enough in the eighteenth       
century1 though only recorded once in   
the seventeenth--as due to the          
accumulation of electricity on the      
surface of polar snows1 and its         
discharge to the equator through the    
upper atmosphere4 ,erasmus ,darwin      
suggested that the luminosity might be  
due to the ignition of hydrogen1 which  
was supposed by many philosophers to    
form the upper atmosphere4 ,dalton1 who 
first measured the height of the aurora1
 estimating it at about one hundred     
miles1 thought the phenomenon due to    
magnetism acting on ferruginous         
particles in the air1 and his           
explanation was perhaps the most popular
 one at the beginning of the last       
century4  ,since then a multitude of    
observers have studied the aurora1 but  
the scientific grasp has found it as    

elusive in fact as it seems to casual   
observation1 and its exact nature is as 
undetermined to-day as it was a hundred 
years ago4 ,there has been no dearth of 
theories concerning it1 however4 ,blot1 
who studied it in the ,shetland ,islands
 in #ahag1 thought it due to electrified
 ferruginous dust1 the origin of which  
he ascribed to ,icelandic volcanoes4    
,much more recently the idea of         
ferruginous particles has been revived1 
their presence being ascribed not to    
volcanoes1 but to the meteorites        
constantly being dissipated in the upper
 atmosphere4 ,ferruginous dust1         
presumably of such origin1 has been     
found on the polar snows1 as well as on 
the snows of mountain-tops1 but whether 
it could produce the phenomena of       
auroras is at least an open question4   
,other theorists have explained the     
aurora as due to the accumulation of    
electricity on clouds or on spicules of 
ice in the upper air4 ,yet others think 
it due merely to the passage of         

electricity through rarefied air itself4
 ,humboldt considered the matter settled
 in yet another way when ,faraday       
showed1 in #ahca1 that magnetism may    
produce luminous effects4 ,but perhaps  
the prevailing theory of to-day assumes 
that the aurora is due to a current of  
electricity generated at the equator and
 passing through upper regions of space1
 to enter the earth at the magnetic     
poles--simply reversing the course which
 ,franklin assumed4  ,the similarity of 
the auroral light to that generated in a
 vacuum bulb by the passage of          
electricity lends support to the        
long-standing supposition that the      
aurora is of electrical origin1 but the 
subject still awaits complete           
elucidation4 ,for once even that        
mystery-solver the spectroscope has been
 baffled1 for the line it sifts from the
 aurora is not matched by that of any   
recognized substance4 ,a like line is   
found in the zodiacal light1 it is true1
 but this is of little aid1 for the     

zodiacal light1 though thought by some  
astronomers to be due to meteor swarms  
about the sun1 is held to be1 on the    
whole1 as mysterious as the aurora      
itself4  ,whatever the exact nature of  
the aurora1 it has long been known to be
 intimately associated with the         
phenomena of terrestrial magnetism4     
,whenever a brilliant aurora is visible1
 the world is sure to be visited with   
what ,humboldt called a magnetic        
storm--a storm which manifests itself to
 human senses in no way whatsoever      
except by deflecting the magnetic needle
 and conjuring with the electric wire4  
,such magnetic storms are curiously     
associated also with spots on the       
sun--just how no one has explained1     
though the fact itself is unquestioned4 
,sun-spots1 too1 seem directly linked   
with auroras1 each of these phenomena   
passing through periods of greatest and 
least frequency in corresponding cycles 
of about eleven years' duration4  ,it   
was suspected a full century ago by     

,herschel that the variations in the    
number of sun-spots had a direct effect 
upon terrestrial weather1 and he        
attempted to demonstrate it by using the
 price of wheat as a criterion of       
climatic conditions1 meantime making    
careful observation of the sun-spots4   
,nothing very definite came of his      
efforts in this direction1 the subject  
being far too complex to be determined  
without long periods of observation4    
,latterly1 however1 meteorologists1     
particularly in the tropics1 are        
disposed to think they find evidence of 
some such connection between sun-spots  
and the weather as ,herschel suspected4 
,indeed1 ,mr4 ,meldrum declares that    
there is a positive coincidence between 
periods of numerous sun-spots and       
seasons of excessive rain in ,india4    
,that some such connection does exist   
seems intrinsically probable4 ,but the  
modern meteorologist1 learning wisdom of
 the past1 is extremely cautious about  
ascribing casual effects to astronomical

 phenomena4 ,he finds it hard to forget 
that until recently all manner of       
climatic conditions were associated with
 phases of the moon2 that not so very   
long ago showers of falling-stars were  
considered prognostic of certain kinds  
of weather2 and that the equinoctial    
storm had been accepted as a verity by  
every one1 until the unfeeling hand of  
statistics banished it from the earth4  
,yet1 on the other hand1 it is easily   
within the possibilities that the       
science of the future may reveal        
associations between the weather and    
sun-spots1 auroras1 and terrestrial     
magnetism that as yet are hardly dreamed
 of4 ,until such time1 however1 these   
phenomena must feel themselves very     
grudgingly admitted to the inner circle 
of meteorology4 ,more and more this     
science concerns itself1 in our age of  
concentration and specialization1 with  
weather and climate4 ,its votaries no   
longer concern themselves with stars or 
planets or comets or                    

shooting-stars--once thought the very   
essence of guides to weather wisdom2 and
 they are even looking askance at the   
moon1 and asking her to show cause why  
she also should not be excluded from    
their domain4 ,equally little do they   
care for the interior of the earth1     
since they have learned that the central
 emanations of heat which ,mairan       
imagined as a main source of aerial     
warmth can claim no such distinction4   
,even such problems as why the magnetic 
pole does not coincide with the         
geographical1 and why the force of      
terrestrial magnetism decreases from the
 magnetic poles to the magnetic equator1
 as ,humboldt first discovered that it  
does1 excite them only to lukewarm      
interest2 for magnetism1 they say1 is   
not known to have any connection        
whatever with climate or weather4       
,,evaporation1 ,,cloud ,,formation1     
,,and ,,dew  ,there is at least one form
 of meteor1 however1 of those that      
interested our forebears whose          

meteorological importance they did not  
overestimate4 ,this is the vapor of     
water4 ,how great was the interest in   
this familiar meteor at the beginning of
 the century is attested by the number  
of theories then extant regarding it2   
and these conflicting theories bear     
witness also to the difficulty with     
which the familiar phenomenon of the    
evaporation of water was explained4     
,franklin had suggested that air        
dissolves water much as water dissolves 
salt1 and this theory was still popular1
 though ,deluc had disproved it by      
showing that water evaporates even more 
rapidly in a vacuum than in air4        
,deluc's own theory1 borrowed from      
earlier chemists1 was that evaporation  
is the chemical union of particles of   
water with particles of the             
supposititious element heat4 ,erasmus   
,darwin combined the two theories1      
suggesting that the air might hold a    
variable quantity of vapor in mere      
solution1 and in addition a permanent   

moiety in chemical combination with     
caloric4  ,undisturbed by these         
conflicting views1 that strangely       
original genius1 ,john ,dalton1         
afterwards to be known as perhaps the   
greatest of theoretical chemists1 took  
the question in hand1 and solved it by  
showing that water exists in the air as 
an utterly independent gas4 ,he reached 
a partial insight into the matter in    
#agic1 when his first volume of         
meteorological essays was published2 but
 the full elucidation of the problem    
came to him in #ahja4 ,the merit of his 
studies was at once recognized1 but the 
tenability of his hypothesis was long   
and ardently disputed4  ,while the      
nature of evaporation was in dispute1 as
 a matter of course the question of     
precipitation must be equally           
undetermined4 ,the most famous theory of
 the period was that formulated by ,dr4 
,hutton in a paper read before the      
,royal ,society of ,edinburgh1 and      
published in the volume of transactions 

which contained also the same author's  
epoch-making paper on geology4 ,this    
theory of rain explained precipitation  
as due to the cooling of a current of   
saturated air by contact with a colder  
current1 the assumption being that the  
surplusage of moisture was precipitated 
in a chemical sense1 just as the excess 
of salt dissolved in hot water is       
precipitated when the water cools4 ,the 
idea that the cooling of the saturated  
air causes the precipitation of its     
moisture is the germ of truth that      
renders this paper of ,hutton's         
important4 ,all correct later theories  
build on this foundation4  ,let us      
suppose the surface of this earth wholly
 covered with water1 said ,hutton1 and  
that the sun were stationary1 being     
always vertical in one place2 then1 from
 the laws of heat and rarefaction1 there
 would be formed a circulation in the   
atmosphere1 flowing from the dark and   
cold hemisphere to the heated and       
illuminated place1 in all directions1   

towards the place of the greatest cold4 
,as there is for the atmosphere of this 
earth a constant cooling cause1 this    
fluid body could only arrive at a       
certain degree of heat2 and this would  
be regularly decreasing from the centre 
of illumination to the opposite point of
 the globe1 most distant from the light 
and heat4 ,between these two regions of 
extreme heat and cold there would1 in   
every place1 be found two streams of air
 following in opposite directions4 ,if  
those streams of air1 therefore1 shall  
be supposed as both sufficiently        
saturated with humidity1 then1 as they  
are of different temperatures1 there    
would be formed a continual condensation
 of aqueous vapor1 in some middle region
 of the atmosphere1 by the commixtion of
 part of those two opposite streams4    
,hence there is reason to believe that  
in this supposed case there would be    
formed upon the surface of the globe    
three different regions--the torrid     
region1 the temperate1 and the frigid4  

,these three regions would continue     
stationary2 and the operations of each  
would be continual4 ,in the torrid      
region1 nothing but evaporation and heat
 would take place2 no cloud could be    
formed1 because in changing the         
transparency of the atmosphere to       
opacity it would be heated immediately  
by the operation of light1 and thus the 
condensed water would be again          
evaporated4 ,but this power of the sun  
would have a termination2 and it is     
these that would begin the region of    
temperate heat and of continual rain4   
,it is not probable that the region of  
temperance would reach far beyond the   
region of light2 and in the hemisphere  
of darkness there would be found a      
region of extreme cold and perfect      
dryness4  ,let us now suppose the earth 
as turning on its axis in the           
equinoctial situation4 ,the torrid      
region would thus be changed into a     
zone1 in which there would be night and 
day2 consequently1 here would be much   

temperance1 compared with the torrid    
region now considered2 and here perhaps 
there would be formed periodical        
condensation and evaporation of         
humidity1 corresponding to the seasons  
of night and day4 ,as temperance would  
thus be introduced into the region of   
torrid extremity1 so would the effect of
 this change be felt over all the globe1
 every part of which would now be       
illuminated1 consequently heated in some
 degree4 ,thus we would have a line of  
great heat and evaporation1 graduating  
each way into a point of great cold and 
congelation4 ,between these two extremes
 of heat and cold there would be found  
in each hemisphere a region of much     
temperance1 in relation to heat1 but of 
much humidity in the atmosphere1 perhaps
 of continual rain and condensation4    
,the supposition now formed must appear 
extremely unfit for making this globe a 
habitable world in every part2 but      
having thus seen the effect of night and
 day in temperating the effects of heat 

and cold in every place1 we are now     
prepared to contemplate the effects of  
supposing this globe to revolve around  
the sun with a certain inclination of   
its axis4 ,by this beautiful            
contrivance1 that comparatively         
uninhabited globe is now divided into   
two hemispheres1 each of which is thus  
provided with a summer and a winter     
season4 ,but our present view is limited
 to the evaporation and condensation of 
humidity2 and1 in this contrivance of   
the seasons1 there must appear an ample 
provision for those alternate operations
 in every part2 for as the place of the 
vertical sun is moved alternately from  
one tropic to the other1 heat and cold1 
the original causes of evaporation and  
condensation1 must be carried over all  
the globe1 producing either annual      
seasons of rain or diurnal seasons of   
condensation and evaporation1 or both   
these seasons1 more or less--that is1 in
 some degree4  ,the original cause of   
motion in the atmosphere is the         

influence of the sun heating the surface
 of the earth exposed to that luminary4 
,we have not supposed that surface to   
have been of one uniform shape and      
similar substance2 from whence it has   
followed that the annual propers of the 
sun1 perhaps also the diurnal propers1  
would produce a regular condensation of 
rain in certain regions1 and the        
evaporation of humidity in others2 and  
this would have a regular progress in   
certain determined seasons1 and would   
not vary4 ,but nothing can be more      
distant from this supposition1 that is  
the natural constitution of the earth2  
for the globe is composed of sea and    
land1 in no regular shape or mixture1   
while the surface of the land is also   
irregular with respect to its elevations
 and depressions1 and various with      
regard to the humidity and dryness of   
that part which is exposed to heat as   
the cause of evaporation4 ,hence a      
source of the most valuable motions in  
the fluid atmosphere with aqueous vapor1

 more or less1 so far as other natural  
operations will admit2 and hence a      
source of the most irregular commixture 
of the several parts of this elastic    
fluid1 whether saturated or not with    
aqueous vapor4  ,according to the       
theory1 nothing is required for the     
production of rain besides the mixture  
of portions of the atmosphere with      
humidity1 and of mixing the parts that  
are in different degrees of heat4 ,but  
we have seen the causes of saturating   
every portion of the atmosphere with    
humidity and of mixing the parts which  
are in different degrees of heat4       
,consequently1 over all the surface of  
the globe there should happen           
occasionally rain and evaporation1 more 
or less2 and also1 in every place1 those
 vicissitudes should be observed to take
 place with some tendency to regularity1
 which1 however1 may be so disturbed as 
to be hardly distinguishable upon many  
occasions4 ,variable winds and variable 
rains should be found in proportion as  

each place is situated in an irregular  
mixture of land and water2 whereas      
regular winds should be found in        
proportion to the uniformity of the     
surface2 and regular rains in proportion
 to the regular changes of those winds  
by which the mixture of the atmosphere  
necessary to the rain may be produced4  
,but as it will be acknowledged that    
this is the case in almost all this     
earth where rain appears according to   
the conditions here specified1 the      
theory is found to be thus in conformity
 with nature1 and natural appearances   
are thus explained by the theory47#a7   
,the next ambitious attempt to explain  
the phenomena of aqueous meteors was    
made by ,luke ,howard1 in his remarkable
 paper on clouds1 published in the      
,philosophical ,magazine in #ahjc--the  
paper in which the names cirrus1        
cumulus1 stratus1 etc41 afterwards so   
universally adopted1 were first         
proposed4 ,in this paper ,howard        
acknowledges his indebtedness to ,dalton

 for the theory of evaporation2 yet he  
still clings to the idea that the vapor1
 though independent of the air1 is      
combined with particles of caloric4 ,he 
holds that clouds are composed of vapor 
that has previously risen from the      
earth1 combating the opinions of those  
who believe that they are formed by the 
union of hydrogen and oxygen existing   
independently in the air2 though he     
agrees with these theorists that        
electricity has entered largely into the
 modus operandi of cloud formation4 ,he 
opposes the opinion of ,deluc and ,de   
,saussure that clouds are composed of   
particles of water in the form of hollow
 vesicles 7miniature balloons1 in short1
 perhaps filled with hydrogen71 which   
untenable opinion was a revival of the  
theory as to the formation of all vapor 
which ,dr4 ,halley had advocated early  
in the eighteenth century4  ,of         
particular interest are ,howard's views 
as to the formation of dew1 which he    
explains as caused by the particles of  

caloric forsaking the vapor to enter the
 cool body1 leaving the water on the    
surface4 ,this comes as near the truth1 
perhaps1 as could be expected while the 
old idea as to the materiality of heat  
held sway4 ,howard believed1 however1   
that dew is usually formed in the air at
 some height1 and that it settles to the
 surface1 opposing the opinion1 which   
had gained vogue in ,france and in      
,america 7where ,noah ,webster          
prominently advocated it71 that dew     
ascends from the earth4  ,the complete  
solution of the problem of dew          
formation--which really involved also   
the entire question of precipitation of 
watery vapor in any form--was made by   
,dr4 ,w4 ,c4 ,wells1 a man of ,american 
birth1 whose life1 however1 after       
boyhood1 was spent in ,scotland 7where  
as a young man he enjoyed the friendship
 of ,david ,hume7 and in ,london4       
,inspired1 no doubt1 by the researches  
of ,mack1 ,hutton1 and their confreres  
of that ,edinburgh school1 ,wells made  

observations on evaporation and         
precipitation as early as #aghd1 but    
other things claimed his attention2 and 
though he asserts that the subject was  
often in his mind1 he did not take it up
 again in earnest until about #ahab4    
,meantime the observations on heat of   
,rumford and ,davy and ,leslie had      
cleared the way for a proper            
interpretation of the facts--about the  
facts themselves there had long been    
practical unanimity of opinion4 ,dr4    
,black1 with his latent-heat            
observations1 had really given the clew 
to all subsequent discussions of the    
subject of precipitation of vapor2 and  
from this time on it had been known that
 heat is taken up when water evaporates1
 and given out again when it condenses4 
,dr4 ,darwin had shown in #aghh1 in a   
paper before the ,royal ,society1 that  
air gives off heat on contracting and   
takes it up on expanding2 and ,dalton1  
in his essay of #agic1 had explained    
this phenomenon as due to the           

condensation and vaporization of the    
water contained in the air4  ,but some  
curious and puzzling observations which 
,professor ,patrick ,wilson1 professor  
of astronomy in the ,university of      
,glasgow1 had communicated to the ,royal
 ,society of ,edinburgh in #aghd1 and   
some similar ones made by ,mr4 ,six1 of 
,canterbury1 a few years later1 had     
remained unexplained4 ,both these       
gentlemen observed that the air is      
cooler where dew is forming than the air
 a few feet higher1 and they inferred   
that the dew in forming had taken up    
heat1 in apparent violation of          
established physical principles4  ,it   
remained for ,wells1 in his memorable   
paper of #ahaf1 to show that these      
observers had simply placed the cart    
before the horse4 ,he made it clear that
 the air is not cooler because the dew  
is formed1 but that the dew is formed   
because the air is cooler--having become
 so through radiation of heat from the  
solids on which the dew forms4 ,the dew 

itself1 in forming1 gives out its latent
 heat1 and so tends to equalize the     
temperature4  ,wells's paper is so      
admirable an illustration of the lucid  
presentation of clearly conceived       
experiments and logical conclusions that
 we should do it injustice not to       
present it entire4 ,the author's mention
 of the observations of ,six and ,wilson
 gives added value to his own           
presentation4   ,dr4 ,wells's ,essay on 
,dew  ,i was led in the autumn of #aghd1
 by the event of a rude experiment1 to  
think it probable that the formation of 
dew is attended with the production of  
cold4 ,in #aghh1 a paper on hoar-frost1 
by ,mr4 ,patrick ,wilson1 of ,glasgow1  
was published in the first volume of the
 ,transactions of the ,royal ,society of
 ,edinburgh1 by which it appeared that  
this opinion bad been entertained by    
that gentleman before it had occurred to
 myself4 ,in the course of the same     
year1 ,mr4 ,six1 of ,canterbury1        
mentioned in a paper communicated to the

 ,royal ,society that on clear and dewy 
nights he always found the mercury lower
 in a thermometer laid upon the ground  
in a meadow in his neighborhood than it 
was in a similar thermometer suspended  
in the air six feet above the former2   
and that upon one night the difference  
amounted to five degrees of             
,fahrenheit's scale4 ,mr4 ,six1 however1
 did not suppose1 agreeably to the      
opinion of ,mr4 ,wilson and myself1 that
 the cold was occasioned by the         
formation of dew1 but imagined that it  
proceeded partly from the low           
temperature of the air1 through which   
the dew1 already formed in the          
atmosphere1 had descended1 and partly   
from the evaporation of moisture from   
the ground1 on which his thermometer had
 been placed4 ,the conjecture of ,mr4   
,wilson and the observations of ,mr4    
,six1 together with many facts which ,i 
afterwards learned in the course of     
reading1 strengthened my opinion2 but ,i
 made no attempt1 before the autumn of  

#ahaa1 to ascertain by experiment if it 
were just1 though it had in the mean    
time almost daily occurred to my        
thoughts4 ,happening1 in that season1 to
 be in that country in a clear and calm 
night1 ,i laid a thermometer upon grass 
wet with dew1 and suspended a second in 
the air1 two feet above the other4 ,an  
hour afterwards the thermometer on the  
grass was found to be eight degrees     
lower1 by ,fahrenheit's division1 than  
the one in the air4 ,similar results    
having been obtained from several       
similar experiments1 made during the    
same autumn1 ,i determined in the next  
spring to prosecute the subject with    
some degree of steadiness1 and with that
 view went frequently to the house of   
one of my friends who lives in ,surrey4 
,at the end of two months ,i fancied    
that ,i had collected information worthy
 of being published2 but1 fortunately1  
while preparing an account of it ,i met 
by accident with a small posthumous work
 by ,mr4 ,six1 printed at ,canterbury in

 #agid1 in which are related differences
 observed on dewy nights between        
thermometers placed upon grass and      
others in the air that are much greater 
than those mentioned in the paper       
presented by him to the ,royal ,society 
in #aghh4 ,in this work1 too1 the cold  
of the grass is attributed1 in agreement
 with the opinion of ,mr4 ,wilson1      
altogether to the dew deposited upon it4
 ,the value of my own observations      
appearing to me now much diminished1    
though they embraced many points left   
untouched by ,mr4 ,six1 ,i gave up my   
intentions of making them known4        
,shortly after1 however1 upon           
considering the subject more closely1 ,i
 began to suspect that ,mr4 ,wilson1    
,mr4 ,six1 and myself had all committed 
an error regarding the cold which       
accompanies dew as an effect of the     
formation of that fluid4 ,i therefore   
resumed my experiments1 and having by   
means of them1 ,i think1 not only       
established the justness of my          

suspicions1 but ascertained the real    
cause both of dew and of several other  
natural appearances which have hitherto 
received no sufficient explanation1 ,i  
venture now to submit to the            
consideration of the learned an account 
of some of my labors1 without regard to 
the order of time in which they were    
performed1 and of various conclusions   
which may be drawn from them1 mixed with
 facts and opinions already published by
 others3  ,there are various occurrences
 in nature which seem to me strictly    
allied to dew1 though their relation to 
it be not always at first sight         
perceivable4 ,the statement and         
explanation of several of these will    
form the concluding part of the present 
essay4  #a4 ,i observed one morning1 in 
winter1 that the insides of the panes of
 glass in the windows of my bedchamber  
were all of them moist1 but that those  
which had been covered by an inside     
shutter during the night were much more 
so than the others which had been       

uncovered4 ,supposing that this         
diversity of appearance depended upon a 
difference of temperature1 ,i applied   
the naked bulbs of two delicate         
thermometers to a covered and uncovered 
pane2 on which ,i found that the former 
was three degrees colder than the       
latter4 ,the air of the chamber1 though 
no fire was kept in it1 was at this time
 eleven and one-half degrees warmer than
 that without4 ,similar experiments were
 made on many other mornings1 the       
results of which were that the warmth of
 the internal air exceeded that of the  
external from eight to eighteen degrees1
 the temperature of the covered panes   
would be from one to five degrees less  
than the uncovered2 that the covered    
were sometimes dewed1 while the         
uncovered were dry2 that at other times 
both were free from moisture2 that the  
outsides of the covered and uncovered   
panes had similar differences with      
respect to heat1 though not so great as 
those of the inner surfaces2 and that no

 variation in the quantity of these     
differences was occasioned by the       
weather's being cloudy or fair1 provided
 the heat of the internal air exceeded  
that of the external equally in both of 
those states of the atmosphere4  ,the   
remote reason of these differences did  
not immediately present itself4 ,i soon1
 however1 saw that the closed shutter   
shielded the glass which it covered from
 the heat that was radiated to the      
windows by the walls and furniture of   
the room1 and thus kept it nearer to the
 temperature of the external air than   
those parts could be which1 from being  
uncovered1 received the heat emitted to 
them by the bodies just mentioned4  ,in 
making these experiments1 ,i seldom     
observed the inside of any pane to be   
more than a little damped1 though it    
might be from eight to twelve degrees   
colder than the general mass of the air 
in the room2 while1 in the open air1 ,i 
had often found a great dew to form on  
substances only three or four degrees   

colder than the atmosphere4 ,this at    
first surprised me2 but the cause now   
seems plain4 ,the air of the chamber had
 once been a portion of the external    
atmosphere1 and had afterwards been     
heated1 when it could receive little    
accessories to its original moisture4   
,it constantly required being cooled    
considerably before it was even brought 
back to its former nearness to repletion
 with water2 whereas the whole external 
air is commonly1 at night1 nearly       
replete with moisture1 and therefore    
readily precipitates dew on bodies only 
a little colder than itself4  ,when the 
air of a room is warmer than the        
external atmosphere1 the effect of an   
outside shutter on the temperature of   
the glass of the window will be directly
 opposite to what has just been stated2 
since it must prevent the radiation1    
into the atmosphere1 of the heat of the 
chamber transmitted through the glass4  
#b4 ,count ,rumford appears to have     
rightly conjectured that the inhabitants

 of certain hot countries1 who sleep at 
nights on the tops of their houses1 are 
cooled during this exposure by the      
radiation of their heat to the sky2 or1 
according to his manner of expression1  
by receiving frigorific rays from the   
heavens4 ,another fact of this kind     
seems to be the greater chill which we  
often experience upon passing at night  
from the cover of a house into the air  
than might have been expected from the  
cold of the external atmosphere4 ,the   
cause1 indeed1 is said to be the        
quickness of transition from one        
situation to another4 ,but if this were 
the whole reason1 an equal chill would  
be felt in the day1 when the difference1
 in point of heat1 between the internal 
and external air was the same as at     
night1 which is not the case4 ,besides1 
if ,i can trust my own observation1 the 
feeling of cold from this cause is more 
remarkable in a clear than in a cloudy  
night1 and in the country than in towns4
 ,the following appears to be the manner

 in which these things are chiefly to be
 explained3  ,during the day our bodies 
while in the open air1 although not     
immediately exposed to the sun's rays1  
are yet constantly deriving heat from   
them by means of the reflection of the  
atmosphere4 ,this heat1 though it       
produces little change on the           
temperature of the air which it         
traverses1 affords us some compensation 
for the heat which we radiate to the    
heavens4 ,at night1 also1 if the sky be 
overcast1 some compensation will be made
 to us1 both in the town and in the     
country1 though in a less degree than   
during the day1 as the clouds will remit
 towards the earth no inconsiderable    
quantity of heat4 ,but on a clear night1
 in an open part of the country1 nothing
 almost can be returned to us from above
 in place of the heat which we radiate  
upward4 ,in towns1 however1 some        
compensation will be afforded even on   
the clearest nights for the heat which  
we lose in the open air by that which is

 radiated to us from the sun round      
buildings4  ,to our loss of heat by     
radiation at times that we derive little
 compensation from the radiation of     
other bodies is probably to be          
attributed a great part of the hurtful  
effects of the night air4 ,descartes    
says that these are not owing to dew1 as
 was the common opinion of his          
contemporaries1 but to the descent of   
certain noxious vapors which have been  
exhaled from the earth during the heat  
of the day1 and are afterwards condensed
 by the cold of a serene night4 ,the    
effects in question certainly cannot be 
occasioned by dew1 since that fluid does
 not form upon a healthy human body in  
temperate climates2 but they may1       
notwithstanding1 arise from the same    
cause that produces dew on those        
substances which do not1 like the human 
body1 possess the power of generating   
heat for the supply of what they lose by
 radiation or any other means47#b7      
,this explanation made it plain why dew 

forms on a clear night1 when there are  
no clouds to reflect the radiant heat4  
,combined with ,dalton's theory that    
vapor is an independent gas1 limited in 
quantity in any given space by the      
temperature of that space1 it solved the
 problem of the formation of clouds1    
rain1 snow1 and hoar-frost4 ,thus this  
paper of ,wells's closed the epoch of   
speculation regarding this field of     
meteorology1 as ,hutton's paper of #aghd
 had opened it4 ,the fact that the      
volume containing ,hutton's paper       
contained also his epoch-making paper on
 geology finds curiously a duplication  
in the fact that ,wells's volume        
contained also his essay on ,albinism1  
in which the doctrine of natural        
selection was for the first time        
formulated1 as ,charles ,darwin freely  
admitted after his own efforts had made 
the doctrine famous4   ,,isotherms ,,and
 ,,ocean ,,currents  ,the very next year
 after ,dr4 ,wells's paper was published
 there appeared in ,france the third    

volume of the ,memoires de ,physique et 
de ,chimie de la ,societe d',arcueil1   
and a new epoch in meteorology was      
inaugurated4 ,the society in question   
was numerically an inconsequential band1
 listing only a dozen members2 but every
 name was a famous one3 ,arago1 ,berard1
 ,berthollet1 ,biot1 ,chaptal1 ,de      
,candolle1 ,dulong1 ,gay-,lussac1       
,humboldt1 ,laplace1 ,poisson1 and      
,thenard--rare spirits every one4       
,little danger that the memoirs of such 
a band would be relegated to the dusty  
shelves where most proceedings of       
societies belong--no milk-for-babes fare
 would be served to such a company4     
,the particular paper which here        
interests us closes this third and last 
volume of memoirs4 ,it is entitled ,des 
,lignes ,isothermes et de la            
,distribution de la ,chaleursurle       
,globe4 ,the author is ,alexander       
,humboldt4 ,needless to say1 the topic  
is handled in a masterly manner4 ,the   
distribution of heat on the surface of  

the globe1 on the mountain-sides1 in the
 interior of the earth2 the causes that 
regulate such distribution2 the climatic
 results--these are the topics          
discussed4 ,but what gives epochal      
character to the paper is the           
introduction of those isothermal lines  
circling the earth in irregular course1 
joining together places having the same 
mean annual temperature1 and thus laying
 the foundation for a science of        
comparative climatology4  ,it is true   
the attempt to study climates           
comparatively was not new4 ,mairan had  
attempted it in those papers in which he
 developed his bizarre ideas as to      
central emanations of heat4 ,euler had  
brought his profound mathematical genius
 to bear on the topic1 evolving the     
extraordinary conclusion that under the 
equator at midnight the cold ought to be
 more rigorous than at the poles in     
winter4 ,and in particular ,richard     
,kirwan1 the ,english chemist1 had      
combined the mathematical and the       

empirical methods and calculated        
temperatures for all latitudes4 ,but    
,humboldt differs from all these        
predecessors in that he grasps the idea 
that the basis of all such computations 
should be not theory1 but fact4 ,he drew
 his isothermal lines not where some    
occult calculation would locate them on 
an ideal globe1 but where practical     
tests with the thermometer locate them  
on our globe as it is4 ,london1 for     
example1 lies in the same latitude as   
the southern extremity of ,hudson ,bay2 
but the isotherm of ,london1 as         
,humboldt outlines it1 passes through   
,cincinnati4  ,of course such deviations
 of climatic conditions between places  
in the same latitude had long been      
known4 ,as ,humboldt himself observes1  
the earliest settlers of ,america were  
astonished to find themselves subjected 
to rigors of climate for which their    
,european experience had not at all     
prepared them4 ,moreover1 sagacious     
travellers1 in particular ,cook's       

companion on his second voyage1 young   
,george ,forster1 had noted as a general
 principle that the western borders of  
continents in temperate regions are     
always warmer than corresponding        
latitudes of their eastern borders2 and 
of course the general truth of          
temperatures being milder in the        
vicinity of the sea than in the interior
 of continents had long been familiar4  
,but ,humboldt's isothermal lines for   
the first time gave tangibility to these
 ideas1 and made practicable a truly    
scientific study of comparative         
climatology4  ,in studying these lines1 
particularly as elaborated by further   
observations1 it became clear that they 
are by no means haphazard in            
arrangement1 but are dependent upon     
geographical conditions which in most   
cases are not difficult to determine4   
,humboldt himself pointed out very      
clearly the main causes that tend to    
produce deviations from the average--or1
 as ,dove later on called it1 the       

normal--temperature of any given        
latitude4 ,for example1 the mean annual 
temperature of a region 7referring      
mainly to the northern hemisphere7 is   
raised by the proximity of a western    
coast2 by a divided configuration of the
 continent into peninsulas2 by the      
existence of open seas to the north or  
of radiating continental surfaces to the
 south2 by mountain ranges to shield    
from cold winds2 by the infrequency of  
swamps to become congealed2 by the      
absence of woods in a dry1 sandy soil2  
and by the serenity of sky in the summer
 months and the vicinity of an ocean    
current bringing water which is of a    
higher temperature than that of the     
surrounding sea4  ,conditions opposite  
to these tend1 of course1               
correspondingly to lower the            
temperature4 ,in a word1 ,humboldt says 
the climatic distribution of heat       
depends on the relative distribution of 
land and sea1 and on the hypsometrical  
configuration of the continents2 and he 

urges that great meteorological         
phenomena cannot be comprehended when   
considered independently of geognostic  
relations--a truth which1 like most     
other general principles1 seems simple  
enough once it is pointed out4  ,with   
that broad sweep of imagination which   
characterized him1 ,humboldt speaks of  
the atmosphere as the aerial ocean1 in  
the lower strata and on the shoals of   
which we live1 and he studies the       
atmospheric phenomena always in relation
 to those of that other ocean of water4 
,in each of these oceans there are vast 
permanent currents1 flowing always in   
determinate directions1 which enormously
 modify the climatic conditions of every
 zone4 ,the ocean of air is a vast      
maelstrom1 boiling up always under the  
influence of the sun's heat at the      
equator1 and flowing as an upper current
 towards either pole1 while an          
undercurrent from the poles1 which      
becomes the trade-winds1 flows towards  
the equator to supply its place4  ,but  

the superheated equatorial air1 becoming
 chilled1 descends to the surface in    
temperate latitudes1 and continues its  
poleward journey as the                 
anti-trade-winds4 ,the trade-winds are  
deflected towards the west1 because in  
approaching the equator they constantly 
pass over surfaces of the earth having a
 greater and greater velocity of        
rotation1 and so1 as it were1 tend to   
lag behind--an explanation which ,hadley
 pointed out in #agce1 but which was not
 accepted until ,dalton independently   
worked it out and promulgated it in     
#agic4 ,for the opposite reason1 the    
anti-trades are deflected towards the   
east2 hence it is that the western1     
borders of continents in temperate zones
 are bathed in moist sea-breezes1 while 
their eastern borders lack this         
cold-dispelling influence4  ,in the     
ocean of water the main currents run as 
more sharply circumscribed              
streams--veritable rivers in the sea4   
,of these the best known and most       

sharply circumscribed is the familiar   
,gulf ,stream1 which has its origin in  
an equatorial current1 impelled westward
 by trade-winds1 which is deflected     
northward in the main at ,cape ,st4     
,roque1 entering the ,caribbean ,sea and
 ,gulf of ,mexico1 to emerge finally    
through the ,strait of ,florida1 and    
journey off across the ,atlantic to warm
 the shores of ,europe4  ,such1 at      
least1 is the ,gulf ,stream as ,humboldt
 understood it4 ,since his time1        
however1 ocean currents in general1 and 
this one in particular1 have been the   
subject of no end of controversy1 it    
being hotly disputed whether either     
causes or effects of the ,gulf ,stream  
are just what ,humboldt1 in common with 
others of his time1 conceived them to   
be4 ,about the middle of the century    
,lieutenant ,m4 ,f4 ,maury1 the         
distinguished ,american hydrographer and
 meteorologist1 advocated a theory of   
gravitation as the chief cause of the   
currents1 claiming that difference in   

density1 due to difference in           
temperature and saltness1 would         
sufficiently account for the oceanic    
circulation4 ,this theory gained great  
popularity through the wide circulation 
of ,maury's ,physical ,geography of the 
,sea1 which is said to have passed      
through more editions than any other    
scientific book of the period2 but it   
was ably and vigorously combated by ,dr4
 ,james ,croll1 the ,scottish geologist1
 in his ,climate and ,time1 and latterly
 the old theory that ocean currents are 
due to the trade-winds has again come   
into favor4 ,indeed1 very recently a    
model has been constructed1 with the aid
 of which it is said to have been       
demonstrated that prevailing winds in   
the direction of the actual trade-winds 
would produce such a current as the     
,gulf ,stream4  ,meantime1 however1 it  
is by no means sure that gravitation    
does not enter into the case to the     
extent of producing an insensible       
general oceanic circulation1 independent

 of the ,gulf ,stream and similar marked
 currents1 and similar in its larger    
outlines to the polar-equatorial        
circulation of the air4 ,the idea of    
such oceanic circulation was first      
suggested in detail by ,professor ,lenz1
 of ,st4 ,petersburg1 in #ahde1 but it  
was not generally recognized until ,dr4 
,carpenter independently hit upon the   
idea more than twenty years later4 ,the 
plausibility of the conception is       
obvious2 yet the alleged fact of such   
circulation has been hotly disputed1 and
 the question is still sub judice4  ,but
 whether or not such general circulation
 of ocean water takes place1 it is      
beyond dispute that the recognized      
currents carry an enormous quantity of  
heat from the tropics towards the poles4
 ,dr4 ,croll1 who has perhaps given more
 attention to the physics of the subject
 than almost any other person1 computes 
that the ,gulf ,stream conveys to the   
,north ,atlantic one-fourth as much heat
 as that body receives directly from the

 sun1 and he argues that were it not for
 the transportation of heat by this and 
similar ,pacific currents1 only a narrow
 tropical region of the globe would be  
warm enough for habitation by the       
existing faunas4 ,dr4 ,croll argues that
 a slight change in the relative values 
of northern and southern trade-winds    
7such as he believes has taken place at 
various periods in the past7 would      
suffice to so alter the equatorial      
current which now feeds the ,gulf       
,stream that its main bulk would be     
deflected southward instead of          
northward1 by the angle of ,cape ,st4   
,roque4 ,thus the ,gulf ,stream would be
 nipped in the bud1 and1 according to   
,dr4 ,croll's estimates1 the results    
would be disastrous for the northern    
hemisphere4 ,the anti-trades1 which now 
are warmed by the ,gulf ,stream1 would  
then blow as cold winds across the      
shores of western ,europe1 and in all   
probability a glacial epoch would       
supervene throughout the northern       

hemisphere4  ,the same consequences1 so 
far as ,europe is concerned at least1   
would apparently ensue were the ,isthmus
 of ,panama to settle into the sea1     
allowing the ,caribbean current to pass 
into the ,pacific4 ,but the geologist   
tells us that this isthmus rose at a    
comparatively recent geological period1 
though it is hinted that there had been 
some time previously a temporary land   
connection between the two continents4  
,are we to infer1 then1 that the two    
,americas in their unions and disunions 
have juggled with the climate of the    
other hemisphere8 ,apparently so1 if the
 estimates made of the influence of the 
,gulf ,stream be tenable4 ,it is a far  
cry from ,panama to ,russia4 ,yet it    
seems within the possibilities that the 
meteorologist may learn from the        
geologist of ,central ,america something
 that will enable him to explain to the 
paleontologist of ,europe how it chanced
 that at one time the mammoth and       
rhinoceros roamed across northern       

,siberia1 while at another time the     
reindeer and musk-ox browsed along the  
shores of the ,mediterranean4           
,possibilities1 ,i said1 not            
probabilities4 ,yet even the faint      
glimmer of so alluring a possibility    
brings home to one with vividness the   
truth of ,humboldt's perspicuous        
observation that meteorology can be     
properly comprehended only when studied 
in connection with the companion        
sciences4 ,there are no isolated        
phenomena in nature4   ,,cyclones ,,and 
,,anti-,,cyclones  ,yet1 after all1 it  
is not to be denied that the chief      
concern of the meteorologist must be    
with that other medium1 the ocean of    
air1 on the shoals of which we live4    
,for whatever may be accomplished by    
water currents in the way of conveying  
heat1 it is the wind currents that      
effect the final distribution of that   
heat4 ,as ,dr4 ,croll has urged1 the    
waters of the ,gulf ,stream do not warm 
the shores of ,europe by direct contact1

 but by warming the anti-trade-winds1   
which subsequently blow across the      
continent4 ,and everywhere the heat     
accumulated by water becomes effectual  
in modifying climate1 not so much by    
direct radiation as by diffusion through
 the medium of the air4  ,this very     
obvious importance of aerial currents   
led to their practical study long before
 meteorology had any title to the rank  
of science1 and ,dalton's explanation of
 the trade-winds had laid the foundation
 for a science of wind dynamics before  
the beginning of the nineteenth century4
 ,but no substantial further advance in 
this direction was effected until about 
#ahbg1 when ,heinrich ,w4 ,dove1 of     
,konigsberg1 afterwards to be known as  
perhaps the foremost meteorologist of   
his generation1 included the winds among
 the subjects of his elaborate          
statistical studies in climatology4     
,dove classified the winds as permanent1
 periodical1 and variable4 ,his great   
discovery was that all winds1 of        

whatever character1 and not merely the  
permanent winds1 come under the         
influence of the earth's rotation in    
such a way as to be deflected from their
 course1 and hence to take on a gyratory
 motion--that1 in short1 all local winds
 are minor eddies in the great          
polar-equatorial whirl1 and tend to     
reproduce in miniature the character of 
that vast maelstrom4 ,for the first     
time1 then1 temporary or variable winds 
were seen to lie within the province of 
law4  ,a generation later1 ,professor   
,william ,ferrel1 the ,american         
meteorologist1 who had been led to take 
up the subject by a perusal of ,maury's 
discourse on ocean winds1 formulated a  
general mathematical law1 to the effect 
that any body moving in a right line    
along the surface of the earth in any   
direction tends to have its course      
deflected1 owing to the earth's         
rotation1 to the right hand in the      
northern and to the left hand in the    
southern hemisphere4 ,this law had      

indeed been stated as early as #ahce by 
the ,french physicist ,poisson1 but no  
one then thought of it as other than a  
mathematical curiosity2 its true        
significance was only understood after  
,professor ,ferrel had independently    
rediscovered it 7just as ,dalton        
rediscovered ,hadley's forgotten law of 
the trade-winds7 and applied it to the  
motion of wind currents4  ,then it      
became clear that here is a key to the  
phenomena of atmospheric circulation1   
from the great polar-equatorial         
maelstrom which manifests itself in the 
trade-winds to the most circumscribed   
riffle which is announced as a local    
storm4 ,and the more the phenomena were 
studied1 the more striking seemed the   
parallel between the greater maelstrom  
and these lesser eddies4 ,just as the   
entire atmospheric mass of each         
hemisphere is seen1 when viewed as a    
whole1 to be carried in a great whirl   
about the pole of that hemisphere1 so   
the local disturbances within this great

 tide are found always to take the form 
of whirls about a local                 
storm-centre--which storm-centre1       
meantime1 is carried along in the major 
current1 as one often sees a little     
whirlpool in the water swept along with 
the main current of the stream4         
,sometimes1 indeed1 the local eddy1     
caught as it were in an ancillary       
current of the great polar stream1 is   
deflected from its normal course and may
 seem to travel against the stream2 but 
such deviations are departures from the 
rule4 ,in the great majority of cases1  
for example1 in the north temperate     
zone1 a storm-centre 7with its attendant
 local whirl7 travels to the northeast1 
along the main current of the           
anti-trade-wind1 of which it is a part2 
and though exceptionally its course may 
be to the southeast instead1 it almost  
never departs so widely from the main   
channel as to progress to the westward4 
,thus it is that storms sweeping over   
the ,united ,states can be announced1 as

 a rule1 at the seaboard in advance of  
their coming by telegraphic             
communication from the interior1 while  
similar storms come to ,europe off the  
ocean unannounced4 ,hence the more      
practical availability of the forecasts 
of weather bureaus in the former        
country4  ,but these local whirls1 it   
must be understood1 are local only in a 
very general sense of the word1 inasmuch
 as a single one may be more than a     
thousand miles in diameter1 and a small 
one is two or three hundred miles       
across4 ,but quite without regard to the
 size of the whirl1 the air composing it
 conducts itself always in one of two   
ways4 ,it never whirls in concentric    
circles2 it always either rushes in     
towards the centre in a descending      
spiral1 in which case it is called a    
cyclone1 or it spreads out from the     
centre in a widening spiral1 in which   
case it is called an anti-cyclone4 ,the 
word cyclone is associated in popular   
phraseology with a terrific storm1 but  

it has no such restriction in technical 
usage4 ,a gentle zephyr flowing towards 
a storm-centre is just as much a cyclone
 to the meteorologist as is the whirl   
constituting a ,west-,indian hurricane4 
,indeed1 it is not properly the wind    
itself that is called the cyclone in    
either case1 but the entire system of   
whirls--including the storm-centre      
itself1 where there may be no wind at   
all4  ,what1 then1 is this storm-centre8
 ,merely an area of low barometric      
pressure--an area where the air has     
become lighter than the air of          
surrounding regions4 ,under influence of
 gravitation the air seeks its level    
just as water does2 so the heavy air    
comes flowing in from all sides towards 
the low-pressure area1 which thus       
becomes a storm-centre4 ,but the        
inrushing currents never come straight  
to their mark4 ,in accordance with      
,ferrel's law1 they are deflected to the
 right1 and the result1 as will readily 
be seen1 must be a vortex current1 which

 whirls always in one direction--namely1
 from left to right1 or in the direction
 opposite to that of the hands of a     
watch held with its face upward4 ,the   
velocity of the cyclonic currents will  
depend largely upon the difference in   
barometric pressure between the         
storm-centre and the confines of the    
cyclone system4 ,and the velocity of the
 currents will determine to some extent 
the degree of deflection1 and hence the 
exact path of the descending spiral in  
which the wind approaches the centre4   
,but in every case and in every part of 
the cyclone system it is true1 as ,buys 
,ballot's famous rule first pointed out1
 that a person standing with his back to
 the wind has the storm-centre at his   
left4  ,the primary cause of the low    
barometric pressure which marks the     
storm-centre and establishes the cyclone
 is expansion of the air through excess 
of temperature4 ,the heated air1 rising 
into cold upper regions1 has a portion  
of its vapor condensed into clouds1 and 

now a new dynamic factor is added1 for  
each particle of vapor1 in condensing1  
gives up its modicum of latent heat4    
,each pound of vapor thus liberates1    
according to ,professor ,tyndall's      
estimate1 enough heat to melt five      
pounds of cast iron2 so the amount given
 out where large masses of cloud are    
forming must enormously add to the      
convection currents of the air1 and     
hence to the storm-developing power of  
the forming cyclone4 ,indeed1 one school
 of meteorologists1 of whom ,professor  
,espy was the leader1 has held that1    
without such added increment of energy  
constantly augmenting the dynamic       
effects1 no storm could long continue in
 violent action4 ,and it is doubted     
whether any storm could ever attain1    
much less continue1 the terrific force  
of that most dreaded of winds of        
temperate zones1 the tornado--a storm   
which obeys all the laws of cyclones1   
but differs from ordinary cyclones in   
having a vortex core only a few feet or 

yards in diameter--without the aid of   
those great masses of condensing vapor  
which always accompany it in the form of
 storm-clouds4  ,the anti-cyclone simply
 reverses the conditions of the cyclone4
 ,its centre is an area of high         
pressure1 and the air rushes out from it
 in all directions towards surrounding  
regions of low pressure4 ,as before1 all
 parts of the current will be deflected 
towards the right1 and the result1      
clearly1 is a whirl opposite in         
direction to that of the cyclone4 ,but  
here there is a tendency to dissipation 
rather than to concentration of energy1 
hence1 considered as a storm-generator1 
the anti-cyclone is of relative         
insignificance4  ,in particular the     
professional meteorologist who conducts 
a weather bureau--as1 for example1 the  
chief of the ,united ,states            
signal-service station in ,new ,york--is
 so preoccupied with the observation of 
this phenomenon that cyclone-hunting    
might be said to be his chief pursuit4  

,it is for this purpose1 in the main1   
that government weather bureaus or      
signal-service departments have been    
established all over the world4 ,their  
chief work is to follow up cyclones1    
with the aid of telegraphic reports1    
mapping their course and recording the  
attendant meteorological conditions4    
,their so-called predictions or         
forecasts are essentially predications1 
gaining locally the effect of           
predictions because the telegraph       
outstrips the wind4  ,at only one place 
on the globe has it been possible as yet
 for the meteorologist to make long-time
 forecasts meriting the title of        
predictions4 ,this is in the middle     
,ganges ,valley of northern ,india4 ,in 
this country the climatic conditions are
 largely dependent upon the periodical  
winds called monsoons1 which blow       
steadily landward from ,april to        
,october1 and seaward from ,october to  
,april4 ,the summer monsoons bring the  
all-essential rains2 if they are delayed

 or restricted in extent1 there will be 
drought and consequent famine4 ,and such
 restriction of the monsoon is likely to
 result when there has been an unusually
 deep or very late snowfall on the      
,himalayas1 because of the lowering of  
spring temperature by the melting snow4 
,thus here it is possible1 by observing 
the snowfall in the mountains1 to       
predict with some measure of success the
 average rainfall of the following      
summer4 ,the drought of #ahif1 with the 
consequent famine and plague that       
devastated ,india the following winter1 
was thus predicted some months in       
advance4  ,this is the greatest present 
triumph of practical meteorology4       
,nothing like it is yet possible        
anywhere in temperate zones4 ,but no one
 can say what may not be possible in    
times to come1 when the data now being  
gathered all over the world shall at    
last be co-ordinated1 classified1 and   
made the basis of broad inductions4     
,meteorology is pre-eminently a science 

of the future4     ,,vi4 ,,modern       
,,theories ,,of ,,heat ,,and ,,light    
,,the eighteenth-century philosopher    
made great strides in his studies of the
 physical properties of matter and the  
application of these properties in      
mechanics1 as the steam-engine1 the     
balloon1 the optic telegraph1 the       
spinning-jenny1 the cotton-gin1 the     
chronometer1 the perfected compass1 the 
,leyden jar1 the lightning-rod1 and a   
host of minor inventions testify4 ,in a 
speculative way he had thought out more 
or less tenable conceptions as to the   
ultimate nature of matter1 as witness   
the theories of ,leibnitz and ,boscovich
 and ,davy1 to which we may recur4 ,but 
he had not as yet conceived the notion  
of a distinction between matter and     
energy1 which is so fundamental to the  
physics of a later epoch4 ,he did not   
speak of heat1 light1 electricity1 as   
forms of energy or force2 he conceived  
them as subtile forms of matter--as     
highly attenuated yet tangible fluids1  

subject to gravitation and chemical     
attraction2 though he had learned to    
measure none of them but heat with      
accuracy1 and this one he could test    
only within narrow limits until late in 
the century1 when ,josiah ,wedgwood1 the
 famous potter1 taught him to gauge the 
highest temperatures with the clay      
pyrometer4  ,he spoke of the matter of  
heat as being the most universally      
distributed fluid in nature2 as entering
 in some degree into the composition of 
nearly all other substances2 as being   
sometimes liquid1 sometimes condensed or
 solid1 and as having weight that could 
be detected with the balance4 ,following
 ,newton1 he spoke of light as a        
corpuscular emanation or fluid1 composed
 of shining particles which possibly are
 transmutable into particles of heat1   
and which enter into chemical           
combination with the particles of other 
forms of matter4 ,electricity he        
considered a still more subtile kind of 
matter-perhaps an attenuated form of    

light4 ,magnetism1 vital fluid1 and by  
some even a gravic fluid1 and a fluid of
 sound were placed in the same scale2   
and1 taken together1 all these supposed 
subtile forms of matter were classed as 
imponderables4  ,this view of the nature
 of the imponderables was in some       
measure a retrogression1 for many       
seventeenth-century philosophers1       
notably ,hooke and ,huygens and ,boyle1 
had held more correct views2 but the    
materialistic conception accorded so    
well with the eighteenth-century        
tendencies of thought that only here and
 there a philosopher like ,euler called 
it in question1 until well on towards   
the close of the century4 ,current      
speech referred to the materiality of   
the imponderables unquestioningly4      
,students of meteorology--a science that
 was just dawning--explained atmospheric
 phenomena on the supposition that heat1
 the heaviest imponderable1 predominated
 in the lower atmosphere1 and that      
light1 electricity1 and magnetism       

prevailed in successively higher strata4
 ,and ,lavoisier1 the most philosophical
 chemist of the century1 retained heat  
and light on a par with oxygen1         
hydrogen1 iron1 and the rest1 in his    
list of elementary substances4   ,,count
 ,,rumford ,,and ,,the ,,vibratory      
,,theory ,,of ,,heat  ,but just at the  
close of the century the confidence in  
the status of the imponderables was     
rudely shaken in the minds of           
philosophers by the revival of the old  
idea of ,fra ,paolo and ,bacon and      
,boyle1 that heat1 at any rate1 is not a
 material fluid1 but merely a mode of   
motion or vibration among the particles 
of ponderable matter4 ,the new champion 
of the old doctrine as to the nature of 
heat was a very distinguished           
philosopher and diplomatist of the time1
 who1 it may be worth recalling1 was an 
,american4 ,he was a sadly expatriated  
,american1 it is true1 as his name1     
given all the official appendages1 will 
amply testify2 but he had been born and 

reared in a ,massachusetts village none 
the less1 and he seems always to have   
retained a kindly interest in the land  
of his nativity1 even though he lived   
abroad in the service of other powers   
during all the later years of his life1 
and was knighted by ,england1 ennobled  
by ,bavaria1 and honored by the most    
distinguished scientific bodies of      
,europe4 ,the ,american1 then1 who      
championed the vibratory theory of heat1
 in opposition to all current opinion1  
in this closing era of the eighteenth   
century1 was ,lieutenant-,general ,sir  
,benjamin ,thompson1 ,count ,rumford1   
,f4,r4,s4  ,rumford showed that heat may
 be produced in indefinite quantities by
 friction of bodies that do not         
themselves lose any appreciable matter  
in the process1 and claimed that this   
proves the immateriality of heat4 ,later
 on he added force to the argument by   
proving1 in refutation of the           
experiments of ,bowditch1 that no body  
either gains or loses weight in virtue  

of being heated or cooled4 ,he thought  
he had proved that heat is only a form  
of motion4  ,his experiment for         
producing indefinite quantities of heat 
by friction is recorded by him in his   
paper entitled1 ,inquiry ,concerning the
 ,source of ,heat ,excited by ,friction4
  ,being engaged1 lately1 in            
superintending the boring of cannon in  
the workshops of the military arsenal at
 ,munich1 he says1 ,i was struck with   
the very considerable degree of heat    
which a brass gun acquires in a short   
time in being bored2 and with the still 
more intense heat 7much greater than    
that of boiling water1 as ,i found by   
experiment7 of the metallic chips       
separated from it by the borer4  ,taking
 a cannon 7a brass six-pounder71 cast   
solid1 and rough1 as it came from the   
foundry1 and fixing it horizontally in a
 machine used for boring1 and at the    
same time finishing the outside of the  
cannon by turning1 ,i caused its        
extremity to be cut off2 and by turning 

down the metal in that part1 a solid    
cylinder was formed1 #g #c_/d inches in 
diameter and #i #h_/aj inches long2     
which1 when finished1 remained joined to
 the rest of the metal 7that which1     
properly speaking1 constituted the      
cannon7 by a small cylindrical neck1    
only #b #a_/e inches in diameter and #c 
#h_/aj inches long4  ,this short        
cylinder1 which was supported in its    
horizontal position1 and turned round   
its axis by means of the neck by which  
it remained united to the cannon1 was   
now bored with the horizontal borer used
 in boring cannon4  ,this cylinder being
 designed for the express purpose of    
generating heat by friction1 by having a
 blunt borer forced against its solid   
bottom at the same time that it should  
be turned round its axis by the force of
 horses1 in order that the heat         
accumulated in the cylinder might from  
time to time be measured1 a small1 round
 hole #j4cg of an inch only in diameter 
and #d4b inches in depth1 for the       

purpose of introducing a small          
cylindrical mercurial thermometer1 was  
made in it1 on one side1 in a direction 
perpendicular to the axis of the        
cylinder1 and ending in the middle of   
the solid part of the metal which formed
 the bottom of the bore4  ,at the       
beginning of the experiment1 the        
temperature of the air in the shade1 as 
also in the cylinder1 was just sixty    
degrees ,fahrenheit4 ,at the end of     
thirty minutes1 when the cylinder had   
made #ifj revolutions about its axis1   
the horses being stopped1 a cylindrical 
mercury thermometer1 whose bulb was     
#cb_/ajj of an inch in diameter and #c  
#a_/d inches in length1 was introduced  
into the hole made to receive it in the 
side of the cylinder1 when the mercury  
rose almost instantly to one hundred and
 thirty degrees4  ,in order1 by one     
decisive experiment1 to determine       
whether the air of the atmosphere had   
any part or not in the generation of the
 heat1 ,i contrived to repeat the       

experiment under circumstances in which 
it was evidently impossible for it to   
produce any effect whatever4 ,by means  
of a piston exactly fitted to the mouth 
of the bore of the cylinder1 through the
 middle of which piston the square iron 
bar1 to the end of which the blunt steel
 borer was fixed1 passed in a square    
hole made perfectly air-tight1 the      
excess of the external air1 to the      
inside of the bore of the cylinder1 was 
effectually prevented4 ,i did not find1 
however1 by this experiment that the    
exclusion of the air diminished in the  
smallest degree the quantity of heat    
excited by the friction4  ,there still  
remained one doubt1 which1 though it    
appeared to me to be so slight as hardly
 to deserve any attention1 ,i was1      
however1 desirous to remove4 ,the piston
 which choked the mouth of the bore of  
the cylinder1 in order that it might be 
air-tight1 was fitted into it with so   
much nicety1 by means of its collars of 
leather1 and pressed against it with so 

much force1 that1 notwithstanding its   
being oiled1 it occasioned a            
considerable degree of friction when the
 hollow cylinder was turned round its   
axis4 ,was not the heat produced1 or at 
least some part of it1 occasioned by    
this friction of the piston8 and1 as the
 external air had free access to the    
extremity of the bore1 where it came    
into contact with the piston1 is it not 
possible that this air may have had some
 share in the generation of the heat    
produced8  ,a quadrangular oblong deal  
box1 water-tight1 being provided with   
holes or slits in the middle of each of 
its ends1 just large enough to receive1 
the one the square iron rod to the end  
of which the blunt steel borer was      
fastened1 the other the small           
cylindrical neck which joined the hollow
 cylinder to the cannon2 when this box  
7which was occasionally closed above by 
a wooden cover or lid moving on hinges7 
was put into its place--that is to say1 
when1 by means of the two vertical      

opening or slits in its two ends1 the   
box was fixed to the machinery in such a
 manner that its bottom being in the    
plane of the horizon1 its axis coincided
 with the axis of the hollow metallic   
cylinder1 it is evident1 from the       
description1 that the hollow1 metallic  
cylinder would occupy the middle of the 
box1 without touching it on either side2
 and that1 on pouring water into the box
 and filling it to the brim1 the        
cylinder would be completely covered and
 surrounded on every side by that fluid4
 ,and1 further1 as the box was held fast
 by the strong1 square iron rod which   
passed in a square hole in the centre of
 one of its ends1 while the round or    
cylindrical neck which joined the hollow
 cylinder to the end of the cannon could
 turn round freely on its axis in the   
round hole in the centre of the other   
end of it1 it is evident that the       
machinery could be put in motion without
 the least danger of forcing the box out
 of its place1 throwing the water out of

 it1 or deranging any part of the       
apparatus4  ,everything being thus      
ready1 the box was filled with cold     
water1 having been made water-tight by  
means of leather collars1 and the       
machinery put in motion4 ,the result of 
this beautiful experiment1 says         
,rumford1 was very striking1 and the    
pleasure it afforded me amply repaid me 
for all the trouble ,i had had in       
contriving and arranging the complicated
 machinery used in making it4 ,the      
cylinder1 revolving at the rate of      
thirty-two times in a minute1 had been  
in motion but a short time when ,i      
perceived1 by putting my hand into the  
water and touching the outside of the   
cylinder1 that heat was generated1 and  
it was not long before the water which  
surrounded the cylinder began to be     
sensibly warm4  ,at the end of one hour 
,i found1 by plunging a thermometer into
 the box1444 that its temperature had   
been raised no less than forty-seven    
degrees ,fahrenheit1 being now one      

hundred and seven degrees ,fahrenheit4  
444 ,one hour and thirty minutes after  
the machinery had been put in motion the
 heat of the water in the box was one   
hundred and forty-two degrees4 ,at the  
end of two hours444 it was raised to one
 hundred and seventy-eight degrees2 and 
at two hours and thirty minutes it      
,,actually ,,boiled6  ,it would be      
difficult to describe the surprise and  
astonishment expressed in the           
countenances of the bystanders on seeing
 so large a quantity of cold water      
heated1 and actually made to boil1      
without any fire4 ,though there was1 in 
fact1 nothing that could justly be      
considered as a surprise in this event1 
yet ,i acknowledge fairly that it       
afforded me a degree of childish        
pleasure which1 were ,i ambitious of the
 reputation of a ,,grave ,,philosopher1 
,i ought most certainly rather to hide  
than to discover4444  ,having thus dwelt
 in detail on these experiments1        
,rumford comes now to the all-important 

discussion as to the significance of    
them--the subject that had been the     
source of so much speculation among the 
philosophers--the question as to what   
heat really is1 and if there really is  
any such thing 7as many believed7 as an 
igneous fluid1 or a something called    
caloric4  ,from whence came this heat   
which was continually given off in this 
manner1 in the foregoing experiments8   
asks ,rumford4 ,was it furnished by the 
small particles of metal detached from  
the larger solid masses on their being  
rubbed together8 ,this1 as we have      
already seen1 could not possibly have   
been the case4  ,was it furnished by the
 air8 ,this could not have been the     
case2 for1 in three of the experiments1 
the machinery being kept immersed in    
water1 the access of the air of the     
atmosphere was completely prevented4    
,was it furnished by the water which    
surrounded the machinery8 ,that this    
could not have been the case is evident3
 first1 because this water was          

continually ,,receiving heat from the   
machinery1 and could not1 at the same   
time1 be ,,giving ,,to and ,,receiving  
,,heat ,,from the same body2 and1       
secondly1 because there was no chemical 
decomposition of any part of this water4
 ,had any such decomposition taken place
 7which1 indeed1 could not reasonably   
have been expected71 one of its         
component elastic fluids 7most probably 
hydrogen7 must1 at the same time1 have  
been set at liberty1 and1 in making its 
escape into the atmosphere1 would have  
been detected2 but1 though ,i frequently
 examined the water to see if any       
air-bubbles rose up through it1 and had 
even made preparations for catching them
 if they should appear1 ,i could        
perceive none2 nor was there any sign of
 decomposition of any kind whatever1 or 
other chemical process1 going on in the 
water4  ,is it possible that the heat   
could have been supplied by means of the
 iron bar to the end of which the blunt 
steel borer was fixed8 ,or by the small 

neck of gun-metal by which the hollow   
cylinder was united to the cannon8      
,these suppositions seem more improbable
 even than either of the                
before-mentioned2 for heat was          
continually going off1 or ,,out ,,of    
,,the ,,machinery1 by both these        
passages during the whole time the      
experiment lasted4  ,and in reasoning on
 this subject we must not forget to     
consider that most remarkable           
circumstance1 that the source of the    
heat generated by friction in these     
experiments appeared evidently to be    
,,inexhaustible4  ,it is hardly         
necessary to add that anything which any
 ,,insulated body1 or system of bodies1 
can continue to furnish ,,without       
,,limitation cannot possibly be a       
,,material substance2 and it appears to 
me to be extremely difficult1 if not    
quite impossible1 to form any distinct  
idea of anything capable of being       
excited and communicated1 in the manner 
the heat was excited and communicated in

 these experiments1 except in           
,,motion47#a7   ,,thomas ,,young ,,and  
,,the ,,wave ,,theory ,,of ,,light  ,but
 contemporary judgment1 while it        
listened respectfully to ,rumford1 was  
little minded to accept his verdict4    
,the cherished beliefs of a generation  
are not to be put down with a single    
blow4 ,where many minds have a similar  
drift1 however1 the first blow may      
precipitate a general conflict2 and so  
it was here4 ,young ,humphry ,davy had  
duplicated ,rumford's experiments1 and  
reached similar conclusions2 and soon   
others fell into line4 ,then1 in #ahjj1 
,dr4 ,thomas ,young--,phenomenon ,young 
they called him at ,cambridge1 because  
he was reputed to know everything--took 
up the cudgels for the vibratory theory 
of light1 and it began to be clear that 
the two imponderables1 heat and light1  
must stand or fall together2 but no one 
as yet made a claim against the fluidity
 of electricity4  ,before we take up the
 details of the assault made by ,young  

upon the old doctrine of the materiality
 of light1 we must pause to consider the
 personality of ,young himself4 ,for it 
chanced that this ,quaker physician was 
one of those prodigies who come but few 
times in a century1 and the full list of
 whom in the records of history could be
 told on one's thumbs and fingers4 ,his 
biographers tell us things about him    
that read like the most patent          
fairy-tales4 ,as a mere infant in arms  
he had been able to read fluently4      
,before his fourth birthday came he had 
read the ,bible twice through1 as well  
as ,watts's ,hymns--poor child6--and    
when seven or eight he had shown a      
propensity to absorb languages much as  
other children absorb nursery tattle and
 ,mother ,goose rhymes4 ,when he was    
fourteen1 a young lady visiting the     
household of his tutor patronized the   
pretty boy by asking to see a specimen  
of his penmanship4 ,the pretty boy      
complied readily enough1 and mildly     
rebuked his interrogator by rapidly     

writing some sentences for her in       
fourteen languages1 including such as1  
,arabian1 ,persian1 and ,ethiopic4      
,meantime languages had been but an     
incident in the education of the lad4   
,he seems to have entered every         
available field of thought--mathematics1
 physics1 botany1 literature1 music1    
painting1 languages1 philosophy1        
archaeology1 and so on to tiresome      
lengths--and once he had entered any    
field he seldom turned aside until he   
had reached the confines of the subject 
as then known and added something new   
from the recesses of his own genius4 ,he
 was as versatile as ,priestley1 as     
profound as ,newton himself4 ,he had the
 range of a mere dilettante1 but        
everywhere the full grasp of the master4
 ,he took early for his motto the saying
 that what one man has done1 another man
 may do4 ,granting that the other man   
has the brain of a ,thomas ,young1 it is
 a true motto4  ,such1 then1 was the    
young ,quaker who came to ,london to    

follow out the humdrum life of a        
practitioner of medicine in the year    
#ahja4 ,but incidentally the young      
physician was prevailed upon to occupy  
the interims of early practice by       
fulfilling the duties of the chair of   
,natural ,philosophy at the ,royal      
,institution1 which ,count ,rumford had 
founded1 and of which ,davy was then    
,professor of ,chemistry--the           
institution whose glories have been     
perpetuated by such names as ,faraday   
and ,tyndall1 and which the ,briton of  
to-day speaks of as the ,pantheon of    
,science4 ,here it was that ,thomas     
,young made those studies which have    
insured him a niche in the temple of    
fame not far removed from that of ,isaac
 ,newton4  ,as early as #agic1 when he  
was only twenty1 ,young had begun to    
,communicate papers to the ,royal       
,society of ,london1 which were adjudged
 worthy to be printed in full in the    
,philosophical ,transactions2 so it is  
not strange that he should have been    

asked to deliver the ,bakerian lecture  
before that learned body the very first 
year after he came to ,london4 ,the     
lecture was delivered ,november #ab1    
#ahja4 ,its subject was ,the ,theory of 
,light and ,colors1 and its reading     
marks an epoch in physical science2 for 
here was brought forward for the first  
time convincing proof of that undulatory
 theory of light with which every       
student of modern physics is            
familiar--the theory which holds that   
light is not a corporeal entity1 but a  
mere pulsation in the substance of an   
all-pervading ether1 just as sound is a 
pulsation in the air1 or in liquids or  
solids4  ,young had1 indeed1 advocated  
this theory at an earlier date1 but it  
was not until #ahja that he hit upon the
 idea which enabled him to bring it to  
anything approaching a demonstration4   
,it was while pondering over the        
familiar but puzzling phenomena of      
colored rings into which white light is 
broken when reflected from thin         

films--,newton's rings1 so called--that 
an explanation occurred to him which at 
once put the entire undulatory theory on
 a new footing4 ,with that sagacity of  
insight which we call genius1 he saw of 
a sudden that the phenomena could be    
explained by supposing that when rays of
 light fall on a thin glass1 part of the
 rays being reflected from the upper    
surface1 other rays1 reflected from the 
lower surface1 might be so retarded in  
their course through the glass that the 
two sets would interfere with one       
another1 the forward pulsation of one   
ray corresponding to the backward       
pulsation of another1 thus quite        
neutralizing the effect4 ,some of the   
component pulsations of the light being 
thus effaced by mutual interference1 the
 remaining rays would no longer give the
 optical effect of white light2 hence   
the puzzling colors4  ,here is ,young's 
exposition of the subject3  ,of the     
,colors of ,thin ,plates  ,when a beam  
of light falls upon two refracting      

surfaces1 the partial reflections       
coincide perfectly in direction2 and in 
this case the interval of retardation   
taken between the surfaces is to their  
radius as twice the cosine of the angle 
of refraction to the radius4  ,let the  
medium between the surfaces be rarer    
than the surrounding mediums2 then the  
impulse reflected at the second surface1
 meeting a subsequent undulation at the 
first1 will render the particles of the 
rarer medium capable of wholly stopping 
the motion of the denser and destroying 
the reflection1 while they themselves   
will be more strongly propelled than if 
they had been at rest1 and the          
transmitted light will be increased4 ,so
 that the colors by reflection will be  
destroyed1 and those by transmission    
rendered more vivid1 when the double    
thickness or intervals of retardation   
are any multiples of the whole breadth  
of the undulations2 and at intermediate 
thicknesses the effects will be reversed
 according to the ,newtonian            

observation4  ,if the same proportions  
be found to hold good with respect to   
thin plates of a denser medium1 which   
is1 indeed1 not improbable1 it will be  
necessary to adopt the connected        
demonstrations of ,prop4 ,,iv41 but1 at 
any rate1 if a thin plate be interposed 
between a rarer and a denser medium1 the
 colors by reflection and transmission  
may be expected to change places4   ,,of
 ,,the ,,colors ,,of ,,thick ,,plates   
,when a beam of light passes through a  
refracting surface1 especially if       
imperfectly polished1 a portion of it is
 irregularly scattered1 and makes the   
surface visible in all directions1 but  
most conspicuously in directions not far
 distant from that of the light itself2 
and if a reflecting surface be placed   
parallel to the refracting surface1 this
 scattered light1 as well as the        
principal beam1 will be reflected1 and  
there will be also a new dissipation of 
light1 at the return of the beam through
 the refracting surface4 ,these two     

portions of scattered light will        
coincide in direction2 and if the       
surfaces be of such a form as to collect
 the similar effects1 will exhibit rings
 of colors4 ,the interval of retardation
 is here the difference between the     
paths of the principal beam and of the  
scattered light between the two         
surfaces2 of course1 wherever the       
inclination of the scattered light is   
equal to that of the beam1 although in  
different planes1 the interval will     
vanish and all the undulations will     
conspire4 ,at other inclinations1 the   
interval will be the difference of the  
secants from the secant of the          
inclination1 or angle of refraction of  
the principal beam4 ,from these causes1 
all the colors of concave mirrors       
observed by ,newton and others are      
necessary consequences2 and it appears  
that their production1 though somewhat  
similar1 is by no means as ,newton      
imagined1 identical with the production 
of thin plates47#b7   ,by following up  

this clew with mathematical precision1  
measuring the exact thickness of the    
plate and the space between the         
different rings of color1 ,young was    
able to show mathematically what must be
 the length of pulsation for each of the
 different colors of the spectrum4 ,he  
estimated that the undulations of red   
light1 at the extreme lower end of the  
visible spectrum1 must number about     
thirty-seven thousand six hundred and   
forty to the inch1 and pass any given   
spot at a rate of four hundred and      
sixty-three millions of millions of     
undulations in a second1 while the      
extreme violet numbers fifty-nine       
thousand seven hundred and fifty        
undulations to the inch1 or seven       
hundred and thirty-five millions of     
millions to the second4   ,the ,colors  
of ,striated ,surfaces  ,young similarly
 examined the colors that are produced  
by scratches on a smooth surface1 in    
particular testing the light from ,mr4  
,coventry's exquisite micrometers1 which

 consist of lines scratched on glass at 
measured intervals4 ,these microscopic  
tests brought the same results as the   
other experiments4 ,the colors were     
produced at certain definite and        
measurable angles1 and the theory of    
interference of undulations explained   
them perfectly1 while1 as ,young        
affirmed with confidence1 no other      
hypothesis hitherto advanced would      
explain them at all4 ,here are his      
words3  ,let there be in a given plane  
two reflecting points very near each    
other1 and let the plane be so situated 
that the reflected image of a luminous  
object seen in it may appear to coincide
 with the points2 then it is obvious    
that the length of the incident and     
reflected ray1 taken together1 is equal 
with respect to both points1 considering
 them as capable of reflecting in all   
directions4 ,let one of the points be   
now depressed below the given plane2    
then the whole path of the light        
reflected from it will be lengthened by 

a line which is to the depression of the
 point as twice the cosine of incidence 
to the radius4  ,if1 therefore1 equal   
undulations of given dimensions be      
reflected from two points1 situated near
 enough to appear to the eye but as one1
 whenever this line is equal to half the
 breadth of a whole undulation the      
reflection from the depressed point will
 so interfere with the reflection from  
the fixed point that the progressive    
motion of the one will coincide with the
 retrograde motion of the other1 and    
they will both be destroyed2 but when   
this line is equal to the whole breadth 
of an undulation1 the effect will be    
doubled1 and when to a breadth and a    
half1 again destroyed2 and thus for a   
considerable number of alternations1 and
 if the reflected undulations be of a   
different kind1 they will be variously  
affected1 according to their proportions
 to the various length of the line which
 is the difference between the lengths  
of their two paths1 and which may be    

denominated the interval of a           
retardation4  ,in order that the effect 
may be the more perceptible1 a number of
 pairs of points must be united into two
 parallel lines2 and if several such    
pairs of lines be placed near each      
other1 they will facilitate the         
observation4 ,if one of the lines be    
made to revolve round the other as an   
axis1 the depression below the given    
plane will be as the sine of the        
inclination2 and while the eye and the  
luminous object remain fixed the        
difference of the length of the paths   
will vary as this sine4  ,the best      
subjects for the experiment are ,mr4    
,coventry's exquisite micrometers2 such 
of them as consist of parallel lines    
drawn on glass1 at a distance of        
one-five-hundredth of an inch1 are the  
most convenient4 ,each of these lines   
appears under a microscope to consist of
 two or more finer lines1 exactly       
parallel1 and at a distance of somewhat 
more than a twentieth more than the     

adjacent lines4 ,i placed one of these  
so as to reflect the sun's light at an  
angle of forty-five degrees1 and fixed  
it in such a manner that while it       
revolved round one of the lines as an   
axis1 ,i could measure its angular      
motion2 ,i found that the longest red   
color occurred at the inclination #aj   
#a_/d degrees1 #bj #c_/d degrees1 #cb   
degrees1 and #de degrees2 of which the  
sines are as the numbers #a1 #b1 #c1 and
 #d4 ,at all other angles also1 when the
 sun's light was reflected from the     
surface1 the color vanished with the    
inclination1 and was equal at equal     
inclinations on either side4  ,this     
experiment affords a very strong        
confirmation of the theory4 ,it is      
impossible to deduce any explanation of 
it from any hypothesis hitherto         
advanced2 and ,i believe it would be    
difficult to invent any other that would
 account for it4 ,there is a striking   
analogy between this separation of      
colors and the production of a musical  

note by successive echoes from          
equidistant iron palisades1 which ,i    
have found to correspond pretty         
accurately with the known velocity of   
sound and the distances of the surfaces4
  ,it is not improbable that the colors 
of the integuments of some insects1 and 
of some other natural bodies1 exhibiting
 in different lights the most beautiful 
versatility1 may be found to be of this 
description1 and not to be derived from 
thin plates4 ,in some cases a single    
scratch or furrow may produce similar   
effects1 by the reflection of its       
opposite edges47#c7   ,this doctrine of 
interference of undulations was the     
absolutely novel part of ,young's       
theory4 ,the all-compassing genius of   
,robert ,hooke had1 indeed1 very nearly 
apprehended it more than a century      
before1 as ,young himself points out1   
but no one else bad so much as vaguely  
conceived it2 and even with the         
sagacious ,hooke it was only a happy    
guess1 never distinctly outlined in his 

own mind1 and utterly ignored by all    
others4 ,young did not know of ,hooke's 
guess until he himself had fully        
formulated the theory1 but he hastened  
then to give his predecessor all the    
credit that could possibly be adjudged  
his due by the most disinterested       
observer4 ,to ,hooke's contemporary1    
,huygens1 who was the originator of the 
general doctrine of undulation as the   
explanation of light1 ,young renders    
full justice also4 ,for himself he      
claims only the merit of having         
demonstrated the theory which these and 
a few others of his predecessors had    
advocated without full proof4  ,the     
following year ,dr4 ,young detailed     
before the ,royal ,society other        
experiments1 which threw additional     
light on the doctrine of interference2  
and in #ahjc he cited still others1     
which1 he affirmed1 brought the doctrine
 to complete demonstration4 ,in applying
 this demonstration to the general      
theory of light1 he made the striking   

suggestion that the luminiferous ether  
pervades the substance of all material  
bodies with little or no resistance1 as 
freely1 perhaps1 as the wind passes     
through a grove of trees4 ,he asserted  
his belief also that the chemical rays  
which ,ritter had discovered beyond the 
violet end of the visible spectrum are  
but still more rapid undulations of the 
same character as those which produce   
light4 ,in his earlier lecture he had   
affirmed a like affinity between the    
light rays and the rays of radiant heat 
which ,herschel detected below the red  
end of the spectrum1 suggesting that    
light differs from heat only in the     
frequency of its undulations or         
vibrations--those undulations which are 
within certain limits with respect to   
frequency affecting the optic nerve and 
constituting light1 and those which are 
slower and probably stronger            
constituting heat only4 ,from the very  
outset he had recognized the affinity   
between sound and light2 indeed1 it had 

been this affinity that led him on to an
 appreciation of the undulatory theory  
of light4  ,but while all these         
affinities seemed so clear to the great 
co-ordinating brain of ,young1 they made
 no such impression on the minds of his 
contemporaries4 ,the immateriality of   
light had been substantially            
demonstrated1 but practically no one    
save its author accepted the            
demonstration4 ,newton's doctrine of the
 emission of corpuscles was too firmly  
rooted to be readily dislodged1 and ,dr4
 ,young had too many other interests to 
continue the assault unceasingly4 ,he   
occasionally wrote something touching on
 his theory1 mostly papers contributed  
to the ,quarterly ,review and similar   
periodicals1 anonymously or under       
pseudonym1 for he had conceived the     
notion that too great conspicuousness in
 fields outside of medicine would injure
 his practice as a physician4 ,his views
 regarding light 7including the original
 papers from the ,philosophical         

,transactions of the ,royal ,society7   
were again given publicity in full in   
his celebrated volume on natural        
philosophy1 consisting in part of his   
lectures before the ,royal ,institution1
 published in #ahjg2 but even then they 
failed to bring conviction to the       
philosophic world4 ,indeed1 they did not
 even arouse a controversial spirit1 as 
his first papers had done4   ,,arago    
,,and ,,fresnel ,,champion ,,the ,,wave 
,,theory  ,so it chanced that when1 in  
#ahae1 a young ,french military         
engineer1 named ,augustin ,jean         
,fresnel1 returning from the ,napoleonic
 wars1 became interested in the         
phenomena of light1 and made some       
experiments concerning diffraction which
 seemed to him to controvert the        
accepted notions of the materiality of  
light1 he was quite unaware that his    
experiments had been anticipated by a   
philosopher across the ,channel4 ,he    
communicated his experiments and results
 to the ,french ,institute1 supposing   

them to be absolutely novel4 ,that body 
referred them to a committee1 of which1 
as good fortune would have it1 the      
dominating member was ,dominique        
,francois ,arago1 a man as versatile as 
,young himself1 and hardly less         
profound1 if perhaps not quite so       
original4 ,arago at once recognized the 
merit of ,fresnel's work1 and soon      
became a convert to the theory4 ,he told
 ,fresnel that ,young had anticipated   
him as regards the general theory1 but  
that much remained to be done1 and he   
offered to associate himself with       
,fresnel in prosecuting the             
investigation4 ,fresnel was not a little
 dashed to learn that his original ideas
 had been worked out by another while he
 was a lad1 but he bowed gracefully to  
the situation and went ahead with       
unabated zeal4  ,the championship of    
,arago insured the undulatory theory a  
hearing before the ,french ,institute1  
but by no means sufficed to bring about 
its general acceptance4 ,on the         

contrary1 a bitter feud ensued1 in which
 ,arago was opposed by the ,jupiter     
,olympus of the ,academy1 ,laplace1 by  
the only less famous ,poisson1 and by   
the younger but hardly less able ,biot4 
,so bitterly raged the feud that a      
life-long friendship between ,arago and 
,biot was ruptured forever4 ,the        
opposition managed to delay the         
publication of ,fresnel's papers1 but   
,arago continued to fight with his      
customary enthusiasm and pertinacity1   
and at last1 in #ahbc1 the ,academy     
yielded1 and voted ,fresnel into its    
ranks1 thus implicitly admitting the    
value of his work4  ,it is a humiliating
 thought that such controversies as this
 must mar the progress of scientific    
truth2 but fortunately the story of the 
introduction of the undulatory theory   
has a more pleasant side4 ,three men1   
great both in character and in          
intellect1 were concerned in pressing   
its claims--,young1 ,fresnel1 and       
,arago--and the relations of these men  

form a picture unmarred by any of those 
petty jealousies that so often dim the  
lustre of great names4 ,fresnel freely  
acknowledged ,young's priority so soon  
as his attention was called to it2 and  
,young applauded the work of the        
,frenchman1 and aided with his counsel  
in the application of the undulatory    
theory to the problems of polarization  
of light1 which still demanded          
explanation1 and which ,fresnel's       
fertility of experimental resource and  
profundity of mathematical insight      
sufficed in the end to conquer4  ,after 
,fresnel's admission to the ,institute  
in #ahbc the opposition weakened1 and   
gradually the philosophers came to      
realize the merits of a theory which    
,young had vainly called to their       
attention a full quarter-century before4
 ,now1 thanks largely to ,arago1 both   
,young and ,fresnel received their full 
meed of appreciation4 ,fresnel was given
 the ,rumford medal of the ,royal       
,society of ,england in #ahbe1 and      

chosen one of the foreign members of the
 society two years later1 while ,young  
in turn was elected one of the eight    
foreign members of the ,french ,academy4
 ,as a fitting culmination of the       
chapter of felicities between the three 
friends1 it fell to the lot of ,young1  
as ,foreign ,secretary of the ,royal    
,society1 to notify ,fresnel of the     
honors shown him by ,england's          
representative body of scientists2 while
 ,arago1 as ,perpetual ,secretary of the
 ,french ,institute1 conveyed to ,young 
in the same year the notification that  
he had been similarly honored by the    
savants of ,france4  ,a few months later
 ,fresnel was dead1 and ,young survived 
him only two years4 ,both died          
prematurely1 but their great work was   
done1 and the world will remember always
 and link together these two names in   
connection with a theory which in its   
implications and importance ranks little
 below the theory of universal          
gravitation4     ,,vii4 ,,the ,,modern  

,,development ,,of ,,electricity ,,and  
,,magnetism  ,,galvani ,,and ,,volta    
,the full importance of ,young's studies
 of light might perhaps have gained     
earlier recognition had it not chanced  
that1 at the time when they were made1  
the attention of the philosophic world  
was turned with the fixity and          
fascination of a hypnotic stare upon    
another field1 which for a time brooked 
no rival4 ,how could the old1 familiar  
phenomenon1 light1 interest any one when
 the new agent1 galvanism1 was in view8 
,as well ask one to fix attention on a  
star while a meteorite blazes across the
 sky4  ,galvanism was so called         
precisely as the ,roentgen ray was      
christened at a later day--as a safe    
means of begging the question as to the 
nature of the phenomena involved4 ,the  
initial fact in galvanism was the       
discovery of ,luigi ,galvani            
7#agcg-agih71 a physician of ,bologna1  
in #agia1 that by bringing metals in    
contact with the nerves of a frog's leg 

violent muscular contractions are       
produced4 ,as this simple little        
experiment led eventually to the        
discovery of galvanic electricity and   
the invention of the galvanic battery1  
it may be regarded as the beginning of  
modern electricity4  ,the story is told 
that ,galvani was led to his discovery  
while preparing frogs' legs to make a   
broth for his invalid wife4 ,as the     
story runs1 he had removed the skins    
from several frogs' legs1 when1         
happening to touch the exposed muscles  
with a scalpel which had lain in close  
proximity to an electrical machine1     
violent muscular action was produced4   
,impressed with this phenomenon1 he     
began a series of experiments which     
finally resulted in his great discovery4
 ,but be this story authentic or not1 it
 is certain that ,galvani experimented  
for several years upon frogs' legs      
suspended upon wires and hooks1 until he
 finally constructed his arc of two     
different metals1 which1 when arranged  

so that one was placed in contact with a
 nerve and the other with a muscle1     
produced violent contractions4  ,these  
two pieces of metal form the basic      
principle of the modern galvanic        
battery1 and led directly to ,alessandro
 ,volta's invention of his voltaic pile1
 the immediate ancestor of the modern   
galvanic battery4 ,volta's experiments  
were carried on at the same time as     
those of ,galvani1 and his invention of 
his pile followed close upon ,galvani's 
discovery of the new form of            
electricity4 ,from these facts the new  
form of electricity was sometimes called
 galvanic and sometimes voltaic         
electricity1 but in recent years the    
term galvanism and galvanic current have
 almost entirely supplanted the use of  
the term voltaic4  ,it was ,volta who   
made the report of ,galvani's wonderful 
discovery to the ,royal ,society of     
,london1 read on ,january #ca1 #agic4   
,in this letter he describes ,galvani's 
experiments in detail and refers to them

 in glowing terms of praise4 ,he calls  
it one of the most beautiful and        
important discoveries1 and regarded it  
as the germ or foundation upon which    
other discoveries were to be made4 ,the 
prediction proved entirely correct1     
,volta himself being the chief          
discoverer4  ,working along lines       
suggested by ,galvani's discovery1      
,volta constructed an apparatus made up 
of a number of disks of two different   
kinds of metal1 such as tin and silver1 
arranged alternately1 a piece of some   
moist1 porous substance1 like paper or  
felt1 being interposed between each pair
 of disks4 ,with this pile1 as it was   
called1 electricity was generated1 and  
by linking together several such piles  
an electric battery could be formed4    
,this invention took the world by storm4
 ,nothing like the enthusiasm it created
 in the philosophic world had been known
 since the invention of the ,leyden jar1
 more than half a century before4       
,within a few weeks after ,volta's      

announcement1 batteries made according  
to his plan were being experimented with
 in every important laboratory in       
,europe4  ,as the century closed1 half  
the philosophic world was speculating as
 to whether galvanic influence were a   
new imponderable1 or only a form of     
electricity2 and the other half was     
eagerly seeking to discover what new    
marvels the battery might reveal4 ,the  
least imaginative man could see that    
here was an invention that would be     
epoch-making1 but the most visionary    
dreamer could not even vaguely adumbrate
 the real measure of its importance4    
,it was evident at once that almost any 
form of galvanic battery1 despite       
imperfections1 was a more satisfactory  
instrument for generating electricity   
than the frictional machine hitherto in 
use1 the advantage lying in the fact    
that the current from the galvanic      
battery could be controlled practically 
at will1 and that the apparatus itself  
was inexpensive and required            

comparatively little attention4 ,these  
advantages were soon made apparent by   
the practical application of the        
electric current in several fields4  ,it
 will be recalled that despite the      
energetic endeavors of such philosophers
 as ,watson1 ,franklin1 ,galvani1 and   
many others1 the field of practical     
application of electricity was very     
limited at the close of the eighteenth  
century4 ,the lightning-rod had come    
into general use1 to be sure1 and its   
value as an invention can hardly be     
overestimated4 ,but while it was the    
result of extensive electrical          
discoveries1 and is a most practical    
instrument1 it can hardly be called one 
that puts electricity to practical use1 
but simply acts as a means of warding   
off the evil effects of a natural       
manifestation of electricity4 ,the      
invention1 however1 had all the effects 
of a mechanism which turned electricity 
to practical account4 ,but with the     
advent of the new kind of electricity   

the age of practical application began4 
,,davy ,,and ,,electric ,,light         
,volta's announcement of his pile was   
scarcely two months old when two        
,englishmen1 ,messrs4 ,nicholson and    
,carlisle1 made the discovery that the  
current from the galvanic battery had a 
decided effect upon certain chemicals1  
among other things decomposing water    
into its elements1 hydrogen and oxygen4 
,on ,may #g1 #ahjj1 these investigators 
arranged the ends of two brass wires    
connected with the poles of a voltaic   
pile1 composed of alternate silver and  
zinc plates1 so that the current coming 
from the pile was discharged through a  
small quantity of ,new ,river water4 ,a 
fine stream of minute bubbles           
immediately began to flow from the point
 of the lower wire in the tube which    
communicated with the silver1 wrote     
,nicholson1 and the opposite point of   
the upper wire became tarnished1 first  
deep orange and then black4444 ,the     
product of gas during two hours and a   

half was two-thirtieths of a cubic inch4
 ,it was then mixed with an equal       
quantity of common air1 continues       
,nicholson1 and exploded by the         
application of a lighted waxen thread4  
,this demonstration was the beginning of
 the very important science of          
electro-chemistry4  ,the importance of  
this discovery was at once recognized by
 ,sir ,humphry ,davy1 who began         
experimenting immediately in this new   
field4 ,he constructed a series of      
batteries in various combinations1 with 
which he attacked the fixed alkalies1   
the composition of which was then       
unknown4 ,very shortly he was able to   
decompose potash into bright metallic   
globules1 resembling quicksilver4 ,this 
new substance he named potassium4 ,then 
in rapid succession the elementary      
substances sodium1 calcium1 strontium1  
and magnesium were isolated4  ,it was   
soon discovered1 also1 that the new     
electricity1 like the old1 possessed    
heating power under certain conditions1 

even to the fusing of pieces of wire4   
,this observation was probably first    
made by ,frommsdorff1 but it was        
elaborated by ,davy1 who constructed a  
battery of two thousand cells with which
 he produced a bright light from points 
of carbon--the prototype of the modern  
arc lamp4 ,he made this demonstration   
before the members of the ,royal        
,institution in #ahaj4 ,but the         
practical utility of such a light for   
illuminating purposes was still a thing 
of the future4 ,the expense of          
constructing and maintaining such an    
elaborate battery1 and the rapid        
internal destruction of its plates1     
together with the constant polarization1
 rendered its use in practical          
illumination out of the question4 ,it   
was not until another method of         
generating electricity was discovered   
that ,davy's demonstration could be     
turned to practical account4  ,in       
,davy's own account of his experiment he
 says3  ,when pieces of charcoal about  

an inch long and one-sixth of an inch in
 diameter were brought near each other  
7within the thirtieth or fortieth of an 
inch71 a bright spark was produced1 and 
more than half the volume of the        
charcoal became ignited to whiteness2   
and1 by withdrawing the points from each
 other1 a constant discharge took place 
through the heated air1 in a space equal
 to at least four inches1 producing a   
most brilliant ascending arch of light1 
broad and conical in form in the middle4
 ,when any substance was introduced into
 this arch1 it instantly became ignited2
 platina melted as readily in it as wax 
in a common candle2 quartz1 the         
sapphire1 magnesia1 lime1 all entered   
into fusion2 fragments of diamond and   
points of charcoal and plumbago seemed  
to evaporate in it1 even when the       
connection was made in the receiver of  
an air-pump2 but there was no evidence  
of their having previously undergone    
fusion4 ,when the communication between 
the points positively and negatively    

electrified was made in the air rarefied
 in the receiver of the air-pump1 the   
distance at which the discharge took    
place increased as the exhaustion was   
made2 and when the atmosphere in the    
vessel supported only one-fourth of an  
inch of mercury in the barometrical     
gauge1 the sparks passed through a space
 of nearly half an inch2 and1 by        
withdrawing the points from each other1 
the discharge was made through six or   
seven inches1 producing a most brilliant
 coruscation of purple light2 the       
charcoal became intensely ignited1 and  
some platina wire attached to it fused  
with brilliant scintillations and fell  
in large globules upon the plate of the 
pump4 ,all the phenomena of chemical    
decomposition were produced with intense
 rapidity by this combination47#a7  ,but
 this experiment demonstrated another   
thing besides the possibility of        
producing electric light and chemical   
decomposition1 this being the heating   
power capable of being produced by the  

electric current4 ,thus ,davy's         
experiment of fusing substances laid the
 foundation of the modern electric      
furnaces1 which are of paramount        
importance in several great commercial  
industries4  ,while some of the results 
obtained with ,davy's batteries were    
practically as satisfactory as could be 
obtained with modern cell batteries1 the
 batteries themselves were anything but 
satisfactory4 ,they were expensive1     
required constant care and attention1   
and1 what was more important from an    
experimental standpoint at least1 were  
not constant in their action except for 
a very limited period of time1 the      
current soon running down4 ,numerous    
experimenters1 therefore1 set about     
devising a satisfactory battery1 and    
when1 in #ahcf1 ,john ,frederick        
,daniell produced the cell that bears   
his name1 his invention was epoch-making
 in the history of electrical progress4 
,the ,royal ,society considered it of   
sufficient importance to bestow the     

,copley medal upon the inventor1 whose  
device is the direct parent of all      
modern galvanic cells4 ,from the time of
 the advent of the ,daniell cell        
experiments in electricity were rendered
 comparatively easy4 ,in the mean while1
 however1 another great discovery was   
made4   ,,electricity ,,and ,,magnetism 
,for many years there had been a growing
 suspicion1 amounting in many instances 
to belief in the close relationship     
existing between electricity and        
magnetism4 ,before the winter of #ahae1 
however1 it was a belief that was       
surmised but not demonstrated4 ,but in  
that year it occurred to ,jean          
,christian ,oersted1 of ,denmark1 to    
pass a current of electricity through a 
wire held parallel with1 but not quite  
touching1 a suspended magnetic needle4  
,the needle was instantly deflected and 
swung out of its position4  ,the first  
experiments in connection with the      
subject which ,i am undertaking to      
explain1 wrote ,oersted1 were made      

during the course of lectures which ,i  
held last winter on electricity and     
magnetism4 ,from those experiments it   
appeared that the magnetic needle could 
be moved from its position by means of a
 galvanic battery--one with a closed    
galvanic circuit4 ,since1 however1 those
 experiments were made with an apparatus
 of small power1 ,i undertook to repeat 
and increase them with a large galvanic 
battery4  ,let us suppose that the two  
opposite ends of the galvanic apparatus 
are joined by a metal wire4 ,this ,i    
shall always call the conductor for the 
sake of brevity4 ,place a rectilinear   
piece of this conductor in a horizontal 
position over an ordinary magnetic      
needle so that it is parallel to it4    
,the magnetic needle will be set in     
motion and will deviate towards the west
 under that part of the conductor which 
comes from the negative pole of the     
galvanic battery4 ,if the wire is not   
more than four-fifths of an inch distant
 from the middle of this needle1 this   

deviation will be about forty-five      
degrees4 ,at a greater distance the     
angle of deviation becomes less4        
,moreover1 the deviation varies         
according to the strength of the        
battery4 ,the conductor can be moved    
towards the east or west1 so long as it 
remains parallel to the needle1 without 
producing any other result than to make 
the deviation smaller4  ,the conductor  
can consist of several combined wires or
 metal coils4 ,the nature of the metal  
does not alter the result except1       
perhaps1 to make it greater or less4 ,we
 have used wires of platinum1 gold1     
silver1 brass1 and iron1 and coils of   
lead1 tin1 and quicksilver with the same
 result4 ,if the conductor is           
interrupted by water1 all effect is not 
cut off1 unless the stretch of water is 
several inches long4  ,the conductor    
works on the magnetic needle through    
glass1 metals1 wood1 water1 and resin1  
through clay vessels and through stone1 
for when we placed a glass plate1 a     

metal plate1 or a board between the     
conductor and the needle the effect was 
not cut off2 even the three together    
seemed hardly to weaken the effect1 and 
the same was the case with an earthen   
vessel1 even when it was full of water4 
,our experiments also demonstrated that 
the said effects were not altered when  
we used a magnetic needle which was in a
 brass case full of water4  ,when the   
conductor is placed in a horizontal     
plane under the magnetic needle all the 
effects we have described take place in 
precisely the same way1 but in the      
opposite direction to what took place   
when the conductor was in a horizontal  
plane above the needle4  ,if the        
conductor is moved in a horizontal plane
 so that it gradually makes             
ever-increasing angles with the magnetic
 meridian1 the deviation of the magnetic
 needle from the magnetic meridian is   
increased when the wire is turned       
towards the place of the needle2 it     
decreases1 on the other hand1 when it is

 turned away from that place4  ,a needle
 of brass which is hung in the same way 
as the magnetic needle is not set in    
motion by the influence of the          
conductor4 ,a needle of glass or rubber 
likewise remains static under similar   
experiments4 ,hence the electrical      
conductor affects only the magnetic     
parts of a substance4 ,that the         
electrical current is not confined to   
the conducting wire1 but is             
comparatively widely diffused in the    
surrounding space1 is sufficiently      
demonstrated from the foregoing         
observations47#b7   ,the effect of      
,oersted's demonstration is almost      
incomprehensible4 ,by it was shown the  
close relationship between magnetism and
 electricity4 ,it showed the way to the 
establishment of the science of         
electrodynamics2 although it was by the 
,french savant ,andre ,marie ,ampere    
7#agge-ahcf7 that the science was       
actually created1 and this within the   
space of one week after hearing of      

,oersted's experiment in deflecting the 
needle4 ,ampere first received the news 
of ,oersted's experiment on ,september  
#aa1 #ahbj1 and on the #ahth of the same
 month he announced to the ,academy the 
fundamental principles of the science of
 electro-dynamics--seven days of rapid  
progress perhaps unequalled in the      
history of science4  ,ampere's          
distinguished countryman1 ,arago1 a few 
months later1 gave the finishing touches
 to ,oersted's and ,ampere's            
discoveries1 by demonstrating           
conclusively that electricity not only  
influenced a magnet1 but actually       
produced magnetism under proper         
circumstances--a complemental fact most 
essential in practical mechanics4  ,some
 four years after ,arago's discovery1   
,sturgeon made the first electro-magnet 
by winding a soft iron core with wire   
through which a current of electricity  
was passed4 ,this study of              
electro-magnets was taken up by         
,professor ,joseph ,henry1 of ,albany1  

,new ,york1 who succeeded in making     
magnets of enormous lifting power by    
winding the iron core with several coils
 of wire4 ,one of these magnets1 excited
 by a single galvanic cell of less than 
half a square foot of surface1 and      
containing only half a pint of dilute   
acids1 sustained a weight of six hundred
 and fifty pounds4  ,thus by ,oersted's 
great discovery of the intimate         
relationship of magnetism and           
electricity1 with further elaborations  
and discoveries by ,ampere1 ,volta1 and 
,henry1 and with the invention of       
,daniell's cell1 the way was laid for   
putting electricity to practical use4   
,soon followed the invention and        
perfection of the electro-magnetic      
telegraph and a host of other but little
 less important devices4   ,,faraday    
,,and ,,electro-,,magnetic ,,induction  
,with these great discoveries and       
inventions at hand1 electricity became  
no longer a toy or a plaything for      
philosophers1 but of enormous and       

growing importance commercially4 ,still1
 electricity generated by chemical      
action1 even in a very perfect cell1 was
 both feeble and expensive1 and1 withal1
 only applicable in a comparatively     
limited field4 ,another important       
scientific discovery was necessary      
before such things as electric traction 
and electric lighting on a large scale  
were to become possible2 but that       
discovery was soon made by ,sir ,michael
 ,faraday4  ,faraday1 the son of a      
blacksmith and a bookbinder by trade1   
had interested ,sir ,humphry ,davy by   
his admirable notes on four of ,davy's  
lectures1 which he had been able to     
attend4 ,although advised by the great  
scientist to stick to his bookbinding   
rather than enter the field of science1 
,faraday became1 at twenty-two years of 
age1 ,davy's assistant in the ,royal    
,institution4 ,there1 for several years1
 he devoted all his spare hours to      
scientific investigations and           
experiments1 perfecting himself in      

scientific technique4  ,a few years     
later he became interested1 like all the
 scientists of the time1 in ,arago's    
experiment of rotating a copper disk    
underneath a suspended compass-needle4  
,when this disk was rotated rapidly1 the
 needle was deflected1 or even rotated  
about its axis1 in a manner quite       
inexplicable4 ,faraday at once conceived
 the idea that the cause of this        
rotation was due to electricity1 induced
 in the revolving disk--not only        
conceived it1 but put his belief in     
writing4 ,for several years1 however1 he
 was unable to demonstrate the truth of 
his assumption1 although he made        
repeated experiments to prove it4 ,but  
in #ahca he began a series of           
experiments that established forever the
 fact of electro-magnetic induction4    
,in his famous paper1 read before the   
,royal ,society in #ahca1 ,faraday      
describes the method by which he first  
demonstrated electro-magnetic induction1
 and then explained the phenomenon of   

,arago's revolving disk4  ,about        
twenty-six feet of copper wire1         
one-twentieth of an inch in diameter1   
were wound round a cylinder of wood as a
 helix1 he said1 the different spires of
 which were prevented from touching by a
 thin interposed twine4 ,this helix was 
covered with calico1 and then a second  
wire applied in the same manner4 ,in    
this way twelve helices were superposed1
 each containing an average length of   
wire of twenty-seven feet1 and all in   
the same direction4 ,the first1 third1  
fifth1 seventh1 ninth1 and eleventh of  
these helices were connected at their   
extremities end to end so as to form one
 helix2 the others were connected in a  
similar manner2 and thus two principal  
helices were produced1 closely          
interposed1 having the same direction1  
not touching anywhere1 and each         
containing one hundred and fifty-five   
feet in length of wire4  ,one of these  
helices was connected with a            
galvanometer1 the other with a voltaic  

battery of ten pairs of plates four     
inches square1 with double coppers and  
well charged2 yet not the slightest     
sensible deflection of the galvanometer 
needle could be observed4  ,a similar   
compound helix1 consisting of six       
lengths of copper and six of soft iron  
wire1 was constructed4 ,the resulting   
iron helix contained two hundred and    
eight feet2 but whether the current from
 the trough was passed through the      
copper or the iron helix1 no effect upon
 the other could be perceived at the    
galvanometer4  ,in these and many       
similar experiments no difference in    
action of any kind appeared between iron
 and other metals4  ,two hundred and    
three feet of copper wire in one length 
were passed round a large block of wood2
 other two hundred and three feet of    
similar wire were interposed as a spiral
 between the turns of the first1 and    
metallic contact everywhere prevented by
 twine4 ,one of these helices was       
connected with a galvanometer and the   

other with a battery of a hundred pairs 
of plates four inches square1 with      
double coppers and well charged4 ,when  
the contact was made1 there was a sudden
 and very slight effect at the          
galvanometer1 and there was also a      
similar slight effect when the contact  
with the battery was broken4 ,but whilst
 the voltaic current was continuing to  
pass through the one helix1 no          
galvanometrical appearances of any      
effect like induction upon the other    
helix could be perceived1 although the  
active power of the battery was proved  
to be great by its heating the whole of 
its own helix1 and by the brilliancy of 
the discharge when made through         
charcoal4  ,repetition of the           
experiments with a battery of one       
hundred and twenty pairs of plates      
produced no other effects2 but it was   
ascertained1 both at this and at the    
former time1 that the slight deflection 
of the needle occurring at the moment of
 completing the connection was always in

 one direction1 and that the equally    
slight deflection produced when the     
contact was broken was in the other     
direction2 and1 also1 that these effects
 occurred when the first helices were   
used4  ,the results which ,i had by this
 time obtained with magnets led me to   
believe that the battery current through
 one wire did1 in reality1 induce a     
similar current through the other wire1 
but that it continued for an instant    
only1 and partook more of the nature of 
the electrical wave passed through from 
the shock of a common ,leyden jar than  
of that from a voltaic battery1 and1    
therefore1 might magnetize a steel      
needle although it scarcely affected the
 galvanometer4  ,this expectation was   
confirmed2 for on substituting a small  
hollow helix1 formed round a glass tube1
 for the galvanometer1 introducing a    
steel needle1 making contact as before  
between the battery and the inducing    
wire1 and then removing the needle      
before the battery contact was broken1  

it was found magnetized4  ,when the     
battery contact was first made1 then an 
unmagnetized needle introduced1 and     
lastly the battery contact broken1 the  
needle was found magnetized to an equal 
degree apparently with the first2 but   
the poles were of the contrary          
kinds47#c7  ,to ,faraday these          
experiments explained the phenomenon of 
,arago's rotating disk1 the disk        
inducing the current from the magnet1   
and1 in reacting1 deflecting the needle4
 ,to prove this1 he constructed a disk  
that revolved between the poles of an   
electro-magnet1 connecting the axis and 
the edge of the disk with a             
galvanometer4 444 ,a disk of copper1    
twelve inches in diameter1 fixed upon a 
brass axis1 he says1 was mounted in     
frames so as to be revolved either      
vertically or horizontally1 its edge    
being at the same time introduced more  
or less between the magnetic poles4 ,the
 edge of the plate was well amalgamated 
for the purpose of obtaining good but   

movable contact2 a part round the axis  
was also prepared in a similar manner4  
,conductors or collectors of copper and 
lead were constructed so as to come in  
contact with the edge of the copper     
disk1 or with other forms of plates     
hereafter to be described4 ,these       
conductors we're about four inches long1
 one-third of an inch wide1 and         
one-fifth of an inch thick2 one end of  
each was slightly grooved1 to allow of  
more exact adaptation to the somewhat   
convex edge of the plates1 and then     
amalgamated4 ,copper wires1             
one-sixteenth of an inch in thickness1  
attached in the ordinary manner by      
convolutions to the other ends of these 
conductors1 passed away to the          
galvanometer4  ,all these arrangements  
being made1 the copper disk was         
adjusted1 the small magnetic poles being
 about one-half an inch apart1 and the  
edge of the plate inserted about half   
their width between them4 ,one of the   
galvanometer wires was passed twice or  

thrice loosely round the brass axis of  
the plate1 and the other attached to a  
conductor1 which itself was retained by 
the hand in contact with the amalgamated
 edge of the disk at the part           
immediately between the magnetic poles4 
,under these circumstances all was      
quiescent1 and the galvanometer         
exhibited no effect4 ,but the instant   
the plate moved the galvanometer was    
influenced1 and by revolving the plate  
quickly the needle could be deflected   
ninety degrees or more47#d7   ,this     
rotating disk was really a dynamo       
electric machine in miniature1 the first
 ever constructed1 but whose direct     
descendants are the ordinary dynamos4   
,modern dynamos range in power from     
little machines operating machinery     
requiring only fractions of a horsepower
 to great dynamos operating street-car  
lines and lighting cities2 but all are  
built on the same principle as          
,faraday's rotating disk4 ,by this      
discovery the use of electricity as a   

practical and economical motive power   
became possible4   ,,storage ,,batteries
  ,when the discoveries of ,faraday of  
electro-magnetic induction had made     
possible the means of easily generating 
electricity1 the next natural step was  
to find a means of storing it or        
accumulating it4 ,this1 however1 proved 
no easy matter1 and as yet a practical  
storage or secondary battery that is    
neither too cumbersome1 too fragile1 nor
 too weak in its action has not been    
invented4 ,if a satisfactory storage    
battery could be made1 it is obvious    
that its revolutionary effects could    
scarcely be overestimated4 ,in the      
single field of aeronautics1 it would   
probably solve the question of aerial   
navigation4 ,little wonder1 then1 that  
inventors have sought so eagerly for the
 invention of satisfactory storage      
batteries4 ,as early as #ahjc ,ritter   
had attempted to make such a secondary  
battery4 ,in #ahdc ,grove also attempted
 it4 ,but it was not until #ahei1 when  

,gaston ,planche produced his invention1
 that anything like a reasonably        
satisfactory storage battery was made4  
,planche discovered that sheets of lead 
immersed in dilute sulphuric acid were  
very satisfactory for the production of 
polarization effects4 ,he constructed a 
battery of sheets of lead immersed in   
sulphuric acid1 and1 after charging     
these for several hours from the cells  
of an ordinary ,bunsen battery1 was able
 to get currents of great strength and  
considerable duration4 ,this battery1   
however1 from its construction of lead1 
was necessarily heavy and cumbersome4   
,faure improved it somewhat by coating  
the lead plates with red-lead1 thus     
increasing the capacity of the cell4    
,faure's invention gave a fresh impetus 
to inventors1 and shortly after the     
market was filled with storage batteries
 of various kinds1 most of them         
modifications of ,planche's or ,faure's4
 ,the ardor of enthusiastic inventors   
soon flagged1 however1 for all these    

storage batteries proved of little      
practical account in the end1 as        
compared with other known methods of    
generating power4  ,three methods of    
generating electricity are in general   
use3 static or frictional electricity is
 generated by plate or static machines2 
galvanic1 generated by batteries based  
on ,volta's discovery2 and induced1 or  
faradic1 generated either by chemical or
 mechanical action4 ,there is still     
another kind1 thermo-electricity1 that  
may be generated in a most simple       
manner4 ,in #ahba ,seebecle1 of ,berlin1
 discovered that when a circuit was     
formed of two wires of different metals1
 if there be a difference in temperature
 at the juncture of these two metals an 
electrical current will be established4 
,in this way heat may be transmitted    
directly into the energy of the current 
without the interposition of the        
steam-engine4 ,batteries constructed in 
this way are of low resistance1 however1
 although by arranging several of them  

in series1 currents of considerable     
strength can be generated4 ,as yet1     
however1 they are of little practical   
importance4  ,about the middle of the   
century ,clerk-,maxwell advanced the    
idea that light waves were really       
electro-magnetic waves4 ,if this were   
true and light proved to be simply one  
form of electrical energy1 then the same
 would be true of radiant heat4 ,maxwell
 advanced this theory1 but failed to    
substantiate it by experimental         
confirmation4 ,but ,dr4 ,heinrich       
,hertz1 a few years later1 by a series  
of experiments1 demonstrated the        
correctness of ,maxwell's surmises4     
,what are now called ,hertzian waves are
 waves apparently identical with light  
waves1 but of much lower pitch or       
period4 ,in his experiments ,hertz      
showed that1 under proper conditions1   
electric sparks between polished balls  
were attended by ether waves of the same
 nature as those of light1 but of a     
pitch of several millions of vibrations 

per second4 ,these waves could be dealt 
with as if they were light              
waves--reflected1 refracted1 and        
polarized4 ,these are the waves that are
 utilized in wireless telegraphy4       
,,roentgen ,,rays1 ,,or ,x-,,rays  ,in  
,december of #ahie word came out of     
,germany of a scientific discovery that 
startled the world4 ,it came first as a 
rumor1 little credited2 then as a       
pronounced report2 at last as a         
demonstration4 ,it told of a new        
manifestation of energy1 in virtue of   
which the interior of opaque objects is 
made visible to human eyes4 ,one had    
only to look into a tube containing a   
screen of a certain composition1 and    
directed towards a peculiar electrical  
apparatus1 to acquire clairvoyant vision
 more wonderful than the discredited    
second-sight of the medium4 ,coins      
within a purse1 nails driven into wood1 
spectacles within a leather case1 became
 clearly visible when subjected to the  
influence of this magic tube2 and when a

 human hand was held before the tube1   
its bones stood revealed in weird       
simplicity1 as if the living1           
palpitating flesh about them were but   
the shadowy substance of a ghost4  ,not 
only could the human eye see these      
astounding revelations1 but the         
impartial evidence of inanimate         
chemicals could be brought forward to   
prove that the mind harbored no         
illusion4 ,the photographic film        
recorded the things that the eye might  
see1 and ghostly pictures galore soon   
gave a quietus to the doubts of the most
 sceptical4 ,within a month of the      
announcement of ,professor ,roentgen's  
experiments comment upon the ,x-ray and 
the new photography had become a part of
 the current gossip of all ,christendom4
  ,it is hardly necessary to say that   
such a revolutionary thing as the       
discovery of a process whereby opaque   
objects became transparent1 or          
translucent1 was not achieved at a      
single bound with no intermediate       

discoveries4 ,in #ahei the ,german      
physicist ,julius ,plucker 7#ahja-ahfh7 
noticed that when there was an          
electrical discharge through an         
exhausted tube at a low pressure1 on the
 surrounding walls of the tube near the 
negative pole1 or cathode1 appeared a   
greenish phosphorescence4 ,this         
discovery was soon being investigated by
 a number of other scientists1 among    
others ,hittorf1 ,goldstein1 and        
,professor 7now ,sir ,william7 ,crookes4
 ,the explanations given of this        
phenomenon by ,professor ,crookes       
concern us here more particularly1      
inasmuch as his views did not accord    
exactly with those held by the other two
 scientists1 and as his researches were 
more directly concerned in the discovery
 of the ,roentgen rays4 ,he held that   
the heat and phosphorescence produced in
 a low-pressure tube were caused by     
streams of particles1 projected from the
 cathode with great velocity1 striking  
the sides of the glass tube4 ,the       

composition of the glass seemed to enter
 into this phosphorescence also1 for    
while lead glass produced blue          
phosphorescence1 soda glass produced a  
yellowish green4 ,the composition of the
 glass seemed to be changed by a        
long-continued pelting of these         
particles1 the phosphorescence after a  
time losing its initial brilliancy1     
caused by the glass becoming tired1 as  
,professor ,crookes said4 ,thus when    
some opaque substance1 such as iron1 is 
placed between the cathode and the sides
 of the glass tube so that it casts a   
shadow in a certain spot on the glass   
for some little time1 it is found on    
removing the opaque substance or        
changing its position that the area of  
glass at first covered by the shadow now
 responded to the rays in a different   
manner from the surrounding glass4  ,the
 peculiar ray's1 now known as the       
cathode rays1 not only cast a shadow1   
but are deflected by a magnet1 so that  
the position of the phosphorescence on  

the sides of the tube may be altered by 
the proximity of a powerful magnet4     
,from this it would seem that the rays  
are composed of particles charged with  
negative electricity1 and ,professor ,j4
 ,j4 ,thomson has modified the          
experiment of ,perrin to show that      
negative electricity is actually        
associated with the rays4 ,there is     
reason for believing1 therefore1 that   
the cathode rays are rapidly moving     
charges of negative electricity4 ,it is 
possible1 also1 to determine the        
velocity at which these particles are   
moving by measuring the deflection      
produced by the magnetic field4  ,from  
the fact that opaque substances cast a  
shadow in these rays it was thought at  
first that all solids were absolutely   
opaque to them4 ,hertz1 however1        
discovered that a small amount of       
phosphorescence occurred on the glass   
even when such opaque substances as     
gold-leaf or aluminium foil were        
interposed between the cathode and the  

sides of the tube4 ,shortly afterwards  
,lenard discovered that the cathode rays
 can be made to pass from the inside of 
a discharge tube to the outside air4    
,for convenience these rays outside the 
tube have since been known as ,lenard   
rays4  ,in the closing days of          
,december1 #ahie1 ,professor ,wilhelm   
,konrad ,roentgen1 of ,wurzburg1        
announced that he had made the discovery
 of the remarkable effect arising from  
the cathode rays to which reference was 
made above4 ,he found that if a plate   
covered with a phosphorescent substance 
is placed near a discharge tube         
exhausted so highly that the cathode    
rays produced a green phosphorescence1  
this plate is made to glow in a peculiar
 manner4 ,the rays producing this glow  
were not the cathode rays1 although     
apparently arising from them1 and are   
what have since been called the         
,roentgen rays1 or ,x-rays4  ,roentgen  
found that a shadow is thrown upon the  
screen by substances held between it and

 the exhausted tube1 the character of   
the shadow depending upon the density of
 the substance4 ,thus metals are almost 
completely opaque to the rays2 such     
substances as bone much less so1 and    
ordinary flesh hardly so at all4 ,if a  
coin were held in the hand that had been
 interposed between the tube and the    
screen the picture formed showed the    
coin as a black shadow2 and the bones of
 the hand1 while casting a distinct     
shadow1 showed distinctly lighter2 while
 the soft tissues produced scarcely any 
shadow at all4 ,the value of such a     
discovery was obvious from the first2   
and was still further enhanced by the   
discovery made shortly that1            
photographic plates are affected by the 
rays1 thus making it possible to make   
permanent photographic records of       
pictures through what we know as opaque 
substances4  ,what adds materially to   
the practical value of ,roentgen's      
discovery is the fact that the apparatus
 for producing the ,x-rays is now so    

simple and relatively inexpensive that  
it is within the reach even of amateur  
scientists4 ,it consists essentially of 
an induction coil attached either to    
cells or a street-current plug for      
generating the electricity1 a focus     
tube1 and a phosphorescence screen4     
,these focus tubes are made in various  
shapes1 but perhaps the most popular are
 in the form of a glass globe1 not      
unlike an ordinary small-sized          
water-bottle1 this tube being closed and
 exhausted1 and having the two poles    
7anode and cathode7 sealed into the     
glass walls1 but protruding at either   
end for attachment to the conducting    
wires from the induction coil4 ,this    
tube may be mounted on a stand at a     
height convenient for manipulation4 ,the
 phosphorescence screen is usually a    
plate covered with some platino-cyanide 
and mounted in the end of a box of      
convenient size1 the opposite end of    
which is so shaped that it fits the     
contour of the face1 shutting out the   

light and allowing the eyes of the      
observer to focalize on the screen at   
the end4 ,for making observations the   
operator has simply to turn on the      
current of electricity and apply the    
screen to his eyes1 pointing it towards 
the glowing tube1 when the shadow of any
 substance interposed between the tube  
and the screen will appear upon the     
phosphorescence plate4  ,the wonderful  
shadow pictures produced on the         
phosphorescence screen1 or the          
photographic plate1 would seem to come  
from some peculiar form of light1 but   
the exact nature of these rays is still 
an open question4 ,whether the ,roentgen
 rays are really a form of light--that  
is1 a form of electro-magnetic          
disturbance propagated through ether1 is
 not fully determined4 ,numerous        
experiments have been undertaken to     
determine this1 but as yet no proof has 
been found that the rays are a form of  
light1 although there appears to be     
nothing in their properties inconsistent

 with their being so4 ,for the moment   
most investigators are content to admit 
that the term ,x-ray virtually begs the 
question as to the intimate nature of   
the form of energy involved4     ,,viii4
 ,,the ,,conservation ,,of ,,energy     
,as we have seen1 it was in #ahca that  
,faraday opened up the field of         
magneto-electricity4 ,reversing the     
experiments of his predecessors1 who had
 found that electric currents may       
generate magnetism1 he showed that      
magnets have power under certain        
circumstances to generate electricity2  
he proved1 indeed1 the                  
interconvertibility of electricity and  
magnetism4 ,then he showed that all     
bodies are more or less subject to the  
influence of magnetism1 and that even   
light may be affected by magnetism as to
 its phenomena of polarization4 ,he     
satisfied himself completely of the true
 identity of all the various forms of   
electricity1 and of the convertibility  
of electricity and chemical action4     

,thus he linked together light1 chemical
 affinity1 magnetism1 and electricity4  
,and1 moreover1 he knew full well that  
no one of these can be produced in      
indefinite supply from another4         
,nowhere1 he says1 is there a pure      
creation or production of power without 
a corresponding exhaustion of something 
to supply it4  ,when ,faraday wrote     
those words in #ahdj he was treading on 
the very heels of a greater             
generalization than any which he        
actually formulated2 nay1 he had it     
fairly within his reach4 ,he saw a great
 truth without fully realizing its      
import2 it was left for others1         
approaching the same truth along another
 path1 to point out its full            
significance4  ,the great generalization
 which ,faraday so narrowly missed is   
the truth which since then has become   
familiar as the doctrine of the         
conservation of energy--the law that in 
transforming energy from one condition  
to another we can never secure more than

 an equivalent quantity2 that1 in short1
 to create or annihilate energy is as   
impossible as to create or annihilate   
matter2 and that all the phenomena of   
the material universe consist in        
transformations of energy alone4 ,some  
philosophers think this the greatest    
generalization ever conceived by the    
mind of man4 ,be that as it may1 it is  
surely one of the great intellectual    
landmarks of the nineteenth century4 ,it
 stands apart1 so stupendous and so     
far-reaching in its implications that   
the generation which first saw the law  
developed could little appreciate it2   
only now1 through the vista of half a   
century1 do we begin to see it in its   
true proportions4  ,a vast              
generalization such as this is never a  
mushroom growth1 nor does it usually    
spring full grown from the mind of any  
single man4 ,always a number of minds   
are very near a truth before any one    
mind fully grasps it4 ,pre-eminently    
true is this of the doctrine of the     

conservation of energy4 ,not ,faraday   
alone1 but half a dozen different men   
had an inkling of it before it gained   
full expression2 indeed1 every man who  
advocated the undulatory theory of light
 and heat was verging towards the goal4 
,the doctrine of ,young and ,fresnel was
 as a highway leading surely on to the  
wide plain of conservation4 ,the        
phenomena of electro-magnetism furnished
 another such highway4 ,but there was   
yet another road which led just as      
surely and even more readily to the same
 goal4 ,this was the road furnished by  
the phenomena of heat1 and the men who  
travelled it were destined to outstrip  
their fellow-workers2 though1 as we have
 seen1 wayfarers on other roads were    
within hailing distance when the leaders
 passed the mark4  ,in order to do even 
approximate justice to the men who      
entered into the great achievement1 we  
must recall that just at the close of   
the eighteenth century ,count ,rumford  
and ,humphry ,davy independently showed 

that labor may be transformed into heat2
 and correctly interpreted this fact as 
meaning the transformation of molar into
 molecular motion4 ,we can hardly doubt 
that each of these men of genius        
realized--vaguely1 at any rate--that    
there must be a close correspondence    
between the amount of the molar and the 
molecular motions2 hence that each of   
them was in sight of the law of the     
mechanical equivalent of heat4 ,but     
neither of them quite grasped or        
explicitly stated what each must vaguely
 have seen2 and for just a quarter of a 
century no one else even came abreast   
their line of thought1 let alone passing
 it4  ,but then1 in #ahbd1 a ,french    
philosopher1 ,sadi ,carnot1 caught step 
with the great ,englishmen1 and took a  
long leap ahead by explicitly stating   
his belief that a definite quantity of  
work could be transformed into a        
definite quantity of heat1 no more1 no  
less4 ,carnot did not1 indeed1 reach the
 clear view of his predecessors as to   

the nature of heat1 for he still thought
 it a form of imponderable fluid2 but he
 reasoned none the less clearly as to   
its mutual convertibility with          
mechanical work4 ,but important as his  
conclusions seem now that we look back  
upon them with clearer vision1 they made
 no impression whatever upon his        
contemporaries4 ,carnot's work in this  
line was an isolated phenomenon of      
historical interest1 but it did not     
enter into the scheme of the completed  
narrative in any such way as did the    
work of ,rumford and ,davy4  ,the man   
who really took up the broken thread    
where ,rumford and ,davy had dropped it1
 and wove it into a completed texture1  
came upon the scene in #ahdj4 ,his home 
was in ,manchester1 ,england2 his       
occupation that of a manufacturer4 ,he  
was a friend and pupil of the great ,dr4
 ,dalton4 ,his name was ,james ,prescott
 ,joule4 ,when posterity has done its   
final juggling with the names of the    
nineteenth century1 it is not unlikely  

that the name of this ,manchester       
philosopher will be a household word1   
like the names of ,aristotle1           
,copernicus1 and ,newton4  ,for ,joule's
 work it was1 done in the fifth decade  
of the century1 which demonstrated      
beyond all cavil that there is a precise
 and absolute equivalence between       
mechanical work and heat2 that whatever 
the form of manifestation of molar      
motion1 it can generate a definite and  
measurable amount of heat1 and no more4 
,joule found1 for example1 that at the  
sea-level in ,manchester a pound weight 
falling through seven hundred and       
seventy-two feet could generate enough  
heat to raise the temperature of a pound
 of water one degree ,fahrenheit4 ,there
 was nothing haphazard1 nothing         
accidental1 about this2 it bore the     
stamp of unalterable law4 ,and ,joule   
himself saw1 what others in time were   
made to see1 that this truth is merely a
 particular case within a more general  
law4 ,if heat cannot be in any sense    

created1 but only made manifest as a    
transformation of another kind of       
motion1 then must not the same thing be 
true of all those other forms of        
force--light1 electricity1              
magnetism--which had been shown to be so
 closely associated1 so mutually        
convertible1 with heat8 ,all analogy    
seemed to urge the truth of this        
inference2 all experiment tended to     
confirm it4 ,the law of the mechanical  
equivalent of heat then became the main 
corner-stone of the greater law of the  
conservation of energy4  ,but while this
 citation is fresh in mind1 we must turn
 our attention with all haste to a      
country across the ,channel--to         
,denmark1 in short--and learn that even 
as ,joule experimented with the         
transformation of heat1 a philosopher of
 ,copenhagen1 ,colding by name1 had hit 
upon the same idea1 and carried it far  
towards a demonstration4 ,and then1     
without pausing1 we must shift yet      
again1 this time to ,germany1 and       

consider the work of three other men1   
who independently were on the track of  
the same truth1 and two of whom1 it must
 be admitted1 reached it earlier than   
either ,joule or ,colding1 if neither   
brought it to quite so clear a          
demonstration4 ,the names of these three
 ,germans are ,mohr1 ,mayer1 and        
,helmholtz4 ,their share in establishing
 the great doctrine of conservation must
 now claim our attention4  ,as to ,karl 
,friedrich ,mohr1 it may be said that   
his statement of the doctrine preceded  
that of any of his fellows1 yet that    
otherwise it was perhaps least          
important4 ,in #ahcg this thoughtful    
,german had grasped the main truth1 and 
given it expression in an article       
published in the ,zeitschrift fur       
,physik1 etc4 ,but the article attracted
 no attention whatever1 even from       
,mohr's own countrymen4 ,still1 ,mohr's 
title to rank as one who independently  
conceived the great truth1 and perhaps  
conceived it before any other man in the

 world saw it as clearly1 even though he
 did not demonstrate its validity1 is   
not to be disputed4  ,it was just five  
years later1 in #ahdb1 that ,dr4 ,julius
 ,robert ,mayer1 practising physician in
 the little ,german town of ,heilbronn1 
published a paper in ,liebig's ,annalen 
on ,the ,forces of ,inorganic ,nature1  
in which not merely the mechanical      
theory of heat1 but the entire doctrine 
of the conservation of energy1 is       
explicitly if briefly stated4 ,two years
 earlier ,dr4 ,mayer1 while surgeon to a
 ,dutch ,india vessel cruising in the   
tropics1 had observed that the venous   
blood of a patient seemed redder than   
venous blood usually is observed to be  
in temperate climates4 ,he pondered over
 this seemingly insignificant fact1 and 
at last reached the conclusion that the 
cause must be the lesser amount of      
oxidation required to keep up the body  
temperature in the tropics4 ,led by this
 reflection to consider the body as a   
machine dependent on outside forces for 

its capacity to act1 he passed on into a
 novel realm of thought1 which brought  
him at last to independent discovery of 
the mechanical theory of heat1 and to   
the first full and comprehensive        
appreciation of the great law of        
conservation4 ,blood-letting1 the modern
 physician holds1 was a practice of very
 doubtful benefit1 as a rule1 to the    
subject2 but once1 at least1 it led to  
marvellous results4 ,no straw is go     
small that it may not point the         
receptive mind of genius to new and     
wonderful truths4   ,,mayer',s ,,paper  
,,of #ahdb  ,the paper in which ,mayer  
first gave expression to his            
revolutionary ideas bore the title of   
,the ,forces of ,inorganic ,nature1 and 
was published in #ahdb4 ,it is one of   
the gems of scientific literature1 and  
fortunately it is not too long to be    
quoted in its entirety4 ,seldom if ever 
was a great revolutionary doctrine      
expounded in briefer compass3  ,what are
 we to understand by 'forces'8 and how  

are different forces related to each    
other8 ,the term force conveys for the  
most part the idea of something unknown1
 unsearchable1 and hypothetical2 while  
the term matter1 on the other hand1     
implies the possession1 by the object in
 question1 of such definite properties  
as weight and extension4 ,an attempt1   
therefore1 to render the idea of force  
equally exact with that of matter is one
 which should be welcomed by all those  
who desire to have their views of nature
 clear and unencumbered by hypothesis4  
,forces are causes2 and accordingly we  
may make full application in relation to
 them of the principle causa aequat     
effectum4 ,if the cause c has the effect
 e1 then c  e2 if1 in its turn1 e is the
 cause of a second effect of f1 we have 
e  f1 and so on3 c  e  f444  c4 ,in a   
series of causes and effects1 a term or 
a part of a term can never1 as is       
apparent from the nature of an equation1
 become equal to nothing4 ,this first   
property of all causes we call their    

indestructibility4  ,if the given cause 
c has produced an effect e equal to     
itself1 it has in that very act ceased  
to be--c has become e4 ,if1 after the   
production of e1 c still remained in the
 whole or in part1 there must be still  
further effects corresponding to this   
remaining cause3 the total effect of c  
would thus be  e1 which would be        
contrary to the supposition c  e4       
,accordingly1 since c becomes e1 and e  
becomes f1 etc41 we must regard these   
various magnitudes as different forms   
under which one and the same object     
makes its appearance4 ,this capability  
of assuming various forms is the second 
essential property of all causes4       
,taking both properties together1 we may
 say1 causes an ,,indestructible        
quantitatively1 and quantitatively      
,,convertible objects4  ,there occur in 
nature two causes which apparently never
 pass one into the other1 said ,mayer4  
,the first class consists of such causes
 as possess the properties of weight and

 impenetrability4 ,these are kinds of   
matter4 ,the other class is composed of 
causes which are wanting in the         
properties just mentioned--namely1      
forces1 called also imponderables1 from 
the negative property that has been     
indicated4 ,forces are therefore        
,,indestructible1 ,,convertible1        
,,imponderable ,,objects4  ,as an       
example of causes and effects1 take     
matter3 explosive gas1 ,h  ,o1 and      
water1 ,,ho1 are related to each other  
as cause and effect2 therefore ,h  ,o   
,,ho4 ,but if ,h  ,o becomes ,,ho1 heat1
 cal41 makes its appearance as well as  
water2 this heat must likewise have a   
cause1 x1 and we have therefore ,h  ,o  
,x  ,,ho  cal4 ,it might be asked1      
however1 whether ,h  ,o is really  ,,ho1
 and x  cal41 and not perhaps ,h  ,o    
cal41 and x  ,,ho1 whence the above     
equation could equally be deduced2 and  
so in many other cases4 ,the phlogistic 
chemists recognized the equation between
 cal4 and x1 or phlogiston as they      

called it1 and in so doing made a great 
step in advance2 but they involved      
themselves again in a system of mistakes
 by putting x in place of ,o4 ,in this  
way they obtained ,h  ,,ho  x4          
,chemistry teaches us that matter1 as a 
cause1 has matter for its effect2 but we
 may say with equal justification that  
to force as a cause corresponds force as
 effect4 ,since c  e1 and e  c1 it is   
natural to call one term of an equation 
a force1 and the other an effect of     
force1 or phenomenon1 and to attach     
different notions to the expression     
force and phenomenon4 ,in brief1 then1  
if the cause is matter1 the effect is   
matter2 if the cause is a force1 the    
effect is also a force4  ,the cause that
 brings about the raising of a weight is
 a force4 ,the effect of the raised     
weight is1 therefore1 also a force2 or1 
expressed in a more general form1       
,,separation ,,in ,,space ,,of          
,,ponderable ,,objects ,,is ,a ,,force2 
and since this force causes the fall of 

bodies1 we call it ,,falling ,,force4   
,falling force and fall1 or1 still more 
generally1 falling force and motion1 are
 forces related to each other as cause  
and effect--forces convertible into each
 other--two different forms of one and  
the same object4 ,for example1 a weight 
resting on the ground is not a force3 it
 is neither the cause of motion nor of  
the lifting of another weight4 ,it      
becomes so1 however1 in proportion as it
 is raised above the ground4 ,the       
cause--that is1 the distance between a  
weight and the earth1 and the effect1 or
 the quantity of motion produced1 bear  
to each other1 as shown by mechanics1 a 
constant relation4  ,gravity being      
regarded as the cause of the falling of 
bodies1 a gravitating force is spoken   
of2 and thus the ideas of ,,property and
 of ,,force are confounded with each    
other4 ,precisely that which is the     
essential attribute of every force--that
 is1 the ,,union of indestructibility   
with convertibility--is wanting in every

 property3 between a property and a     
force1 between gravity and motion1 it is
 therefore impossible to establish the  
equation required for a rightly         
conceived causal relation4 ,if gravity  
be called a force1 a cause is supposed  
which produces effects without itself   
diminishing1 and incorrect conceptions  
of the causal connections of things are 
thereby fostered4 ,in order that a body 
may fall1 it is just as necessary that  
it be lifted up as that it should be    
heavy or possess gravity4 ,the fall of  
bodies1 therefore1 ought not to be      
ascribed to their gravity alone4 ,the   
problem of mechanics is to develop the  
equations which subsist between falling 
force and motion1 motion and falling    
force1 and between different motions4   
,here is a case in point3 ,the magnitude
 of the falling force v is directly     
proportional 7the earth's radius being  
assumed--oo7 to the magnitude of the    
mass m1 and the height d1 to which it is
 raised--that is1 v  md4 ,if the height 

d  l1 to which the mass m is raised1 is 
transformed into the final velocity c  l
 of this mass1 we have also v  mc2 but  
from the known relations existing       
between d and c1 it results that1 for   
other values of d or of c1 the measure  
of the force v is mc squared2           
accordingly v  md  mcsquared4 ,the law  
of the conservation of vis viva is thus 
found to be based on the general law of 
the indestructibility of causes4  ,in   
many cases we see motion cease without  
having caused another motion or the     
lifting of a weight4 ,but a force once  
in existence cannot be annihilated--it  
can only change its form4 ,and the      
question therefore arises1 what other   
forms is force1 which we have become    
acquainted with as falling force and    
motion1 capable of assuming8 ,experience
 alone can lead us to a conclusion on   
this point4 ,that we may experiment to  
advantage1 we must select implements    
which1 besides causing a real cessation 
of motion1 are as little as possible    

altered by the objects to be examined4  
,for example1 if we rub together two    
metal plates1 we see motion disappear1  
and heat1 on the other hand1 make its   
appearance1 and there remains to be     
determined only whether ,,motion is the 
cause of heat4 ,in order to reach a     
decision on this point1 we must discuss 
the question whether1 in the numberless 
cases in which the expenditure of motion
 is accompanied by the appearance of    
heat1 the motion has not some other     
effect than the production of heat1 and 
the heat some other cause than the      
motion4  ,a serious attempt to ascertain
 the effects of ceasing motion has never
 been made4 ,without wishing to exclude 
a priori the hypothesis which it may be 
possible to establish1 therefore1 we    
observe only that1 as a rule1 this      
effect cannot be supposed to be an      
alteration in the state of aggregation  
of the moved 7that is1 rubbing1 etc47   
bodies4 ,if we assume that a certain    
quantity of motion v is expended in the 

conversion of a rubbing substance m into
 n1 we must then have m  v - n1 and n  m
  v2 and when n is reconverted into m1 v
 must appear again in some form or      
other4  ,by the friction of two metallic
 plates continued for a very long time1 
we can gradually cause the cessation of 
an immense quantity of movement2 but    
would it ever occur to us to look for   
even the smallest trace of the force    
which has disappeared in the metallic   
dust that we could collect1 and to try  
to regain it thence8 ,we repeat1 the    
motion cannot have been annihilated2 and
 contrary1 or positive and negative1    
motions cannot be regarded as  o any    
more than contrary motions can come out 
of nothing1 or a weight can raise       
itself4  ,without the recognition of a  
causal relation between motion and heat1
 it is just as difficult to explain the 
production of heat as it is to give any 
account of the motion that disappears4  
,the heat cannot be derived from the    
diminution of the volume of the rubbing 

substances4 ,it is well known that two  
pieces of ice may be melted by rubbing  
them together in vacuo2 but let any one 
try to convert ice into water by        
pressure1 however enormous4 ,the author 
has found that water undergoes a rise of
 temperature when shaken violently4 ,the
 water so heated 7from twelve to        
thirteen degrees centigrade7 has a      
greater bulk after being shaken than it 
had before4 ,whence now comes this      
quantity of heat1 which by repeated     
shaking may be called into existence in 
the same apparatus as often as we       
please8 ,the vibratory hypothesis of    
heat is an approach towards the doctrine
 of heat being the effect of motion1 but
 it does not favor the admission of this
 causal relation in its full generality4
 ,it rather lays the chief stress on    
restless oscillations4  ,if it be       
considered as now established that in   
many cases no other effect of motion can
 be traced except heat1 and that no     
other cause than motion can be found for

 the heat that is produced1 we prefer   
the assumption that heat proceeds from  
motion to the assumption of a cause     
without effect and of an effect without 
a cause4 ,just as the chemist1 instead  
of allowing oxygen and hydrogen to      
disappear without further investigation1
 and water to be produced in some       
inexplicable manner1 establishes a      
connection between oxygen and hydrogen  
on the one hand1 and water on the other4
  ,we may conceive the natural          
connection existing between falling     
force1 motion1 and heat as follows3 ,we 
know that heat makes its appearance when
 the separate particles of a body       
approach nearer to each other2          
condensation produces heat4 ,and what   
applies to the smallest particles of    
matter1 and the smallest intervals      
between them1 must also apply to large  
masses and to measurable distances4 ,the
 falling of a weight is a diminution of 
the bulk of the earth1 and must         
therefore without doubt be related to   

the quantity of heat thereby developed2 
this quantity of heat must be           
proportional to the greatness of the    
weight and its distance from the ground4
 ,from this point of view we are easily 
led to the equations between falling    
force1 motion1 and heat that have       
already been discussed4  ,but just as   
little as the connection between falling
 force and motion authorizes the        
conclusion that the essence of falling  
force is motion1 can such a conclusion  
be adopted in the case of heat4 ,we are1
 on the contrary1 rather inclined to    
infer that1 before it can become heat1  
motion must cease to exist as motion1   
whether simple1 or vibratory1 as in the 
case of light and radiant heat1 etc4    
,if falling force and motion are        
equivalent to heat1 heat must also      
naturally be equivalent to motion and   
falling force4 ,just as heat appears as 
an ,,effect of the diminution of bulk   
and of the cessation of motion1 so also 
does heat disappear as a ,,cause when   

its effects are produced in the shape of
 motion1 expansion1 or raising of       
weight4  ,in water-mills the continual  
diminution in bulk which the earth      
undergoes1 owing to the fall of the     
water1 gives rise to motion1 which      
afterwards disappears again1 calling    
forth unceasingly a great quantity of   
heat2 and1 inversely1 the steam-engine  
serves to decompose heat again into     
motion or the raising of weights4 ,a    
locomotive with its train may be        
compared to a distilling apparatus2 the 
heat applied under the boiler passes off
 as motion1 and this is deposited again 
as heat at the axles of the wheels4     
,mayer then closes his paper with the   
following deduction3 ,the solution of   
the equations subsisting between falling
 force and motion requires that the     
space fallen through in a given time--e4
 g41 the first second--should be        
experimentally determined4 ,in like     
manner1 the solution of the equations   
subsisting between falling force and    

motion on the one hand and heat on the  
other requires an answer to the         
question1 ,how great is the quantity of 
heat which corresponds to a given       
quantity of motion or falling force8    
,for instance1 we must ascertain how    
high a given weight requires to be      
raised above the ground in order that   
its falling force maybe equivalent to   
the raising of the temperature of an    
equal weight of water from #j degrees to
 #a degrees centigrade4 ,the attempt to 
show that such an equation is the       
expression of a physical truth may be   
regarded as the substance of the        
foregoing remarks4  ,by applying the    
principles that have been set forth to  
the relations subsisting between the    
temperature and the volume of gases1 we 
find that the sinking of a mercury      
column by which a gas is compressed is  
equivalent to the quantity of heat set  
free by the compression2 and hence it   
follows1 the ratio between the capacity 
for heat of air under constant pressure 

and its capacity under constant volume  
being taken as  #a4dba1 that the warming
 of a given weight of water from #j     
degrees to  equal weight from the height
 of about three hundred and sixty-five  
metres4 ,if we compare with this result 
the working of our best steam-engines1  
we see how small a part only of the heat
 applied under the boiler is really     
transformed into motion or the raising  
of weights2 and this may serve as       
justification for the attempts at the   
profitable production of motion by some 
other method than the expenditure of the
 chemical difference between carbon and 
oxygen--more particularly by the        
transformation into motion of           
electricity obtained by chemical        
means47#a7   ,,mayer ,,and ,,helmholtz  
,here1 then1 was this obscure ,german   
physician1 leading the humdrum life of a
 village practitioner1 yet seeing such  
visions as no human being in the world  
had ever seen before4  ,the great       
principle he had discovered became the  

dominating thought of his life1 and     
filled all his leisure hours4 ,he       
applied it far and wide1 amid all the   
phenomena of the inorganic and organic  
worlds4 ,it taught him that both        
vegetables and animals are machines1    
bound by the same laws that hold sway   
over inorganic matter1 transforming     
energy1 but creating nothing4 ,then his 
mind reached out into space and met a   
universe made up of questions4 ,each    
star that blinked down at him as he rode
 in answer to a night-call seemed an    
interrogation-point asking1 ,how do ,i  
exist8 ,why have ,i not long since      
burned out if your theory of            
conservation be true8 ,no one had       
hitherto even tried to answer that      
question2 few had so much as realized   
that it demanded an answer4 ,but the    
,heilbronn physician understood the     
question and found an answer4 ,his      
meteoric hypothesis1 published in #ahdh1
 gave for the first time a tenable      
explanation of the persistent light and 

heat of our sun and the myriad other    
suns--an explanation to which we shall  
recur in another connection4  ,all this 
time our isolated philosopher1 his brain
 aflame with the glow of creative       
thought1 was quite unaware that any one 
else in the world was working along the 
same lines4 ,and the outside world was  
equally heedless of the work of the     
,heilbronn physician4 ,there was no     
friend to inspire enthusiasm and give   
courage1 no kindred spirit to react on  
this masterful but lonely mind4 ,and    
this is the more remarkable because     
there are few other cases where a       
master-originator in science has come   
upon the scene except as the pupil or   
friend of some other master-originator4 
,of the men we have noticed in the      
present connection1 ,young was the      
friend and confrere of ,davy2 ,davy1 the
 protege of ,rumford2 ,faraday1 the     
pupil of ,davy2 ,fresnel1 the co-worker 
with ,arago2 ,colding1 the confrere of  
,oersted2 ,joule1 the pupil of ,dalton4 

,but ,mayer is an isolated              
phenomenon--one of the lone             
mountain-peak intellects of the century4
 ,that estimate may be exaggerated which
 has called him the ,galileo of the     
nineteenth century1 but surely no       
lukewarm praise can do him justice4     
,yet for a long time his work attracted 
no attention whatever4 ,in #ahdg1 when  
another ,german physician1 ,hermann von 
,helmholtz1 one of the most massive and 
towering intellects of any age1 had been
 independently led to comprehension of  
the doctrine of the conservation of     
energy and published his treatise on the
 subject1 he had hardly heard of his    
countryman ,mayer4 ,when he did hear of 
him1 however1 he hastened to renounce   
all claim to the doctrine of            
conservation1 though the world at large 
gives him credit of independent even    
though subsequent discovery4            
,,joule',s ,,paper ,,of #ahdc           
,meantime1 in ,england1 ,joule was going
 on from one experimental demonstration 

to another1 oblivious of his ,german    
competitors and almost as little noticed
 by his own countrymen4 ,he read his    
first paper before the chemical section 
of the ,british ,association for the    
,advancement of ,science in #ahdc1 and  
no one heeded it in the least4 ,it is   
well worth our while1 however1 to       
consider it at length4 ,it bears the    
title1 ,on the ,calorific ,effects of   
,magneto-,electricity1 and the          
,mechanical ,value of ,heat4 ,the full  
text1 as published in the ,report of the
 ,british ,association1 is as follows3  
,although it has been long known that   
fine platinum wire can be ignited by    
magneto-electricity1 it still remained a
 matter of doubt whether heat was       
evolved by the ,,coils in which the     
magneto-electricity was generated2 and  
it seemed indeed not unreasonable to    
suppose that ,,cold was produced there  
in order to make up for the heat evolved
 by the other part of the circuit4 ,the 
author therefore has endeavored to clear

 up this uncertainty by experiment4 ,his
 apparatus consisted of a small compound
 electro-magnet1 immersed in water1     
revolving between the poles of a        
powerful stationary magnet4 ,the        
magneto-electricity developed in the    
coils of the revolving electro-magnet   
was measured by an accurate             
galvanometer2 and the temperature of the
 water was taken before and after each  
experiment by a very delicate           
thermometer4 ,the influence of the      
temperature of the surrounding          
atmospheric air was guarded against by  
covering the revolving tube with        
flannel1 etc41 and by the adoption of a 
system of interpolation4 ,by an         
extensive series of experiments with the
 above apparatus the author succeeded in
 proving that heat is evolved by the    
coils of the magneto-electrical machine1
 as well as by any other part of the    
circuit1 in proportion to the resistance
 to conduction of the wire and the      
square of the current2 the magneto      

having1 under comparable circumstances1 
the same calorific power as the voltaic 
electricity4  ,professor ,jacobi1 of    
,st4 ,petersburg1 bad shown that the    
motion of an electro-magnetic machine   
generates magneto-electricity in        
opposition to the voltaic current of the
 battery4 ,the author had observed the  
same phenomenon on arranging his        
apparatus as an electro-magnetic        
machine2 but had found that no          
additional heat was evolved on account  
of the conflict of forces in the coil of
 the electro-magnet1 and that the heat  
evolved by the coil remained1 as before1
 proportional to the square of the      
current4 ,again1 by turning the machine 
contrary to the direction of the        
attractive forces1 so as to increase the
 intensity of the voltaic current by the
 assistance of the magneto-electricity1 
he found that the evolution of heat was 
still proportional to the square of the 
current4 ,the author discovered1        
therefore1 that the heat evolved by the 

voltaic current is invariably           
proportional to the square of the       
current1 however the intensity of the   
current may be varied by magnetic       
induction4 ,but ,dr4 ,faraday has shown 
that the chemical effects of the current
 are simply as its quantity4 ,therefore 
he concluded that in the                
electro-magnetic engine a part of the   
heat due to the chemical actions of the 
battery is lost by the circuit1 and     
converted into mechanical power2 and    
that when the electro-magnetic engine is
 turned ,,contrary to the direction of  
the attractive forces1 a greater        
quantity of heat is evolved by the      
circuit than is due to the chemical     
reactions of the battery1 the over-plus 
quantity being produced by the          
conversion of the mechanical force      
exerted in turning the machine4 ,by a   
dynamometrical apparatus attached to his
 machine1 the author has ascertained    
that1 in all the above cases1 a quantity
 of heat1 capable of increasing the     

temperature of a pound of water by one  
degree of ,fahrenheit's scale1 is equal 
to the mechanical force capable of      
raising a weight of about eight hundred 
and thirty pounds to the height of one  
foot47#b7   ,,joule ,,or ,,mayer8  ,two 
years later ,joule wished to read       
another paper1 but the chairman hinted  
that time was limited1 and asked him to 
confine himself to a brief verbal       
synopsis of the results of his          
experiments4 ,had the chairman but known
 it1 he was curtailing a paper vastly   
more important than all the other papers
 of the meeting put together4 ,however1 
the synopsis was given1 and one man was 
there to hear it who had the genius to  
appreciate its importance4 ,this was    
,william ,thomson1 the present ,lord    
,kelvin1 now known to all the world as  
among the greatest of natural           
philosophers1 but then only a novitiate 
in science4 ,he came to ,joule's aid1   
started rolling the ball of controversy1
 and subsequently associated himself    

with the ,manchester experimenter in    
pursuing his investigations4  ,but      
meantime the acknowledged leaders of    
,british science viewed the new doctrine
 askance4 ,faraday1 ,brewster1          
,herschel--those were the great names in
 physics at that day1 and no one of them
 could quite accept the new views       
regarding energy4 ,for several years no 
older physicist1 speaking with          
recognized authority1 came forward in   
support of the doctrine of conservation4
 ,this culminating thought of the first 
half of the nineteenth century came     
silently into the world1 unheralded and 
unopposed4 ,the fifth decade of the     
century had seen it elaborated and      
substantially demonstrated in at least  
three different countries1 yet even the 
leaders of thought did not so much as   
know of its existence4 ,in #ahec        
,whewell1 the historian of the inductive
 sciences1 published a second edition of
 his history1 and1 as ,huxley has       
pointed out1 he did not so much as refer

 to the revolutionizing thought which   
even then was a full decade old4  ,by   
this time1 however1 the battle was      
brewing4 ,the rising generation saw the 
importance of a law which their elders  
could not appreciate1 and soon it was   
noised abroad that there were more than 
one claimant to the honor of discovery4 
,chiefly through the efforts of         
,professor ,tyndall1 the work of ,mayer 
became known to the ,british public1 and
 a most regrettable controversy ensued  
between the partisans of ,mayer and     
those of ,joule--a bitter controversy1  
in which ,davy's contention that science
 knows no country was not always        
regarded1 and which left its scars upon 
the hearts and minds of the great men   
whose personal interests were involved4 
,and so to this day the question who is 
the chief discoverer of the law of the  
conservation of energy is not           
susceptible of a categorical answer that
 would satisfy all philosophers4 ,it is 
generally held that the first choice    

lies between ,joule and ,mayer4         
,professor ,tyndall has expressed the   
belief that in future each of these men 
will be equally remembered in connection
 with this work4 ,but history gives us  
no warrant for such a hope4 ,posterity  
in the long run demands always that its 
heroes shall stand alone4 ,who remembers
 now that ,robert ,hooke contested with 
,newton the discovery of the doctrine of
 universal gravitation8 ,the judgment of
 posterity is unjust1 but it is         
inexorable4 ,and so we can little doubt 
that a century from now one name will be
 mentioned as that of the originator of 
the great doctrine of the conservation  
of energy4 ,the man whose name is thus  
remembered will perhaps be spoken of as 
the ,galileo1 the ,newton1 of the       
nineteenth century2 but whether the name
 thus dignified by the final verdict of 
history will be that of ,colding1 ,mohr1
 ,mayer1 ,helmholtz1 or ,joule1 is not  
as1 yet decided4   ,,lord ,,kelvin ,,and
 ,,the ,,dissipation ,,of ,,energy  ,the

 gradual permeation of the field by the 
great doctrine of conservation simply   
repeated the history of the introduction
 of every novel and revolutionary       
thought4 ,necessarily the elder         
generation1 to whom all forms of energy 
were imponderable fluids1 must pass away
 before the new conception could claim  
the field4 ,even the word energy1 though
 ,young had introduced it in #ahjg1 did 
not come into general use till some time
 after the middle of the century4 ,to   
the generality of philosophers 7the word
 physicist was even less in favor at    
this time7 the various forms of energy  
were still subtile fluids1 and never was
 idea relinquished with greater         
unwillingness than this4 ,the           
experiments of ,young and ,fresnel had  
convinced a large number of philosophers
 that light is a vibration and not a    
substance2 but so great an authority as 
,biot clung to the old emission idea to 
the end of his life1 in #ahfb1 and held 
a following4  ,meantime1 however1 the   

company of brilliant young men who had  
just served their apprenticeship when   
the doctrine of conservation came upon  
the scene had grown into authoritative  
positions1 and were battling actively   
for the new ideas4 ,confirmatory        
evidence that energy is a molecular     
motion and not an imponderable form of  
matter accumulated day by day4 ,the     
experiments of two ,frenchmen1          
,hippolyte ,l4 ,fizeau and ,leon        
,foucault1 served finally to convince   
the last lingering sceptics that light  
is an undulation2 and by implication    
brought heat into the same category1    
since ,james ,david ,forbes1 the ,scotch
 physicist1 had shown in #ahcg that     
radiant heat conforms to the same laws  
of polarization and double refraction   
that govern light4 ,but1 for that       
matter1 the experiments that had        
established the mechanical equivalent of
 heat hardly left room for doubt as to  
the immateriality of this imponderable4 
,doubters had indeed1 expressed         

scepticism as to the validity of        
,joule's experiments1 but the further   
researches1 experimental and            
mathematical1 of such workers as        
,thomson 7,lord ,kelvin71 ,rankine1 and 
,tyndall in ,great ,britain1 of         
,helmholtz and ,clausius in ,germany1   
and of ,regnault in ,france1 dealing    
with various manifestations of heat1    
placed the evidence beyond the reach of 
criticism4  ,out of these studies1 just 
at the middle of the century1 to which  
the experiments of ,mayer and ,joule had
 led1 grew the new science of           
thermo-dynamics4 ,out of them also grew 
in the mind of one of the investigators 
a new generalization1 only second in    
importance to the doctrine of           
conservation itself4 ,professor ,william
 ,thomson 7,lord ,kelvin7 in his studies
 in thermodynamics was early impressed  
with the fact that whereas all the molar
 motion developed through labor or      
gravity could be converted into heat1   
the process is not fully reversible4    

,heat can1 indeed1 be converted into    
molar motion or work1 but in the process
 a certain amount of the heat is        
radiated into space and lost4 ,the same 
thing happens whenever any other form of
 energy is converted into molar motion4 
,indeed1 every transmutation of energy1 
of whatever character1 seems complicated
 by a tendency to develop heat1 part of 
which is lost4 ,this observation led    
,professor ,thomson to his doctrine of  
the dissipation of energy1 which he     
formulated before the ,royal ,society of
 ,edinburgh in #aheb1 and published also
 in the ,philosophical ,magazine the    
same year1 the title borne being1 ,on a 
,universal ,tendency in ,nature to the  
,dissipation of ,mechanical ,energy4    
,from the principle here expressed      
,professor ,thomson drew the startling  
conclusion that1 since any restoration  
of this mechanical energy without more  
than an equivalent dissipation is       
impossible1 the universe1 as known to   
us1 must be in the condition of a       

machine gradually running down2 and in  
particular that the world we live on has
 been within a finite time unfit for    
human habitation1 and must again become 
so within a finite future4 ,this thought
 seems such a commonplace to-day that it
 is difficult to realize how startling  
it appeared half a century ago4 ,a      
generation trained1 as ours has been1 in
 the doctrines of the conservation and  
dissipation of energy as the very       
alphabet of physical science can but ill
 appreciate the mental attitude of a    
generation which for the most part had  
not even thought it problematical       
whether the sun could continue to give  
out heat and light forever4 ,but those  
advance thinkers who had grasped the    
import of the doctrine of conservation  
could at once appreciate the force of   
,thomson's doctrine of dissipation1 and 
realize the complementary character of  
the two conceptions4  ,here and there a 
thinker like ,rankine did1 indeed1      
attempt to fancy conditions under which 

the energy lost through dissipation     
might be restored to availability1 but  
no such effort has met with success1 and
 in time ,professor ,thomson's          
generalization and his conclusions as to
 the consequences of the law involved   
came to be universally accepted4  ,the  
introduction of the new views regarding 
the nature of energy followed1 as ,i    
have said1 the course of every other    
growth of new ideas4 ,young and         
imaginative men could accept the new    
point of view2 older philosophers1 their
 minds channelled by preconceptions1    
could not get into the new groove4 ,so  
strikingly true is this in the          
particular case now before us that it is
 worth while to note the ages at the    
time of the revolutionary experiments of
 the men whose work has been mentioned  
as entering into the scheme of evolution
 of the idea that energy is merely a    
manifestation of matter in motion4 ,such
 a list will tell the story better than 
a volume of commentary4  ,observe1 then1

 that ,davy made his epochal experiment 
of melting ice by friction when he was a
 youth of twenty4 ,young was no older   
when he made his first communication to 
the ,royal ,society1 and was in his     
twenty-seventh year when he first       
actively espoused the undulatory theory4
 ,fresnel was twenty-six when he made   
his first important discoveries in the  
same field2 and ,arago1 who at once     
became his champion1 was then but two   
years his senior1 though for a decade he
 had been so famous that one            
involuntarily thinks of him as belonging
 to an elder generation4  ,forbes was   
under thirty when he discovered the     
polarization of heat1 which pointed the 
way to ,mohr1 then thirty-one1 to the   
mechanical equivalent4 ,joule was       
twenty-two in #ahdj1 when his great work
 was begun2 and ,mayer1 whose           
discoveries date from the same year1 was
 then twenty-six1 which was also the age
 of ,helmholtz when he published his    
independent discovery of the same law4  

,william ,thomson was a youth just past 
his majority when he came to the aid of 
,joule before the ,british ,society1 and
 but seven years older when he          
formulated his own doctrine of the      
dissipation of energy4 ,and ,clausius   
and ,rankine1 who are usually mentioned 
with ,thomson as the great developers of
 thermo-dynamics1 were both far advanced
 with their novel studies before they   
were thirty4 ,with such a list in mind1 
we may well agree with the father of    
inductive science that the man who is   
young in years may be old in hours4     
,yet we must not forget that the shield 
has a reverse side4 ,for was not the    
greatest of observing astronomers1      
,herschel1 past thirty-five before he   
ever saw a telescope1 and past fifty    
before he discovered the heat rays of   
the spectrum8 ,and had not ,faraday     
reached middle life before he turned his
 attention especially to electricity8   
,clearly1 then1 to make this phrase     
complete1 ,bacon should have added that 

the man who is old in years may be young
 in imagination4 ,here1 however1 even   
more appropriate than in the other      
case--more's the pity--would have been  
the application of his qualifying       
clause3 but that happeneth rarely4      
,,the ,,final ,,unification  ,there are 
only a few great generalizations as yet 
thought out in any single field of      
science4 ,naturally1 then1 after a great
 generalization has found definitive    
expression1 there is a period of lull   
before another forward move4 ,in the    
case of the doctrines of energy1 the    
lull has lasted half a century4         
,throughout this period1 it is true1 a  
multitude of workers have been delving  
in the field1 and to the casual observer
 it might seem as if their activity had 
been boundless1 while the practical     
applications of their ideas--as         
exemplified1 for example1 in the        
telephone1 phonograph1 electric light1  
and so on--have been little less than   
revolutionary4 ,yet the most competent  

of living authorities1 ,lord ,kelvin1   
could assert in #ahie that in fifty     
years he had learned nothing new        
regarding the nature of energy4  ,this1 
however1 must not be interpreted as     
meaning that the world has stood still  
during these two generations4 ,it means 
rather that the rank and file have been 
moving forward along the road the       
leaders had already travelled4 ,only a  
few men in the world had the range of   
thought regarding the new doctrine of   
energy that ,lord ,kelvin had at the    
middle of the century4 ,the few leaders 
then saw clearly enough that if one form
 of energy is in reality merely an      
undulation or vibration among the       
particles of ponderable matter or of    
ether1 all other manifestations of      
energy must be of the same nature4 ,but 
the rank and file were not even within  
sight of this truth for a long time     
after they had partly grasped the       
meaning of the doctrine of conservation4
 ,when1 late in the fifties1 that       

marvellous young ,scotchman1 ,james     
,clerk-,maxwell1 formulating in other   
words an idea of ,faraday's1 expressed  
his belief that electricity and         
magnetism are but manifestations of     
various conditions of stress and motion 
in the ethereal medium 7electricity a   
displacement of strain1 magnetism a     
whirl in the ether71 the idea met with  
no immediate popularity4 ,and even less 
cordial was the reception given the same
 thinker's theory1 put forward in #ahfc1
 that the ethereal undulations producing
 the phenomenon we call light differ in 
no respect except in their wave-length  
from the pulsations of                  
electro-magnetism4  ,at about the same  
time ,helmholtz formulated a somewhat   
similar electro-magnetic theory of      
light2 but even the weight of this      
combined authority could not give the   
doctrine vogue until very recently1 when
 the experiments of ,heinrich ,hertz1   
the pupil of ,helmholtz1 have shown that
 a condition of electrical strain may be

 developed into a wave system by        
recurrent interruptions of the electric 
state in the generator1 and that such   
waves travel through the ether with the 
rapidity of light4 ,since then the      
electro-magnetic theory of light has    
been enthusiastically referred to as the
 greatest generalization of the century2
 but the sober thinker must see that it 
is really only what ,hertz himself      
called it--one pier beneath the great   
arch of conservation4 ,it is an         
interesting detail of the architecture1 
but the part cannot equal the size of   
the whole4  ,more than that1 this       
particular pier is as yet by no means a 
very firm one4 ,it has1 indeed1 been    
demonstrated that waves of              
electro-magnetism pass through space    
with the speed of light1 but as yet no  
one has developed electric waves even   
remotely approximating the shortness of 
the visual rays4 ,the most that can     
positively be asserted1 therefore1 is   
that all the known forms of radiant     

energy-heat1 light1                     
electro-magnetism--travel through space 
at the same rate of speed1 and consist  
of traverse vibrations--lateral quivers1
 as ,fresnel said of light--known to    
differ in length1 and not positively    
known to differ otherwise4 ,it has1     
indeed1 been suggested that the newest  
form of radiant energy1 the famous      
,x-ray of ,professor ,roentgen's        
discovery1 is a longitudinal vibration1 
but this is a mere surmise4 ,be that as 
it may1 there is no one now to question 
that all forms of radiant energy1       
whatever their exact affinities1 consist
 essentially of undulatory motions of   
one uniform medium4  ,a full century of 
experiment1 calculation1 and controversy
 has thus sufficed to correlate the     
imponderable fluids of our forebears1   
and reduce them all to manifestations of
 motion among particles of matter4 ,at  
first glimpse that seems an enormous    
change of view4 ,and yet1 when closely  
considered1 that change in thought is   

not so radical as the change in phrase  
might seem to imply4 ,for the           
nineteenth-century physicist1 in        
displacing the imponderable fluids of   
many kinds--one each for light1 heat1   
electricity1 magnetism--has been obliged
 to substitute for them one             
all-pervading fluid1 whose various      
quivers1 waves1 ripples1 whirls or      
strains produce the manifestations which
 in popular parlance are termed forms of
 force4 ,this all-pervading fluid the   
physicist terms the ether1 and he thinks
 of it as having no weight4 ,in effect1 
then1 the physicist has dispossessed the
 many imponderables in favor of a single
 imponderable--though the word          
imponderable has been banished from his 
vocabulary4 ,in this view the           
ether--which1 considered as a recognized
 scientific verity1 is essentially a    
nineteenth-century discovery--is about  
the most interesting thing in the       
universe4 ,something more as to its     
properties1 real or assumed1 we shall   

have occasion to examine as we turn to  
the obverse side of physics1 which      
demands our attention in the next       
chapter4     ,,ix4 ,,the ,,ether ,,and  
,,ponderable ,,matter   ,whatever       
difficulties we may have in forming a   
consistent idea of the constitution of  
the ether1 there can be no doubt that   
the interplanetary and interstellar     
spaces are not empty1 but are occupied  
by a material substance or body which is
 certainly the largest and probably the 
most uniform body of which we have any  
knowledge4  ,such was the verdict       
pronounced some thirty years ago by     
,james ,clerk-,maxwell1 one of the very 
greatest of nineteenth-century          
physicists1 regarding the existence of  
an all-pervading plenum in the universe1
 in which every particle of tangible    
matter is immersed4 ,and this verdict   
may be said to express the attitude of  
the entire philosophical world of our   
day4 ,without exception1 the            
authoritative physicists of our time    

accept this plenum as a verity1 and     
reason about it with something of the   
same confidence they manifest in        
speaking of ponderable matter or of1    
energy4 ,it is true there are those     
among them who are disposed to deny that
 this all-pervading plenum merits the   
name of matter4 ,but that it is a       
something1 and a vastly important       
something at that1 all are agreed4      
,without it1 they allege1 we should know
 nothing of light1 of radiant heat1 of  
electricity or magnetism2 without it    
there would probably be no such thing as
 gravitation2 nay1 they even hint that  
without this strange something1 ether1  
there would be no such thing as matter  
in the universe4 ,if these contentions  
of the modern physicist are justified1  
then this intangible ether is           
incomparably the most important as well 
as the largest and most uniform         
substance or body in the universe4 ,its 
discovery may well be looked upon as one
 of the most important feats of the     

nineteenth century4  ,for a discovery of
 that century it surely is1 in the sense
 that all the known evidences of its    
existence were gathered in that epoch4  
,true dreamers of all ages have1 for    
metaphysical reasons1 imagined the      
existence of intangible fluids in       
space--they had1 indeed1 peopled space  
several times over with different kinds 
of ethers1 as ,maxwell remarks--but such
 vague dreamings no more constituted the
 discovery of the modern ether than the 
dream of some pre-,columbian visionary  
that land might lie beyond the unknown  
waters constituted the discovery of     
,america4 ,in justice it must be        
admitted that ,huyghens1 the            
seventeenth-century originator of the   
undulatory theory of light1 caught a    
glimpse of the true ether2 but his      
contemporaries and some eight           
generations of his successors were      
utterly deaf to his claims2 so he bears 
practically the same relation to the    
nineteenth-century discoverers of ether 

that the ,norseman bears to ,columbus4  
,the true ,columbus of the ether was    
,thomas ,young4 ,his discovery was      
consummated in the early days of the    
nineteenth century1 when he brought     
forward the first1 conclusive proofs of 
the undulatory theory of light4 ,to say 
that light consists of undulations is to
 postulate something that undulates2 and
 this something could not be air1 for   
air exists only in infinitesimal        
quantity1 if at all1 in the interstellar
 spaces1 through which light freely     
penetrates4 ,but if not air1 what then8 
,why1 clearly1 something more intangible
 than air2 something supersensible1     
evading all direct efforts to detect it1
 yet existing everywhere in seemingly   
vacant space1 and also interpenetrating 
the substance of all transparent liquids
 and solids1 if not1 indeed1 of all     
tangible substances4 ,this intangible   
something ,young rechristened the       
,luminiferous ,ether4  ,in the early    
days of his discovery ,young thought of 

the undulations which produce light and 
radiant heat as being longitudinal--a   
forward and backward pulsation1         
corresponding to the pulsations of      
sound--and as such pulsations can be    
transmitted by a fluid medium with the  
properties of ordinary fluids1 he was   
justified in thinking of the ether as   
being like a fluid in its properties1   
except for its extreme intangibility4   
,but about #ahah the experiments of     
,fresnel and ,arago with polarization of
 light made it seem very doubtful       
whether the theory of longitudinal      
vibrations is sufficient1 and it was    
suggested by ,young1 and independently  
conceived and demonstrated by ,fresnel1 
that the luminiferous undulations are   
not longitudinal1 but transverse2 and   
all the more recent experiments have    
tended to confirm this view4 ,but it    
happens that ordinary fluids--gases and 
liquids--cannot transmit lateral        
vibrations2 only rigid bodies are       
capable of such a vibration4 ,so it     

became necessary to assume that the     
luminiferous ether is a body possessing 
elastic rigidity--a familiar property of
 tangible solids1 but one quite unknown 
among fluids4  ,the idea of transverse  
vibrations carried with it another      
puzzle4 ,why does not the ether1 when   
set aquiver with the vibration which    
gives us the sensation we call light1   
have produced in its substance          
subordinate quivers1 setting out at     
right angles from the path of the       
original quiver8 ,such perpendicular    
vibrations seem not to exist1 else we   
might see around a corner2 how explain  
their absence8 ,the physicist could     
think of but one way3 they must assume  
that the ether is incompressible4 ,it   
must fill all space--at any rate1 all   
space with which human knowledge        
deals--perfectly full4  ,these          
properties of the ether1                
incompressibility and elastic rigidity1 
are quite conceivable by themselves2 but
 difficulties of thought appear when we 

reflect upon another quality which the  
ether clearly must possess--namely1     
frictionlessness4 ,by hypothesis this   
rigid1 incompressible body pervades all 
space1 imbedding every particle of      
tangible matter2 yet it seems not to    
retard the movements of this matter in  
the slightest degree4 ,this is          
undoubtedly the most difficult to       
comprehend of the alleged properties of 
the ether4 ,the physicist explains it as
 due to the perfect elasticity of the   
ether1 in virtue of which it closes in  
behind a moving particle with a push    
exactly counterbalancing the stress     
required to penetrate it in front4  ,to 
a person unaccustomed to think of       
seemingly solid matter as really        
composed of particles relatively wide   
apart1 it is hard to understand the     
claim that ether penetrates the         
substance of solids--of glass1 for      
example--and1 to use ,young's           
expression1 which we have previously    
quoted1 moves among them as freely as   

the wind moves through a grove of trees4
 ,this thought1 however1 presents few   
difficulties to the mind accustomed to  
philosophical speculation4 ,but the     
question early arose in the mind of     
,fresnel whether the ether is not       
considerably affected by contact with   
the particles of solids4 ,some of his   
experiments led him to believe that a   
portion of the ether which penetrates   
among the molecules of tangible matter  
is held captive1 so to speak1 and made  
to move along with these particles4 ,he 
spoke of such portions of the ether as  
bound ether1 in contradistinction to the
 great mass of free ether4 ,half a      
century after ,fresnel's death1 when the
 ether hypothesis had become an accepted
 tenet of science1 experiments were     
undertaken by ,fizeau in ,france1 and by
 ,clerk-,maxwell in ,england1 to        
ascertain whether any portion of ether  
is really thus bound to particles of    
matter2 but the results of the          
experiments were negative1 and the      

question is still undetermined4  ,while 
the undulatory theory of light was still
 fighting its way1 another kind of      
evidence favoring the existence of an   
ether was put forward by ,michael       
,faraday1 who1 in the course of his     
experiments in electrical and magnetic  
induction1 was led more and more to     
perceive definite lines or channels of  
force in the medium subject to          
electro-magnetic influence4 ,faraday's  
mind1 like that of ,newton and many     
other philosophers1 rejected the idea of
 action at a distance1 and he felt      
convinced that the phenomena of         
magnetism and of electric induction told
 strongly for the existence of an       
invisible plenum everywhere in space1   
which might very probably be the same   
plenum that carries the undulations of  
light and radiant heat4  ,then1 about   
the middle of the century1 came that    
final revolution of thought regarding   
the nature of energy which we have      
already outlined in the preceding       

chapter1 and with that the case for     
ether was considered to be fully        
established4 ,the idea that energy is   
merely a mode of motion 7to adopt       
,tyndall's familiar phrase71 combined   
with the universal rejection of the     
notion of action at a distance1 made the
 acceptance of a plenum throughout space
 a necessity of thought--so1 at any     
rate1 it has seemed to most physicists  
of recent decades4 ,the proof that all  
known forms of radiant energy move      
through space at the same rate of speed 
is regarded as practically a            
demonstration that but one plenum--one  
ether--is concerned in their            
transmission4 ,it has1 indeed1 been     
tentatively suggested1 by ,professor ,j4
 ,oliver ,lodge1 that there may be two  
ethers1 representing the two opposite   
kinds of electricity1 but even the      
author of this hypothesis would hardly  
claim for it a high degree of           
probability4  ,the most recent          
speculations regarding the properties of

 the ether have departed but little from
 the early ideas of ,young and ,fresnel4
 ,it is assumed on all sides that the   
ether is a continuous1 incompressible   
body1 possessing rigidity and           
elasticity4 ,lord ,kelvin has even      
calculated the probable density of this 
ether1 and its coefficient of rigidity4 
,as might be supposed1 it is all but    
infinitely tenuous as compared with any 
tangible solid1 and its rigidity is but 
infinitesimal as compared with that of  
steel4 ,in a word1 it combines          
properties of tangible matter in a way  
not known in any tangible substance4    
,therefore we cannot possibly conceive  
its true condition correctly4 ,the      
nearest approximation1 according to     
,lord ,kelvin1 is furnished by a mould  
of transparent jelly4 ,it is a crude1   
inaccurate analogy1 of course1 the      
density and resistance of jelly in      
particular being utterly different from 
those of the ether2 but the quivers that
 run through the jelly when it is       

shaken1 and the elastic tension under   
which it is placed when its mass is     
twisted about1 furnish some analogy to  
the quivers and strains in the ether1   
which are held to constitute radiant    
energy1 magnetism1 and electricity4     
,the great physicists of the day being  
at one regarding the existence of this  
all-pervading ether1 it would be a      
manifest presumption for any one        
standing without the pale to challenge  
so firmly rooted a belief4 ,and1 indeed1
 in any event1 there seems little ground
 on which to base such a challenge4 ,yet
 it may not be altogether amiss to      
reflect that the physicist of to-day is 
no more certain of his ether than was   
his predecessor of the eighteenth       
century of the existence of certain     
alleged substances which he called      
phlogiston1 caloric1 corpuscles of      
light1 and magnetic and electric fluids4
 ,it would be but the repetition of     
history should it chance that before the
 close of another century the ether     

should have taken its place along with  
these discarded creations of the        
scientific imagination of earlier       
generations4 ,the philosopher of to-day 
feels very sure that an ether exists2   
but when he says there is no doubt of   
its existence he speaks incautiously1   
and steps beyond the bounds of          
demonstration4 ,he does not ,,know that 
action cannot take place at a distance2 
he does not ,,know that empty space     
itself may not perform the functions    
which he ascribes to his space-filling  
ether4  ,meantime1 however1 the ether1  
be it substance or be it only           
dream-stuff1 is serving an admirable    
purpose in furnishing a fulcrum for     
modern physics4 ,not alone to the       
student of energy has it proved         
invaluable1 but to the student of matter
 itself as well4 ,out of its            
hypothetical mistiness has been reared  
the most tenable theory of the          
constitution of ponderable matter which 
has yet been suggested--or1 at any rate1

 the one that will stand as the         
definitive nineteenth-century guess at  
this riddle of the ages4 ,i mean1 of    
course1 the vortex theory of atoms--that
 profound and fascinating doctrine which
 suggests that matter1 in all its       
multiform phases1 is neither more nor   
less than ether in motion4  ,the author 
of this wonderful conception is ,lord   
,kelvin4 ,the idea was born in his mind 
of a happy union of mathematical        
calculations with concrete experiments4 
,the mathematical calculations were     
largely the work of ,hermann von        
,helmholtz1 who1 about the year #aheh1  
had undertaken to solve some unique     
problems in vortex motions4 ,helmholtz  
found that a vortex whirl1 once         
established in a frictionless medium1   
must go on1 theoretically1 unchanged    
forever4 ,in a limited medium such a    
whirl may be ,v-shaped1 with its ends at
 the surface of the medium4 ,we may     
imitate such a vortex by drawing the    
bowl of a spoon quickly through a cup of

 water4 ,but in a limitless medium the  
vortex whirl must always be a closed    
ring1 which may take the simple form of 
a hoop or circle1 or which may be       
indefinitely contorted1 looped1 or1 so  
to speak1 knotted4 ,whether simple or   
contorted1 this endless chain of        
whirling matter 7the particles revolving
 about the axis of the loop as the      
particles of a string revolve when the  
string is rolled between the fingers7   
must1 in a frictionless medium1 retain  
its form and whirl on with undiminished 
speed forever4  ,while these theoretical
 calculations of ,helmholtz were fresh  
in his mind1 ,lord ,kelvin 7then ,sir   
,william ,thomson7 was shown by         
,professor ,p4 ,g4 ,tait1 of ,edinburgh1
 an apparatus constructed for the       
purpose of creating vortex rings in air4
 ,the apparatus1 which any one may      
duplicate1 consisted simply of a box    
with a hole bored in one side1 and a    
piece of canvas stretched across the    
opposite side in lieu of boards4 ,fumes 

of chloride of ammonia are generated    
within the box1 merely to render the air
 visible4 ,by tapping with the band on  
the canvas side of the box1 vortex rings
 of the clouded air are driven out1     
precisely similar in appearance to those
 smoke-rings which some expert          
tobacco-smokers can produce by tapping  
on their cheeks1 or to those larger ones
 which we sometimes see blown out from  
the funnel of a locomotive4  ,the       
advantage of ,professor ,tait's         
apparatus is its manageableness and the 
certainty with which the desired result 
can be produced4 ,before ,lord ,kelvin's
 interested observation it threw out    
rings of various sizes1 which moved     
straight across the room at varying     
rates of speed1 according to the initial
 impulse1 and which behaved very        
strangely when coming in contact with   
one another4 ,if1 for example1 a rapidly
 moving ring overtook another moving in 
the same path1 the one in advance seemed
 to pause1 and to spread out its        

periphery like an elastic band1 while   
the pursuer seemed to contract1 till it 
actually slid through the orifice of the
 other1 after which each ring resumed   
its original size1 and continued its    
course as if nothing had happened4      
,when1 on the other hand1 two rings     
moving in slightly different directions 
came near each other1 they seemed to    
have an attraction for each other2 yet  
if they impinged1 they bounded away1    
quivering like elastic solids4 ,if an   
effort were made to grasp or to cut one 
of these rings1 the subtle thing shrank 
from the contact1 and slipped away as if
 it were alive4  ,and all the while the 
body which thus conducted itself        
consisted simply of a whirl in the air1 
made visible1 but not otherwise         
influenced1 by smoky fumes4 ,presently  
the friction of the surrounding air wore
 the ring away1 and it faded into the   
general atmosphere--often1 however1 not 
until it had persisted for many seconds1
 and passed clear across a large room4  

,clearly1 if there were no friction1 the
 ring's inertia must make it a permanent
 structure4 ,only the frictionless      
medium was lacking to fulfil all the    
conditions of ,helmholtz's              
indestructible vortices4 ,and at once   
,lord ,kelvin bethought him of the      
frictionless medium which physicists had
 now begun to accept--the all-pervading 
ether4 ,what if vortex rings were       
started in this ether1 must they not    
have the properties which the vortex    
rings in air had exhibited--inertia1    
attraction1 elasticity8 ,and are not    
these the properties of ordinary        
tangible matter8 ,is it not probable1   
then1 that what we call matter consists 
merely of aggregations of infinitesimal 
vortex rings in the ether8  ,thus the   
vortex theory of atoms took form in     
,lord ,kelvin's mind1 and its expression
 gave the world what many philosophers  
of our time regard as the most plausible
 conception of the constitution of      
matter hitherto formulated4 ,it is only 

a theory1 to be sure2 its author would  
be the last person to claim finality for
 it4 ,it is only a dream1 ,lord ,kelvin 
said to me1 in referring to it not long 
ago4 ,but it has a basis in mathematical
 calculation and in analogical          
experiment such as no other theory of   
matter can lay claim to1 and it has a   
unifying or monistic tendency that makes
 it1 for the philosophical mind1 little 
less than fascinating4 ,true or false1  
it is the definitive theory of matter of
 the twentieth century4  ,quite aside   
from the question of the exact          
constitution of the ultimate particles  
of matter1 questions as to the          
distribution of such particles1 their   
mutual relations1 properties1 and       
actions1 came in for a full share of    
attention during the nineteenth century1
 though the foundations for the modern  
speculations were furnished in a        
previous epoch4 ,the most popular       
eighteenth-century speculation as to the
 ultimate constitution of matter was    

that of the learned ,italian priest1    
,roger ,joseph ,boscovich1 published in 
#ageh1 in his ,theoria ,philosophiae    
,naturalis4 ,in this theory1 according  
to an early commentator1 the whole mass 
of which the bodies of the universe are 
composed is supposed to consist of an   
exceedingly great yet finite number of  
simple1 indivisible1 inextended atoms4  
,these atoms are endued by the ,creator 
with ,,repulsive and ,,attractive       
forces1 which vary according to the     
distance4 ,at very small distances the  
particles of matter repel each other2   
and this repulsive force increases      
beyond all limits as the distances are  
diminished1 and will consequently       
forever prevent actual contact4 ,when   
the particles of matter are removed to  
sensible distances1 the repulsive is    
exchanged for an attractive force1 which
 decreases in inverse ratio with the    
squares of the distances1 and extends   
beyond the spheres of the most remote   
comets4  ,this conception of the atom as

 a mere centre of force was hardly such 
as could satisfy any mind other than the
 metaphysical4 ,no one made a           
conspicuous attempt to improve upon the 
idea1 however1 till just at the close of
 the century1 when ,humphry ,davy was   
led1 in the course of his studies of    
heat1 to speculate as to the changes    
that occur in the intimate substance of 
matter under altered conditions of      
temperature4 ,davy1 as we have seen1    
regarded heat as a manifestation of     
motion among the particles of matter4   
,as all bodies with which we come in    
contact have some temperature1 ,davy    
inferred that the intimate particles of 
every substance must be perpetually in a
 state of vibration4 ,such vibrations1  
he believed1 produced the repulsive     
force which 7in common with ,boscovich7 
he admitted as holding the particles of 
matter at a distance from one another4  
,to heat a substance means merely to    
increase the rate of vibration of its   
particles2 thus also1 plainly1          

increasing the repulsive forces and     
expanding the bulk of the mass as a     
whole4 ,if the degree of heat applied be
 sufficient1 the repulsive force may    
become strong enough quite to overcome  
the attractive force1 and the particles 
will separate and tend to fly away from 
one another1 the solid then becoming a  
gas4  ,not much attention was paid to   
these very suggestive ideas of ,davy1   
because they were founded on the idea   
that heat is merely a motion1 which the 
scientific world then repudiated2 but   
half a century later1 when the new      
theories of energy had made their way1  
there came a revival of practically the 
same ideas of the particles of matter   
7molecules they were now called7 which  
,davy had advocated4 ,then it was that  
,clausius in ,germany and               
,clerk-,maxwell in ,england took up the 
investigation of what came to be known  
as the kinetic theory of gases--the now 
familiar conception that all the        
phenomena of gases are due to the       

helter-skelter flight of the showers of 
widely separated molecules of which they
 are composed4 ,the specific idea that  
the pressure or spring of gases is due  
to such molecular impacts was due to    
,daniel ,bournelli1 who advanced it     
early in the eighteenth century4 ,the   
idea1 then little noticed1 had been     
revived about a century later by        
,william ,herapath1 and again with some 
success by ,j4 ,j4 ,waterston1 of       
,bombay1 about #ahdf2 but it gained no  
distinct footing until taken in hand by 
,clausius in #aheg and by               
,clerk-,maxwell in #ahei4  ,the         
considerations that led ,clerk-,maxwell 
to take up the computations may be      
stated in his own words1 as formulated  
in a paper ,on the ,motions and         
,collisions of ,perfectly ,elastic      
,spheres4  ,so many of the properties of
 matter1 especially when in the gaseous 
form1 he says1 can be deduced from the  
hypothesis that their minute parts are  
in rapid motion1 the velocity increasing

 with the temperature1 that the precise 
nature of this motion becomes a subject 
of rational curiosity4 ,daniel          
,bournelli1 ,herapath1 ,joule1 ,kronig1 
,clausius1 etc41 have shown that the    
relations between pressure1 temperature1
 and density in a perfect gas can be    
explained by supposing the particles to 
move with uniform velocities in straight
 lines1 striking against the sides of   
the containing vessel and thus producing
 pressure4 ,it is not necessary to      
suppose each particle to travel to any  
great distance in the same straight     
line2 for the effect in producing       
pressure will be the same if the        
particles strike against each other2 so 
that the straight line described may be 
very short4 ,m4 ,clausius has determined
 the mean length of path in terms of the
 average of the particles1 and the      
distance between the centres of two     
particles when the collision takes      
place4 ,we have at present no means of  
ascertaining either of these distances2 

but certain phenomena1 such as the      
internal friction of gases1 the         
conduction of heat through a gas1 and   
the diffusion of one gas through        
another1 seem to indicate the           
possibility of determining accurately   
the mean length of path which a particle
 describes between two successive       
collisions4 ,in order to lay the        
foundation of such investigations on    
strict mechanical principles1 ,i shall  
demonstrate the laws of motion of an    
indefinite number of small1 hard1 and   
perfectly elastic spheres acting on one 
another only during impact4 ,if the     
properties of such a system of bodies   
are found to correspond to those of     
gases1 an important physical analogy    
will be established1 which may lead to  
more accurate knowledge of the          
properties of matter4 ,if experiments on
 gases are inconsistent with the        
hypothesis of these propositions1 then  
our theory1 though consistent with      
itself1 is proved to be incapable of    

explaining the phenomena of gases4 ,in  
either case it is necessary to follow   
out these consequences of the           
hypothesis4  ,instead of saying that the
 particles are hard1 spherical1 and     
elastic1 we may1 if we please1 say the  
particles are centres of force1 of which
 the action is insensible except at a   
certain very small distance1 when it    
suddenly appears as a repulsive force of
 very great intensity4 ,it is evident   
that either assumption will lead to the 
same results4 ,for the sake of avoiding 
the repetition of a long phrase about   
these repulsive bodies1 ,i shall proceed
 upon the assumption of perfectly       
elastic spherical bodies4 ,if we suppose
 those aggregate molecules which move   
together to have a bounding surface     
which is not spherical1 then the        
rotatory motion of the system will close
 up a certain proportion of the whole   
vis viva1 as has been shown by          
,clausius1 and in this way we may       
account for the value of the specific   

heat being greater than on the more     
simple hypothesis47#a7   ,the elaborate 
investigations of ,clerk-,maxwell served
 not merely to substantiate the         
doctrine1 but threw a flood of light    
upon the entire subject of molecular    
dynamics4 ,soon the physicists came to  
feel as certain of the existence of     
these showers of flying molecules making
 up a gas as if they could actually see 
and watch their individual actions4     
,through study of the viscosity of      
gases--that is to say1 of the degree of 
frictional opposition they show to an   
object moving through them or to another
 current of gas--an idea was gained1    
with the aid of mathematics1 of the rate
 of speed at which the particles of the 
gas are moving1 and the number of       
collisions which each particle must     
experience in a given time1 and of the  
length of the average free path         
traversed by the molecule between       
collisions1 ,these measurements were    
confirmed by study of the rate of       

diffusion at which different gases mix  
together1 and also by the rate of       
diffusion of heat through a gas1 both   
these phenomena being chiefly due to the
 helter-skelter flight of the molecules4
  ,it is sufficiently astonishing to be 
told that such measurements as these    
have been made at all1 but the          
astonishment grows when one hears the   
results4 ,it appears from               
,clerk-,maxwell's calculations that the 
mean free path1 or distance traversed by
 the molecules between collisions in    
ordinary air1 is about                  
one-half-millionth of an inch2 while the
 speed of the molecules is such that    
each one experiences about eight        
billions of collisions per second6 ,it  
would be hard1 perhaps1 to cite an      
illustration showing the refinements of 
modern physics better than this2 unless1
 indeed1 one other result that followed 
directly from these calculations be     
considered such--the feat1 namely1 of   
measuring the size of the molecules     

themselves4 ,clausius was the first to  
point out how this might be done from a 
knowledge of the length of free path2   
and the calculations were made by       
,loschmidt in ,germany and by ,lord     
,kelvin in ,england1 independently4     
,the work is purely mathematical1 of    
course1 but the results are regarded as 
unassailable2 indeed1 ,lord ,kelvin     
speaks of them as being absolutely      
demonstrative within certain limits of  
accuracy4 ,this does not mean1 however1 
that they show the exact dimensions of  
the molecule2 it means an estimate of   
the limits of size within which the     
actual size of the molecule may lie4    
,these limits1 ,lord ,kelvin estimates1 
are about the one-ten-millionth of a    
centimetre for the maximum1 and the     
one-one-hundred-millionth of a          
centimetre for the minimum4 ,such       
figures convey no particular meaning to 
our blunt senses1 but ,lord ,kelvin has 
given a tangible illustration that aids 
the imagination to at least a vague     

comprehension of the unthinkable        
smallness of the molecule4 ,he estimates
 that if a ball1 say of water or glass1 
about as large as a football1 were to be
 magnified up to the size of the earth1 
each constituent molecule being         
magnified in the same proportion1 the   
magnified structure would be more       
coarse-grained than a heap of shot1 but 
probably less coarse-grained than a heap
 of footballs4  ,several other methods  
have been employed to estimate the size 
of molecules4 ,one of these is based    
upon the phenomena of contact           
electricity2 another upon the           
wave-theory of light2 and another upon  
capillary attraction1 as shown in the   
tense film of a soap-bubble6 ,no one of 
these methods gives results more        
definite than that due to the kinetic   
theory of gases1 just outlined2 but the 
important thing is that the results     
obtained by these different methods 7all
 of them due to ,lord ,kelvin7 agree    
with one another in fixing the          

dimensions of the molecule at somewhere 
about the limits already mentioned4 ,we 
may feel very sure indeed1 therefore1   
that the molecules of matter are not the
 unextended1 formless points which      
,boscovich and his followers of the     
eighteenth century thought them4 ,but   
all this1 it must be borne in mind1     
refers to the molecule1 not to the      
ultimate particle of matter1 about which
 we shall have more to say in another   
connection4 ,curiously enough1 we shall 
find that the latest theories as to the 
final term of the series are not so very
 far afield from the dreamings of the   
eighteenth-century philosophers2 the    
electron of ,j4 ,j4 ,thompson shows many
 points of resemblance to the formless  
centre of ,boscovich4  ,whatever the    
exact form of the molecule1 its outline 
is subject to incessant variation2 for  
nothing in molecular science is regarded
 as more firmly established than that   
the molecule1 under all ordinary        
circumstances1 is in a state of intense 

but variable vibration4 ,the entire     
energy of a molecule of gas1 for        
example1 is not measured by its         
momentum1 but by this plus its energy of
 vibration and rotation1 due to the     
collisions already referred to4         
,clausius has even estimated the        
relative importance of these two        
quantities1 showing that the            
translational motion of a molecule of   
gas accounts for only three-fifths of   
its kinetic energy4 ,the total energy of
 the molecule 7which we call heat7      
includes also another factor--namely1   
potential energy1 or energy of position1
 due to the work that has been done on  
expanding1 in overcoming external       
pressure1 and internal attraction       
between the molecules themselves4 ,this 
potential energy 7which will be         
recovered when the gas contracts7 is the
 latent heat of ,black1 which so long   
puzzled the philosophers4 ,it is latent 
in the same sense that the energy of a  
ball thrown into the air is latent at   

the moment when the ball poises at its  
greatest height before beginning to     
fall4  ,it thus appears that a variety  
of motions1 real and potential1 enter   
into the production of the condition we 
term heat4 ,it is1 however1 chiefly the 
translational motion which is measurable
 as temperature2 and this1 too1 which   
most obviously determines the physical  
state of the substance that the         
molecules collectively compose--whether1
 that is to say1 it shall appear to our 
blunt perceptions as a gas1 a liquid1 or
 a solid4 ,in the gaseous state1 as we  
have seen1 the translational motion of  
the molecules is relatively enormous1   
the molecules being widely separated4   
,it does not follow1 as we formerly     
supposed1 that this is evidence of a    
repulsive power acting between the      
molecules4 ,the physicists of to-day1   
headed by ,lord ,kelvin1 decline to     
recognize any such power4 ,they hold    
that the molecules of a gas fly in      
straight lines by virtue of their       

inertia1 quite independently of one     
another1 except at times of collision1  
from which they rebound by virtue of    
their elasticity2 or on an approach to  
collision1 in which latter case1 coming 
within the range of mutual attraction1  
two molecules may circle about each     
other1 as a comet circles about the sun1
 then rush apart again1 as the comet    
rushes from the sun4  ,it is obvious    
that the length of the mean free path of
 the molecules of a gas may be increased
 indefinitely by decreasing the number  
of the molecules themselves in a        
circumscribed space4 ,it has been shown 
by ,professors ,tait and ,dewar that a  
vacuum may be produced artificially of  
such a degree of rarefaction that the   
mean free path of the remaining         
molecules is measurable in inches4 ,the 
calculation is based on experiments made
 with the radiometer of ,professor      
,crookes1 an instrument which in itself 
is held to demonstrate the truth of the 
kinetic theory of gases4 ,such an       

attenuated gas as this is considered by 
,professor ,crookes as constituting a   
fourth state of matter1 which he terms  
ultra-gaseous4  ,if1 on the other hand1 
a gas is subjected to pressure1 its     
molecules are crowded closer together1  
and the length of their mean free path  
is thus lessened4 ,ultimately1 the      
pressure being sufficient1 the molecules
 are practically in continuous contact4 
,meantime the enormously increased      
number of collisions has set the        
molecules more and more actively        
vibrating1 and the temperature of the   
gas has increased1 as1 indeed1          
necessarily results in accordance with  
the law of the conservation of energy4  
,no amount of pressure1 therefore1 can  
suffice by itself to reduce the gas to a
 liquid state4 ,it is believed that even
 at the centre of the sun1 where the    
pressure is almost inconceivably great1 
all matter is to be regarded as really  
gaseous1 though the molecules must be so
 packed together that the consistency is

 probably more like that of a solid4    
,if1 however1 coincidently with the     
application of pressure1 opportunity be 
given for the excess of heat to be      
dissipated to a colder surrounding      
medium1 the molecules1 giving off their 
excess of energy1 become relatively     
quiescent1 and at a certain stage the   
gas becomes a liquid4 ,the exact point  
at which this transformation occurs1    
however1 differs enormously for         
different substances4 ,in the case of   
water1 for example1 it is a temperature 
more than four hundred degrees above    
zero1 centigrade2 while for atmospheric 
air it is one hundred and ninety-four   
degrees centigrade below zero1 or more  
than a hundred and fifty degrees below  
the point at which mercury freezes4  ,be
 it high or low1 the temperature above  
which any substance is always a gas1    
regardless of pressure1 is called the   
critical temperature1 or absolute       
boiling-point1 of that substance4 ,it   
does not follow1 however1 that below    

this point the substance is necessarily 
a liquid4 ,this is a matter that will be
 determined by external conditions of   
pressure4 ,even far below the critical  
temperature the molecules have an       
enormous degree of activity1 and tend to
 fly asunder1 maintaining what appears  
to be a gaseous1 but what technically is
 called a vaporous1 condition--the      
distinction being that pressure alone   
suffices to reduce the vapor to the     
liquid state4 ,thus water may change    
from the gaseous to the liquid state at 
four hundred degrees above zero1 but    
under conditions of ordinary atmospheric
 pressure it does not do so until the   
temperature is lowered three hundred    
degrees further4 ,below four hundred    
degrees1 however1 it is technically a   
vapor1 not a gas2 but the sole          
difference1 it will be understood1 is in
 the degree of molecular activity4  ,it 
thus appeared that the prevalence of    
water in a vaporous and liquid rather   
than in a permanently gaseous condition 

here on the globe is a mere incident of 
telluric evolution4 ,equally incidental 
is the fact that the air we breathe is  
permanently gaseous and not liquid or   
solid1 as it might be were the earth's  
surface temperature to be lowered to a  
degree which1 in the larger view1 may be
 regarded as trifling4 ,between the     
atmospheric temperature in tropical and 
in arctic regions there is often a      
variation of more than one hundred      
degrees2 were the temperature reduced   
another hundred1 the point would be     
reached at which oxygen gas becomes a   
vapor1 and under increased pressure     
would be a liquid4 ,thirty-seven degrees
 more would bring us to the critical    
temperature of nitrogen4  ,nor is this a
 mere theoretical assumption2 it is a   
determination of experimental science1  
quite independent of theory4 ,the       
physicist in the laboratory has produced
 artificial conditions of temperature   
enabling him to change the state of the 
most persistent gases4 ,some fifty years

 since1 when the kinetic theory was in  
its infancy1 ,faraday liquefied         
carbonic-acid gas1 among others1 and the
 experiments thus inaugurated have been 
extended by numerous more recent        
investigators1 notably by ,cailletet in 
,switzerland1 by ,pictet in ,france1 and
 by ,dr4 ,thomas4 ,andrews and          
,professor ,james ,dewar in ,england4   
,in the course of these experiments not 
only has air been liquefied1 but        
hydrogen also1 the most subtle of gases2
 and it has been made more and more     
apparent that gas and liquid are1 as    
,andrews long ago asserted1 only distant
 stages of a long series of continuous  
physical changes4 ,of course1 if the    
temperature be lowered still further1   
the liquid becomes a solid2 and this    
change also has been effected in the    
case of some of the most permanent      
gases1 including air4  ,the degree of   
cold--that is1 of absence of heat--thus 
produced is enormous1 relatively to     
anything of which we have experience in 

nature here at the earth now1 yet the   
molecules of solidified air1 for        
example1 are not absolutely quiescent4  
,in other words1 they still have a      
temperature1 though so very low4 ,but it
 is clearly conceivable that a stage    
might be reached at which the molecules 
became absolutely quiescent1 as regards 
either translational or vibratory       
motion4 ,such a heatless condition has  
been approached1 but as yet not quite   
attained1 in laboratory experiments4 ,it
 is called the absolute zero of         
temperature1 and is estimated to be     
equivalent to two hundred and           
seventy-three degrees ,centigrade below 
the freezing-point of water1 or ordinary
 zero4  ,a temperature 7or absence of   
temperature7 closely approximating this 
is believed to obtain in the ethereal   
ocean of interplanetary and interstellar
 space1 which transmits1 but is thought 
not to absorb1 radiant energy4 ,we here 
on the earth's surface are protected    
from exposure to this cold1 which would 

deprive every organic thing of life     
almost instantaneously1 solely by the   
thin blanket of atmosphere with which   
the globe is coated4 ,it would seem as  
if this atmosphere1 exposed to such a   
temperature at its surface1 must there  
be incessantly liquefied1 and thus fall 
back like rain to be dissolved into gas 
again while it still is many miles above
 the earth's surface4 ,this may be the  
reason why its scurrying molecules have 
not long ago wandered off into space and
 left the world without protection4     
,but whether or not such liquefaction of
 the air now occurs in our outer        
atmosphere1 there can be no question as 
to what must occur in its entire depth  
were we permanently shut off from the   
heating influence of the sun1 as the    
astronomers threaten that we may be in a
 future age4 ,each molecule1 not alone  
of the atmosphere1 but of the entire    
earth's substance1 is kept aquiver by   
the energy which it receives1 or has    
received1 directly or indirectly1 from  

the sun4 ,left to itself1 each molecule 
would wear out its energy and fritter it
 off into the space about it1 ultimately
 running completely down1 as surely as  
any human-made machine whose power is   
not from time to time restored4 ,if1    
then1 it shall come to pass in some     
future age that the sun's rays fail us1 
the temperature of the globe must       
gradually sink towards the absolute     
zero4 ,that is to say1 the molecules of 
gas which now fly about at such         
inconceivable speed must drop helpless  
to the earth2 liquids must in turn      
become solids2 and solids themselves1   
their molecular quivers utterly stilled1
 may perhaps take on properties the     
nature of which we cannot surmise4  ,yet
 even then1 according to the current    
hypothesis1 the heatless molecule will  
still be a thing instinct with life4    
,its vortex whirl will still go on1     
uninfluenced by the dying-out of those  
subordinate quivers that produced the   
transitory effect which we call         

temperature4 ,for those transitory      
thrills1 though determining the physical
 state of matter as measured by our     
crude organs of sense1 were no more than
 non-essential incidents2 but the vortex
 whirl is the essence of matter itself4 
,some estimates as to the exact         
character of this intramolecular motion1
 together with recent theories as to the
 actual structure of the molecule1 will 
claim our attention in a later volume4  
,we shall also have occasion in another 
connection to make fuller inquiry as to 
the phenomena of low temperature4       
,,appendix    ,,reference-,,list        
,,chapter ,i    ,,the ,,successors ,,of 
,,newton ,,in ,,astronomy 7#a7 7p4 #aj74
 ,an ,account of ,several               
,extraordinary ,meteors or ,lights in   
the ,sky1 by ,dr4 ,edmund ,halley4      
,phil4   ,trans4 of ,royal ,society of  
,london1 vol4 ,,xxix1 pp4 #aei-afb4     
,read before   the ,royal ,society in   
the autumn of #agad4 7#b7 7p4 #ac74     
,phil4 ,trans4 of   ,royal ,society of  

,london for #agdh1 vol4 ,,xlv41 pp4 #h1 
#i4 ,from ,a ,letter to   the ,right    
,honorable ,george1 ,earl of            
,macclesfield1 concerning an ,apparent  
,motion observed in some of the ,fixed  
,stars1 by ,james ,bradley1 ,d4,d41     
,astronomer ,royal and ,f4,r4,s4        
,,chapter ,,ii    ,,the ,,progress ,,of 
,,modern ,,astronomy    7#a7 7p4 #be74  
,william ,herschel1 ,phil4 ,trans4 for  
#aghc1 vol4 ,,lxxiii4 7#b7   7p4 #cj74  
,kant's ,cosmogony1 ed4 and trans4 by   
,w4 ,hartie1 ,d4,d41 ,glasgow1   #ijj1  
pp4 #gd-ha4 7#c7 7p4 #ci74 ,exposition  
du systeme du monde 7included in        
oeuvres ,completes71 by ,m4 le ,marquis 
de ,laplace1 vol4 ,,vi41 p4 #dih4 7#d7  
7p4 #dh74 ,from ,the ,scientific ,papers
 of ,j4 ,clerk-,maxwell1 edited by ,w4  
,d4 ,nevin1 ,m4,a4 7#b vols471 vol4 ,i41
 pp4 #cgb-cgd4 ,this is a reprint of    
,clerk-,maxwell's prize paper of #ahei4 
,,chapter ,,iii    ,,the ,,new ,,science
 ,,of ,,paleontology    7#a7 7p4 #ha74  
,baron de ,cuvier1 ,theory of the       

,earth1 ,new ,york1 #ahah1 p4   #ih4    
7#b7 7p4 #hh74 ,charles ,lyell1         
,principles of ,geology 7#d vols471     
,london1 #ahcd4 7p4 #ib74 ,ibid41 vol4  
,,iii41 pp4 #eif-eih4 7#d7 7p4 #ajj74   
,hugh   ,falconer1 in ,paleontological  
,memoirs1 vol4 ,,ii41 p4 #eif4 7#e7 7p4 
#aja74   ,ibid41 p4 #eih4 7#f7 7p4      
#ajb74 ,ibid41 p4 #eii4 7#g7 7p4 #aaa74 
,fossil ,horses   in ,america 7reprinted
 from ,american ,naturalist1 vol4       
,,viii41 ,may1 #ahgd71   by ,o4 ,c4     
,marsh1 pp4 #bhh1 #bhi4    ,,chapter    
,,iv    ,,the ,,origin ,,and            
,,development ,,of ,,modern ,,geology   
7#a7 7p4 #abc74 ,james ,hutton1 from    
,transactions of the ,royal ,society of 
,edinburgh1 #aghh1 vol4 ,i41 p4 #bad4 ,a
 paper on the ,theory of the ,earth1    
read before the ,society in #agha4 7#b7 
7p4 #abh74 ,ibid41 p4 #baf4 7#c7   7p4  
#aci74 ,consideration on ,volcanoes1 by 
,g4 ,poulett ,scrope1 ,esq41 pp4        
#bbh-bcd4 7#d7 7p4 #aec74 ,l4 ,agassiz1 
,etudes sur les glaciers1 ,neufchatel1  

#ahdj1 p4 #bdj4    ,,chapter ,v    ,,the
 ,,new ,,science ,,of ,,meteorology     
7#a7 7p4 #ahb74 ,theory of ,rain1 by    
,james ,hutton1 in ,transactions of the 
,royal ,society of ,edinburgh1 #aghh1   
vol4 #a1 pp4 #ec-ef4 7#b7 7p4 #aia74    
,essay   on ,dew1 by ,w4 ,c4 ,wells1    
,m4,d41 ,f4,r4,s41 ,london1 #ahah1 pp4  
#abd f4    ,,chapter ,,vi    ,,modern   
,,theories ,,of ,,heat ,,and ,,light    
7#a7 7p4 #bae74 ,essays ,political1     
,economical1 and ,philosophical1 by     
,benjamin ,thompson1 ,count of ,rumford 
7#b vols471 ,vol4 ,,ii41 pp4 #dgj-dic1  
,london2 ,t4 ,cadell1 ,jr41 and ,w4     
,davies1 #agig4 7#b7 7p4 #bbj74 ,thomas 
,young1   ,phil4 ,trans41 #ahjb1 p4 #ce4
 7#c7 7p4 #bbc74 ,ibid41 p4 #cf4        
,,chapter ,,vii    ,,the ,,modern       
,,development ,,of ,,electricity ,,and  
,,magnetism    7#a7 7p4 #bce74 ,davy's  
paper before ,royal ,institution1 #ahaj4
 7#b7 7p4 #bch74   ,hans ,christian     
,oersted1 ,experiments with the ,effects
 of the ,electric   ,current on the     

,magnetic ,needle1 #ahae4 7#c7 7p4      
#bdc74 ,on the ,induction   of ,electric
 ,currents1 by ,michael ,faraday1       
,f4,r4,s41 ,phil4 ,trans4 of ,royal     
,society of ,london for #ahcb1 pp4      
#abf-abh4 7#d7 7p4 #bde74 ,explication  
of   ,arago's ,magnetic ,phenomena1 by  
,michael ,faraday1 ,f4,r4,s41 ,phil4    
,trans4   ,royal ,society of ,london for
 #ahcb1 pp4 #adf-adi4    ,,chapter      
,,viii    ,,the ,,conservation ,,of     
,,energy    7#a7 7p4 #bfg74 ,the ,forces
 of ,inorganic ,nature1 a paper by ,dr4 
,julius   ,robert ,mayer1 ,liebig's     
,annalen1 #ahdb4 7#b7 7p4 #bgb74 ,on the
 ,calorific   ,effects of               
,magneto-,electricity and the           
,mechanical ,value of ,heat1 by ,j4     
,p4 ,joule1 in ,report of the ,british  
,association for the ,advancement of    
,science1 vol4 ,,xii41 p4 #cc4          
,,chapter ,,ix    ,,the ,,ether ,,and   
,,ponderable ,,matter    7#a7 7p4 #big74
 ,james ,clerk-,maxwell1 ,philosophical 
,magazine for ,january   and ,july1     

#ahfj4  ,,end ,,of ,,vol4 ,,iii