,transcriber ,note    ,text emphasis    
denoted by ,italics4                    
,illustration3 ,,john ,,tyndall         
,,the ,,forms ,,of ,,water ,,in ,,clouds
 ,,and ,,rivers ,,ice ,,and ,,glaciers  
,,by                         ,,john     
,,tyndall1 ,,ll4,d41 ,f4 ,r4 ,s4        
,,with ,,twenty-,,five ,,illustrations  
,,drawn ,,and ,,engraved ,,under ,,the  
,,direction                             
,,of ,,the ,,author                     
,,new ,,york                            
,d4 ,,appleton ,,and ,,company          
#ahii                                   
,copyright1 #ahgb1                      
,by ,d4 ,,appleton ,,and ,,company4     
,electrotyped and ,printed              
at the ,appleton ,press1 ,u4 ,s4 ,a4    
,,american ,,preface ,,to ,,the         
,,international ,,scientific ,,series4  
,the rapid development of science in the
 present age1 and the  increasing public
 interest in its results1 make it       
desirable that the  most efficient      
measures should be adopted to elevate   

the character  of its popular           
literature4 ,the tendency of careless   
and unscrupulous  book-makers to cater  
to public ignorance and love of the     
marvellous1  and to foist their crude   
productions upon those who are too      
little  instructed to judge of their    
real quality1 has hitherto been so      
strong as to cast discredit upon the    
idea of popular science4 ,it  is highly 
important to counteract this evil       
tendency by furnishing  the public with 
popular scientific books of a superior  
character4  ,the publication of the     
present volume is the first step in     
carrying  out a systematic enterprise of
 this kind4 ,it initiates a series of   
such works on a wide range of scientific
 subjects1 to be prepared  by the       
leading thinkers of different countries1
 and known as the  ,international       
,scientific ,series4    ,it is designed 
to consist of compendious scientific    
treatises1  representing the latest     
advances of thought upon subjects of    

general  interest1 theoretical and      
practical1 to all classes of readers4   
,the  familiar phenomena of surrounding 
,nature1 in their physical and  chemical
 aspects1 the knowledge of which has    
recently undergone  marked extension or 
revision1 will be considered in their   
latest  interpretations4 ,biology1 or   
the general science of life1 which has  
lately come into prominence1 will be    
explained in its leading and  most      
important principles4 ,the subject of   
mind1 which1 under the  inductive method
 and on the basis of its physical       
accompaniments  and conditions1 is      
giving rise to a new psychology1 will be
 treated  with the fulness to which it  
is entitled4 ,the laws of man's social  
development1 or the natural history of  
society1 which are now being  studied by
 the scientific method1 will also       
receive a due share of  attention4      
,while the books of this series are to  
deal with a wide  diversity of topics1  
it will be a leading object of the      

enterprise  to present the bearings of  
inquiry upon the higher questions of the
  time1 and to throw the latest light of
 science upon the phenomena of  human   
nature and the economy of human life4   
,as the first requisite of such a series
 of works is trustworthiness1  their    
preparation has been confided only to   
men of eminent ability1  and who are    
recognized authorities in their several 
departments4  ,as they are to address   
the non-scientific public1 it is a      
further  requisite that they should be  
written in familiar and intelligible    
language4 ,it is not to be expected that
 the authors will all attain  to the    
same standard in this respect1 but they 
are pledged to the  utmost simplicity of
 exposition that is possible            
consistently with  clear and accurate   
representation4    ,as science is now   
the supreme interest of civilization1   
and concerns  alike the people of every 
country1 and as1 moreover1 it affords a 
common ground upon which men of all     

races1 tongues1 faiths1 and             
nationalities1 may work together in     
harmony1 it seemed fitting that  an     
undertaking of this kind should be of   
comprehensive scope and  stand upon an  
international basis4 ,with the growing  
sentiment of  sympathy and brotherhood  
among the most widely-separated students
 of  ,nature1 and the extensive         
facilities of business intercourse that 
now  exist1 there appeared no reason why
 an international combination of        
authors and publishers should not be    
effected that would be equally          
favourable to their own private         
interests and advantageous to the       
public4 ,to gain this end and guarantee 
to authors better remuneration  for     
their work1 is a distinctive purpose of 
the present enterprise4  ,but there was 
this difficulty in the way of any such  
arrangement1  that1 while the rights of 
foreign authors are guarded by all other
  civilized governments1 they are not   
protected by the government of  the     

,united ,states4 ,to escape this        
difficulty1 and secure ,american        
coperation1 the first thing needed was  
to obtain the consent of an  ,american  
publishing-house to grant voluntarily to
 foreign authors  the justice which our 
government denies them4 ,it was agreed  
by  ,messrs4 ,appleton that they would  
pay the foreign contributors to  this   
series the full rates of copyright that 
are usually allowed  to ,american       
authors4 ,when this was done1           
engagements were made  with             
distinguished scientists of ,england1   
,france1 ,germany1 and the  ,united     
,states1 to prepare works for the       
series1 and with ,henry ,s4  ,king      
,co41 of ,london1 ,germer ,baillire1 of 
,paris1 and ,messieurs  ,brockhaus1 of  
,leipsic1 to publish them4 ,negotiations
 are pending for  the reproduction of   
the series in other countries1 but the  
present  arrangements secure to the     
authors the benefits of the four leading
  markets of the world4    ,it is a fact

 not without significance1 that the     
proposal of this  enterprise was        
received with the most cordial favour by
 the eminent  scientific men who were   
solicited to aid in carrying it forward4
 ,most  of them consented at once2 but1 
while some were so heavily burdened     
with work that they could enter into no 
immediate engagements1 not  one of them 
declined to coperate1 and all promised  
to do so at the  earliest practicable   
opportunity4 ,the feeling of the        
desirableness  of such an undertaking   
was strong and unanimous4 ,the old      
dislike of  the cultivators of science  
to participate in the work of popular   
teaching1 seems very much to have passed
 away2 and in ,england1  ,france1 and   
,germany1 alike it was freely           
acknowledged that savants  have an      
imperative duty to discharge in relation
 to the work of  general scientific     
education4 ,as remarked by ,prof4       
,virchow1 of  ,berlin1 the destiny of   
science is the service of humanity4     

,it was stipulated by the authors that  
they should have ample time  for the    
preparation of their books1 and1 as the 
arrangements were  recently made1 only a
 few of the works are yet ready4        
,several1  however1 are now in press1   
and will shortly appear4    ,those      
interested in the series are under many 
obligations to ,prof4  ,tyndall for his 
kindness in consenting to furnish its   
commencing  volume4 ,being prepared in a
 short time1 amid great pressure both   
of laboratory and literary work1 it     
contains somewhat less matter  than may 
be expected in the ensuing volumes4 ,it 
treats of subjects  upon which he is    
perhaps the highest living authority2   
and it is an  admirable example of that 
vivid1 stirring1 impressive style for   
which  its author is so distinguished4  
,prof4 ,tyndall is not only a master in 
the scientific use of the imagination1  
but in kindling the action  of that     
faculty in his readers4 ,he writes in   
pictures1 so as to make  them see what  

he sees4 ,in this volume he addresses   
himself directly  to his juvenile       
friends1 groups them around him1 takes  
them with him  to his favourite         
mountains1 and thus adds a dramatic     
element and the  effect of personal     
sympathy to familiar colloquial         
exposition4    ,the ,international      
,scientific ,series will form an elegant
 and  valuable library of popular       
science1 fresh in treatment1 attractive 
in form1 strong in character1 moderate  
in price1 and indispensable to  all who 
care for the acquisition of solid and   
serviceable knowledge2  and it is       
commended to ,american readers as a help
 in the important  work of sound public 
education4                              
,e4 ,l4 ,y4      ,new ,york1 ,september1
 #ahgb4          ,,author',s ,,preface4 
,after an absence of twelve years1 ,i   
visited the ,mer de ,glace last  ,june4 
,it exhibited in a striking degree that 
excess of consumption  over supply      
which1 if continued1 would eventually   

reduce the ,swiss  glaciers to the mere 
spectres of their former selves4 ,when  
,i first  saw the ,mer de ,glace its    
ice-cliffs towered over ,les ,mottets1  
and an  arm of the ,arveiron1 issuing   
from the cliffs1 plunged as a powerful  
cascade down the rocks4 ,the ice has now
 shrunk far behind them4 ,a  huge       
moraine1 left behind by the retreating  
glacier1 will mark1 for  some time to   
come1 its recent magnitude4 ,the vault  
of the ,arveiron  has dwindled          
considerably4 ,the way up to the        
,chapeau lies on the  top of a lateral  
moraine1 reached a few years ago by the 
surface  of the glacier1 the present    
surface lying far below4 ,the visible   
and continual breaking away of the      
moraines1 left thus stranded on  the    
mountain flank1 explains the absence of 
ancient ridges on the  mountains where  
the slopes are steep4 ,the ice-cascades 
of the ,gant  has suffered much from the
 general waste4 ,its crevasses are still
  wild1 but the ice-cliffs and sracs of 

former days are but poorly  represented 
to-day4    ,the great ,aletsch and its  
neighbours exhibit similar evidences of 
diminution4 ,i found moreover this year 
that the two ancient moraines  mentioned
 in paragraph #cfd are parts of the same
 great lateral  moraine which flanked   
the glacier for a long period1 during   
which its  magnitude must have remained 
practically constant4 ,the place        
occupied  by the ancient ice-river is   
rendered strikingly conspicuous by this 
well-preserved boundary4    ,during my  
residence at the ,bel ,alp this year1 a 
catastrophe occurred  which renders1 for
 the time being1 the description of the 
,mrgelin  ,see given in  #ej            
inappropriate4 ,in company with two     
young friends ,i  had descended the     
glacier and passed through the gorge of 
the ,massa4  ,on our return to the ,bel 
,alp we found the domestics of the hotel
  leaning out of the windows and looking
 excitedly towards the glacier4  ,from  
it proceeded a sound which resembled the

 roar of a cataract4  ,the servants     
remarked that the ,mrgelin ,see must    
have broken loose4  ,this was the case4 
,for a time1 however1 the water flowed  
beneath the  glacier2 but at a point    
about midway between the ,bel ,alp and  
the  ggischhorn1 it broke forth on the  
ggischhorn side1 and formed a  torrent  
between the glacier and the slope of the
 mountain4 ,in some  places this river  
was more than sixty yards wide1 at      
others it was  contracted to less than  
one-fifth of this width4 ,broken        
cascades of  great height were formed   
here and there by successive ledges of  
ice1  the torrent leaping with          
indescribable fury from ledge to ledge1 
and  sending a smoke of spray into the  
air4 ,at one place the bottom of  the   
torrent was deep soft sand1 which1 after
 the water had passed1  could be seen to
 have been tortured into huge funnels by
 the whirling  eddies overhead4    ,soon
 after we reached the ,bel ,alp1 on the 
occasion just referred to1  the front of

 the torrent appeared at the opposite   
side of the valley  carrying everything 
movable before it1 and immediately      
afterwards  swept through the hollow    
that we had traversed a little earlier  
in  the day4 ,when at the end of the    
glacier ,i was struck by the force and  
volume of the ,massa1 and the grandeur  
of its vault1 but ,i could not  then    
account for the huge blocks of ice which
 it incessantly carried  down4          
,doubtless the eruption above had been  
partial before the grand  rush set in4  
,the ,rhone was considerably swollen1   
crops were damaged  or ruined1 and the  
driver of the diligence was sorely      
perplexed to  find himself in three feet
 of water1 without any apparent reason1 
on the public highway4 ,two or three    
days subsequently ,i learned  at the    
ggischhorn that an engineer had been    
sent up to report on  the possibility of
 opening a channel1 so as to prevent any
 future  accumulation of water in the   
,mrgelin ,see4 ,if this be done a useful

  end will be gained1 by the abolition1 
however1 of one of the most  beautiful  
objects in ,switzerland4                
,j4 ,tyndall4      ,september1 #ahgb4   
,,preface ,,to ,,the ,,fourth ,,edition4
      ,at a meeting of the ,managers of 
the ,royal ,institution held on         
,december #ab1 #ahbe1 the ,committee    
appointed to consider what lectures     
should be delivered in the ,institution 
in the next session1 reported  that they
 had consulted ,mr4 ,faraday on the     
subject of engaging him  to take a part 
in the juvenile lectures proposed to be 
given during  the ,christmas and ,easter
 recesses1 and they found his avocations
 were  such that it would be exceedingly
 inconvenient for him to engage in  such
 lectures4    ,at a general monthly     
meeting of the members of the ,royal    
,institution1  held on ,december #d1    
#ahbf1 the ,managers reported that they 
had  engaged ,mr4 ,wallis to deliver a  
course of lectures on ,astronomy1       
adapted to a juvenile auditory1 during  

the ,christmas vacation4    ,in a report
 dated ,april #af1 #ahbg1 the ,board of 
,visitors express  their satisfaction at
 finding that the plan of juvenile      
courses of  lectures had been resorted  
to4 ,they feel sure that the influence  
of  the ,institution cannot be extended 
too far1 and that the system of         
instructing the younger portion of the  
community is one of the most  effective 
means which the ,institution possesses  
for the diffusion of  science4          
,faraday's holding aloof was but        
temporary1 for at ,christmas #ahbg we   
find him giving a ,course of ,six       
,elementary ,lectures on ,chemistry1    
adapted to a ,juvenile ,auditory4,a     
,a ,there is no record to show that ,mr4
 ,wallis gave the ,astronomical         
lectures referred to1 and our librarian 
believes that the ,christmas  courses   
were opened by ,faraday4    ,the ,easter
 lectures were soon abandoned2 but from 
the date here  referred to to the       
present time the ,christmas lectures    

have been a  marked feature of the      
,royal ,institution4    ,in #ahga it    
fell to my lot to give one of these     
courses4 ,i had been  frequently invited
 to write on ,glaciers in encyclopdias1 
journals1  and magazines1 but had always
 declined to do so4 ,i had also         
abstained  from making them the subject 
of a course of lectures1 wishing to take
  no advantage of my position here1 and 
indeed to avoid writing a line  or      
uttering a sentence on the subject for  
which ,i could not be held  personally  
responsible4 ,in view of the discussions
 which the subject  had provoked1 ,i    
thought this the fairest course4        
,but1 in #ahga1 the time 7,i imagined7  
had come when1 without risk of  offence1
 ,i might tell our young people         
something about the labours  of those   
who had unravelled for their instruction
 the various  problems of the ice-world4
 ,my lamented friend and ever-helpful   
counsellor1 ,dr4 ,bence ,jones1 thought 
the subject a good one1 and  accordingly

 it was chosen4 ,strong in my sympathy  
with youth1 and  remembering the damage 
done by defective exposition to my own  
young  mind1 ,i sought1 to the best of  
my ability1 to confer upon these        
lectures clearness1 thoroughness1 and   
life4    ,wishing1 moreover1 to render  
them of permanent value1 ,i wrote out   
copious ,notes of the course1 and had   
them distributed among the boys  and    
girls4 ,in preparing these ,notes ,i    
aimed at nothing less than  presenting  
to my youthful audience1 in a           
concentrated but perfectly  digestible  
form1 every essential point embraced in 
the literature of  the glaciers1 and    
some things in addition1 which1 derived 
as they  were from my own recent        
researches1 no book previously published
 on  the subject contained4    ,but my  
theory of education agrees with that of 
,emerson1 according  to which           
instruction is only half the battle1    
what he calls  provocation being the    
other half4 ,by this he means that power

 of  the teacher1 through the force of  
his character and the vitality  of his  
thought1 to bring out all the latent    
strength of his pupil1  and to invest   
with interest even the driest matters of
 detail4 ,in  the present instance ,i   
was determined to shirk nothing         
essential1  however dry2 and1 to keep my
 mind alive to the requirements of my   
pupil1 ,i proposed a series of ideal    
ramblings1 in which he should be  always
 at my side4 ,oddly enough1 though ,i   
was here dealing with what  might be    
called the abstract idea of a boy1 ,i   
realised his presence  so fully as to   
entertain for him1 before our excursions
 ended1 an  affection consciously warm  
and real4    ,the ,notes here referred  
to were at first intended for the use of
 my  audience alone4 ,at the urgent     
request of a friend ,i slightly expanded
  them1 and converted them into the     
little book here presented to the       
reader4    ,the amount of attention     
bestowed upon the volume induces me to  

give  this brief history of its origin4 
,a ,german critic1 whom ,i have no      
reason to regard as specially           
favourable to me or it1 makes the       
following remark on the style of  the   
book3 ,this passion for the mountains   
tempts him frequently  to reveal more of
 his ,alpine wanderings than is         
necessary for  his demonstrations4 ,the 
reader1 however1 will not find this a   
disagreeable interruption of the course 
of thought2 for the book  thereby gains 
wonderfully in vividness4 ,this1 ,i     
would say1 was the  express aim of the  
breaks referred to4 ,i desired to keep  
my companion  fresh as well as          
instructed1 and these interruptions were
 so many  breathing-places where the    
intellectual tension was purposely      
relaxed and the mind of the pupil braced
 to fresh action4    ,of other          
criticisms1 flattering and otherwise1 ,i
 forbear to speak4  ,as regards some of 
them1 indeed1 it would be a reproach to 
that  manliness which ,i have sought to 

encourage in my pupil to return  blow   
for blow4 ,if the reader be acquainted  
with them1 this will let  him know how  
,i regard them2 and if he be not        
acquainted with them1  ,i would         
recommend him to ignore them1 and to    
form his own judgment  of this book4 ,no
 fair-minded person who reads it will   
dream that ,i1  in writing it1 had a    
thought of acting otherwise than justly 
and  generously towards my predecessors1
 the last of whom1 to the grief of  all 
who knew him1 has recently passed away4 
,john ,tyndall4      ,april1 #ahgd4     
,,contents4        ,cloud-banner of the 
,aiguille du ,dru                       
,frontispiece                           
,,page       #a1 #b4 ,clouds1 ,rains1   
and ,rivers                             
#a1 #f        #c4 ,the ,waves of ,light 
#h        #d4 ,the ,waves of ,heat which
 produce the ,vapour of our             
,atmosphere and melt our ,glaciers      
#aa        #e4 ,experiments to prove the
 foregoing statements                #ad

        #f4 ,oceanic ,distillation      
#ai        #g4 ,tropical ,rains         
#bc        #h4 ,mountain ,condensers    
#bg        #i4 ,architecture of ,snow   
#bi       #aj4 ,atomic ,poles           
#cb       #aa4 ,architecture of ,lake   
,ice                                    
#ce       #ab4 ,the ,source of the      
,arveiron4 ,ice ,pinnacles1 ,towers1 and
           ,chasms of the ,glacier des  
,bois4 ,passage to the ,montanvert  #ch 
#ac4 ,the ,mer de ,glace and its        
,sources4 ,our ,first ,climb to the     
,cleft ,station                         
#dc       #ad4 ,ice-cascade and ,snows  
of the ,col du ,gant                    
#df       #ae4 ,questioning the         
,glaciers                               
#dh       #af4 ,branches and ,medial    
,moraines of the ,mer de ,glace from the
           ,cleft ,station              
#ea       #ag4 ,the ,talfre and the     
,jardin4 ,work among the ,crevasses     
#eb       #ah4 ,first ,questions        
regarding ,glacier ,motion4 ,drifting of

           ,bodies buried in a ,crevasse
                                #ed     
#ai4 ,the ,motion of ,glaciers4         
,measurements by ,hugi and ,agassiz4    
,drifting of ,huts on the ,ice          
#fi       #bj4 ,precise ,measurements of
 ,agassiz and ,forbes4 ,motion of a     
,glacier proved to resemble the ,motion 
of a ,river           #fj       #ba4    
,the ,theodolite and its ,use4 ,our own 
,measurements             #fb       #bb4
 ,motion of the ,mer de ,glace          
#ff       #bc4 ,unequal ,motion of the  
two ,sides of the ,mer de ,glace        
#gj       #bd4 ,suggestion of a new     
,likeness of ,glacier ,motion to ,river 
,motion4 ,conjecture tested             
#gb       #be4 ,new ,law of ,glacier    
,motion                                 
#gf       #bf4 ,motion of ,axis of ,mer 
de ,glace                               
#gh       #bg4 ,motion of ,tributary    
,glaciers                               
#gi       #bh4 ,motion of ,top and      
,bottom of ,glacier                     

#hj       #bi4 ,lateral ,compression of 
a ,glacier                              
#ha       #cj4 ,longitudinal            
,compression of a ,glacier              
#hd       #ca4 ,sliding and ,flowing4   
,hard ,ice and ,soft ,ice               
#hf       #cb4 ,winter on the ,mer de   
,glace                                  
#hh       #cc4 ,winter ,motion of the   
,mer de ,glace                          
#ic       #cd4 ,motion of the           
,grindelwald and ,aletsch ,glacier      
#ic       #ce4 ,motion of ,morteratsch  
,glacier                                
#ie       #cf4 ,birth of a ,crevasse3   
,reflections                            
#ih       #cg4 ,icicles                 
#ii       #ch4 ,the ,bergschrund        
#ajb       #ci4 ,transverse ,crevasses  
#ajc       #dj4 ,marginal ,crevasses    
#aje       #da4 ,longitudinal ,crevasses
                                        
#aji       #db4 ,crevasses in relation  
to ,curvature of ,glacier               
#aaj       #dc4 ,moraine-ridges1        

,glacier ,tables1 and ,sand-,cones      
#aab       #dd4 ,the ,glacier ,mills or 
,moulins                                
#aaf       #de4 ,the ,changes of ,volume
 of ,water by ,heat and ,cold           
#aah       #df4 ,consequences flowing   
from the foregoing ,properties of       
,water4 ,correction of ,errors          
#abb       #dg4 ,the ,molecular         
,mechanism of ,water-,congelation       
#abe       #dh4 ,the ,dirt ,bands of the
 ,mer de ,glace                         
#abg       #di4 ,sea-ice and ,icebergs  
#acb       #ej4 ,the ggischhorn1 the    
,mrgelin ,see and its ,icebergs         
#acf       #ea4 ,the ,bel ,alp          
#aci       #eb4 ,the ,riffelberg and    
,grner ,glacier                         
#adj       #ec4 ,ancient ,glaciers of   
,switzerland                            
#ade       #ed4 ,erratic ,blocks        
#adg       #ee4 ,ancient ,glaciers of   
,england1 ,ireland1 ,scotland1 and      
,wales   #aej       #ef4 ,the ,glacier  
,epoch                                  

#aeb       #eg4 ,glacial ,theories      
#aee       #eh4 ,dilatation and ,sliding
 ,theories                              
#aee       #ei4 ,plastic ,theory        
#aef       #fj4 ,viscous ,theory        
#afa       #fa4 ,regelation ,theory     
#afc       #fb4 ,cause of ,regelation   
#afg       #fc4 ,faraday's ,view of     
,regelation                             
#aga       #fd4 ,the ,blue ,veins of    
,glaciers                               
#agf       #fe4 ,relation of ,structure 
to ,pressure                            
#ahc       #ff4 ,slate ,cleavage and    
,glacier ,lamination                    
#ahg       #fg4 ,conclusion             
#aia    ,illustration3 ,,cloud-,,banner 
,,of ,,the ,,aiguille ,,du ,,dru 7par4  
#hd and #bbg74          ,,the ,,forms   
,,of ,,water    ,,in ,,clouds ,,and     
,,rivers1 ,,ice ,,and ,,glaciers4       
#a4 ,clouds1 ,rains1 and ,rivers4    #a4
 ,every occurrence in ,nature is        
preceded by other occurrences which  are
 its causes1 and succeeded by others    

which are its effects4 ,the  human mind 
is not satisfied with observing and     
studying any natural  occurrence alone1 
but takes pleasure in connecting every  
natural fact  with what has gone before 
it1 and with what is to come after it4  
#b4 ,thus1 when we enter upon the study 
of rivers and glaciers1 our  interest   
will be greatly augmented by taking into
 account not only  their actual         
appearances1 but also their causes and  
effects4    #c4 ,let us trace a river to
 its source4 ,beginning where it empties
  itself into the sea1 and following it 
backwards1 we find it from  time to time
 joined by tributaries which swell its  
waters4 ,the river  of course becomes   
smaller as these tributaries are passed4
 ,it shrinks  first to a brook1 then to 
a stream2 this again divides itself into
 a  number of smaller streamlets1 ending
 in mere threads of water4 ,these       
constitute the source of the river1 and 
are usually found among hills4    #d4   
,thus the ,severn has its source in the 

,welsh ,mountains2 the ,thames  in the  
,cotswold ,hills2 the ,danube in the    
hills of the ,black ,forest2  the ,rhine
 and the ,rhone in the ,alps2 the       
,ganges in the ,himalaya  ,mountains2   
the ,euphrates near ,mount ,ararat2 the 
,garonne in the  ,pyrenees2 the ,elbe in
 the ,giant ,mountains of ,bohemia2 the 
,missouri in  the ,rocky ,mountains1 and
 the ,amazon in the ,andes of ,peru4    
#e4 ,but it is quite plain that we have 
not yet reached the real  beginning of  
the rivers4 ,whence do the earliest     
streams derive their  water8 ,a brief   
residence among the mountains would     
prove to you that  they are fed by      
rains4 ,in dry weather you would find   
the streams  feeble1 sometimes indeed   
quite dried up4 ,in wet weather you     
would see  them foaming torrents4 ,in   
general these streams lose themselves as
  little threads of water upon the hill 
sides2 but sometimes you may  trace a   
river to a definite spring4 ,the river  
,albula in ,switzerland1  for instance1 

rushes at its origin in considerable    
volume from a  mountain side4 ,but you  
very soon assure yourself that such     
springs  are also fed by rain1 which has
 percolated through the rocks or soil1  
and which1 through some orifice that it 
has found or formed1 comes to  the light
 of day4    #f4 ,but we cannot end here4
 ,whence comes the rain which forms the 
mountain streams8 ,observation enables  
you to answer the question4  ,rain does 
not come from a clear sky4 ,it comes    
from clouds4 ,but what  are clouds8 ,is 
there nothing you are acquainted with   
which they  resemble8 ,you discover at  
once a likeness between them and the    
condensed steam of a locomotive4 ,at    
every puff of the engine a cloud  is    
projected into the air4 ,watch the cloud
 sharply3 you notice that  it first     
forms at a little distance from the top 
of the funnel4 ,give  close attention   
and you will sometimes see a perfectly  
clear space  between the funnel and the 
cloud4 ,through that clear space the    

thing  which makes the cloud must pass4 
,what1 then1 is this thing which  at one
 moment is transparent and invisible1   
and at the next moment  visible as a    
dense opaque cloud8    #g4 ,it is the   
steam or vapour of water from the       
boiler4 ,within  the boiler this steam  
is transparent and invisible2 but to    
keep it  in this invisible state a heat 
would be required as great as that      
within the boiler4 ,when the vapour     
mingles with the cold air above  the hot
 funnel it ceases to be vapour4 ,every  
bit of steam shrinks  when chilled1 to a
 much more minute particle of water4    
,the liquid  particles thus produced    
form a kind of water-dust of exceeding  
fineness1 which floats in the air1 and  
is called a cloud4    #h4 ,watch the    
cloud-banner from the funnel of a       
running locomotive2  you see it growing 
gradually less dense4 ,it finally melts 
away  altogether1 and if you continue   
your observations you will not fail  to 
notice that the speed of its            

disappearance depends upon the          
character of the day4 ,in humid weather 
the cloud hangs long and  lazily in the 
air2 in dry weather it is rapidly licked
 up4 ,what has  become of it8 ,it has   
been reconverted into true invisible    
vapour4    #i4 ,the drier the air1 and  
the hotter the air1 the greater is the  
amount of cloud which can be thus       
dissolved in it4 ,when the cloud  first 
forms1 its quantity is far greater than 
the air is able to  maintain in an      
invisible state4 ,but as the cloud mixes
 gradually  with a larger mass of air it
 is more and more dissolved1 and finally
  passes altogether from the condition  
of a finely-divided liquid into  that of
 transparent vapour or gas4    #aj4     
,make the lid of a kettle air-tight1 and
 permit the steam to issue  from the    
pipe2 a cloud is precipitated in all    
respects similar to  that issuing from  
the funnel of the locomotive4    #aa4   
,permit the steam as it issues from the 
pipe to pass through the  flame of a    

spirit-lamp1 the cloud is instantly     
dissolved by the heat1  and is not again
 precipitated4 ,with a special boiler   
and a special  nozzle the experiment may
 be made more striking1 but not more    
instructive1 than with the kettle4      
#ab4 ,look to your bedroom windows when 
the weather is very cold  outside2 they 
sometimes stream with water derived from
 the  condensation of the aqueous vapour
 from your own lungs4 ,the windows  of  
railway carriages in winter show this   
condensation in a striking  manner4     
,pour cold water into a dry             
drinking-glass on a summer's day3  the  
outside surface of the glass becomes    
instantly dimmed by the  precipitation  
of moisture4 ,on a warm day you notice  
no vapour in  front of your mouth1 but  
on a cold day you form there a little   
cloud  derived from the condensation of 
the aqueous vapour from the lungs4      
#ac4 ,you may notice in a ball-room that
 as long as the door and  windows are   
kept closed1 and the room remains hot1  

the air remains  clear2 but when the    
doors or windows are opened a dimness is
 visible1  caused by the precipitation  
to fog of the aqueous vapour of the     
ball-room4 ,if the weather be intensely 
cold the entrance of fresh  air may even
 cause snow to fall4 ,this has been     
observed in ,russian  ball-rooms2 and   
also in the subterranean stables at     
,erzeroom1 when  the doors are opened   
and the cold morning air is permitted to
 enter4    #ad4 ,even on the driest day 
this vapour is never absent from our    
atmosphere4 ,the vapour diffused through
 the air of this room may be  congealed 
to hoar-frost in your presence4 ,this is
 done by filling  a vessel with a       
mixture of pounded ice and salt1 which  
is colder  than the ice itself1 and     
which1 therefore1 condenses and freezes 
the  aqueous vapour4 ,the surface of the
 vessel is finally coated with a  frozen
 fur1 so thick that it may be scraped   
away and formed into a  snow-ball4      
#ae4 ,to produce the cloud1 in the case 

of the locomotive and the  kettle1 heat 
is necessary4 ,by heating the water we  
first convert  it into steam1 and then  
by chilling the steam we convert it into
  cloud4 ,is there any fire in nature   
which produces the clouds of our        
atmosphere8 ,there is3 the fire of the  
sun4    #af4 ,thus1 by tracing backward1
 without any break in the chain of      
occurrences1 our river from its end to  
its real beginnings1 we come  at length 
to the sun4       #b4    #ag4 ,there    
are1 however1 rivers which have sources 
somewhat different  from those just     
mentioned4 ,they do not begin by        
driblets on a hill  side1 nor can they  
be traced to a spring4 ,go1 for example1
 to the  mouth of the river ,rhone1 and 
trace it backwards to ,lyons1 where it  
turns to the east4 ,bending round by    
,chambery1 you come at length  to the   
,lake of ,geneva1 from which the river  
rushes1 and which you  might be disposed
 to regard as the source of the ,rhone4 
,but go to  the head of the lake1 and   

you find that the ,rhone there enters   
it1  that the lake is in fact a kind of 
expansion of the river4 ,follow  this   
upwards2 you find it joined by smaller  
rivers from the mountains  right and    
left4 ,pass these1 and push your journey
 higher still4 ,you  come at length to a
 huge mass of ice the--end of a         
glacier--which  fills the ,rhone valley1
 and from the bottom of the glacier the 
river  rushes4 ,in the glacier of the   
,rhone you thus find the source of the  
river ,rhone4    #ah4 ,but again we have
 not reached the real beginning of the  
river4  ,you soon convince yourself that
 this earliest water of the ,rhone is   
produced by the melting of the ice4 ,you
 get upon the glacier and walk  upwards 
along it4 ,after a time the ice         
disappears and you come upon  snow4 ,if 
you are a competent mountaineer you may 
go to the very top  of this great       
snow-field1 and if you cross the top and
 descend at the  other side you finally 
quit the snow1 and get upon another     

glacier  called the ,trift1 from the end
 of which rushes a river smaller than   
the ,rhone4    #ai4 ,you soon learn that
 the mountain snow feeds the glacier4   
,by some  means or other the snow is    
converted into ice4 ,but whence comes   
the  snow8 ,like the rain1 it comes from
 the clouds1 which1 as before1 can  be  
traced to vapour raised by the sun4     
,without solar fire we could  have no   
atmospheric vapour1 without vapour no   
clouds1 without clouds  no snow1 and    
without snow no glaciers4 ,curious then 
as the conclusion  may be1 the cold ice 
of the ,alps has its origin in the heat 
of the  sun4       #c4 ,the ,waves of   
,light4    #bj4 ,but what is the sun8   
,we know its size and its weight4 ,we   
also  know that it is a globe of fire   
far hotter than any fire upon earth4    
,but we now enter upon another enquiry4 
,we have to learn definitely  what is   
the meaning of solar light and solar    
heat2 in what way they  make themselves 
known to our senses2 by what means they 

get from the  sun to the earth1 and how1
 when there1 they produce the clouds of 
our  atmosphere1 and thus originate our 
rivers and our glaciers4    #ba4 ,if in 
a dark room you close your eyes and     
press the eyelid  with your finger-nail1
 a circle of light will be seen opposite
 to  the point pressed1 while a sharp   
blow upon the eye produces the          
impression of a flash of light4 ,there  
is a nerve specially devoted to  the    
purposes of vision which comes from the 
brain to the back of the  eye1 and there
 divide into fine filaments1 which are  
woven together  to a kind of screen     
called the retina4 ,the retina can be   
excited  in various ways so as to       
produce the consciousness of light2 it  
may1  as we have seen1 be excited by the
 rude mechanical action of a blow       
imparted to the eye4    #bb4 ,there is  
no spontaneous creation of light by the 
healthy eye4  ,to excite vision the     
retina must be affected by something    
coming  from without4 ,what is that     

something8 ,in some way or other        
luminous  bodies have the power of      
affecting the retina--but how8    #bc4  
,it was long supposed that from such    
bodies issued1 with  inconceivable      
rapidity1 an inconceivably fine matter1 
which flew  through space1 passed       
through the pores supposed to exist in  
the  humours of the eye1 reached the    
retina behind1 and by their shock       
against the retina1 aroused the         
sensation of light4    #bd4 ,this       
theory1 which was supported by the      
greatest men1 among  others by ,sir     
,isaac ,newton1 was found competent to  
explain a great  number of the phenomena
 of light1 but it was not found         
competent  to explain all the phenomena4
 ,as the skill and knowledge of         
experimenters increased1 large classes  
of facts were revealed which  could only
 be explained by assuming that light was
 produced1 not by a  fine matter flying 
through space and hitting the retina1   
but by the  shock of minute waves       

against the retina4    #be4 ,dip your   
finger into a basin of water1 and cause 
it to quiver  rapidly to and fro4 ,from 
the point of disturbance issue small    
ripples  which are carried forward by   
the water1 and which finally strike the 
basin4 ,here1 in the vibrating finger1  
you have a source of agitation2  in the 
water you have a vehicle through which  
the finger's motion  is transmitted1 and
 you have finally the side of the basin 
which  receives the shock of the little 
waves4    #bf4 ,in like manner1         
according to the wave theory of light1  
you  have a source of agitation in the  
vibrating atoms1 or smallest  particles1
 of the luminous body2 you have a       
vehicle of transmission  in a substance 
which is supposed to fill all space1 and
 to be  diffused through the humours of 
the eye2 and finally1 you have the      
retina1 which receives the successive   
shocks of the waves4 ,these  shocks are 
supposed to produce the sensation of    
light4    #bg4 ,we are here dealing for 

the most part with suppositions and     
assumptions merely4 ,we have never seen 
the atoms of a luminous body1  nor their
 motions4 ,we have never seen the medium
 which transmits  their motions1 nor the
 waves of that medium4 ,how1 then1 do we
 come to  assume their existence8       
#bh4 ,before such an idea could have    
taken any real root in the human  mind1 
it must have been well disciplined and  
prepared by observations  and           
calculations of ordinary wave-motion4   
,it was necessary to know  how both     
water-waves and sound-waves are formed  
and propagated4 ,it  was above all      
things necessary to know how waves1     
passing through  the same medium1 act   
upon each other4 ,thus disciplined1 the 
mind was  prepared to detect any        
resemblance presenting itself between   
the  action of light and that of waves4 
,great classes of optical phenomena     
accordingly appeared which could be     
accounted for in the most  complete and 
satisfactory manner by assuming them to 

be produced by  waves1 and which could  
not be otherwise accounted for4 ,it is  
because  of its competence to explain   
all the phenomena of light that the wave
  theory now receives universal         
acceptance on the part of scientific    
men4    ,let me use an illustration4 ,we
 infer from the flint implements        
recently found in such profusion all    
over ,england and in other  countries   
that they were produced by men1 and also
 that the ,pyramids  of ,egypt were     
built by men1 because1 as far as our    
experience goes1  nothing but men could 
form such implements or build such      
,pyramids4  ,in like manner1 we infer   
from the phenomena of light the agency  
of  waves1 because1 as far as our       
experience goes1 no other agency could  
produce the phenomena4       #d4 ,the   
,waves of ,heat which produce the       
,vapour of our ,atmosphere  and melt our
 ,glaciers4    #bi4 ,thus1 in a general 
way1 ,i have given you the conception   
and  the grounds of the conception1     

which regards light as the product  of  
wave-motion2 but we must go farther than
 this1 and follow the  conception into  
some of its details4 ,we have all seen  
the waves of  water1 and we know they   
are of different sizes different in     
length  and different in height4 ,when1 
therefore1 you are told that the  atoms 
of the sun1 and of almost all other     
luminous bodies1 vibrate  at different  
rates1 and produce waves of different   
sizes1 your  experience of water-waves  
will enable you to form a tolerably     
clear  notion of what is meant4    #cj4 
,as observed above1 we have never seen  
the light-waves1 but we  judge of their 
presence1 their position1 and their     
magnitude1 by  their effects4 ,their    
lengths have been thus determined1 and  
found to  vary from about #a_/cjjjjth to
 #a_/fjjjjth of an inch4    #ca4 ,but   
besides those which produce light1 the  
sun sends forth  incessantly a multitude
 of waves which produce no light4 ,the  
largest  waves which the sun sends forth

 are of this non-luminous character1    
though they possess the highest heating 
power4    #cb4 ,a common sunbeam        
contains waves of all kinds1 but it is  
possible  to sift or filter the beam so 
as to intercept all its light1 and  to  
allow its obscure heat to pass          
unimpeded4 ,for substances have been    
discovered which1 while intensely opaque
 to the light-waves1 are  almost        
perfectly transparent to the others4 ,on
 the other hand1 it is  possible1 by the
 choice of proper substances1 to        
intercept in a great  degree the pure   
heat-waves1 and to allow the pure       
light-waves free  transmission4 ,this   
last separation is1 however1 not so     
perfect as the  first4    #cc4 ,we shall
 learn presently how to detach the one  
class of waves  from the other class1   
and to prove that waves competent to    
light a  fire1 fuse metal1 or burn the  
hand like a hot solid1 may exist in a   
perfectly dark place4    #cd4           
,supposing1 then1 that we withdraw1 in  

the first instance the  large           
heat-waves1 and allow the light-waves   
alone to pass4 ,these  may be           
concentrated by suitable lenses and sent
 into water without  sensibly warming   
it4 ,let the light-waves now be         
withdrawn1 and the  larger heat-waves   
concentrated in the same manner2 they   
may be caused  to boil the water almost 
instantaneously4    #ce4 ,this is the   
point to which ,i wished to lead you1   
and which  without due preparation could
 not be understood4 ,you now perceive   
the  important part played by these     
large darkness-waves1 if ,i may use  the
 term1 in the work of evaporation4 ,when
 they plunge into seas1  lakes1 and     
rivers1 they are intercepted close to   
the surface1 and  they heat the water at
 the surface1 thus causing it to        
evaporate2  the light-waves at the same 
time entering to great depths without   
sensibly heating the water through which
 they pass4 ,not only1  therefore1 is it
 the sun's fire which produces          

evaporation1 but a  particular          
constituent of that fire1 the existence 
of which you  probably were not aware   
of4    #cf4 ,further1 it is these       
selfsame lightless waves which1 falling 
upon  the glaciers of the ,alps1 melt   
the ice and produce all the rivers      
flowing from the glaciers2 for ,i shall 
prove to you presently that  the        
light-waves1 even when concentrated to  
the uttermost1 are unable  to melt the  
most delicate hoar-frost2 much less     
would they be able to  produce the      
copious liquefaction observed upon the  
glaciers4    #cg4 ,these large lightless
 waves of the sun1 as well as the       
heat-waves issuing from non-luminous hot
 bodies1 are frequently  called obscure 
or invisible heat4    ,we have here an  
example of the manner in which          
phenomena1 apparently  remote1 are      
connected together in this wonderful    
system of things  that we call ,nature4 
,you cannot study a snow-flake          
profoundly without  being led back by it

 step by step to the constitution of the
 sun4 ,it  is thus throughout ,nature4  
,all its parts are interdependent1 and  
the  study of any one part completely   
would really involve the study of  all4 
#e4 ,experiments to prove the foregoing 
,statements4    #ch4 ,heat issuing from 
any source not visibly red cannot be    
concentrated so as to produce the       
intense effects just referred to4  ,to  
produce these it is necessary to employ 
the obscure heat of a body  raised to   
the highest possible state of           
incandescence4 ,the sun is  such a body1
 and its dark heat is therefore suitable
 for experiments  of this nature4       
#ci4 ,but in the atmosphere of ,london1 
and for experiments such as  ours1 the  
heat-waves emitted by coke raised to    
intense whiteness by a  current of      
electricity are much more manageable    
than the sun's waves4  ,the electric    
light has also the advantage that its   
dark radiation  embraces a larger       
proportion of the total radiation than  

the dark  heat of the sun4 ,in fact1 the
 force or energy1 if ,i may use the     
term1  of the dark waves of the electric
 light is fully seven times that of  its
 light-waves4 ,the electric light1      
therefore1 shall be employed in  our    
experimental demonstrations4    #dj4    
,from this source a powerful beam is    
sent through the room1  revealing its   
track by the motes floating in the air  
of the room2 for  were the motes        
entirely absent the beam would be       
unseen4 ,it falls  upon a concave mirror
 7a glass one silvered behind will      
answer7 and  is gathered up by the      
mirror into a cone of reflected rays2   
the  luminous apex of the cone1 which is
 the focus of the mirror1 being  about  
fifteen inches distant from its         
reflecting surface4 ,let us mark  the   
focus accurately by a pointer4    #da4  
,and now let us place in the path of the
 beam a substance  perfectly opaque to  
light4 ,this substance is iodine        
dissolved in a  liquid called bisulphide

 of carbon4 ,the light at the focus     
instantly  vanishes when the dark       
solution is introduced4 ,but the        
solution is  intensely transparent to   
the dark waves1 and a focus of such     
waves  remains in the air of the room   
after the light has been abolished4     
,you may feel the heat of these waves   
with your hand2 you may let them  fall  
upon a thermometer1 and thus prove their
 presence2 or1 best of  all1 you may    
cause them to produce a current of      
electricity1 which  deflects a large    
magnetic needle4 ,the magnitude of the  
deflection is  a measure of the heat4   
#db4 ,our object now is1 by the use of a
 more powerful lamp1 and  a better      
mirror 7one silvered in front and with a
 shorter focal  distance71 to intensify 
the action here rendered so sensible4   
,as  before1 the focus is rendered      
strikingly visible by the intense       
illumination of the dust particles4 ,we 
will first filter the beam so  as to    
intercept its dark waves1 and then      

permit the purely luminous  waves to    
exert their utmost power on a small     
bundle of gun-cotton  placed at the     
focus4    #dc4 ,no effect whatever is   
produced4 ,the gun-cotton might remain  
there  for a week without ignition4 ,let
 us now permit the unfiltered beam  to  
act upon the cotton4 ,it is instantly   
dissipated in an explosive  flash4 ,this
 experiment proves that the light-waves 
are incompetent to  explode the cotton1 
while the waves of the full beam are    
competent to  do so2 hence we may       
conclude that the dark waves are the    
real agents  in the explosion4    #dd4  
,but this conclusion would be only      
probable2 for it might be urged  that   
the mixture of the dark waves and the   
light-waves is necessary  to produce the
 result4 ,let us then1 by means of our  
opaque solution1  isolate our dark waves
 and converge them on the cotton4 ,it   
explodes  as before4    #de4 ,hence it  
is the dark waves1 and they only1 that  
are concerned in  the ignition of the   

cotton4    #df4 ,at the same dark focus 
sheets of platinum are raised to vivid  
redness2 zinc is burnt up2 paper        
instantly blazes2 magnesium wire is     
ignited2 charcoal within a receiver     
containing oxygen is set burning2  a    
diamond similarly placed is caused to   
glow like a star1 being  afterward      
gradually dissipated4 ,and all this     
while the air at the  focus remains as  
cool as in any other part of the room4  
#dg4 ,to obtain the light-waves we      
employ a clear solution of alum in      
water2 to obtain the dark waves we      
employ the solution of iodine  above    
referred to4 ,but as before stated      
7#cb71 the alum is not so  perfect a    
filter as the iodine2 for it transmits a
 portion of the  obscure heat4    #dh4  
,though the light-waves here prove their
 incompetence to ignite  gun-cotton1    
they are able to burn up black paper2   
or1 indeed1 to  explode the cotton when 
it is blackened4 ,the white cotton does 
not  absorb the light1 and without      

absorption we have no heating4 ,the     
blackened cotton absorbs1 is heated1 and
 explodes4    #di4 ,instead of a        
solution of alum1 we will employ for our
 next  experiment a cell of pure water1 
through which the light passes  without 
sensible absorption4 ,at the focus is   
placed a test-tube also  containing     
water1 the full force of the light being
 concentrated upon  it4 ,the water is   
not sensibly warmed by the concentrated 
waves4 ,we  now remove the cell of      
water2 no change is visible in the beam1
 but  the water contained in the        
test-tube now boils4    #ej4 ,the       
light-waves being thus proved           
ineffectual1 and the full beam          
effectual1 we may infer that it is the  
dark waves that do the work of  heating4
 ,but we clench our inference by        
employing our opaque iodine  filter4    
,placing it on the path of the beam1 the
 light is entirely  stopped1 but the    
water boils exactly as it did when the  
full beam  fell upon it4    #ea4 ,the   

truth of the statement made in paragraph
 7#cd7 is thus  demonstrated4    #eb4   
,and now with regard to the melting of  
ice4 ,on the surface of  a flask        
containing a freezing mixture we obtain 
a thick fur of  hoar-frost4 ,sending the
 beam through a water-cell1 its luminous
 waves  are concentrated upon the       
surface of the flask4 ,not a spicula of 
the  frost is dissolved4 ,we now remove 
the water-cell1 and in a moment a  patch
 of the frozen fur as large as          
half-a-crown is melted4 ,hence1         
inasmuch as the full beam produces this 
effect1 and the luminous part  of the   
beam does not produce it1 we fix upon   
the dark portion the  melting of the    
frost4    #ec4 ,as before1 we clench    
this inference by concentrating the dark
  waves alone upon the flask4 ,the frost
 is dissipated exactly as it was  by the
 full beam4    #ed4 ,these effects are  
rendered strikingly visible by darkening
 with  ink the freezing mixture within  
the flask4 ,when the hoar-frost is      

removed1 the blackness of the surface   
from which it had been melted  comes out
 in strong contrast with the adjacent   
snowy whiteness4 ,when  the flask       
itself1 instead of the freezing mixture1
 is blackened1 the  purely luminous     
waves being absorbed by the glass1 warm 
it2 the glass  reacts upon the frost1   
and melts it4 ,hence the wisdom of      
darkening1  instead of the flask itself1
 the mixture within the flask4    #ee4  
,this experiment proves to demonstration
 the statement in  paragraph 7#cf73 that
 it is the dark waves of the sun that   
melt the  mountain snow and ice1 and    
originate all the rivers derived from   
glaciers4    ,there are writers who seem
 to regard science as an aggregate of   
facts1 and hence doubt its efficacy as  
an exercise of the reasoning  powers4   
,but all that ,i have here taught you is
 the result of reason1  taking its      
stand1 however1 upon the sure basis of  
observation and  experiment4 ,and this  
is the spirit in which our further      

studies are  to be pursued4       #f4   
,oceanic ,distillation4    #ef4 ,the    
sun1 you know1 is never exactly overhead
 in ,england4 ,but at  the equator1 and 
within certain limits north and south of
 it1 the sun  at certain periods of the 
year is directly overhead at noon4      
,these  limits are called the ,tropics  
of ,cancer and of ,capricorn4 ,upon the 
belt comprised between these two circles
 the sun's rays fall with  their        
mightiest power2 for here they shoot    
directly downward1 and  heat both earth 
and sea more than when they strike      
slantingly4    #eg4 ,when the vertical  
sunbeams strike the land they heat it1  
and the  air in contact with the hot    
soil becomes heated in turn4 ,but when  
heated the air expands1 and when it     
expands it becomes lighter4 ,this       
lighter air rises1 like wood plunged    
into water1 through the heavier  air    
overhead4    #eh4 ,when the sunbeams    
fall upon the sea the water is warmed1  
though  not so much as the land4 ,the   

warmed water expands1 becomes thereby   
lighter1 and therefore continues to     
float upon the top4 ,this upper  layer  
of water warms to some extent the air in
 contact with it1  but it also sends up 
a quantity of aqueous vapour1 which     
being far  lighter than air1 helps the  
latter to rise4 ,thus both from the land
  and from the sea we have ascending    
currents established by the action  of  
the sun4    #ei4 ,when they reach a     
certain elevation in the atmosphere1    
these  currents divide and flow1 part   
towards the north and part towards  the 
south2 while from the north and the     
south a flow of heavier and  colder air 
sets in to supply the place of the      
ascending warm air4    #fj4 ,incessant  
circulation is thus established in the  
atmosphere4 ,the  equatorial air and    
vapour flow above towards the north and 
south  poles1 while the polar air flows 
below towards the equator4 ,the two     
currents of air thus established are    
called the upper and the lower  trade   

winds4    #fa4 ,but before the air      
returns from the poles great changes    
have  occurred4 ,for the air as it      
quitted the equatorial regions was laden
  with aqueous vapour1 which could not  
subsist in the cold polar  regions4 ,it 
is there precipitated1 falling sometimes
 as rain1 or  more commonly as snow4    
,the land near the pole is covered with 
this  snow1 which gives birth to vast   
glaciers in a manner hereafter to be    
explained4    #fb4 ,it is necessary that
 you should have a perfectly clear view 
of  this process1 for great mistakes    
have been made regarding the manner  in 
which glaciers are related to the heat  
of the sun4    #fc4 ,it was supposed    
that if the sun's heat were diminished1 
greater  glaciers than those now        
existing would be produced4 ,but the    
lessening  of the sun's heat would      
infallibly diminish the quantity of     
aqueous  vapour1 and thus cut off the   
glaciers at their source4 ,a brief      
illustration will complete your         

knowledge here4    #fd4 ,in the process 
of ordinary distillation1 the liquid to 
be  distilled is heated and converted   
into vapour in one vessel1 and  chilled 
and reconverted into liquid in another4 
,what has just been  stated renders it  
plain that the earth and its atmosphere 
constitute  a vast distilling apparatus 
in which the equatorial ocean plays the 
part of the boiler1 and the chill       
regions of the poles the part of  the   
condenser4 ,in this process of          
distillation heat plays quite as        
necessary a part as cold1 and before    
,bishop ,heber could speak of           
,greenland's icy mountains1 the         
equatorial ocean had to be warmed by    
the sun4 ,we shall have more to say upon
 this question afterwards4              
,illustrative ,experiments4    #fe4 ,i  
have said that when heated1 air expands4
 ,if you wish to verify  this for       
yourself1 proceed thus4 ,take an empty  
flask1 stop it by a  cork2 pass through 
the cork a narrow glass tube4 ,by       

heating the tube  in a spirit-lamp you  
can bend it downwards1 so that when the 
flask is  standing upright the open end 
of the narrow tube may dip into water4  
,now cause the flame of your spirit-lamp
 to play against the flask4  ,the flame 
heats the glass1 the glass heats the    
air2 the air expands1  is driven through
 the narrow tube1 and issues in a storm 
of bubbles  from the water4    #ff4     
,were the heated air unconfined1 it     
would rise in the heavier  cold air4    
,allow a sunbeam or any other intense   
light to fall upon a  white wall or     
screen in a dark room4 ,bring a heated  
poker1 a candle1  or a gas flame        
underneath the beam4 ,an ascending      
current rises from  the heated body     
through the beam1 and the action of the 
air upon the  light is such as to render
 the wreathing and waving of the current
  strikingly visible upon the screen4   
,when the air is hot enough1 and        
therefore light enough1 if entrapped in 
a paper bag it carries the  bag upwards1

 and you have the ,fire-balloon4    #fg4
 ,fold two sheets of paper into two     
cones and suspend them with  their      
closed points upwards from the end of a 
delicate balance4 ,see  that the cones  
balance each other4 ,then place for a   
moment the flame  of a spirit-lamp      
beneath the open base of one of them2   
the hot air  ascends from the lamp and  
instantly tosses upwards the cone above 
it4    #fh4 ,into an inverted glass     
shade introduce a little smoke4 ,let the
  air come to rest1 and then simply     
place your hand at the open mouth  of   
the shade4 ,mimic hurricanes are        
produced by the air warmed by the  hand1
 which are strikingly visible when the  
smoke is illuminated by a  strong light4
    #fi4 ,the heating of the tropical   
air by the sun is indirect4 ,the  solar 
beams have scarcely any power to heat   
the air through which  they pass2 but   
they heat the land and ocean1 and these 
communicate  their heat to the air in   
contact with them4 ,the air and vapour  

start  upwards charged with the heat    
thus communicated4       #g4 ,tropical  
,rains4    #gj4 ,but long before the air
 and vapour from the equator reach the  
poles1 precipitation occurs4 ,wherever a
 humid warm wind mixes with a  cold dry 
one1 rain falls4 ,indeed the heaviest   
rains occur at those  places where the  
sun is vertically overhead4 ,we must    
enquire a little  more closely into     
their origin4    #ga4 ,fill a bladder   
about two-thirds full of air at the sea 
level1  and take it to the summit of    
,mont ,blanc4 ,as you ascend1 the       
bladder  becomes more and more          
distended2 at the top of the mountain it
 is  fully distended1 and has evidently 
to bear a pressure from within4         
,returning to the sea level you find    
that the tightness disappears1  the     
bladder finally appearing as flaccid as 
at first4    #gb4 ,the reason is plain4 
,at the sea level the air within the    
bladder has to bear the pressure of the 
whole atmosphere1 being  thereby        

squeezed into a comparatively small     
volume4 ,in ascending  the mountain1 you
 leave more and more of the atmosphere  
behind2 the  pressure becomes less and  
less1 and by its expansive force the air
  within the bladder swells as the      
outside pressure is diminished4 ,at  the
 top of the mountain the expansion is   
quite sufficient to render  the bladder 
tight1 the pressure within being then   
actually greater  than the pressure     
without4 ,by means of an air-pump we can
 show the  expansion of a balloon partly
 filled with air1 when the external     
pressure has been in part removed4      
#gc4 ,but why do ,i dwell upon this8    
,simply to make plain to you that  the  
unconfined air1 heated at the earth's   
surface1 and ascending by  its          
lightness1 must expand more and more the
 higher it rises in the  atmosphere4    
#gd4 ,and now ,i have to introduce to   
you a new fact1 towards the  statement  
of which ,i have been working for some  
time4 ,it is this3  ,the ascending air  

is chilled by its expansion4 ,indeed    
this chilling  is one source of the     
coldness of the higher atmospheric      
regions4 ,and  now fix your eye upon    
those mixed currents of air and aqueous 
vapour  which rise from the warm        
tropical ocean4 ,they start with plenty 
of  heat to preserve the vapour as      
vapour2 but as they rise they come  into
 regions already chilled1 and they are  
still further chilled by  their own     
expansion4 ,the consequence might be    
foreseen4 ,the load of  vapour is in    
great part precipitated1 dense clouds   
are formed1 their  particles coalesce to
 rain-drops1 which descend daily in     
gushes so  profuse that the word        
torrential is used to express the       
copiousness  of the rainfall4 ,i could  
show you this chilling by expansion1 and
  also the consequent precipitation of  
clouds4    #ge4 ,thus long before the   
air from the equator reaches the poles  
its vapour is in great part removed from
 it1 having redescended to  the earth as

 rain4 ,still a good quantity of the    
vapour is carried  forward1 which yields
 hail1 rain1 and snow in northern and   
southern  lands4      ,illustrative     
,experiments4    #gf4 ,i have said that 
the air is chilled during its expansion4
 ,prove  this1 if you like1 thus4 ,with 
a condensing syringe1 you can force air 
into an iron box furnished with a       
stopcock1 to which the syringe is       
screwed4 ,do so till the density of the 
air within the box is doubled  or       
trebled4 ,immediately after this        
condensation1 both the box and  the air 
within it are warm1 and can be proved to
 be so by a proper  thermometer4 ,simply
 turn the cock and allow the compressed 
air to  stream into the atmosphere4 ,the
 current1 if allowed to strike the      
thermometer1 visibly chills it2 and with
 other instruments the chill  may be    
made more evident still4 ,even the hand 
feels the chill of the  expanding air4  
#gg4 ,throw a strong light1 a           
concentrated sunbeam for example1 across

  the issuing current2 if the compressed
 air be ordinary humid air1 you  see the
 precipitation of a little cloud by the 
chill accompanying the  expansion4 ,this
 cloud-formation may1 however1 be better
 illustrated  in the following way3--   
#gh4 ,in a darkened room send a strong  
beam of light through a glass  tube     
three feet long and three inches wide1  
stopped at its ends by  glass plates4   
,connect the tube by means of a stopcock
 with a vessel  of about one-fourth its 
capacity1 from which the air has been   
removed  by an air-pump4 ,the exhausted 
cylinder of the pump itself will answer 
capitally4 ,fill the glass tube with    
humid air2 then simply turn on  the     
stopcock which connects it with the     
exhausted vessel4 ,having  more room the
 air expands1 cold accompanies the      
expansion1 and1 as a  consequence1 a    
dense and brilliant cloud immediately   
fills the tube4  ,if the experiment be  
made for yourself alone you may see the 
cloud  in ordinary daylight2 indeed1 the

 brisk exhaustion of any receiver       
filled with humid air is known to       
produce this condensation4    #gi4      
,other vapours than that of water may be
 thus precipitated1  some of them       
yielding clouds of intense brilliancy1  
and displaying  iridescences1 such as   
are sometimes1 but not frequently1 seen 
in the  clouds floating over the ,alps4 
#hj4 ,in science what is true for the   
small is true for the large4 ,thus  by  
combining the conditions observed on a  
large scale in nature we  obtain on a   
small scale the phenomena of atmospheric
 clouds4       #h4 ,mountain            
,condensers4    #ha4 ,to complete our   
view of the process of atmospheric      
precipitation  we must take into account
 the action of mountains4 ,imagine a    
south-west wind blowing across the      
,atlantic towards ,ireland4 ,in  its    
passage it charges itself with aqueous  
vapour4 ,in the south of  ,ireland it   
encounters the mountains of ,kerry3 the 
highest of these  is ,magillicuddy's    

,reeks1 near ,killarney4 ,now the lowest
 stratum of  this ,atlantic wind is that
 which is most fully charged with       
vapour4  ,when it encounters the base of
 the ,kerry mountains it is tilted up   
and flows bodily over them4 ,its load of
 vapour is therefore carried  to a      
height1 it expands on reaching the      
height1 it is chilled in  consequence of
 the expansion1 and comes down in       
copious showers  of rain4 ,from this1 in
 fact1 arises the luxuriant vegetation  
of  ,killarney2 to this1 indeed1 the    
lakes owe their water supply4 ,the  cold
 crests of the mountains also aid in the
 work of condensation4    #hb4 ,note the
 consequence4 ,there is a town called   
,cahirciveen to  the south-west of      
,magillicuddy's ,reeks1 at which        
observations of  the rainfall have been 
made1 and a good distance farther to the
  north-east1 right in the course of the
 south-west wind1 there is  another     
town1 called ,portarlington1 at which   
observations of rainfall  have also been

 made4 ,but before the wind reaches the 
latter station  it has passed over the  
mountains of ,kerry and left a great    
portion of  its moisture behind it4     
,what is the result8 ,at ,cahirciveen1  
as shown  by ,dr4 ,lloyd1 the rainfall  
amounts to #ei inches in a year1 while  
at  ,portarlington it is only #ba       
inches4    #hc4 ,again1 you may         
sometimes descend from the ,alps when   
the fall of  rain and snow is heavy and 
incessant1 into ,italy1 and find the sky
  over the plains of ,lombardy blue and 
cloudless1 the wind at the same  time   
blowing over the plain towards the      
,alps4 ,below the wind is hot  enough to
 keep its vapour in a perfectly         
transparent state2 but it  meets the    
mountains1 is tilted up1 expanded1 and  
chilled4 ,the cold of  the higher       
summits also helps the chill4 ,the      
consequence is that the  vapour is      
precipitated as rain or snow1 thus      
producing bad weather  upon the heights1
 while the plains below1 flooded with   

the same air1  enjoy the aspect of the  
unclouded summer sun4 ,clouds blowing   
from  the ,alps are also sometimes      
dissolved over the plains of ,lombardy4 
#hd4 ,in connection with the formation  
of clouds by mountains1 one             
particularly instructive effect may be  
here noticed4 ,you frequently  see a    
streamer of cloud many hundred yards in 
length drawn out from  an ,alpine peak4 
,its steadiness appears perfect1 though 
a strong  wind may be blowing at the    
same time over the mountain head4 ,why  
is the cloud not blown away8 ,it is     
blown away2 its permanence is  only     
apparent4 ,at one end it is incessantly 
dissolved1 at the other  end it is      
incessantly renewed3 supply and         
consumption being thus  equalized1 the  
cloud appears as changeless as the      
mountain to which  it seems to cling4   
,when the red sun of the evening shines 
upon these  cloud-streamers they        
resemble vast torches with their flames 
blown  through the air4       #i4       

,architecture of ,snow4    #he4 ,we now 
resemble persons who have climbed a     
difficult peak1  and thereby earned the 
enjoyment of a wide prospect4 ,having   
made  ourselves masters of the          
conditions necessary to the production  
of  mountain snow1 we are able to take a
 comprehensive and intelligent  view of 
the phenomena of glaciers4    #hf4 ,a   
few words are still necessary as to the 
formation of snow4 ,the  molecules and  
atoms of all substances1 when allowed   
free play1 build  themselves into       
definite and1 for the most part1        
beautiful forms  called crystals4 ,iron1
 copper1 gold1 silver1 lead1 sulphur1   
when  melted and permitted to cool      
gradually1 all show this crystallizing  
power4 ,the metal bismuth shows it in a 
particularly striking manner1  and when 
properly fused and solidified1          
self-built crystals of great  size and  
beauty are formed of this metal4    #hg4
 ,if you dissolve saltpetre in water1   
and allow the solution to  evaporate    

slowly1 you may obtain large crystals1  
for no portion of  the salt is converted
 into vapour4 ,the water of our         
atmosphere is  fresh though it is       
derived from the salt sea4 ,sugar       
dissolved in  water1 and permitted to   
evaporate1 yields crystals of           
sugar-candy4  ,alum readily crystallizes
 in the same way4 ,flints dissolved1 as 
they  sometimes are in nature1 and      
permitted to crystallize1 yield the     
prisms and pyramids of rock crystal4    
,chalk dissolved and crystallized       
yields ,iceland spar4 ,the diamond is   
crystallized carbon4 ,all our  precious 
stones1 the ruby1 sapphire1 beryl1      
topaz1 emerald1 are all  examples of    
this crystallizing power4    #hh4 ,you  
have heard of the force of gravitation1 
and you know that  it consists of an    
attraction of every particle of matter  
for every  other particle4 ,you know    
that planets and moons are held in their
  orbits by this attraction4 ,but       
gravitation is a very simple affair     

compared to the force1 or rather forces1
 of crystallization4 ,for here  the     
ultimate particles of matter1           
inconceivably small as they are1  show  
themselves possessed of attractive and  
repellent poles1 by the  mutual action  
of which the shape and structure of the 
crystal are  determined4 ,in the solid  
condition the attracting poles are      
rigidly  locked together2 but if        
sufficient heat be applied the bond of  
union  is dissolved1 and in the state of
 fusion the poles are pushed so far     
asunder as to be practically out of each
 other's range4 ,the natural  tendency  
of the molecules to build themselves    
together is thus  neutralized4    #hi4  
,this is the case with water1 which as a
 liquid is to all  appearance formless4 
,when sufficiently cooled the molecules 
are  brought within the play of the     
crystallizing force1 and they then      
arrange themselves in forms of          
indescribable beauty4 ,when snow  is    
produced in calm air1 the icy particles 

build themselves into  beautiful stellar
 shapes1 each star possessing six rays4 
,there is no  deviation from this type1 
though in other respects the appearances
  of the snow-stars are infinitely      
various4 ,in the polar regions these    
exquisite forms were observed by ,dr4   
,scoresby1 who gave numerous  drawings  
of them4 ,i have observed them in       
mid-winter filling the air1  and loading
 the slopes of the ,alps4 ,but in       
,england they are also to  be seen1 and 
no words of mine could convey so vivid  
an impression of  their beauty as the   
annexed drawings of a few of them1      
executed at  ,greenwich by ,mr4         
,glaisher4    #ij4 ,it is worth pausing 
to think what wonderful work is going on
 in  the atmosphere during the formation
 and descent of every snow-shower3  what
 building power is brought into play6   
and how imperfect seem the  productions 
of human minds and hands when compared  
with those formed  by the blind forces  
of nature6    #ia4 ,but who ventures to 

call the forces of nature blind8 ,in    
reality1  when we speak thus we are     
describing our own condition4 ,the      
blindness  is ours2 and what we really  
ought to say1 and to confess1 is that   
our  powers are absolutely unable to    
comprehend either the origin or the  end
 of the operations of nature4    #ib4   
,but while we thus acknowledge our      
limits1 there is also reason  for wonder
 at the extent to which science has     
mastered the system  of nature4 ,from   
age to age1 and from generation to      
generation1 fact  has been added to     
fact1 and law to law1 the true method   
and order  of the ,universe being       
thereby more and more revealed4 ,in     
doing this  science has encountered and 
overthrown various forms of superstition
  and deceit1 of credulity and          
imposture4 ,but the world continually   
produces weak persons and wicked        
persons2 and as long as they  continue  
to exist side by side1 as they do in    
this our day1 very  debasing beliefs    

will also continue to infest the world4 
#aj4 ,atomic ,poles4    #ic4 ,what did  
,i mean when1 a few moments ago 7#hh71  
,i spoke of  attracting and repellent   
poles8 ,let me try to answer this       
question4  ,you know that astronomers   
and geographers speak of the earth's    
poles1  and you have also heard of      
magnetic poles1 the poles of a magnet   
being the points at which the attraction
 and repulsion of the magnet  are as it 
were concentrated4    ,illustration3    
,,snow ,,crystals4    #id4 ,every magnet
 possesses1 two such poles2 and if iron 
filings be  scattered over a magnet1    
each particle becomes also endowed with 
two poles4 ,suppose such particles      
devoid of weight and floating in  our   
atmosphere1 what must occur when they   
come near each other8  ,manifestly the  
repellent poles will retreat from each  
other1 while  the attractive poles will 
approach and finally lock themselves    
together4 ,and supposing the particles1 
instead of a single pair1 to  possess   

several pairs of poles arranged at      
definite points over their  surfaces2   
you can then picture them1 in obedience 
to their mutual  attractions and        
repulsions1 building themselves together
 to form  masses of definite shape and  
structure4    #ie4 ,imagine the         
molecules of water in calm cold air to  
be gifted  with poles of this           
description1 which compel the particles 
to lay  themselves together in a        
definite order1 and you have before your
  mind's eye the unseen architecture    
which finally produces the  visible and 
beautiful crystals of the snow4 ,thus   
our first notions  and conceptions of   
poles are obtained from the sight of our
 eyes  in looking at the effects of     
magnetism2 and we then transfer these   
notions and conceptions to particles    
which no eye has ever seen4 ,the  power 
by which we thus picture to ourselves   
effects beyond the range  of the senses 
is what philosophers call the           
,imagination1 and in the  effort of the 

mind to seize upon the unseen           
architecture of crystals1  we have an   
example of the scientific use of this   
faculty4 ,without  imagination we might 
have critical power1 but not creative   
power  in science4       #aa4           
,architecture of ,lake ,ice4    #if4 ,we
 have thus made ourselves acquainted    
with the beautiful  snow-flowers        
self-constructed by the molecules of    
water in calm cold  air4 ,do the        
molecules show this architectural power 
when ordinary  water is frozen8 ,what1  
for example1 is the structure of the ice
 over  which we skate in winter8 ,quite 
as wonderful as the flowers of the      
snow4 ,the observation is rare1 if not  
new1 but ,i have seen in water  slowly  
freezing six-rayed ice-stars formed1 and
 floating free on the  surface4 ,a      
six-rayed star1 moreover1 is typical of 
the construction  of all our lake ice4  
,it is built up of such forms           
wonderfully  interlaced4    #ig4 ,take a
 slab of lake ice and place it in the   

path of a  concentrated sunbeam4 ,watch 
the track of the beam through the ice4  
,part of the beam is stopped1 part of it
 goes through2 the former  produces     
internal liquefaction1 the latter has no
 effect whatever  upon the ice4 ,but the
 liquefaction is not uniformly diffused4
 ,from  separate spots of the ice little
 shining points are seen to sparkle     
forth4 ,every one of those points is    
surrounded by a beautiful liquid  flower
 with six petals4    #ih4 ,ice and water
 are so optically alike that unless the 
light fall  properly upon these flowers 
you cannot see them4 ,but what is the   
central spot8 ,a vacuum4 ,ice swims on  
water because1 bulk for bulk1  it is    
lighter than water2 so that when ice is 
melted it shrinks in  size4 ,can the    
liquid flowers then occupy the whole    
space of the ice  melted8 ,plainly no4  
,a little empty space is formed with the
 flowers1  and this space1 or rather its
 surface1 shines in the sun with the    
lustre of burnished silver4    #ii4 ,in 

all cases the flowers are formed        
parallel to the surface of  freezing4   
,they are formed when the sun shines    
upon the ice of every  lake2 sometimes  
in myriads1 and so small as to require a
 magnifying  glass to see them4 ,they   
are always attainable1 but their beauty 
is  often marred by internal defects of 
the ice4 ,even one portion of the  same 
piece of ice may show them exquisitely1 
while the second portion  shows them    
imperfectly4    #ajj4 ,annexed is a very
 imperfect sketch of these beautiful    
figures4    #aja4 ,here we have a       
reversal of the process of              
crystallization4 ,the  searching solar  
beam is delicate enough to take the     
molecules down  without deranging the   
order of their architecture4 ,try the   
experiment  for yourself with a         
pocket-lens on a sunny day4 ,you will   
not find the  flowers confused2 they all
 lie parallel to the surface of         
freezing4  ,in this exquisite way every 
bit of the ice over which our skaters   

glide in winter is put together4        
#ajb4 ,i said in 7#ig7 that a portion of
 the sunbeam was stopped by the  ice and
 liquefied it4 ,what is this portion8   
,the dark heat of the  sun4 ,the great  
body of the light waves and even a      
portion of the dark  ones1 pass through 
the ice without losing any of their     
heating power4  ,when properly          
concentrated on combustible bodies1 even
 after having  passed through the ice1  
their burning power becomes manifest4   
,illustration3 ,,liquid ,,flowers ,,in  
,,lake ,,ice4    #ajc4 ,and the ice     
itself may be employed to concentrate   
them4 ,with an  ice-lens in the polar   
regions ,dr4 ,scoresby has often        
concentrated the  sun's rays so as to   
make them burn wood1 fire gunpowder1 and
 melt  lead2 thus proving that the      
heating power is retained by the rays1  
even after they have passed through so  
cold a substance4    #ajd4 ,by rendering
 the rays of the electric lamp parallel1
 and then  sending them through a lens  

of ice1 we obtain all the effects which 
,dr4 ,scoresby obtained with the rays of
 the sun4       #ab4 ,the ,source of the
 ,arveiron4 ,ice ,pinnacles1 ,towers1   
and ,chasms  of the ,glacier des ,bois4 
,passage to the ,montanvert4    #aje4   
,our preparatory studies are for the    
present ended1 and thus  informed1 let  
us approach the ,alps4 ,through the     
village of ,chamouni1  in ,savoy1 a     
river rushes which is called the ,arve4 
,let us trace this  river backwards from
 ,chamouni4 ,at a little distance from  
the village  the river forks2 one of its
 branches still continues to be called  
the ,arve1 the other is the ,arveiron4  
,following this latter we come  to what 
is called the source of the ,arveiron--a
 short hour's walk  from ,chamouni4     
,here1 as in the case of the ,rhone     
already referred  to1 you are fronted by
 a huge mass of ice1 the end of a       
glacier1 and  from an arch in the ice   
the ,arveiron issues4 ,do not trust the 
arch in  summer4 ,its roof falls at     

intervals with a startling crash1 and   
would  infallibly crush any person on   
whom it might fall4    #ajf4 ,we must   
now be observant4 ,looking about us     
here1 we find in  front of the ice      
curious heaps and ridges of dbris1 which
 are more  or less concentric4 ,these   
are the terminal moraines of the        
glacier4  ,we shall examine them        
subsequently4    #ajg4 ,we now turn to  
the left1 and ascend the slope beside   
the  glacier4 ,as we ascend we get a    
better view1 and find that the ice  here
 fills a narrow valley4 ,we come upon   
another singular ridge1  not of fresh   
dbris1 like those lower down1 but       
covered in part  with trees1 and        
appearing to be literally as old as the 
hills4 ,it  tells a wonderful tale4 ,we 
soon satisfy ourselves that the ridge is
  an ancient moraine1 and at once       
conclude that the glacier1 at some      
former period of its existence1 was     
vastly larger than it is now4  ,this old
 moraine stretches right across the main

 valley1 and abuts  against the         
mountains at the opposite side4         
,illustration3 ,,source ,,of ,,the      
,,arveiron4    #ajh4 ,having passed the 
terminal portion of the glacier1 which  
is  covered with stones and rubbish1 we 
find ourselves beside a very  wonderful 
exhibition of ice4 ,the glacier descends
 a steep gorge1 and  in doing so is     
riven and broken in the most            
extraordinary manner4  ,here are towers1
 and pinnacles1 and fantastic shapes    
wrought out by  the action of the       
weather1 which put one in mind of rude  
sculpture4  ,annexed is a sketch of an  
ice-pinnacle4 ,from deep chasms in the  
glacier issues a delicate shimmer of    
blue light4 ,at times we hear a  sound  
like thunder1 which arises either from  
the falling of a tower  of ice1 or from 
the tumble of a huge stone into a chasm4
 ,the glacier  maintains this wild and  
chaotic character for some time2 and the
 best  iceman would find himself        
defeated in any attempt to get along it4

    ,illustration3 ,,ice-,,pinnacle4    
#aji4 ,we reach a place called the      
,chapeau1 where1 if we wish1 we can     
have refreshment in a little mountain   
hut4 ,we then pass the ,mauvais  ,pas1 a
 precipitous rock1 on the face of which 
steps are hewn1 and  the unpractised    
traveller is assisted by a rope4 ,we    
pursue our  journey1 partly along the   
mountain side1 and partly along a ridge 
of  singularly artificial aspect a      
lateral moraine4 ,we at length face a   
house perched upon an eminence at the   
opposite side of the glacier4  ,this is 
the auberge of the ,montanvert1 well    
known to all visitors to  this portion  
of the ,alps4    #aaj4 ,here we cross   
the glacier4 ,i should have told you    
that its lower  part1 including the     
broken portion we have passed1 is called
 the  ,glacier des ,bois2 while the     
place that we are now about to cross is 
the beginning of the ,mer de ,glace4    
,you feel that this term is not  quite  
appropriate1 for the glacier here is    

much more like a river  of ice than a   
sea4 ,the valley which it fills is about
 half a mile  wide4    #aaa4 ,the ice   
may be riven where we enter upon it1 but
 with the  necessary care there is no   
difficulty in crossing this portion  of 
the ,mer de ,glace4 ,the clefts and     
chasms in the ice are called  crevasses2
 we shall make their acquaintance on a  
grander scale by  and by4               
,illustration3 ,,the ,,mer ,,de ,,glace1
 ,,showing ,,mont ,,tacul ,,and ,,the   
,,grande  ,,jorasse1 ,,with ,,our       
,,cleft ,,above ,,tr,,leporte ,,to ,,the
 ,,right4    #aab4 ,look up and down    
this side of the glacier4 ,it is        
considerably  riven1 but as we advance  
the crevasses will diminish1 and we     
shall  find very few of them at the     
other side4 ,note this for future use4  
,the ice is at first dirty2 but the dirt
 soon disappears1 and you come  upon the
 clean crisp surface of the glacier4    
,you have already noticed  that the     
clean ice is white1 and that from a     

distance it resembles  snow rather than 
ice4 ,this is caused by the breaking up 
of the  surface by the solar heat4 ,when
 you pound transparent rock-salt into   
powder it is as white as table-salt1 and
 it is the minute fissuring  of the     
surface of the glacier by the sun's rays
 that causes it to  appear white4       
,within the glacier the ice is          
transparent4 ,after an  exhilarating    
passage we get upon the opposite lateral
 moraine1 and  ascend the steep slope   
from it to the ,montanvert ,inn4        
#ac4 ,the ,mer de ,glace and its        
,sources4 ,our ,first ,climb to the     
,cleft  ,station4    #aac4 ,here the    
view before us is very grand4 ,we look  
across the  glacier at the beautiful    
pyramid of the ,aiguille du ,dru 7shown 
in our  frontispiece72 and to the right 
at the ,aiguille des ,charmoz1 with  its
 sharp pinnacles bent as if they were   
ductile4 ,looking straight  up the      
glacier the view is bounded by the great
 crests called ,la  ,grande ,jorasse1   

nearly #ad1jjj feet high4 ,our object   
now is to get  into the very heart of   
the mountains1 and to pursue to its     
origin the  wonderful frozen river which
 we have just crossed4    #aad4         
,starting from the ,montanvert with1 the
 glacier below us to our  left1 we soon 
reach some rocks resembling the ,mauvais
 ,pas2 they are  called les ,fonts4 ,we 
cross them and reach l',angle1 where we 
quit  the land for the ice4 ,we walk up 
the glacier1 but before reaching  the   
promontory called ,trlaporte1 we take   
once more to the mountain  side2 for    
though the path here has been forsaken  
on account of its  danger1 for the sake 
of knowledge we are prepared to incur   
danger  to a reasonable extent4 ,a      
little glacier reposes on the slope to  
our right4 ,we may see a huge boulder or
 two poised on the end of  the glacier1 
and1 if fortunate1 also see the boulder 
liberated and  plunging violently down  
the slope4 ,presence of mind is all that
 is  necessary to render our safety     

certain2 but travellers do not always   
show presence of mind1 and hence the    
path which formerly led over  this slope
 has been forsaken4 ,the whole slope is 
cumbered by masses  of rock which this  
little glacier has sent down4 ,these ,i 
wished you  to see2 by and by they shall
 be fully accounted for4    #aae4 ,above
 ,trlaporte to the right you see a most 
singular cleft in  the rocks1 in the    
middle of which stands an isolated      
pillar1 hewn out  by the weather4 ,our  
next object is to get to the tower of   
rock to  the left of that cleft1 for    
from that position we shall gain a most 
commanding and instructive view of the  
,mer de ,glace and its sources4    #aaf4
 ,the cleft referred to1 with its       
pillar1 may be seen to the  right of the
 preceding engraving of the ,mer de     
,glace4 ,below the cleft  is also seen  
the little glacier just referred to4    
#aag4 ,we may reach this cleft by a     
steep gully1 visible from our  present  
position1 and leading directly up to the

 cleft4 ,but these  gullies1 or         
couloirs1 are very dangerous1 being the 
pathways of  stones falling from the    
heights4 ,we will therefore take the    
rocks  to the left of the gully1 by     
close inspection ascertain their        
assailable points1 and there attack     
them4 ,in the ,alps as elsewhere        
wonderful things may be done by looking 
steadfastly at difficulties1  and       
testing them wherever they appear       
assailable4 ,we thus reach our  station1
 where the glory of the prospect1 and   
the insight that we  gain as to the     
formation of the ,mer de ,glace1 far    
more than repay us  for the labour of   
our ascent4    #aah4 ,for we see the    
glacier below us1 stretching its frozen 
tongue  downwards past the ,montanvert4 
,and we now find this single glacier    
branching out into three others1 some of
 them wider than itself4  ,regard the   
branch to the right1 the ,glacier du    
,gant4 ,it stretches  smoothly up for a 
long distance1 then becomes disturbed1  

and then  changes to a great frozen     
cascade1 down which the ice appears to  
tumble in wild confusion4 ,above the    
cascade you see an expanse of  shining  
snow1 occupying an area of some square  
miles4       #ad4 ,ice-cascade and      
,snows of the ,col du ,gant4    #aai4   
,instead of climbing to the height where
 we now stand1 we might  have continued 
our walk upon the ,mer de ,glace1 turned
 round the  promontory of ,trlaporte1   
and walked right up the ,glacier du     
,gant4  ,we should have found ice under 
our feet up to the bottom of the        
cascade4 ,it is not so compact as the   
ice lower down1 but you would  not think
 of refusing to call it ice4    #abj4   
,as we approach the fall1 the smooth and
 unbroken character of  the glacier     
changes more and more4 ,we encounter    
transverse ridges  succeeding each other
 with augmenting steepness4 ,the ice    
becomes more  and more fissured and     
confused4 ,we wind through tortuous     
ravines1  climb huge ice-mounds1 and    

creep cautiously along crumbling crests1
  with crevasses right and left4 ,the   
confusion increases until further       
advance along the centre of the glacier 
is impossible4    #aba4 ,but with the   
aid of an axe to cut steps in the       
steeper ice-walls  and slopes we might1 
by swerving to either side of the       
glacier1 work  our way to the top of the
 cascade4 ,if we ascended to the right1 
we should have to take care of the ice  
avalanches which sometimes  thunder down
 the slopes2 if to the left1 we should  
have to take care  of the stones let    
loose from the ,aiguille ,noire4 ,after 
we had cleared  the cascade1 we should  
have to beware for a time of the        
crevasses1  which for some distance     
above the fall yawn terribly4 ,but by   
caution  we could get round them1 and   
sometimes cross them by bridges of snow4
  ,here the skill and knowledge to be   
acquired only by long practice  come    
into play2 and here also the use of the 
,alpine rope suggests  itself4 ,for not 

only are the 'snow bridges often frail1 
but whole  crevasses are sometimes      
covered1 the unhappy traveller being    
first  made aware of their existence by 
the snow breaking under his feet4  ,many
 lives have thus been lost1 and some    
quite recently4    #abb4 ,once upon the 
plateau above the ice-fall we find the  
surface  totally changed4 ,below the    
fall we walked upon ice2 here we are    
upon snow4 ,after a gentle but long     
ascent we reach a depression of  the    
ridge which bounds the snow-field at the
 top1 and now look over  ,italy4 ,we    
stand upon the famous ,col du ,gant4    
#abc4 ,they were no idle scamperers on  
the mountains that made these  wild     
recesses first known2 it was not the    
desire for health which  now brings     
some1 or the desire for grandeur and    
beauty which brings  others1 or the wish
 to be able to say that they have       
climbed a  mountain or crossed a col1   
which ,i fear brings a good many more2  
it  was a desire for knowledge that     

brought the first explorers here1  and  
on this col the celebrated ,de ,saussure
 lived for seventeen days1  making      
scientific observations4       #ae4     
,questioning the ,glaciers4    #abd4 ,i 
would now ask you to consider for a     
moment the facts which  such an         
excursion places in our possession4 ,the
 snow through which  we have in idea    
trudged is the snow of last winter and  
spring4 ,had  we placed last ,august a  
proper mark upon the surface of the     
snow1 we  should find it this ,august at
 a certain depth beneath the surface4 ,a
  good deal has been melted by the      
summer sun1 but a good deal of it       
remains1 and it will continue until the 
snows of the coming winter  fall and    
cover it4 ,this again will be in part   
preserved till next  ,august1 a good    
deal of it remaining until it is covered
 by the snow  of the subsequent winter4 
,we thus arrive at the certain          
conclusion  that on the plateau of the  
,col du ,gant the quantity of snow that 

falls annually exceeds the quantity     
melted4    #abe4 ,had we come in the    
month of ,april or ,may1 we should have 
found  the glacier below the ice-fall   
also covered with snow1 which is now    
entirely cleared away by the heat of    
summer4 ,nay1 more1 the ice there  is   
obviously melting1 forming running      
brooks which cut channels in  the ice1  
and expand here and there into small    
blue-green lakes4 ,hence  you conclude  
with certainty that below the ice-fall  
the quantity of  frozen material falling
 upon the glacier is less than the      
quantity  melted4    #abf4 ,and this    
forces upon us another conclusion3      
between the glacier  below the ice-fall 
and the plateau above it there must     
exist a line  where the quantity of snow
 which falls is exactly equal to the    
quantity annually melted4 ,this is the  
snow-line4 ,on some glaciers  it is     
quite distinct1 and it would be distinct
 here were the ice less  broken and     
confused than it actually is4    #abg4  

,the ,french term nv is applied to the  
glacial region above  the snow-line1    
while the word glacier is restricted to 
the ice  below it4 ,thus the snows of   
the ,col du ,gant constitute the nv of  
the ,glacier du ,gant1 and in part1 the 
nv of the ,mer de ,glace4    #abh4 ,but 
if every year thus leaves a residue of  
snow upon the plateau  of the ,col du   
,gant1 it necessarily follows that the  
plateau must get  annually higher1      
provided the snow remain upon it4       
,equally certain  is the conclusion that
 the whole length of the glacier below  
the  cascade must sink gradually lower1 
if the waste of annual melting  be not  
made good4 ,supposing two feet of snow a
 year to remain upon  the ,col1 this    
would raise it to a height far          
surpassing that of ,mont  ,blanc in five
 thousand years4 ,such accumulation must
 take place if  the snow remain upon the
 ,col2 but the accumulation does not    
take  place1 hence the snow does not    
remain on the ,col4 ,the question then  

is1 whither does it go8                 
,illustration3 ,,sketch-,,plan1         
,,showing ,,the ,,moraines1 a1 b1 c1 d1 
e1 ,,of ,,the ,,mer ,,de ,,glace4       
#af4 ,branches and ,medial ,moraines of 
the ,mer de ,glace from the  ,cleft     
,station4    #abi4 ,we shall grapple    
with this question immediately4         
,meanwhile  look at that ice-valley in  
front of us1 stretching up between ,mont
  ,tacul and the ,aiguille de ,lchaud1  
to the base of the great ridge  called  
the ,grande ,jorasse4 ,this is called   
the ,glacier de ,lchaud4 ,it  receives  
at its head the snows of the ,jorasse   
and of ,mont ,mallet1  and joins the    
,glacier du ,gant at the promontory of  
the ,tacul4 ,the  glaciers seem welded  
together where they join1 but they      
continue  distinct4 ,between them you   
clearly trace a stripe of dbris 7c on   
the annexed sketch-plan72 you trace a   
similar though smaller stripe  7a on the
 sketch71 from the junction of the      
,glacier du ,gant with  the ,glacier des

 ,priades at the foot of the ,aiguille  
,noire1 which you  also follow along the
 ,mer de ,glace4    #acj4 ,we also see  
another glacier1 or a portion of it1 to 
the left1  falling apparently in broken 
fragments through a narrow gorge        
7,cascade du ,talfre on the sketch7 and 
joining the ,lchaud1 and from  their    
point of junction also a stripe of dbris
 7d7 runs downwards  along the ,mer de  
,glace4 ,beyond this again we notice    
another stripe  7e71 which seems to     
begin at the bottom of the ice-fall1    
rising  as it were from the body of the 
glacier4 ,beyond all of these we can    
notice the lateral moraine of the ,mer  
de ,glace4    #aca4 ,these stripes are  
the medial moraines of the ,mer de      
,glace4 ,we  shall learn more about them
 immediately4    #acb4 ,and now1 having 
informed our minds by these             
observations1 let  our eyes wander over 
the whole glorious scene1 the splintered
 peaks  and the hacked and jagged       
crests1 the far-stretching snow-fields1 

the  smaller glaciers which nestle on   
the heights1 the deep blue heaven  and  
the sailing clouds4 ,is it not worth    
some labour to gain command  of such a  
scene8 ,but the delight it imparts is   
heightened by the  fact that we did not 
come expressly to see it2 we came to    
instruct  ourselves about the glacier1  
and this high enjoyment is an incident  
of our labour4 ,you will find it thus   
through life2 without honest  labour    
there can be no deep joy4       #ag4    
,the ,talfre and the ,jardin4 ,work     
among the ,crevasses4    #acc4 ,and now 
let us descend to the ,mer de ,glace1   
for ,i want to take  you across the     
glacier to that broken ice-fall the     
origin of which we  have not yet seen4  
,we aim at the farther side of the      
glacier1 and to  reach it we must cross 
those dark stripes of dbris which we    
observed  from the heights4 ,looked at  
from above1 these moraines seemed flat1 
but now we find them to be ridges of    
stones and rubbish1 from twenty  to     

thirty feet high4    #acd4 ,we quit the 
ice at a place called the ,couvercle1   
and wind round  this promontory1        
ascending all the time4 ,we squeeze     
ourselves through  the gralets1 a kind  
of natural staircase in the rock1 and   
soon  afterwards obtain a full view of  
the ice-fall1 the origin of which we    
wish to find4 ,the ice upon the fall is 
much broken2 we have pinnacles  and     
towers1 some erect1 some leaning1 and   
some1 if we are fortunate1  falling like
 those upon the ,glacier des ,bois2 and 
we have chasms from  which issues a     
delicate blue light4 ,with the ice-fall 
to our right  we continue to ascend1    
until at length we command a view of a  
huge  glacier basin1 almost level1 and  
on the middle of which stands a         
solitary island1 entirely surrounded by 
ice4 ,we stand at the edge of  the      
,glacier du ,talfre1 and connect it with
 the ice-fall we have  passed4 ,the     
glacier is bounded by rocky ridges1     
hacked and torn at  the top into teeth  

and edges1 and buttressed by snow fluted
 by the  descending stones4    #ace4 ,we
 cross the basin to the central island1 
and find grass and  flowers at the place
 where we enter upon it4 ,this is the   
celebrated  ,jardin1 of which you have  
often heard4 ,the upper part of the     
,jardin  is bare rock4 ,close at hand is
 one of the noblest peaks in this       
portion of the ,alps1 the ,aiguille     
,verte4 ,it is between thirteen and     
fourteen thousand feet high1 and down   
its sides1 after freshly-fallen  snow1  
avalanches incessantly thunder4 ,from   
one of its projections a  streak of     
moraine starts down the ,talfre2 from   
the ,jardin also a  similar streak of   
moraine issues4 ,both continue side by  
side to the  top of the ice-fall1 where 
they are engulphed in the chasms4 ,but  
at  the bottom of the fall they         
reappear1 as if newly emerging from the 
body of the glacier1 and afterwards they
 continue along the ,mer de  ,glace4    
#acf4 ,walk with me now alongside the   

moraine from the ,jardin down  towards  
the ice-fall4 ,for a time our work is   
easy1 such fissures as  appear offering 
no impediment to our march4 ,but the    
crevasses become  gradually wider and   
wilder1 following each other at length  
so rapidly  as to leave merely walls of 
ice between them4 ,here perfect         
steadiness  of foot is necessary a slip 
would be death4 ,we look towards the    
fall1  and observe the confusion of     
walls and blocks and chasms below us    
increasing4 ,at length prudence and     
reason cry ,halt6 ,we may swerve  to the
 right or to the left1 and making our   
way along crests of ice1  with chasms on
 both hands1 reach either the right     
lateral moraine or  the left lateral    
moraine of the glacier4       #ah4      
,first ,questions regarding ,glacier    
,motion4 ,drifting of ,bodies  buried in
 a ,crevasse4    #acg4 ,but what are    
these lateral moraines8 ,as you and ,i  
go from day  to day along the glaciers1 
their origin is gradually made plain4   

,we  see at intervals the stones and    
rubbish descending from the mountain    
sides and arrested by the ice4 ,all     
along the fringe of the glacier  the    
stones and rubbish fall1 and it soon    
becomes evident that we  have here the  
source of the lateral moraines4    #ach4
 ,but how are the medial moraines to be 
accounted for8 ,how does  the dbris     
range itself upon the glacier in stripes
 some hundreds  of yards from its edge1 
leaving the space between them and the  
edge  clear of rubbish8 ,some have      
supposed the stones to have rolled  over
 the glacier from the sides1 but the    
supposition will not bear  examination4 
,call to mind now our reasoning         
regarding the excess of  snow which     
falls above the snow-line1 and our      
subsequent question1  ,how is the snow  
disposed of4 ,can it be that the entire 
mass is moving  slowly downwards8 ,if   
so1 the lateral moraines would be       
carried along  by the ice on which they 
rest1 and when two branch glaciers unite

  they would lay their adjacent lateral 
moraines together to form a  medial     
moraine upon the trunk glacier4    #aci4
 ,there is1 in fact1 no way that we can 
see of disposing of the  excess of snow 
above the snow-line2 there is no way of 
making good  the constant waste of the  
ice below the snow-line2 there is no way
 of  accounting for the medial moraines 
of the glacier1 but by supposing  that  
from the highest snow-fields of the ,col
 du ,gant1 the ,lchaud1  and the        
,talfre1 to the extreme end of the      
,glacier des ,bois1 the  whole mass of  
frozen matter is moving downwards4      
#adj4 ,if you were older1 it would give 
me pleasure to take you up  ,mont       
,blanc4 ,starting from ,chamouni1 we    
should first pass through  woods and    
pastures1 then up the steep hill-face   
with the ,glacier des  ,bossons to our  
right1 to a rock known as the ,pierre   
,pointue2 thence  to a higher rock      
called the ,pierre l'chelle1 because    
here a ladder  is usually placed to     

assist in crossing the chasms of the    
glacier4  ,at the ,pierre l'chelle we   
should strike the ice1 and passing under
  the ,aiguille du ,midi1 which towers  
to the left1 and which sometimes  sweeps
 a portion of the track with stone      
avalanches1 we should cross  the        
,glacier des ,bossons2 amid heaped-up   
mounds and broken towers of  ice2 up    
steep slopes2 over chasms so deep that  
their bottoms are hid  in darkness4     
#ada4 ,we reach the rocks of the ,grands
 ,mulets1 which form a kind  of barren  
islet in the icy sea2 thence to the     
higher snow-fields1  crossing the ,petit
 ,plateau1 which we should find cumbered
 by blocks  of ice4 ,looking to the     
right1 we should see whence they came1  
for  rising here with threatening aspect
 high above us are the broken           
ice-crags,b of the ,dme du ,got4 ,the   
guides wish to pass this place  in      
silence1 and it is just as well to      
humour them1 however much you  may doubt
 the competence of the human voice to   

bring the ice-crags  down4 ,from the    
,petit ,plateau a steep snow-slope would
 carry us to the  ,grand ,plateau1 and  
at day-dawn ,i know nothing in the whole
 ,alps more  grand and solemn than this 
place4    ,b ,named sracs from their    
resemblance in shape and colour to an   
inferior kind of curdy cheese called by 
this name at ,chamouni4    #adb4 ,one   
object of our ascent would be now       
attained2 for here at the  head of the  
,grand ,plateau1 and at the foot of the 
final slope of ,mont  ,blanc1 ,i should 
show you a great crevasse1 into which   
three guides  were poured by an         
avalanche in the year #ahbj4            
,illustration3 ,,crevasse ,,on ,,grand  
,,plateau4    #adc4 ,is this language   
correct8 ,a crevasse hardly to be       
distinguished  from the present one     
undoubtedly existed here in #ahbj4 ,but 
was it  the identical crevasse now      
existing8 ,is the ice riven here to-day 
the same as that riven fifty-one years  
ago8 ,by no means4 ,how is this  proved8

 ,by the fact that more than forty years
 after their interment1  the remains of 
those three guides were found near the  
end of the  ,glacier des ,bossons1 many 
miles below the existing crevasse4      
#add4 ,the same observation proves to   
demonstration that it is the ice  near  
the bottom of the higher nv that becomes
 the surface-ice  of the glacier near   
its end4 ,the waste of the surface below
 the  snow-line brings the deeper       
portions of the ice more and more to the
  light of day4    #ade4 ,there are     
numerous obvious indications of the     
existence of  glacier motion1 though it 
is too slow to catch the eye at once4   
,the crevasses change within certain    
limits from year to year1 and  sometimes
 from month to month2 and this could not
 be if the ice did  not move4 ,rocks and
 stones also are observed1 which have   
been plainly  torn from the mountain    
sides4 ,blocks seen to fall from        
particular  points are afterwards       
observed lower down4 ,on the moraines   

rocks  are found of a totally different 
mineralogical character from those      
composing the mountains right and left2 
and in all such cases strata  of the    
same character are found bordering the  
glacier higher up4  ,hence the          
conclusion that the foreign boulders    
have been floated  down by the ice4     
,further1 the ends or snouts of many    
glaciers act  like ploughshares on the  
land in front of them1 overturning with 
slow  but merciless energy huts and     
chalets that stand in their way4 ,facts 
like these have been long known to the  
inhabitants of the ,high ,alps1  who    
were thus made acquainted in a vague and
 general way with the  motion of the    
glaciers4       #ai4 ,the ,motion of    
,glaciers4 ,measurements by ,hugi and   
,agassiz4  ,drifting of ,huts on the    
,ice4    #adf4 ,but the growth of       
knowledge is from vagueness towards     
precision1  and exact determinations of 
the rate of glacier motion were soon    
desired4 ,with reference to such        

measurements one glacier in the         
,bernese ,oberland will remain forever  
memorable4 ,from the little town  of    
,meyringen in ,switzerland you proceed  
up the valley of ,hasli1 past  the      
celebrated waterfall of ,handeck1 where 
the river ,aar plunges into  a chasm    
more than #bjj feet deep4 ,you approach 
the ,grimsel ,pass1 but  instead of     
crossing it you turn to the right and   
follow the course of  the ,aar upwards4 
,like the ,rhone and the ,arveiron1 you 
find the ,aar  issuing from a glacier4  
#adg4 ,get upon the ice1 or rather upon 
the deep moraine shingle which  covers  
the ice1 and walk upwards4 ,it is hard  
walking1 but after  some time you get   
clear of the rubbish1 and on to a wide  
glacier  with a great medial moraine    
running along its back4 ,this moraine is
  formed by the junction of two branch  
glaciers1 the ,lauteraar and the        
,finsteraar1 which unite at a promontory
 called the ,abschwung to form  the     
trunk glacier of the ,unteraar4    #adh4

 ,on this great medial moraine in #ahbg 
an intrepid and  enthusiastic ,swiss    
professor1 ,hugi1 of ,solothurm 7,french
 ,soleure71  built a hut with a view to 
observations upon the glacier4 ,his hut 
moved1 and he measured its motion4 ,in  
the three years--from #ahbg to          
#ahcj--;it had moved #ccj feet          
downwards4 ,in #ahcf it had moved #b1ced
  feet2 and in #ahda ,m4 ,agassiz found 
it #d1gab feet below its first          
position4    #adi4 ,in #ahdj1 ,m4       
,agassiz himself and some bold          
companions took  shelter under a great  
overhanging slab of rock on the same    
moraine1  to which they added side walls
 and other means of protection4 ,and    
because he and his comrades came from   
,neufchtel1 the hut was called  long    
afterwards the ,htel des ,neuchtelois4  
,two years subsequent  to its erection  
,m4 ,agassiz found that the hotel had   
moved #dhf feet  downwards4       #bj4  
,precise ,measurements of ,agassiz and  
,forbes4 ,motion of a  ,glacier proved  

to resemble the ,motion of a ,river4    
#aej4 ,we now approach an epoch in the  
scientific history of glaciers4  ,had   
the first observers been practically    
acquainted with the  instruments of     
precision used in surveying1 accurate   
measurements  of the motion of glaciers 
would probably have been earlier        
executed4  ,we are now on the point of  
seeing such instruments introduced      
almost  simultaneously by ,m4 ,agassiz  
on the glacier of the ,unteraar1 and by 
,professor ,forbes on the ,mer de       
,glace4 ,attempts had been made by ,m4  
,escher de la ,linth to determine the   
motion of a series of wooden  stakes    
driven into the ,aletsch glacier1 but   
the melting was so  rapid that the      
stakes soon fell4 ,to remedy this1 ,m4  
,agassiz in #ahda  undertook the great  
labour of carrying boring tools to his  
hotel1  and piercing the ,unteraar      
glacier at six different places to a    
depth  of ten feet1 in a straight line  
across the glacier4 ,into the holes  six

 piles were so firmly driven that they  
remained in the glacier for  a year1 and
 in #ahdb the displacements of all six  
were determined4  ,they were found to be
 #afj feet1 #bbe feet1 #bfi feet1 #bde  
feet1 #baj  feet1 and #abe feet1        
respectively4    #aea4 ,a great step is 
here gained4 ,you notice that the middle
 numbers  are the largest4 ,they        
correspond to the central portion of the
  glacier4 ,hence1 these measurements   
conclusively establish1 not only  the   
fact of glacier motion1 but that the    
centre of a glacier1 like  that of a    
river1 moves more rapidly than the      
sides4    #aeb4 ,with the aid of trained
 engineers ,m4 ,agassiz followed up     
these  measurements in subsequent years4
 ,his researches are recorded in a  work
 entitled ,systme glaciaire1 which is   
accompanied by a very  noble ,atlas of  
the ,glacier of the ,unteraar1 published
 in #ahdg4    #aec4 ,these              
determinations were made by means of a  
theodolite1 of  which ,i will give you  

some notion immediately4 ,the same      
instrument  was employed the same year  
by the late ,professor ,forbes upon the 
,mer de ,glace4 ,he established         
independently the greater central       
motion4 ,he showed1 moreover1 that it is
 not necessary to wait a  year1 or even 
a week to determine the motion of a     
glacier2 with a  correctly-adjusted     
theodolite he was able to determine the 
motion  of various points of the ,mer de
 ,glace from day to day4 ,he affirmed1  
and with truth1 that the motion of the  
glacier might be determined  from hour  
to hour4 ,we shall prove this farther on
 7#afb74 ,professor  ,forbes also       
triangulated the ,mer de ,glace1 and    
laid down an excellent  map of it4 ,his 
first observations and his survey are   
recorded in a  celebrated book published
 in #ahdc1 and entitled ,travels in the 
,alps4    #aed4 ,these observations were
 also followed up in subsequent years1  
the results being recorded in a series  
of detached letters and essays  of great

 interest4 ,these were subsequently     
collected in a volume  entitled         
,occasional ,papers on the ,theory of   
,glaciers1 published in  #ahei4 ,the    
labours of ,agassiz and ,forbes are the 
two chief sources of  our knowledge of  
glacier phenomena4       #ba4 ,the      
,theodolite and its ,use4 ,our own      
,measurements4    #aee4 ,my object thus 
far is attained4 ,i have given you      
proofs of  glacier motion1 and a        
historic account of its measurement4    
,and  now we must try to add a little to
 the knowledge of glaciers by  our own  
labours on the ice4 ,resolution must not
 be wanting at  the commencement of our 
work1 nor steadfast patience during its 
prosecution4 ,look then at this         
theodolite2 it consists mainly of a     
telescope and a graduated circle1 the   
telescope capable of motion  up and     
down1 and the circle1 carrying the      
telescope along with it1  capable of    
motion right and left4 ,when desired to 
make the motion  exceedingly fine and   

minute1 suitable screws1 called tangent 
screws1  are employed4 ,the instrument  
is supported by three legs1 movable1 but
  firm when properly planted4    #aef4  
,two spirit-levels are fixed at right   
angles to each other on  the circle just
 referred to4 ,practice enables one to  
take hold of  the legs of the           
instrument1 and so to fix them that the 
circle shall  be nearly horizontal4 ,by 
means of four levelling screws we render
 it  accurately horizontal4 ,exactly    
under the centre of the instrument  is a
 small hook from which a plummet is     
suspended2 the point of the  bob just   
touches a rock on which we make a mark2 
or if the earth be  soft underneath1 we 
drive a stake into it exactly under the 
plummet4  ,by re-suspending the plummet 
at any future time we can find to a     
hairbreadth the position occupied by the
 instrument to-day4    #aeg4 ,look      
through the telescope2 you see it       
crossed by two fibres  of the finest    
spider's thread4 ,in actual work we     

first direct the  telescope across the  
glacier1 until the intersection of the  
two  fibres accurately covers some      
well-defined point of rock or tree at   
the other side of the valley4 ,this1 our
 fixed standard1 we sketch  with its    
surroundings in a note-book1 so as to be
 able immediately  to recognise it on   
our return to this place4 ,imagine a    
straight line  drawn from the centre of 
the telescope to this point1 and that   
this  line is permitted to drop straight
 down upon the glacier1 every point  of 
it falling as a stone would fall2 along 
such a line we have now to  fix a series
 of stakes4    #aeh4 ,a trained         
assistant is already upon the glacier4  
,he erects  his staff and stands behind 
it2 the telescope is lowered without    
swerving to the right or to the left2 in
 mathematical language it  remains in   
the same vertical plane4 ,the crossed   
fibres of the  telescope probably strike
 the ice a little away from the staff of
 the  assistant2 by a wave of the arm he

 moves right or left2 he may move  too  
much1 so we wave him back again4 ,after 
a trial or two he knows  whether he is  
near the proper point1 and if so makes  
his motions  small4 ,he soon exactly    
strikes the point covered by the        
intersection  of the fibres4 ,a signal  
is made which tells him that he is      
right2 he  pierces the ice with an auger
 and drives in a stake4 ,he then goes   
forward1 and in precisely the same      
manner takes up another point4  ,after  
one or two stakes have been driven in1  
the assistant is able to  take up the   
other points very rapidly4 ,any         
requisite number of stakes  may thus be 
fixed in a straight line across the     
glacier4    #aei4 ,next morning we      
measure the motion of all the stakes4   
,the  theodolite is mounted in its      
former position and carefully levelled4 
,the telescope is directed first upon   
the standard point at the  opposite side
 of the valley1 being moved by a tangent
 screw until the  intersection of the   

spider's threads accurately covers the  
point4  ,the telescope is then lowered  
to the first stake1 beside which our    
trained assistant is already standing4  
,he is provided with a staff  with feet 
and inches marked on it4 ,a glance shows
 us the stake has  moved down4 ,by our  
signals the assistant recovers the point
 from  which we started yesterday1 and  
then determines the distance from  this 
point to the stake4 ,it is1 say1 #f     
inches2 through this distance1          
therefore1 the stake has moved4    #afj4
 ,we are careful to note the hour and   
minute at which each stake  is driven   
in1 and the hour and the minute when its
 distance from its  first position is   
measured2 this enables us to calculate  
the accurate  daily motion of the point 
in question4 ,the distances through     
which  all the other points have moved  
are determined in precisely the same    
way4    #afa4 ,thus we shall proceed to 
work1 first making clear to our minds   
what is to be done1 and then making sure

 that it shall be accurately  done4 ,to 
give our work reality1 ,i will here     
record the actual  measurements         
executed1 and the actual thoughts       
suggested1 on the  ,mer de ,glace in    
#aheg4 ,the only unreality that ,i would
 ask you to  allow1 is that you and ,i  
are supposed to be making the           
observations  together4 ,the labour of  
measuring was undertaken for the most   
part  by ,mr4 ,hirst4       #bb4 ,motion
 of the ,mer de ,glace4    #afb4 ,on    
,july #ad1 then1 we find ourselves at   
the end of the ,glacier  des ,bois1 not 
far from the source of the ,arveiron4   
,we direct our  telescope across the    
glacier1 and fix the intersection of its
  spider's threads accurately upon the  
edge of a pinnacle of ice4 ,we  leave   
the instrument untouched1 looking       
through it from hour to  hour4 ,the edge
 of ice moves slowly1 but plainly1 past 
the fibres1  and at the end of three    
hours we assure ourselves that the      
motion  has amounted to several inches4 

,while standing near the vault of the   
,arveiron1 and talking about going into 
it1 its roof gives way1 and  falls with 
the sound of thunder4 ,it is not1       
therefore1 without reason  that ,i      
warned you against entering these vaults
 in summer4    #afc4 ,we ascend to the  
,montanvert ,inn1 fix on it as a        
residence1 and  then descend to the     
lateral moraine of the glacier a little 
below the  inn4 ,here we erect our      
theodolite1 and mark its exact position 
by  a plummet4 ,we must first make sure 
that our line is perpendicular1  or     
nearly so1 to the axis or middle line of
 the glacier4 ,our  instructed assistant
 lays down a long staff in the direction
 of  the axis1 assuring himself1 by     
looking up and down1 that it is the     
true direction4 ,with another staff in  
his hand1 pointed towards  our          
theodolite1 he shifts his position until
 the second staff is  perpendicular to  
the first4 ,here he gives us a signal4  
,we direct our  telescope upon him1 and 

then gradually raising its end in a     
vertical  plane we find1 and note by    
sketching1 a standard point at the other
  side of the glacier4 ,this point      
known1 and our plummet mark known1 we   
can on any future day find our line4    
7,to render the measurements more       
intelligible1 ,i append on the next page
 an outline diagram of the ,mer  de     
,glace1 and of its tributaries47        
#afd4 ,along the line just described ten
 stakes were set on ,july #ag1  #aheg4  
,their displacements were measured on   
the following day4 ,two of  them had    
fallen1 but here are the distances      
passed over by the eight  remaining ones
 in twenty-four hours4    ,,daily       
,,motion ,,of ,,the ,,mer ,,de ,,glace4 
,first ,line3 ,a ,a' upon the ,sketch4  
,east                 ,west    ,stake   
#a  #b  #c  #d  #e  #g  #i #aj          
,inches #ab #ag #bc #bf #be #bf #bg #cc 
#afe4 ,you have already assured yourself
 by actual contact that the  body of the
 glacier is real ice1 and you may have  

read that glaciers  move2 but the actual
 observation of the motion of a body    
apparently  so rigid is strangely       
interesting4 ,and not only does the ice 
move  bodily1 but one part of it moves  
past another2 the rate of motion        
augmenting gradually from #ab inches a  
day at the side to #cc inches a  day at 
a distance from the side4 ,this quicker 
movement of the central  ice of glaciers
 had been already observed by ,agassiz  
and ,forbes2 we  verify their results1  
and now proceed to something new4       
,crossing the  ,glacier du ,gant1 which 
occupies more than half the valley1 we  
find  that our line of stakes is not yet
 at an end4 ,the #ajth stake stands  on 
the part of the ice which comes from the
 ,talfre4    ,illustration3 ,,outline   
,,plan1 ,,showing ,,the ,,measured      
,,lines ,,of ,,the ,,mer ,,de  ,,glace  
,,and ,,its ,,tributaries4    #aff4 ,now
 the motion of the sides is slow1       
because of the friction of  the ice     
against its boundaries2 but then one    

would think that midway  between the    
boundaries1 where the friction of the   
sides is least1 the  motion ought to be 
greatest4 ,this is clearly not the case2
 for though  the #ajth stake is nearer  
than the #ith to the eastern or ,chapeau
  side of the valley1 the #ajth stake   
surpasses the #ith by #f inches a  day4 
#afg4 ,here we have something to think  
of2 but before a natural  philosopher   
can think with comfort he must be       
perfectly sure of his  facts4 ,the      
foregoing line ran across the glacier a 
little below the  ,montanvert4 ,we will 
run another line across a little way    
above the  hotel4 ,on ,july #ah we set  
out this line1 and to multiply our      
chances  of discovery we place along it 
#ca stakes4 ,on the subsequent day five 
of these were found unfit for use2 but  
here are the distances passed  over by  
the remaining six-and-twenty in #bd     
hours4    ,second ,line3 ,b ,b' upon the
 ,sketch4             ,west    ,stake   
#b  #c  #d  #e  #f  #g  #h  #i #aj #aa  

#ab #ac    ,inches #aa #ab #ae #ae #af  
#ag #ah #ai #bj #bj #ba #ba    ,stake   
#ae #af #ag #ah #ai #bj #ba #bb #bc #bd 
#be #bf    ,inches #bc #bc #bc #ba #bc  
#ba #be #bb #bb #bc #be #bf             
,east    #afh4 ,look at these numbers4  
,the first broad fact they reveal is the
  advance in the rate of motion from    
first to last4 ,there are however  some 
irregularities2 from #bc inches at the  
#agth stake we fall to #ba  inches at   
the #ahth2 from #bc inches at the #aith 
we fall to #ba inches  at the #bjth2    
from #be inches at the #bast we fall to 
#bb inches at the  #bbnd and #bcrd2 but 
notwithstanding these small ups and     
downs1 the  general advance of the rate 
of motion is manifest4 ,now there may   
have  been some slight displacement of  
the stakes by melting1 sufficient to    
account for these small deviations from 
uniformity in the increase  of the      
motion4 ,but another solution is also   
possible4 ,we shall  afterwards learn   
that the glacier is retarded not only by

 its sides  but by its bed2 that the    
upper portions of the ice slide over the
  lower ones4 ,now if the bed of the    
,mer de ,glace should have eminences    
here and there rising sufficiently near 
to the surface to retard the  motion of 
the surface1 they might produce the     
small irregularities  noticed above4    
#afi4 ,we note particularly1 while upon 
the ice1 that the #bfth stake1  like the
 #ajth stake in our last line1 stands   
much nearer to the  eastern than to the 
western side of the glacier2 the        
measurements1  therefore1 offer a       
further proof that the centre of this   
portion of  the glacier is not the place
 of swiftest motion4       #bc4 ,unequal
 ,motion of the two ,sides of the ,mer  
de ,glace4    #agj4 ,but in neither the 
first line nor the second were we able  
to  push our measurements quite across  
the glacier4 ,why8 ,in attempting  to do
 one thing we are often taught another1 
and thus in science1 if  we are only    
steadfast in our work1 our very defeats 

are converted  into means of            
instruction4 ,we at first planted our   
theodolite on the  lateral moraine of   
the ,mer de ,glace1 expecting to be able
 to command  the glacier from side to   
side4 ,but we are now undeceived2 the   
centre  of the glacier proves to be     
higher than its sides1 and from our last
  two positions the view of the ice near
 the opposite side of the  glacier was  
intercepted by the elevation at the     
centre4 ,the mountain  slopes1 in fact1 
are warm in summer1 and they melt the   
ice nearest to  them1 thus causing a    
fall from the centre to the sides4      
#aga4 ,but yonder on the heights at the 
other side of the glacier we  see a     
likely place for our theodolite4 ,we    
cross the glacier and plant  our        
instrument in a position from which we  
sweep the glacier from  side to side4   
,our first line was below the           
,montanvert1 our second  line above it2 
this third line is exactly opposite the 
,montanvert2  in fact1 the mark on which

 we have fixed the fibre-cross of the   
theodolite is a corner of one of the    
windows of the little inn4 ,along  this 
line we fix twelve stakes on ,july #bj4 
,on the #bast one of them  had fallen2  
but the velocities of the remaining     
eleven in #bd hours  were found to be as
 follows3--    ,third ,line3 ,c ,c' upon
 the ,sketch4              ,east        
,west    ,stake     #a  #b  #c  #d  #e  
#f  #g  #h  #i #aj #aa    ,inches   #bj 
#bc #bi #cj #cd #bh #be #be #be #ah  #i 
#agb4 ,both the first stake and the     
eleventh in this series stood  near the 
sides of the glacier4 ,on the eastern   
side the motion is  #bj inches1 while on
 the western side it is only #i4 ,it    
rises on  the eastern side from #bj to  
#cd inches at the #eth stake1 which we1 
standing upon the glacier1 can see to be
 much nearer to the eastern  than to the
 western side4 ,the united evidence of  
these three lines  places the fact      
beyond doubt1 that opposite the         
,montanvert1 and for  some distance     

above it and below it1 the whole eastern
 side of the  glacier is moving more    
quickly than the western side4          
#bd4 ,suggestion of a new ,likeness of  
,glacier ,motion to ,river  ,motion4    
,conjecture tested4    #agc4 ,here we   
have cause for reflection1 and facts are
 comparatively  worthless if they do not
 provoke this exercise of the mind4 ,it 
is because facts of nature are not      
isolated but connected1 that  science1  
to follow them1 must also form a        
connected whole4 ,the mind  of the      
natural philosopher must1 as it were1 be
 a web of thought  corresponding in all 
its fibres with the web of fact in      
nature4    #agd4 ,let us1 then1 ascend  
to a point which commands a good view   
of this portion of the ,mer de ,glace4  
,the ice-river we see is not  straight  
but curved1 and its curvature is from   
the ,montanvert2  that is to say1 its   
convex side is east1 and its concave    
side is  west 7look to the sketch74 ,you
 have already pondered the fact that a  

glacier1 in some respects1 moves like a 
river4 ,how would a river  move through 
a curved channel8 ,this is known4 ,were 
the ice of the  ,mer de ,glace displaced
 by water1 the point of swiftest motion 
at the  ,montanvert would not be the    
centre1 but a point east of the centre4 
,can it be then that this water-rock1 as
 ice is sometimes called1  acts in this 
respect also like water8    #age4 ,this 
is a thought suggested on the spot2 it  
may or it may not  be true1 but the     
means of testing it are at hand4        
,looking up the  glacier1 we see that at
 les ,ponts it also bends1 but that     
there  its convex curvature is towards  
the western side of the valley 7look    
again to the sketch74 ,if our surmise be
 true1 the point of swiftest  motion    
opposite les ,ponts ought to lie west of
 the axis of the  glacier4    #agf4 ,let
 us test this conjecture4 ,on ,july #be 
we fix in a line across  this portion of
 the glacier seventeen stakes2 every one
 of them has  remained firm1 and on the 

#bfth we find the motion for #bd hours  
to be  as follows3--    ,fourth ,line3  
,d ,d' upon the ,sketch4                
,east                                   
,west    ,stake   #a #b  #c  #d  #e  #h 
#g  #h  #i #aj #aa #ab #ac #ad #ae      
,inches  #g #h #ac #ae #af #ai #bj #ba  
#ba #bc #bc #ba #bb #ag #ae    #agg4    
,inspected by the naked eye alone1 the  
stakes #aj and #aa1 where  the glacier  
reaches its greatest motion1 are seen to
 be considerably  to the west of the    
axis of the glacier4 ,thus far we have a
 perfect  verification of the guess     
which prompted us to make these         
measurements4 ,you will here observe    
that the guesses of science are  not the
 work of chance1 but of thoughtful      
pondering over antecedent  facts4 ,the  
guess is the induction facts1 to be     
ratified or exploded  by the test of    
subsequent experiment4    #agh4 ,and    
though even now we have exceedingly     
strong reason for  holding that the     
point of maximum velocity obeys the law 

of liquid  motion1 the strength of our  
conclusion will be doubled if we can    
show that the point shifts back to the  
eastern side of the axis at  another    
place of flexure4 ,fortunately such a   
place exists opposite  ,trlaporte4 ,here
 the convex curvature of the valley     
turns again to  the east4 ,across this  
portion of the glacier a line was set   
out on  ,july #bh1 and from measurements
 on the #cast1 the rate of motion per   
#bd  hours was determined4    ,fifth    
,line3 ,e ,e' upon the ,sketch4         
,west                                   
,east    ,stake     #a  #b  #c  #d  #e  
#f  #g  #h  #i #aj #aa #ab #ac #ad #ae  
,inches   #aa #ad #ac #ae #ae #af #ag   
#ai #bj #ai #bj #ah #af #ae #aj    #agi4
 ,here1 again1 the mere estimate of     
distances by the eye would  show us that
 the three stakes which moved fastest1  
viz4 the #ith1  #ajth1 and #aath1 were  
all to the east of the middle line of   
the  glacier4 ,the demonstration that   
the point of swiftest motion wanders  to

 and fro across the axis1 as the flexure
 of the valley changes1 is1             
therefore1--shall ,i say complete8      
#ahj4 ,not yet4 ,for if surer means are 
open to us we must not rest  content    
with estimates by the eye4 ,we have with
 us a surveying chain3  let us shake it 
out and measure these lines1 noting the 
distance of  every stake from the side  
of the glacier4 ,this is no easy work   
among  the crevasses1 but ,i confide it 
confidently to ,mr4 ,hirst and you4  ,we
 can afterwards compare a number of     
stakes on the eastern side  with the    
same number of stakes taken at the same 
distances from the  western side4 ,for  
example1 a pair of stakes1 one ten yards
 from the  eastern side and the other   
ten yards from the western side2 another
  pair1 one fifty yards from the eastern
 side and the other fifty yards  from   
the western side1 and so on1 can be     
compared together4 ,for the  sake of    
easy reference1 let us call the points  
thus compared in  pairs1 equivalent     

points4    #aha4 ,there were five pairs 
of such points upon our fourth line1 ,d 
,d'1  and here are their velocities3    
,eastern points2 motion in inches    #ac
 #ae #af #ah #bj    ,western            
#ae #ag #bb #bc #bc    ,in every case   
here the stake at the western side moved
 more rapidly  than the equivalent stake
 at the eastern side4    #ahb4 ,applying
 the same analysis to our fifth line1 ,e
 ,e'1 we have the  following series of  
velocities of three pairs of equivalent 
points3--      ,eastern points2 motion  
in inches    #ae #ah #ai    ,western    
#ac #ae #ag    #ahc4 ,here the three    
points on the eastern side move more    
rapidly than  the equivalent points on  
the western side4    #ahd4 ,it is thus  
proved3--    #a4 ,that opposite the     
,montanvert the eastern half of the ,mer
 de ,glace  moves more rapidly than the 
western half4    #b4 ,that opposite les 
,fonts the western half of the glacier  
moves  more rapidly than the eastern    
half4    #c4 ,that opposite ,trlaporte  

the eastern half of the glacier again   
moves more rapidly than the western     
half4    #d4 ,that these changes in the 
place of greatest motion are determined 
by the flexures of the valley through   
which the ,mer de ,glace moves4         
#be4 ,new ,law of ,glacier ,motion4     
#ahe4 ,let us express these facts in    
another way4 ,supposing the points  of  
swiftest motion for a very great number 
of lines crossing the  ,mer de ,glace to
 be determined2 the line joining all    
those points  together is what          
mathematicians would call the locus of  
the point  of swiftest motion4    #ahf4 
,at ,trlaporte this line would lie east 
of the centre2 at the  ,ponts it would  
lie west of the centre2 hence in passing
 from  ,trlaporte to the ,ponts it would
 cross the centre4 ,but at the          
,montanvert it would again lie east of  
the centre2 hence between the  ,ponts   
and the ,montanvert the centre must be  
crossed a second time4  ,if there were  
further sinuosities upon the ,mer de    

,glace there would  be further crossings
 of the axis of the glacier4    #ahg4   
,the points on the axis which mark the  
transition from eastern to  western     
bending1 and the reverse1 may be called 
points of contrary  flexure4    #ahh4   
,now what is true of the ,mer de ,glace 
is true of all other  glaciers moving   
through sinuous valleys2 so that the    
facts  established in the ,mer de ,glace
 may be expanded into the following     
general law of glacier motion3--        
,when a glacier moves through a sinuous 
valley1 the locus of the  points of     
maximum motion does not coincide with   
the centre of the  glacier1 but1 on the 
contrary1 always lies on the convex side
 of  the central line4 ,the locus is    
therefore a curved line more deeply     
sinuous than the valley itself1 and     
crosses the axis of the glacier  at each
 point of contrary flexure4    #ahi4    
,the dotted line on the ,outline ,plan  
7page #fh7 represents the  locus of the 
point of maximum motion1 the firm line  

marking the  centre of the glacier4     
#aij4 ,substituting the word river for  
glacier1 this law is  also true4 ,the   
motion of the water is ruled by         
precisely the same  conditions as the   
motion of the ice4    #aia4 ,let us now 
apply our law to the explanation of a   
difficulty4  ,turning to the careful    
measurements executed by ,m4 ,agassiz on
  the glacier of the ,unteraar1 we      
notice in the discussion of these       
measurements a section of the ,systme   
glaciaire devoted to the  ,migrations of
 the ,centre4 ,it is here shown that the
 middle of the  ,unteraar glacier is not
 always the point of swiftest motion4   
,this  fact has hitherto remained       
without explanation2 but a glance at the
  ,unteraar valley1 or at the map of the
 valley1 shows the enigma to be  an     
illustration of the law which we have   
just established on the ,mer  de ,glace4
       #bf4 ,motion of ,axis of ,mer de 
,glace4    #aib4 ,we have now measured  
the rate of motion of five different    

lines  across the trunk of the ,mer de  
,glace4 ,do they all move alike8 ,no4   
,like a river1 a glacier at different   
places moves at different rates4        
,comparing together the points of       
maximum motion of all five lines1 we    
have this result3    ,,motion ,,of ,,mer
 ,,de ,,glace4      ,at ,trlaporte      
#bj inches a day4    ,at les ,ponts     
#bc              ,above the ,montanvert 
#bf              ,at the ,montanvert    
#cd              ,below the ,montanvert 
#cc;,c           ,c ,this is probably   
under the mark4 ,i think it likely that 
the  swiftest motion of this portion of 
the ,mer de ,glace in #aheg amounted  to
 a yard in twenty-four hours4    #aic4  
,there is thus an increase of rapidity  
as we descend the glacier  from         
,trlaporte to the ,montanvert2 the      
maximum1 motion at the  ,montanvert     
being fourteen inches a day greater than
 at ,trlaporte4       #bg4 ,motion of   
,tributary ,glaciers4    #aid4 ,so much 
for the trunk glacier2 let us now       

investigate the  branches1 permitting1  
as we have hitherto done1 reflection on 
known  facts to precede our attempts to 
discover unknown ones4    #aie4 ,as we  
stood upon our cleft station1 whence we 
had so capital  a view of the ,mer de   
,glace1 we were struck by the fact that 
some of  the tributaries of the glacier 
were wider than the glacier itself4     
,supposing water to be substituted for  
the ice1 how do you suppose  it would   
behave8 ,you would doubtless conclude   
that the motion down  the broad and     
slightly-inclined valleys of the ,gant  
and the ,lchaud  would be comparatively 
slow1 but that the water would force    
itself  with increased rapidity through 
the narrows of ,trlaporte4 ,let us  test
 this notion as applied to the ice4     
#aif4 ,planting our theodolite in the   
shadow of ,mont ,tacul1 and  choosing a 
suitable point at the opposite side of  
the ,glacier du  ,gant1 we fix on ,july 
#bi a series of ten stakes across the   
glacier4  ,the motion of this line in   

twenty-four hours was as follows3--     
,,motion ,,of ,,glacier ,,du ,g,,ant4   
,sixth ,line3 ,h ,h' upon ,sketch4      
,stake     #a  #b  #c  #d  #e  #f  #g   
#h #i #aj    ,inches   #aa #aj #ab #ac  
#ab #ac #aa #aj #i  #e    #aig4 ,our    
conjecture is fully verified4 ,the      
maximum motion here is  seven inches a  
day less than that of the ,mer de ,glace
 at ,trlaporte  7#aib74    #aih4 ,and   
now for the ,lchaud branch4 ,on ,august 
#a we fix ten stakes  across this       
glacier above the point where it is     
joined by the  ,talfre4 ,measured on    
,august #c1 and reduced to twenty-four  
hours1 the  motion was found to be--    
,,motion ,,of ,,glacier ,,de ,l,,chaud4 
,seventh ,line3 ,k ,k' upon ,sketch4    
,stake  #a #b  #c #d #e #f #g #h #i #aj 
,inches #e #h #aj #i #i #h #f #i #g  #f 
#aii4 ,here our conjecture is still     
further verified1 the rate of  motion   
being even less than that of the        
,glacier du ,gant4       #bh4 ,motion of
 ,top and ,bottom of ,glacier4    #bjj4 

,we have here the most ample and varied 
evidence that the sides  of a glacier1  
like those of a river1 are retarded by  
friction against  its boundaries4 ,but  
the likeness does not end here4 ,the    
motion of a  river is retarded by the   
friction against its bed4 ,two          
observers1  viz4 ,prof4 ,forbes and ,m4 
,charles ,martins1 concur in showing the
 same  to be the case with a glacier4   
,the observations of both have been     
objected to2 hence it is all the more   
incumbent on us to seek for  decisive   
evidence4    #bja4 ,at the ,tacul 7near 
the point a upon the sketch plan1 p4    
#hc7 a  wall of ice about #aej feet high
 has already attracted our attention4   
,bending round to join the ,lchaud the  
,glacier du ,gant is here drawn  away   
from the mountain side1 and exposes a   
fine section4 ,we try to  measure it    
top1 bottom1 and middle1 and are        
defeated twice over4 ,we  try it a third
 time and succeed4 ,a stake is fixed at 
the summit of  the ice-precipice1       

another at #d feet from the bottom1 and 
a third at  #ce feet above the bottom4  
,these lower stakes are fixed at some   
risk  of boulders falling upon us from  
above2 but by skill and caution  we     
succeed in measuring the motions of all 
three4 ,for #bd hours the  motions      
are3--      ,top stake      #f  inches4 
,middle stake   #d       ,bottom stake  
#b       #bjb4 ,the retarding influence 
of the bed of the glacier is reduced to 
demonstration by these measurements4    
,the bottom does not move with  half the
 velocity of the surface4       #bi4    
,lateral ,compression of a ,glacier4    
#bjc4 ,furnished with the knowledge     
which these labours and  measurements   
have given us1 let us once more climb to
 our station  beside the ,cleft under   
the ,aiguille de ,charmoz4 ,at our first
 visit  we saw the medial moraines of   
the glacier1 but we knew nothing about  
their cause4 ,we now know that they mark
 upon the trunk its tributary  glaciers4
 ,cast your eye1 then1 first upon the   

,glacier du ,gant2  realise its width in
 its own valley1 and see how much it is 
narrowed  at ,trlaporte4 ,the broad     
ice-stream of the ,lchaud is still more 
surprising1 being squeezed upon the ,mer
 de ,glace to a narrow white  band      
between its bounding moraines4 ,the     
,talfre undergoes similar  compression4 
,let us now descend1 shake out our      
chain1 measure1 and  express in numbers 
the width of the tributaries1 and the   
actual  amount of compression suffered  
at ,trlaporte4    #bjd4 ,we find the    
width of the ,glacier du ,gant to be    
#e1aee links1 or  #a1acd yards4    #bje4
 ,the width of the ,glacier de ,lchaud  
we find to be #c1gbe links1  or #hbe    
yards4    #bjf4 ,the width of the       
,talfre we find to be #b1ijj links1 or  
#fch yards4    #bjg4 ,the sum of the    
widths of the three branch glaciers is  
therefore  #b1eig yards4    #bjh4 ,at   
,trlaporte these three branches are     
forced through a gorge  #hic yards wide1
 or one-third of their previous width1  

at the rate of  twenty inches a day4    
#bji4 ,if we limit our view to the      
,glacier de ,lchaud1 the facts are      
still more astonishing4 ,previous to its
 junction with the ,talfre1  this       
glacier has a width of #hbe yards2 in   
passing through the jaws of  the granite
 vice at ,trlaporte1 its width is       
reduced to eighty-eight  yards1 or in   
round numbers to one-tenth of its       
previous width4 7,look  to the sketch on
 the next page47    ,illustration3      
,,sketch-,,plan ,,showing ,,the         
,,moraines1 a1 b1 c1 d1  e1 ,,of ,,the  
,,mer ,,de ,,glace4    #baj4 ,are we to 
understand by this that the ice of the  
,lchaud is  squeezed to one-tenth of its
 former volume8 ,by no means4 ,it is    
mainly a change of form1 not of volume1 
that occurs at ,trlaporte4  ,previous to
 its compression1 the glacier resembles 
a plate of ice  lying flat upon its bed4
 ,after its compression1 it resembles a 
plate fixed upon its edge4 ,the         
squeezing1 doubtless1 has deepened  the 

ice4       #cj4 ,longitudinal           
,compression of a ,glacier4    #baa4    
,the ice is forced through the gorge at 
,trlaporte by a pressure  from behind2  
in fact the ,glacier du ,gant1          
immediately above  ,trlaporte1          
represents a piston or a plug which     
drives the ice  through the gorge4 ,what
 effect must this pressure have upon the
 plug  itself8 ,reasoning alone renders 
it probable that the pressure will      
shorten the plug2 that the lower part of
 the ,glacier du ,gant will to  some    
extent yield to the pressure from       
behind4    #bab4 ,let us test this      
notion4 ,about three-quarters of a mile 
above  the ,tacul1 and on the mountain  
slope to the left as we ascend1 we      
observe a patch of verdure4 ,thither we 
climb2 there we plant our  theodolite1  
and set out across the ,glacier du      
,gant1 a line1 which we  will call line 
,no4 #a 7,f ,f' upon sketch1 p4 #fh74   
#bac4 ,about a quarter of a mile lower  
down we find a practicable  couloir on  

the mountain side2 we ascend it1 reach a
 suitable  platform1 plant our          
instrument1 and set out a second line1  
,no4 #b 7,g  ,g' upon sketch74 ,we must 
hasten our work here1 for along this    
couloir  stones are discharged from a   
small glacier which rests upon the slope
  of ,mont ,tacul4    #bad4 ,still lower
 down by another quarter of a mile1     
which brings us  near the ,tacul1 we set
 out a third line1 ,no4 #c 7,h ,h' upon 
sketch71  across the glacier4    #bae4  
,the daily motion of the centres of     
these three lines is as  follows3--     
,inches     ,distances asunder    ,no4  
#a       #ejee                          
#ede yards4    ,no4 #b       #aedc      
#dhg       ,no4 #c       #abge     #baf4
 ,the first line here moves five inches 
a day more than the  second2 and the    
second nearly three inches a day more   
than the third4  ,the reasoning is      
therefore confirmed4 ,the ice-plug1     
which is in round  numbers one thousand 
yards long1 is shortened by the pressure

 exerted  on its front at the rate of   
about eight inches a day4    #bag4 ,a   
river descending the ,valley du ,gant   
would behave in  substantially the same 
fashion4 ,it would have its motion on   
approaching ,trlaporte diminished1 and  
it would pour through the  defile with a
 velocity greater than that of the water
 behind4       #ca4 ,sliding and        
,flowing4 ,hard ,ice and ,soft ,ice4    
#bah4 ,we have thus far confined        
ourselves to the measurement and        
discussion of glacier motion2 but in our
 excursions we have noticed  many things
 besides4 ,here and there1 where the ice
 has retreated  from the mountain side1 
we have seen the rocks fluted1 scored1  
and  polished2 thus proving that the ice
 had slidden over them and ground  them 
down4 ,at the source of the ,arveiron we
 noticed the water rushing  from beneath
 the glacier charged with fine matter4  
,all glacier rivers  are similarly      
charged4 ,the ,rhone carries its load of
 matter into the  ,lake of ,geneva2 the 

rush of the river is here arrested1 the 
matter  subsides1 and the ,rhone quits  
the lake clear and blue4 ,the ,lake of  
,geneva1 and many other ,swiss lakes1   
are in part filled up with this  matter1
 and will1 in all probability1 finally  
be obliterated by it4    #bai4 ,one     
portion of the motion of a glacier is   
due to this bodily  sliding of the mass 
over its bed4    #bbj4 ,we have seen in 
our journeys over the glacier streams   
formed by  the melting of the ice1 and  
escaping through cracks and crevasses   
to the bed of the glacier4 ,the fine    
matter ground down is thus washed  away2
 the bed is kept lubricated1 and the    
sliding of the ice rendered  more easy  
than it would otherwise be4    #bba4 ,as
 a skater also you know how much ice is 
weakened by a thaw4  ,before it actually
 melts it becomes rotten and unsafe4    
,test such ice  with your penknife3 you 
can dig the blade readily into it1 or   
cut the  ice with ease4 ,try good sound 
ice in the same way3 you find it much   

more resistant4 ,the one1 indeed1       
resembles soft chalk2 the other hard    
stone4    #bbb4 ,now the ,mer de ,glace 
in summer is in this thawing condition4 
,its  ice is rendered soft and yielding 
by the sun2 its motion is thereby       
facilitated4 ,we have seen that not only
 does the glacier slide over  its bed1  
but that the upper layers slide over the
 under ones1 and  that the centre slides
 past the sides4 ,the softer and more   
yielding  the ice is1 the more free will
 be this motion1 and the more readily   
also will it be forced through a defile 
like ,trlaporte4    #bbc4 ,but in winter
 the thaw ceases2 the quantity of water 
reaching  the bed of the glacier is     
diminished or entirely cut off4 ,the    
ice also1 to a certain depth at least1  
is frozen hard4 ,these  considerations  
would justify the opinion that in winter
 the glacier1  if it moves at all1 must 
move more slowly than in summer4 ,at all
  events1 the summer measurements give  
no clue to the winter motion4    #bbd4  

,this point merits examination4 ,i will 
not1 however1 ask you to  visit the     
,alps in mid-winter2 but1 if you allow  
me1 ,i will be your  deputy to the      
mountains1 and report to you faithfully 
the aspect of  the region and the       
behaviour of the ice4       #cb4 ,winter
 on the ,mer de ,glace4    #bbe4 ,the   
winter chosen is an inclement one4      
,there is snow in ,london1  snow in     
,paris1 snow in ,geneva2 snow near      
,chamouni so deep that the  road fences 
are entirely effaced4 ,on ,christmas    
night--nearly at  mid-night--#ahei1 your
 deputy reaches ,chamouni4    #bbf4 ,the
 snow fell heavily on ,december #bf2 but
 on the #bgth1 during a  lull in the    
storm1 we turn out4 ,there are with me  
four good guides  and a porter4 ,they   
tie planks to their feet to prevent them
 from  sinking in the snow2 ,i neglect  
this precaution and sink often to the   
waist4 ,four or five times during our   
ascent the slope cracks with an         
explosive sound1 and the snow threatens 

to come down in avalanches4,d    ,d     
,four years later1 viz4 in the spring of
 #ahfc1 a mighty climber  and noble     
guide and companion of mine1 named      
,johann ,joseph ,bennen1  was lost1     
through the cracking and subsequent     
slipping of snow on  such a slope4      
,the freshly-fallen snow was in that    
particular condition which causes  its  
granules to adhere1 and hence every     
flake falling on the trees  had been    
retained there4 ,the laden pines        
presented beautiful and  often fantastic
 forms4    #bbg4 ,after five hours and a
 half of arduous work the ,montanvert   
was  attained4 ,we unlocked the forsaken
 auberge1 round which the snow  was     
reared in buttresses4 ,i have already   
spoken of the complex play  of          
crystallising forces4 ,the frost figures
 on the window-panes of  the auberge    
were wonderful3 mimic shrubs and ferns  
wrought by the  building power while    
hampered by the adhesion between the    
glass and  the film in which it worked4 

,the appearance of the glacier was very 
impressive2 all sounds were stilled4    
,the cascades which in summer  fill the 
air with their music were silent1       
hanging from the ledges  of the rocks in
 fluted columns of ice4 ,the surface of 
the glacier  was obviously higher than  
it had been in summer2 suggesting the   
thought that while the winter cold      
maintained the lower end of the  glacier
 jammed between its boundaries1 the     
upper portions still moved  downwards   
and thickened the ice4 ,the peak of the 
,aiguille du ,dru  shook out a          
cloud-banner1 the origin and nature of  
which have been  already explained      
7#hd74 7,see ,frontispiece47            
,illustration3 ,,snow-,,laden           
,,pine-,,tree4    #bbh4 ,on the morning 
of the #bhth this banner was strikingly 
large and  grand1 and reddened by the   
light of the rising sun1 it glowed like 
a  flame4 ,roses of cloud also clustered
 round the crests of the ,grande        
,jorasse and hung upon the pinnacles of 

,charmoz4 ,four men1 well roped         
together1 descended to the glacier4 ,i  
had trained one of them in  #aheg1 and  
he was now to fix the stakes4 ,the storm
 had so distributed  the snow as to     
leave alternate lengths of the glacier  
bare and  thickly covered4 ,where much  
snow lay great caution was required1 for
  hidden crevasses were underneath4 ,the
 men sounded with their staffs  at every
 step4 ,once while looking at the party 
through my telescope  the leader        
suddenly disappeared2 the roof of a     
crevasse had given  way beneath him2 but
 the other three men promptly gathered  
round and  lifted him out of the        
fissure4 ,the true line was soon picked 
up by  the theodolite2 one by one the   
stakes were fixed until a series of     
eleven of them stood across the glacier4
    #bbi4 ,to get higher up the valley  
was impracticable2 the snow was  too    
deep1 and the aspect of the weather too 
threatening2 so the  theodolite was     
planted amid the pines a ,little way    

below the  ,montanvert1 whence through a
 vista ,i could see across the glacier4 
,the men were wrapped at intervals by   
whirling snow-wreaths which  quite hid  
them1 and we had to take advantage of   
the lulls in the  wind4 ,fitfully it    
came up the valley1 darkening the air1  
catching the  snow upon the glacier1 and
 tossing it throughout its entire length
  into high and violently agitated      
clouds1 separated from each other  by   
cloudless spaces corresponding to the   
naked portions of the ice4  ,in the     
midst of this turmoil the men continued 
to work4 ,bravely and  steadfastly stake
 after stake was set1 until at length a 
series of  ten of them was fixed across 
the glacier4    #bcj4 ,many of the      
stakes were fixed in the snow4 ,they    
were four feet  in length1 and were     
driven in to a depth of about three     
feet4 ,but  that night1 while listening 
to the wild onset of the storm1 ,i      
thought  it possible that the stakes and
 the snow which held them might be      

carried bodily away before the morning4 
,the wind1 however1 lulled4  ,we rose   
with the dawn1 but the air was thick    
with descending snow4  ,it was all      
composed of those exquisite six-petaled 
flowers1 or  six-rayed stars1 which have
 been already figured and described 7   
#i74 ,the weather brightening1 the      
theodolite was planted at the end  of   
the first line4 ,the men descended1 and1
 trained by their previous  experience1 
rapidly executed the measurements4 ,the 
first line was  completed before #aa ,a4
 ,m4 ,again the snow began to fall1     
filling  all the air4 ,spangles         
innumerable were showered upon the      
heights4  ,contrary to expectation1 the 
men could be seen and directed through  
the shower4    #bca4 ,to reach the      
position occupied by the theodolite at  
the end of  our second line1 ,i had to  
wade breast-deep through snow which     
seemed  as dry and soft as flour4 ,the  
toil of the men upon the glacier in     
breaking through the snow was           

prodigious4 ,but they did not flinch1   
and after a time the leader stood behind
 the farthest stake1 and  cried1 ,nous  
avons fini4 ,i was surprised to hear him
 so distinctly1  for falling snow had   
been thought very deadening to sound4   
,the work  was finished1 and ,i struck  
my theodolite with a feeling of a       
general  who had won a small battle4    
#bcb4 ,we put the house in order1 packed
 up1 and shot by glissade down  the     
steep slopes of ,la ,filia to the vault 
of the ,arveiron4 ,we found  the river  
feeble1 but not dried up4 ,many weeks   
must have elapsed  since any water had  
been sent down from the surface of the  
glacier4  ,but at the setting in of     
winter the fissures were in a great     
measure  charged with water2 and the    
,arveiron of to-day was probably due to 
the gradual drainage of the glacier4    
,there was now no danger of  entering   
the vault1 for the ice seemed as firm as
 marble4 ,in the  cavern we were bathed 
by blue light4 ,the strange beauty of   

the place  suggested magic1 and put me  
in mind of stories about fairy caves    
which ,i had read when a boy4 ,at the   
source of the ,arveiron our winter      
visit to the ,mer de ,glace ends2 next  
morning your deputy was on his  way to  
,london4       #cc4 ,winter ,motion of  
the ,mer de ,glace4    #bcc4 ,here are  
the measurements executed in the winter 
of #ahei3--    ,line ,no4 ,i4           
,stake  #a  #b  #c  #d  #e  #f  #g  #h  
#i #aj #aa    ,inches #g #aa #ad #ac #ad
 #ad #af #af #ab #ab  #g    ,line ,no4  
,,ii4      ,stake  #a  #b  #c  #d  #e   
#f  #g  #h  #i #aj    ,inches #h #aj #ad
 #af #af #af #ah #ag #ae #ad    #bcd4   
,thus the winter motion of the ,mer de  
,glace near the ,montanvert  is1 in     
round numbers1 half the summer motion4  
#bce4 ,as in summer1 the eastern side of
 the glacier at this place  moved       
quicker than the western4       #cd4    
,motion of the ,grindelwald and ,aletsch
 ,glaciers4    #bcf4 ,as regards the    
question of motion1 to no other glacier 

have we  devoted ourselves with such    
thoroughness as to the ,mer de ,glace2  
we  are1 however1 able to add a few     
measurements of other celebrated        
glaciers4 ,rear the village of          
,grindelwald in the ,bernese ,oberland1 
there are two great ice-streams called  
respectively the ,upper and the  ,lower 
,grindelwald glaciers1 the second of    
which is frequently visited  by         
travellers in the ,alps4 ,across it on  
,august #f1 #ahfj1 a series of  twelve  
stakes was fixed by ,mr4 ,vaughan       
,hawkins and myself4 ,measured  on the  
#hth and reduced to its daily rate1 the 
motion of these stakes  was as          
follows3--    ,,motion ,,of ,,lower     
,,grindelwald ,,glacier4      ,stake    
#a  #b  #c  #d  #e  #f  #g  #h  #i #aj  
#aa #ab    ,inches #ah #ai #bj #ba #ba  
#ba #bb #bj #ai #ah #ag #ad    #bcg4    
,the theodolite was here planted a      
little below the footway  leading to the
 higher glacier region1 and at about a  
mile above  the end of the glacier4 ,the

 measurement was rendered difficult by  
crevasses4    #bch4 ,the largest glacier
 in ,switzerland is the ,great ,aletsch1
 to  which further reference shall      
subsequently be made4 ,across it on     
,august #ad1 #ahfj1 a series of         
thirty-four stakes was planted by ,mr4  
,hawkins and me4 ,measured on the #afth 
and reduced to their daily rate1  the   
velocities were found to be as          
follows3--    ,,motion ,,of ,,great     
,,aletsch ,,glacier4              ,east 
,stake    #a #b #c #d  #e  #f  #g  #h   
#i #aj #aa #ab    ,inches   #b #c #d #f 
#h #aa #ac #ad #af #ag #ag #ai    ,stake
   #ac #ad #ae #af #ag #ah #ai #bj #ba  
#bb #bc    ,inches  #ai #ah #ah #ag #ai 
#ai #ai #ai #ag #ag #ae    ,stake   #bd 
#be #bf #bg #bh #bi #cj #ca #cb #cc #cd 
,inches  #af #ag #ag #ag #ag #ag #ag #ag
 #af #ab #ab                            
,west    #bci4 ,the maximum motion here 
is nineteen inches a day4 ,probably the 
eastern side of the glacier is shallow1 
the retardation of the bed  making the  

motion of the eastern stakes            
inconsiderable4 ,the width of  the      
glacier here is #i1jcj links1 or about a
 mile and a furlong4 ,the  theodolite   
was planted high among the rocks on the 
western flank of  the mountain1 about   
half a mile above the ,mrgelin ,see4    
#ce4 ,motion of ,morteratsch ,glacier4  
#bdj4 ,far to the east of the ,oberland 
and in that interesting part  of        
,switzerland known as the ,ober         
,engadin1 stands a noble group of       
mountains1 less in height than those of 
the ,oberland1 but still  of commanding 
elevation4 ,the group derives its name  
from its most  dominant peak1 the ,piz  
,bernina4 ,to reach the place we travel 
by  railway from ,basel to ,zrich1 and  
from ,zrich to ,chur 7,french ,coire71  
whence we pass by diligence over either 
the ,albula pass or the ,julier  pass to
 the village of ,pontresina4 ,here we   
are in the immediate  neighbourhood of  
the ,bernina mountains4    #bda4 ,from  
,pontresina we may walk or drive along a

 good coach road  over the ,bernina pass
 into ,italy4 ,at about an hour above   
the village  you would look from the    
road into the heart of the mountains1   
the  line of vision passing through a   
valley1 in which is couched a  glacier  
of considerable size4 ,along its back   
you would trace a medial  moraine1 and  
you could hardly fail to notice how the 
moraine1 from a  mere narrow streak at  
first1 widens gradually as it descends1 
until  finally it quite covers the lower
 end of the glacier4 ,nor is this an    
effect of perspective2 for were you to  
stand upon the mountain slopes  which   
nourish the glacier1 you would see      
thence also the widening  of the streak 
of rubbish1 though the perspective here 
would tend to  narrow the moraine as it 
retreats downwards4    #bdb4 ,the       
ice-stream here referred to is the      
,morteratsch glacier1 the  end of which 
is a short hour's walk from the village 
of ,pontresina4  ,we have now to        
determine its rate of motion and to     

account for the  widening of its medial 
moraine4    #bdc4 ,in the summer of     
#ahfd ,mr4 ,hirst and myself set out    
three lines  of stakes across the       
glacier4 ,the first line crossed the ice
 high up2  the second a good distance   
lower down1 and the third lower still4  
,even the third line1 however1 was at a 
considerable distance above  the actual 
snout of the glacier4 ,the daily motion 
of these three  lines was as follows3-- 
,first ,line4      ,stake      #a  #b   
#c  #d  #e  #f  #g  #h  #i #aj #aa      
,inches     #h #ab #ac #ac #ad #ac #ab  
#ab #aj  #g  #e    ,second ,line4       
,stake      #a #b #c #d  #e  #f  #g  #h 
#i #aj #aa    ,inches     #a #d #f #h   
#aj #aa #aa #aa #aa #aa #aa    ,third   
,line4      ,stake      #a #b #c #d #e  
#f #g #h #i #aj #aa    ,inches     #a #b
 #d #e #f #f #g #g #e  #e  #d    #bdd4  
,compare these lines together4 ,you     
notice the velocity of the  first is    
greater than that of the second1 and the
 velocity of the  second greater than   

that of the third4    #bde4 ,the lines  
were permitted to move down wards for   
#ajj hours1  at the end of which time   
the spaces passed over by the points of 
swiftest motion of the three lines were 
as follows3    ,maximum ,motion in #ajj 
,hours4      ,first line  #ef inches4   
,second line #de       ,third line  #cj 
#bdf4 ,here then is a demonstration that
 the upper portions of the  ,morteratsch
 glacier are advancing on the lower     
ones4 ,in #ahga the  motion of a point  
on the middle of the glacier near its   
snout was  found to be less than two    
inches a day6    #bdg4 ,what1 then1 is  
the consequence of this swifter march of
  the upper glacier8 ,obviously to      
squeeze this medial moraine             
longitudinally1 and to cause it to      
spread out laterally4 ,we have here     
distinctly revealed the cause of the    
widening of the medial moraine4    #bdh4
 ,it has been a question much discussed1
 whether a glacier is  competent to     
scoop out or deepen a valley through    

which it moves1 and  this very          
,morteratsch glacier has been cited to  
prove that such is  not the case4       
,observers went to the snout of the     
glacier1 and finding  it sensibly       
quiescent1 they concluded that no       
scooping occurred4 ,but  those who      
contended for the power of glaciers to  
excavate valleys  never stated1 or meant
 to state1 that it was the snout of the 
glacier which did the work4 ,in the     
,morteratsch glacier the work of        
excavation1 which certainly goes on to a
 greater or less extent1  must be far   
more effectual high up the valley than  
at the end of the  glacier4       #cf4  
,birth of a ,crevasse3 ,reflections4    
#bdi4 ,preserving the notion that we are
 working together1 we will  now enter   
upon a new field of enquiry4 ,we have   
wrapped up our  chain1 and are turning  
homewards after a hard day's work upon  
the  ,glacier du ,gant1 when under our  
feet1 as if coming from the body  of the
 glacier1 an explosion is heard4        

,somewhat startled1 we look  enquiringly
 over the ice4 ,the sound is repeated1  
several shots  being fired in quick     
succession4 ,they seem sometimes to our 
right1  sometimes to our left1 giving   
the impression that the glacier is      
breaking all round us4 ,still nothing is
 to be seen4    #bej4 ,we closely scan  
the ice1 and after an hour's strict     
search  we discover the cause of the    
reports4 ,they announce the birth of  a 
crevasse4 ,through a pool upon the      
glacier we notice air bubbles           
ascending1 and find the bottom of the   
pool crossed by a narrow crack1  from   
which the bubbles issue4 ,eight and left
 from this pool we trace  the young     
fissure through long distances4 ,it is  
sometimes almost  too feeble to be seen1
 and at no place is it wide enough to   
admit a  knife-blade4    #bea4 ,it is   
difficult to believe that the formidable
 fissures among  which you and ,i have  
so often trodden with awe1 could        
commence in  this small way4 ,such1     

however1 is the case4 ,the great and    
gaping  chasms on and above the         
ice-falls of the ,gant and the ,talfre  
begin as narrow cracks1 which open      
gradually to crevasses4 ,we are  thus   
taught in an instructive and impressive 
way that appearances  suggestive of very
 violent action may really be produced  
by processes  so slow as to require     
refined observations to detect them4 ,in
 the  production of natural phenomena   
two things always come into play1 the   
intensity of the acting force1 and the  
time during which it acts4  ,make the   
intensity great1 and the time small1 and
 you have sudden  convulsion2 but       
precisely the same apparent effect may  
be produced  by making the intensity    
small1 and the time great4 ,this truth  
is  strikingly illustrated by the       
,alpine ice-falls and crevasses2  and   
many geological phenomena1 which at     
first sight suggest  violent convulsion1
 may be really produced in the selfsame 
almost  imperceptible way4       #cg4   

,icicles4    #beb4 ,the crevasses are   
grandest on the higher nvs1 where they  
sometimes appear as long yawning        
fissures1 and sometimes as chasms  of   
irregular outline4 ,a delicate blue     
light shimmers from them1 but  this is  
gradually lost in the darkness of their 
profounder portions4  ,over the edges of
 the chasms1 and mostly over the        
southern edges1  hangs a coping of snow1
 and from this depend like stalactites  
rows  of transparent icicles1 #aj1 #bj1 
#cj feet long4 ,these pendent spears    
constitute one of the most beautiful    
features of the higher crevasses4       
#bec4 ,how are they produced8 ,evidently
 by the thawing of the snow4 ,but  why1 
when once thawed1 should the water      
freeze again to solid spears8  ,you have
 seen icicles pendent from a house-eave1
 which have been  manifestly produced by
 the thawing of the snow upon the roof4 
,if we  understand these1 we shall also 
understand the vaster stalactites of    
the ,alpine crevasses4    #bed4         

,gathering up such knowledge as we      
possess1 and reflecting upon  it        
patiently1 let us found upon it1 if we  
can1 a theory of icicles4    #bee4      
,first1 then1 you are to know that the  
air of our atmosphere  is hardly heated 
at all by the rays of the sun1 whether  
visible or  invisible4 ,the air is      
highly transparent to all kinds of rays1
 and  it is only the scanty fraction to 
which it is not transparent that  expend
 their force in warming it4    #bef4    
,not so1 however1 with the snow on which
 the sunbeams fall4 ,it  absorbs the    
solar heat1 and on a sunny day you may  
see the summits of  the high ,alps      
glistening with the water of            
liquefaction4 ,the air  above and around
 the mountains may at the same time be  
many degrees  below the freezing point  
in temperature4    #beg4 ,you have only 
to pass from sunshine into shade to     
prove this4 ,a  single step suffices to 
carry you from a place where the        
thermometer  stands high to one where it

 stands low2 the change being due1 not  
to any difference in the temperature of 
the air1 but simply to the  withdrawal  
of the thermometer from the direct      
action of the solar  rays4 ,nay1 without
 shifting the thermometer at all1 by    
interposing a  suitable screen1 which   
cuts off the sun's rays1 the coldness of
 the  air may be demonstrated4    #beh4 
,look now to the snow upon your house   
roof4 ,the sun plays upon  it1 and melts
 it2 the water trickles to the eave and 
then drops down4  ,if the eave face the 
sun the water remains water2 but if the 
eave  do not face the sun1 the drop1    
before it quits its parent snow1 is     
already in shadow4 ,now the shaded      
space1 as we have learnt1 may be  below 
the freezing temperature4 ,if so the    
drop1 instead of falling1  congeals1 and
 the rudiment of an icicle is formed4   
,other drops and  driblets succeed1     
which trickle over the rudiment1 congeal
 upon it in  part and thicken it at the 
root4 ,but a portion of the water       

reaches  the free end of the icicle1    
hangs from it1 and is there congealed   
before it escapes4 ,the icicle is thus  
lengthened4 ,in the ,alps1  where the   
liquefaction is copious and the cold of 
the shaded crevasse  intense1 the       
icicles1 though produced in the same    
way1 naturally grow  to a greater size4 
,the drainage of the snow after the     
sun's power is  withdrawn also produces 
icicles4    #bei4 ,it is interesting and
 important that you should be able to   
explain the formation of an icicle2 but 
it is far more important  that you      
should realise the way in which the     
various threads of what  we call ,nature
 are woven together4 ,you cannot fully  
understand an  icicle without first     
knowing that solar beams powerful enough
 to  fuse the snows and blister the     
human skin1 nay1 it might be added1     
powerful enough1 when concentrated1 to  
burn up the human body itself1  may pass
 through the air1 and still leave it at 
an icy temperature4       #ch4 ,the     

,bergschrund4    #bfj4 ,having cleared  
away this difficulty1 let us turn once  
more to  the crevasses1 taking them in  
the order of their formation4 ,first    
then above the nv we have the final     
,alpine peaks and crests1  against which
 the snow is often reared as a steep    
buttress4 ,we have  already learned that
 both nvs and glaciers are moving slowly
  downwards2 but it usually happens that
 the attachment of the highest  portion 
of the buttress to the rocks is great   
enough to enable it to  hold on while   
the lower portion breaks away4 ,a very  
characteristic  crevasse is thus formed1
 called in the ,german-speaking portion 
of the  ,alps a ,bergschrund4 ,it often 
surrounds a peak like a fosse1 as if  to
 defend it against the assaults of      
climbers4    #bfa4 ,look more closely   
into its formation4 ,imagine the snow as
 yet  unbroken4 ,its higher portions    
cling to the rocks1 and move downwards  
with extreme slowness4 ,but its lower   
portions1 whether from their  greater   

depth and weight1 or their less perfect 
attachment1 are  compelled to move more 
quickly4 ,a pull is therefore exerted1  
tending to separate the lower from the  
upper snow4 ,for a time this  pull is   
resisted by the cohesion of the nv2 but 
this at length  gives way1 and a crack  
is formed exactly across the line in    
which  the pull is exerted4 ,in other   
words1 a crevasse is formed at right    
angles to the line of tension4          
#ci4 ,transverse ,crevasses4    #bfb4   
,both on the nv and on the glacier the  
origin of the crevasses  is the same4   
,through some cause or other the ice is 
thrown into a  state of strain1 and as  
it cannot stretch it breaks across the  
line of tension4 ,take for example1 the 
ice-fall of the ,gant1 or  of the       
,talfre1 above which you know the       
crevasses yawn terribly4  ,imagine the  
nv and the glacier entirely peeled away1
 so as to  expose the surface over which
 they move4 ,from the ,col du ,gant we  
should see this surface falling gently  

to the place now occupied by  the brow  
of the cascade4 ,here the surface would 
fall steeply down to  the bed of the    
present ,glacier du ,gant1 where the    
slope would become  gentle once more4   
#bfc4 ,think of the nv moving over such 
a surface4 ,it descends from  the ,col  
till it reaches the brow just referred  
to4 ,it crosses the  brow1 and must bend
 down to keep upon its bed4 ,realise    
clearly what  must occur4 ,the surface  
of the nv is evidently thrown into a    
state of strain2 it breaks and forms a  
crevasse4 ,each fresh portion  of the nv
 as it passes the brow is similarly     
broken1 and thus a  succession of       
crevasses is sent down the fall4        
,between every two  chasms is a great   
transverse ridge4 ,through local strains
 upon the  fall those ridges are also   
frequently broken across1 towers of     
ice--sracs--being the result4 ,down the 
fall both ridges and sracs  are borne1  
the dislocation being augmented during  
the descent4    #bfd4 ,what must occur  

at the foot of the fall8 ,here the slope
 suddenly  lessens in steepness4 ,it is 
plain that the crevasses must not only  
cease to open here1 but that they must  
in whole or in part close  up4 ,at the  
summit of the fall1 the bending was such
 as to make the  surface convex2 at the 
bottom of the fall the bending renders  
the  surface concave4 ,in the one case  
we have strain1 in the other  pressure4 
,in the one case1 therefore1 we have the
 opening1 and  in the other the closing 
of crevasses4 ,this reasoning           
corresponds  exactly with the facts of  
observation4    #bfe4 ,lay bare your arm
 and stretch it straight4 ,make two ink 
dots  half an inch or an inch apart1    
exactly opposite the elbow4 ,bend your  
arm1 the dots approach each other1 and  
are finally brought together4  ,let the 
two dots represent the two sides of a   
crevasse at the bottom  of an ice-fall2 
the bending of the arm resembles the    
bending of the  ice1 and the closing up 
of the dots resembles the closing of the

  fissures4    #bff4 ,the same remarks  
apply to various portions of the ,mer de
 ,glace4  ,at certain places the        
inclination changes from a gentler to a 
steeper  slope1 and on crossing the brow
 between both the glacier breaks its    
back4 ,transverse crevasses are thus    
formed4 ,there is such a change  of     
inclination opposite to the ,angle1 and 
a still greater but similar  change at  
the head of the ,glacier des ,bois4 ,the
 consequence is that  the ,mer de ,glace
 at the former point is impassable1 and 
at the latter  the rending and          
dislocation are such as we have seen and
 described4  ,below the ,angle1 and at  
the bottom of the ,glacier des ,bois1   
the  steepness relaxes1 the crevasses   
heal up1 and the glacier becomes  once  
more continuous and compact4       #dj4 
,marginal ,crevasses4    #bfg4          
,supposing1 then1 that we had no changes
 of inclination1 should  we have no     
crevasses8 ,we should certainly have    
less of them1 but they  would not wholly

 disappear4 ,for other circumstances    
exist to throw  the ice into a state of 
strain1 and to determine its fracture4  
,the  principal of these is the more    
rapid movement of the centre of the     
glacier4    #bfh4 ,helped by the labours
 of an eminent man1 now dead1 the late  
,mr4  ,wm4 ,hopkins1 of ,cambridge1 let 
us master the explanation of this  point
 together4 ,but the pleasure of         
mastering it would be enhanced  if we   
could see beforehand the perplexing and 
delusive appearances  accounted for by  
the explanation4 ,could my wishes be    
followed out1 ,i  would at this point of
 our researches carry you off with me to
 ,basel1  thence to ,thun1 thence to    
,interlaken1 thence to ,grindelwald1    
where  you would find yourself in the   
actual presence of the ,wetterhorn and  
the ,eiger1 with all the greatest peaks 
of the ,bernese ,oberland1 the          
,finsteraarhorn1 the ,schreckhorn1 the  
,monch1 the ,jungfrau1 at hand4  ,at    
,grindelwald1 as we have already learnt1

 there are two well-known  glaciers--the
 ,ober ,grindelwald and the ,unter      
,grindelwald glaciers--on  the latter of
 which our observations should commence4
    #bfi4 ,dropping down from the       
village to the bottom of the valley1 we 
should breast the opposite mountain1 and
 with the great limestone  precipices of
 the ,wetterhorn to our left1 we should 
get upon a path  which commands a view  
of the glacier4 ,here we should see     
beautiful  examples of the opening of   
crevasses at the summit of a brow1 and  
their closing at the bottom4 ,but the   
chief point of interest would  be the   
crevasses formed at the side of this    
glacier--the marginal  crevasses1 as    
they may be called4    #bgj4 ,we should 
find the side copiously fissured1 even  
at those places  where the centre is    
compact2 and we should particularly     
notice that  the fissures would neither 
run in the direction of the glacier1 nor
  straight across it1 but that they     
would be oblique to it1 enclosing  an   

angle of about #de degrees with the     
sides4 ,starting from the side  of the  
glacier the crevasses would be seen to  
point upwards2 that  is to say1 the ends
 of the fissures abutting against the   
bounding  mountain would appear to be   
dragged down4 ,were you less instructed 
than you now are1 ,i might lay a wager  
that the aspect of these  fissures would
 cause you to conclude that the centre  
of the glacier  is left behind by the   
quicker motion of the sides4    #bga4   
,this indeed was the conclusion drawn by
 ,m4 ,agassiz from this  very           
appearance1 before he had measured the  
motion of the sides and  centre of the  
glacier of the ,unteraar4 ,intimately   
versed with the  treatment of mechanical
 problems1 ,mr4 ,hopkins immediately    
deduced  the obliquity of the lateral   
crevasses from the quicker flow of the  
centre4 ,standing beside the glacier    
with pencil and note-book in  hand1 ,i  
would at once make the matter clear to  
you thus4    ,illustration    #bgb4 ,let

 ,a ,c1 in the annexed figure1 be one   
side of the glacier1 and  ,b ,d the     
other2 and let the direction of motion  
be that indicated  by the arrow4 ,let ,s
 ,t be a transverse slice of the        
glacier1 taken  straight across it1 say 
to-day4 ,a few days or weeks hence this 
slice will have been carried down1 and  
because the centre moves more  quickly  
than the sides it will not remain       
straight1 but will bend  into the form  
,s' ,t'4    #bgc4 ,supposing ,t i to be 
a small square of the original slice    
near  the side of the glacier4 ,in its  
new position the square will be         
distorted to the lozenge-shaped figure  
,t' i'4 ,fix your attention  upon the   
diagonal ,t i of the square2 in the     
lowest position this  diagonal1 if the  
ice could stretch1 would be lengthened  
to ,t' i'4  ,but the ice does not       
stretch2 it breaks1 and we have a       
crevasse  formed at right angles to ,t' 
i'4 ,the mere inspection of the diagram 
will assure you that the crevasse will  

point obliquely upwards4    #bgd4 ,along
 the whole side of the glacier the      
quicker movement of the  centre produces
 a similar state of strain2 and the     
consequence is  that the sides are      
copiously cut by those oblique          
crevasses1 even at  places where the    
centre is free from them4    #bge4 ,it  
is curious to see at other places the   
transverse fissures  of the centre      
uniting with those at the sides1 so as  
to form great  curved crevasses which   
stretch across the glacier from side to 
side4 ,the convexity of the curve is    
turned upwards1 as mechanical           
principles declare it ought to be4 7,see
 sketch on opposite page47  ,but if you 
were ignorant of those principles1 you  
would never infer  from the aspect of   
these curves the quicker motion of the  
centre4 ,in  landslips1 and in the      
motion of partially indurated mud1 you  
may  sometimes notice appearances       
similar to those exhibited by the ice4  
,illustration3 ,,sketch ,,of ,,curved   

,,crevasses3 ,,the ,,glacier ,,moves    
,,from  ,,left ,,to ,,right4       #da4 
,longitudinal ,crevasses4    #bgf4 ,we  
have thus unravelled the origin of both 
transverse and  marginal crevasses4 ,but
 where a glacier issues from a steep and
  narrow defile upon a comparatively    
level plain which allows it room  to    
expand laterally1 its motion is in part 
arrested1 and the level  portion has to 
bear the thrust of the steeper portions 
behind4 ,here  the line of thrust is in 
the direction of the glacier1 while the 
direction at right angles to this is one
 of tension4 ,across this  latter the   
glacier breaks1 and longitudinal        
crevasses are formed4    #bgg4 ,examples
 of this kind of crevasse are furnished 
by the lower  part of the ,glacier of   
the ,rhone1 when looked down upon from  
the  ,grimsel ,pass1 or from any        
commanding point on the flanking        
mountains4       #db4 ,crevasses in     
relation to ,curvature of ,glacier4     
#bgh4 ,one point in addition remains to 

be discussed1 and your present          
knowledge will enable you to master it  
in a moment4 ,you remember at  an early 
period of ,,out researches that we      
crossed the ,mer de ,glace  from the    
,chapeau side to the ,montanvert side4  
,i then desired you to  notice that the 
,chapeau side of the glacier was more   
fissured than  either the centre or the 
,montanvert side 7#ge74 ,why should this
 be so8  ,knowing as we now do that the 
,chapeau side of the glacier moves more 
quickly than the other2 that the point  
of maximum motion does not  lie on the  
centre but far east of it1 we are       
prepared to answer this  question in a  
perfectly satisfactory manner4    #bgi4 
,let ,a ,b and ,c ,d1 in the diagram    
opposite1 represent the two  curved     
sides of the ,mer de ,glace at the      
,montanvert1 and let m n be  a straight 
line across the glacier4 ,let o be the  
point of maximum  motion4 ,the          
mechanical state of the two sides of the
 glacier may be  thus made plain4       

,supposing the line m n to be a straight
 elastic  string with its ends fixed2   
let it be grasped firmly at the point  o
 by the finger and thumb1 and drawn to  
o'1 keeping the distance  between o' and
 the side ,c ,d constant4 ,here the     
length1 n o of  the string would have   
stretched to n o'1 and the length m o to
  m o' and you see plainly that the     
stretching of the short line1 in        
comparison with its length1 is greater  
than that of the long line in           
comparison with its length4 ,in other   
words1 the strain upon n o' is  greater 
than that upon m o'2 so that if one of  
them were to break  under the strain1 it
 would be the short one4                
,illustration3 ,montanvert    #bhj4     
,these two lines represent the          
conditions of strain upon the  two sides
 of the glacier4 ,the sides are held    
back1 and the centre  tries to move on1 
a strain being thus set up between the  
centre and  sides4 ,but the displacement
 of the point of maximum motion through 

the curvature of the valley makes the   
strain upon the eastern ice  greater    
than that upon the western4 ,the eastern
 side of the glacier  is therefore more 
crevassed than the western4    #bha4    
,here indeed resides the difficulty of  
getting along the eastern  side of the  
,mer de ,glace3 a difficulty which was  
one reason for our  crossing the glacier
 opposite to the ,montanvert4 ,there are
 two convex  sweeps on the eastern side 
to one on the western side1 hence on the
  whole the eastern side of the ,mer de 
,glace is most riven4       #dc4        
,moraine-ridges1 ,glacier ,tables1 and  
,sand-,cones4    #bhb4 ,when you and ,i 
first crossed the ,mer de ,glace from   
,trlaporte  to the ,couvercle1 we found 
that the stripes of rocks and rubbish   
which constituted the medial moraines   
were ridges raised above the  general   
level of the glacier to a height at some
 places of twenty or  thirty feet4 ,on  
examining these ridges we found the     
rubbish to be  superficial1 and that it 

rested upon a great spine of ice which  
ran  along the back of the glacier4 ,by 
what means has this ridge of ice  been  
raised8    #bhc4 ,most boys have read   
the story of ,dr4 ,franklin's placing   
bits of  cloth of various colours upon  
snow on a sunny day4 ,the bits of cloth 
sank in the snow1 the dark ones most4   
#bhd4 ,consider this experiment4 ,the   
sun's rays first of all fall  upon the  
upper surface of the cloth and warm it4 
,the heat is then  conducted through the
 cloth to the under surface1 and the    
under  surface passes it on to the snow1
 which is finally liquefied by the      
heat4 ,it is quite manifest that the    
quantity of snow melted will  altogether
 depend upon the amount of heat sent    
from the upper to the  under surface of 
the cloth4    #bhe4 ,now cloth is what  
is called a bad conductor4 ,it does not 
permit  heat to travel freely through   
it4 ,but where it has merely to pass    
through the thickness of a single bit of
 cloth1 a good quantity of  the heat    

gets through4 ,but if you double or     
treble or quintuple the  thickness of   
the cloth2 or1 what is easier1 if you   
put several pieces  one upon the other1 
you come at length to a point where no  
sensible  amount of heat could get      
through from the upper to the under     
surface4    #bhf4 ,what must occur if   
such a thick piece1 or such a series of 
pieces of cloth1 were placed upon snow  
on which a strong sun is  falling8 ,the 
snow round the cloth is melted1 but that
 underneath the  cloth is protected4 ,if
 the action continue long enough the    
inevitable  result will be1 that the    
level of the snow all round the cloth   
will  sink1 and the cloth will be left  
behind perched upon an eminence of      
snow4    #bhg4 ,if you understand this1 
you have already mastered the cause of  
the moraine-ridges4 ,they are not       
produced by any swelling of the ice     
upwards4 ,but the ice underneath the    
rocks and rubbish being protected  from 
the sun1 the glacier right and left     

melts away and leaves a  ridge behind4  
#bhh4 ,various other appearances upon   
the glacier are accounted for  in the   
same way4 ,here upon the ,mer de ,glace 
we have flat slabs of  rock sometimes   
lifted up on pillars of ice4 ,these are 
the so-called  ,glacier ,tables4 ,they  
are produced1 not by the growth of a    
stalk of  ice out of the glacier1 but by
 the melting of the glacier all round   
the ice protected by the stone4 ,here is
 a sketch of one of the ,tables  of the 
,mer de ,glace4    ,illustration        
#bhi4 ,notice moreover that a glacier   
table is hardly ever set square  upon   
its pillar4 ,it generally leans to one  
side1 and repeated  observation teaches 
you that it so leans as to enable you   
always to  draw the north and south line
 upon the glacier4 ,for the sun being   
south of the zenith at noon pours its   
rays against the southern end  of the   
table1 while the northern end remains in
 shadow4 ,the southern  end1 therefore1 
being most warmed does not protect the  

ice underneath  it so effectually as the
 northern end4 ,the table becomes       
inclined1  and ends by sliding bodily   
off its pedestal4    #bij4 ,in the      
figure opposite we have what maybe      
called an ideal  ,table4 ,the oblique   
lines represent the direction of the    
sunbeams1  and the consequent tilting of
 the table here shown resembles that    
observed upon the glaciers4    #bia4 ,a 
pebble will not rise thus3 like         
,franklin's single bit of  cloth1 a     
dark-coloured pebble sinks in the ice4  
,a spot of black mould  will not rest   
upon the surface1 but will sink2 and    
various parts of  the ,glacier du ,gant 
are honeycombed by the sinking of such  
spots of  dirt into the ice4            
,illustration    #bib4 ,but when the    
dirt is of a thickness sufficient to    
protect the  ice the case is different4 
,sand is often washed away by a stream  
from  the mountains1 or from the        
moraines1 and strewn over certain spaces
  of the glacier4 ,a most curious action

 follows3 the sanded surface  rises1 the
 part on which the sand lies thickest   
rising highest4  ,little peaks and      
eminences jut forth1 and when the       
distribution  of the sand is favourable1
 and the action sufficiently prolonged1 
you have little mountains formed1       
sometimes singly1 and sometimes  grouped
 so as to mimic the ,alps themselves4   
,the ,sand-,cones of the  ,mer de ,glace
 are not striking2 but on the ,grner1   
the ,aletsch1 the  ,morteratsch1 and    
other glaciers1 they form singly and in 
groups1  reaching sometimes a height of 
ten or twenty feet4       #dd4 ,the     
,glacier ,mills or ,moulins4    #bic4   
,you and ,i have learned by long        
experience the character of the  ,mer de
 ,glace4 ,we have marched over it daily1
 with a definite object  in view1 but we
 have not closed our eyes to other      
objects4 ,it is  from side glimpses of  
things which are not at the moment      
occupying  our attention that fresh     
subjects of enquiry arise in scientific 

investigation4    #bid4 ,thus in        
marching over the ice near ,trlaporte we
 were often  struck by a sound          
resembling low rumbling thunder4 ,we    
subsequently  sought out the origin of  
this sound1 and found it4    #bie4 ,a   
large area of this portion of the       
glacier is unbroken4  ,driblets of water
 have room to form rills2 rills to unite
 and form  streams2 streams to combine  
to form rushing brooks1 which sometimes 
cut deep channels in the ice4 ,sooner or
 later these streams reach  a strained  
portion of the glacier1 where a crack is
 formed across  the stream4 ,a way is   
thus opened for the water to the bottom 
of the  glacier4 ,by long action the    
stream hollows out a shaft1 the crack   
thus becoming the starting-point of a   
funnel of unseen depth1 into  which the 
water leaps with the sound of thunder4  
#bif4 ,this funnel and its cataract form
 a glacier ,mill or ,moulin4    #big4   
,let me grasp your hand firmly while you
 stand upon the edge of  this shaft and 

look into it4 ,the hole1 with its pure  
blue shimmer1  is beautiful1 but it is  
terrible4 ,incautious persons have      
fallen  into these shafts1 a second or  
two of bewilderment being followed by   
sudden death4 ,but caution upon the     
glaciers and mountains ought1 by  habit1
 to be made a second nature to explorers
 like you and me4    #bih4 ,the crack   
into which the stream first descended to
 form the  moulin1 moves down with the  
glacier4 ,a succeeding portion of the   
ice  reaches the place where the        
breaking strain is exerted4 ,a new crack
  is then formed above the moulin1 which
 is thenceforth forsaken by the  stream1
 and moves downward as an empty shaft4  
,here upon the ,mer de  ,glace1 in      
advance of the ,grand ,moulin1 we see no
 less than six of  these forsaken holes4
 ,some of them we sound to a depth of   
#ij feet4    #bii4 ,but you and ,i both 
wish to determine1 if possible1 the     
entire  depth of the ,mer de ,glace4    
,the ,grand ,moulin offers a chance of  

doing  this which we must not neglect4  
,our first effort to sound the moulin   
fails through the breaking of our cord  
by the impetuous plunge of the  water4  
,a lump of grease in the hollow of a    
weight enables a mariner  to judge of a 
sea bottom4 ,we employ such a weight1   
but cannot reach  the bed of the        
glacier4 ,a depth of #afc feet is the   
utmost reached by  our plummet4    #cjj4
 ,from ,july #bh to ,august #h we have  
watched the progress of the  ,grand     
,moulin4 ,on the former date the        
position of the ,moulin was  fixed4 ,on 
the #cast it had moved down #ej inches2 
a little more than  a day afterwards it 
had moved #gd inches4 ,on ,august #h it 
had moved  #aih inches1 which gives an  
average of about #ah inches in          
twenty-four  hours4 ,no doubt next      
summer upon the ,mer de ,glace a ,grand 
,moulin will  be found thundering near  
,trlaporte2 but like the crevasse of the
  ,grand ,plateau1 already referred to 7
 #af71 it will not be our ,moulin4      

,this1 or rather the ice which it       
penetrated1 is now probably more  than a
 mile lower down than it was in #aheg4  
#de4 ,the ,changes of ,volume of ,water 
by ,heat and ,cold4    #cja4 ,we have   
noticed upon the glacier shafts and pits
 filled with  water of the most delicate
 blue4 ,in some cases these have been   
the  shafts of extinct moulins closed at
 the bottom4 ,a theory has been         
advanced to account for them1 which1    
though it may be untenable1  opens out  
considerations regarding the properties 
of water that  ought to be familiar to  
enquirers like you and me4    #cjb4 ,in 
our dissection of lake ice by a beam of 
heat 7 #aa7 we  noticed little vacuous  
spots at the centres of the liquid      
flowers  formed by the beam4 ,these     
spots we referred to the fact that when 
ice  is melted the water produced is    
less in volume than the ice1 and that   
hence the water of the flower was not   
able to occupy the whole space  covered 
by the flower4    #cjc4 ,let us more    

fully illustrate this subject4 ,stop a  
small flask  water-tight with a cork1   
and through the cork introduce a narrow 
glass tube also water-tight4 ,it is easy
 to fill the flask with water  so that  
the liquid shall stand at a certain     
height in the glass tube4    #cjd4 ,let 
us now warm the flask with the flame of 
a spirit-lamp4 ,on  first applying the  
flame you notice a momentary sinking of 
the liquid  in the glass tube4 ,this is 
due to the momentary expansion of the   
flask by heat2 it becomes suddenly      
larger when the flame is first  applied4
    #cje4 ,but the expansion of the     
water soon overtakes that of the flask  
and surpasses it4 ,we immediately see   
the rise of the liquid column  in the   
glass tube1 exactly as mercury rises in 
the tube of a warmed  thermometer4      
#cjf4 ,our glass tube is ten inches     
long1 and at starting the water  stood  
in it at a height of five inches4 ,we   
will apply the spirit-lamp  flame until 
the water rises quite to the top of the 

tube and trickles  over4 ,this          
experiment suffices to show the         
expansion of the water by  heat4        
#cjg4 ,we now take a common finger-glass
 and put into it a little  pounded ice  
and salt4 ,on this we place the flask1  
and then build  round it the freezing   
mixture4 ,the liquid column retreats    
down the  tube1 proving the contraction 
of the liquid by cold4 ,we allow the    
shrinking to continue for some minutes1 
noticing that the downward  retreat of  
the liquid becomes gradually slower1 and
 that it finally  ceases altogether4    
#cjh4 ,keep your eye upon the liquid    
column2 it remains quiescent for  a     
fraction of a minute1 and then moves    
once more4 ,but its motion is  now      
upwards instead of downwards4 ,the      
freezing mixture now acts  exactly like 
the flame4    #cji4 ,it would not be    
difficult to pass a thermometer through 
the cork  into the flask1 and it would  
tell us the exact temperature at which  
the liquid ceased to contract and began 

to expand4 ,at that moment we  should   
find the temperature of the liquid a    
shade over #ci ,fahr4    #caj4 ,at this 
temperature1 then1 water attains its    
maximum density4    #caa4 ,seven degrees
 below this temperature1 or at #cb      
,fahr41 the  liquid begins to turn into 
solid crystals of ice1 which you know   
swims upon water because it is bulkier  
for a given weight4 ,in fact1  this halt
 of the approaching molecules at the    
temperature of #ci1  is but the         
preparation for the subsequent act of   
crystallisation1  in which the expansion
 by cold culminates4 ,up to the point of
  solidification the increase of volume 
is slow and gradual2 while in  the act  
of solidification it is sudden1 and of  
overwhelming strength4    #cab4 ,by this
 force of expansion the ,florentine     
,academicians long  ago burst a sphere  
of copper nearly three quarters of an   
inch in  thickness4 ,by the same force  
the celebrated astronomer ,huyghens     
burst  in #affg iron cannons a finger   

breadth thick4 ,such experiments have   
been frequently made since4 ,major      
,williams during a severe ,quebec       
winter filled a mortar with water1 and  
closed it by driving into  its muzzle a 
plug of wood4 ,exposed to a temperature 
#ej ,fahr4 below  the freezing point of 
water1 the metal resisted the strain1   
but the  plug gave way1 being projected 
to a distance of #djj feet4 ,at ,warsaw 
howitzer shells have been thus exploded2
 and you and ,i have shivered  thick    
bombshells to fragments1 by placing them
 for half an hour in a  freezing        
mixture4    #cac4 ,the theory of the    
shafts and pits referred to at the      
beginning  of this section is this3 ,the
 water at the surface of the shaft is   
warmed by the sun1 say to a temperature 
of #ci ,fahr4 ,the water at  the bottom1
 in contact with the ice1 must be at #cb
 or near it4 ,the  heavier water is     
therefore at the top2 it will descend to
 the bottom1  melt the ice there1 and   
thus deepen the shaft4    #cad4 ,the    

circulation here referred to undoubtedly
 goes on1 and  some curious effects are 
due to it2 but not1 ,i think1 the one   
here  ascribed to it4 ,the deepening of 
a shaft implies a quicker melting  of   
its bottom than of the surface of the   
glacier4 ,it is not easy to  see how the
 fact of the solar heat being first     
absorbed by water1  and then conveyed by
 it to the bottom of the shaft1 should  
make the  melting of the bottom more    
rapid than that of the ice which        
receives  the direct impact of the solar
 rays4 ,the surface of the glacier must 
sink at least as rapidly as the bottom  
of the pit1 so that the  circulation1   
though actually existing1 cannot produce
 the effect  ascribed to it4       #df4 
,consequences flowing from the foregoing
 ,properties of ,water4  ,correction of 
,errors4    #cae4 ,i was not much above 
your age when the property of water     
ceasing  to contract by cold at a       
temperature of #ci ,fahr4 was made known
 to  me1 and ,i still remember the      

impression it made upon me4 ,for ,i was 
asked to consider what would occur in   
case this solitary exception to  an     
otherwise universal law ceased to exist4
    #caf4 ,i was asked to reflect upon  
the condition of a lake stored with     
fish and offering its surface to very   
cold air4 ,it was made clear  to me that
 the water on being first chilled would 
shrink in volume  and become heavier1   
that it would therefore sink and have   
its place  supplied by the warmer and   
lighter water from the deeper portions  
of  the lake4    #cag4 ,it was pointed  
out to me that without the law referred 
to  this process of circulation would go
 on until the whole water of  the lake  
had been lowered to the freezing        
temperature4 ,congelation  would then   
begin1 and would continue as long as any
 water remained  to be solidified4 ,one 
consequence of this would be to destroy 
every  living thing contained in the    
lake4 ,other calamities were added1  all
 of which were said to be prevented by  

the perfectly exceptional  arrangement1 
that after a certain time the colder    
water becomes the  lighter1 floats on   
the surface of the lake1 is there       
congealed1  thus throwing a protecting  
roof over the life below4    #cah4      
,count ,rumford1 one of the most solid  
of scientific men1 writes  in the       
following strain about this             
question3--,it does not appear to  me   
that there is anything which human      
sagacity can fathom1 within the         
wide-extended bounds of the visible     
creation1 which affords a more  striking
 or more palpable proof of the wisdom of
 the ,creator1 and  of the special care 
,he has taken in the general arrangement
 of the  universe1 to preserve animal   
life1 than this wonderful contrivance4  
#cai4 ,let me beg the attention of my   
readers while ,i endeavour to           
investigate this most interesting       
subject2 and let me at the same  time   
bespeak his candour and indulgence4 ,i  
feel the danger to which a  mortal      

exposes himself who has the temerity to 
explain the designs  of ,infinite       
,wisdom4 ,the enterprise is adventurous1
 but it surely  cannot be improper4     
#cbj4 ,had not ,providence interfered on
 this occasion in a manner  which may   
well be considered as miraculous1 all   
the fresh water  within the polar circle
 must inevitably have been frozen to a  
very  great depth in winter1 and every  
plant and tree destroyed4    #cba4      
,through many pages of his book ,count  
,rumford continues in this  strain to   
expound the ways and intentions of the  
,almighty1 and he  does not hesitate to 
apply very harsh words to those who     
cannot  share his notions4 ,he calls    
them hardened and degraded4 ,we are here
  warned of the fact1 which is too often
 forgotten1 that the pleasure  or       
comfort of a belief1 or the warmth or   
exaltation of feeling which  it         
produces1 is no guarantee of its truth4 
,for the whole of ,count  ,rumford's    
delight and enthusiasm in connexion with

 this subject1 and  the whole of his ire
 against those who did not share his    
opinions1  were founded upon an         
erroneous notion4    #cbb4 ,water is not
 a solitary exception to an otherwise   
general law4  ,there are other molecules
 than those of this liquid which require
  more room in the solid crystalline    
condition than in the adjacent  molten  
condition4 ,iron is a case in point4    
,solid iron floats upon  molten iron    
exactly as ice floats upon water4       
,bismuth is a still  more impressive    
case1 and we could shiver a bomb as     
certainly by the  solidification of     
bismuth as by that of water4 ,there is  
no fish1 to  be taken care of here1     
still the contrivance is the same4      
#cbc4 ,i am reluctant to mention them in
 the same breath with ,count  ,rumford1 
but ,i am told that in our own day there
 are people who  profess to find the    
comforts of a religion in a superstition
 lower  than any that has hitherto      
degraded the civilized human mind4 ,so  

that  the happiness of a faith and the  
truth of a faith are two totally        
different things4    #cbd4 ,life and the
 conditions of life are in necessary    
harmony4 ,this  is a truism1 for without
 the suitable conditions life could not 
exist4 ,but both life and its conditions
 set forth the operations of            
inscrutable ,power4 ,we know not its    
origin2 we know not its end4 ,and  the  
presumption1 if not the degradation1    
rests with those who place  upon the    
throne of the universe a magnified image
 of themselves1 and  make its doings a  
mere colossal imitation of their own4   
#dg4 ,the ,molecular ,mechanism of      
,water-,congelation4    #cbe4 ,but let  
us return to our science4 ,how are we to
 picture this act  of expansion on the  
part of freezing water8 ,by what        
operation do the  molecules demand with 
such irresistible emphasis more room in 
the  solid than in the adjacent liquid  
condition8 ,in all cases of this  kind  
we must derive our conceptions from the 

world of the senses1 and  transfer them 
afterwards to a world transcending the  
range of the  senses4    #cbf4 ,you have
 not forgotten our conversation         
regarding atomic  poles 7 #aj71 and how 
the notion of polar force came to be    
applied  to crystals4 ,with this fresh  
in your memory1 you will have no great  
difficulty in understanding how         
expansion of volume may accompany the   
act of crystallisation4    #cbg4 ,i     
place a number of magnets before you4   
,they1 as matter1 are  affected by      
gravity1 and1 if perfectly free1 they   
would move towards  each other in       
obedience to the attraction of gravity4 
#cbh4 ,but they are not only matter1 but
 magnetic matter4 ,they not  only act   
upon each other by the simple force of  
gravity1 but by the  polar force of     
magnetism4 ,imagine them placed at a    
distance from each  other1 and perfectly
 free to move4 ,gravity first makes     
itself felt  and draws them together4   
,for a time the magnetic force issuing  

from  the poles is insensible2 but when 
a certain nearness is attained1 the     
polar force comes into play4 ,the       
mutually attracting points close up1    
the mutually repellent points retreat1  
and it is easy to see that  this action 
may produce an arrangement of the       
magnets which requires  more room4      
,suppose them surrounded by a box which 
exactly encloses  them at the moment the
 polar force first comes into play4 ,it 
is easy  to see that in arranging       
themselves subsequently the repelled    
corners  and ends of the magnets may be 
caused to press against the sides of    
the box1 and even to burst it1 if the   
forces be sufficiently strong4    #cbi4 
,here then we have a conception which   
may be applied to the  molecules of     
water4 ,they1 like the magnets1 are     
acted upon by two  distinct forces4 ,for
 a time while the liquid is being cooled
 they  approach each other1 in obedience
 to their general attraction for  each  
other4 ,but at a certain point new      

forces1 some attractive1  some          
repulsive1 emanating from special points
 of the molecules1  come into play4 ,the
 attracted points close up1 the repelled
 points  retreat4 ,thus the molecules   
turn and rearrange themselves1          
demanding1  as they do so1 more space1  
and overcoming all ordinary resistance  
by  the energy of their demand4 ,this1  
in general terms1 is an explanation  of 
the expansion of water in solidifying3  
it would be easy to  construct an       
apparatus for its illustration4         
#dh4 ,the ,dirt ,bands of the ,mer de   
,glace4    #ccj4 ,pass from bright      
sunshine into a moderately lighted room2
 for a  time all appears so dark that   
the objects in the room are not to be   
clearly distinguished4 ,hit violently by
 the waves of light 7 #c7 the  optic    
nerve is numbed1 and requires time to   
recover its sensitiveness4    #cca4 ,it 
is for this reason that ,i choose the   
present hour for a  special observation 
on the ,mer de ,glace4 ,the sun has sunk

 behind the  ridge of ,charmoz1 and the 
surface of the glacier is in sober      
shade4  ,the main portion of our day's  
work is finished1 but we have still     
sufficient energy to climb the slopes   
adjacent to the ,montanvert to  a height
 of a thousand feet or thereabouts above
 the ice4    ,illustration    #ccb4 ,we 
now look fairly down upon the glacier1  
and see it less  foreshortened than from
 the ,montanvert4 ,we notice the diet   
overspreading its eastern side1 due to  
the crowding together of  its medial    
moraines4 ,we see the comparatively     
clean surface of the  ,glacier du ,gant2
 but we notice upon this surface an     
appearance  which we have not hitherto  
seen4 ,it is crossed by a series of grey
  bent bands1 which follow each other in
 succession1 from ,trlaporte  downwards4
 ,we count eighteen of these from our   
present position4 7,see  sketch1 page   
#abh47    ,illustration    #ccc4 ,these 
are the ,dirt ,bands of the ,mer de     
,glace2 they were first  observed by    

,professor ,forbes in #ahdb4            
,illustration    #ccd4 ,they extend down
 the glacier further than we can see2   
and if we  cross the valley of          
,chamouni1 and climb the mountains at   
the opposite  side1 to a point near the 
little auberge1 called ,la ,flgre1 we   
shall  command a view of the end of the 
glacier and observe the completion  of  
the series of bands4 ,we notice that    
they are confined throughout  to the    
portion of the glacier derived from the 
,col du ,gant4 7,see  sketch1 page      
#abi47    #cce4 ,we must trace them to  
their source4 ,you know how noble and   
complete a view is obtained of the      
glacier and ,col du ,gant from the      
,cleft ,station above ,trlaporte4       
,thither we must once more climb2  and  
thence we can see the succession of     
bands stretching downwards  to the      
,montanvert1 and upwards to the base of 
the ice-cascade upon  the ,glacier du   
,gant4 ,the cascade is evidently        
concerned in their  formation4 7,see    

sketch opposite47    #ccf4 ,and how8    
,simply enough4 ,the glacier1 as we     
know1 is broken  transversely at the    
summit of the ice-fall1 and descends the
  declivity in a series of great        
transverse ridges4 ,at the base of the  
fall1 the chasms are closed1 but the    
ridges in part remain forming           
protuberances1 which run like vast      
wrinkles across the glacier4 ,these     
protuberances are more and more bent    
because of the quicker motion  of the   
centre1 and the depressions between them
 form receptacles for  the fine mud and 
dbris washed by the little rills from   
the adjacent  slopes4    #ccg4 ,the     
protuberances sink gradually through the
 wasting action of  the sun1 so that    
long before ,trlaporte is reached they  
have wholly  disappeared4 ,not so the   
dirt of which they were the collectors3 
it  continues to occupy1 in transverse  
bands1 the flat surface of the  glacier4
 ,at ,trlaporte1 moreover1 where the    
valley becomes narrow1  the bands are   

much sharpened1 obtaining there the     
character which  they afterwards        
preserve throughout the ,mer de ,glace4 
,other glaciers  with cascades also     
exhibit similar bands4       #di4 ,sea  
,ice and ,icebergs4    #cch4 ,we are now
 equipped intellectually for a campaign 
into another  territory4 ,water becomes 
heavier and more difficult to freeze    
when  salt is dissolved in it4 ,sea     
water is therefore heavier than fresh1  
and the ,greenland ,ocean requires to   
freeze it a temperature #c  degrees     
lower than fresh water4 ,when           
concentrated till its specific  gravity 
reaches #a4ajde1 sea water requires for 
its congelation a  temperature #ah      
degrees lower than the ordinary         
freezing-point4,e    ,e ,scoresby4      
#cci4 ,but even when the water is       
saturated with salt1 the  crystallising 
force studiously rejects the salt1 and  
devotes itself  to the congelation of   
the water alone4 ,hence the ice of sea  
water1  when melted1 produces fresh     

water4 ,the only saline particles       
existing  in such ice are those         
entangled 'mechanically in its pores4   
,they have  no part or lot in the       
structure of the crystal4    #cdj4 ,this
 exclusiveness1 if ,i may use the term1 
of the water  molecules2 this entire    
rejection of all foreign elements from  
the  edifices which they build1 is      
enforced to a surprising degree4        
,sulphuric acid has so strong an        
affinity for water that it is one  of   
the most powerful agents known to the   
chemist for the removal of  humidity    
from air4 ,still1 as shown by ,faraday1 
when a mixture of  sulphuric acid and   
water is frozen1 the crystal formed is  
perfectly  sweet and free from acidity4 
,the water alone has lent itself to the 
crystallising force4    #cda4 ,every    
winter in the ,arctic regions the sea   
freezes1 roofing  itself with ice of    
enormous thickness and vast extent4 ,by 
the summer  heat1 and the tossing of the
 waves1 this is broken up2 the fragments

  are drifted by winds and borne by     
currents4 ,they clash1 they crush  each 
other1 they pile themselves into heaps1 
thus constituting the  chief danger     
encountered by mariners in the polar    
seas4    #cdb4 ,but among the drifting  
masses of flat sea-ice1 vaster masses   
sail1 which spring from a totally       
different source4 ,these are the        
,icebergs of the ,arctic seas4 ,they    
rise sometimes to an elevation of       
hundreds of feet above the water1 while 
the weight of ice submerged  is about   
seven times that seen above4    #cdc4   
,the first observers of striking natural
 phenomena generally  allow wonder and  
imagination more than their due place4  
,but to  exclude all error arising from 
this cause1 ,i will refer to the        
journal of a cool and intrepid ,arctic  
navigator1 ,sir ,leopold  ,mc,clintock4 
,he describes an iceberg #bej feet high1
 which was aground  in #ejj feet of     
water4 ,this would make the entire      
height of the berg  #gej feet1 not an   

unusual altitude for the greater        
icebergs4    #cdd4 ,from ,baffin's ,bay 
these mighty masses come sailing down   
through  ,davis' ,straits into the broad
 ,atlantic4 ,a vast amount of heat is   
demanded for the simple liquefaction of 
ice 7 #dh72 and the melting  of icebergs
 is on this account so slow1 that when  
large they  sometimes maintain          
themselves till they have been drifted  
#bjjj miles  from their place of birth4 
#cde4 ,what is their origin8 ,the       
,arctic glaciers4 ,from the mountains   
in the interior the indurated snows     
slide into the valleys and fill  them   
with ice4 ,the glaciers thus formed move
 like the ,swiss ones1  incessantly     
downward4 ,but the ,arctic glaciers     
reach the sea1 enter  it1 often         
ploughing up its bottom into submarine  
moraines4 ,undermined  by the lapping of
 the waves1 and unable to resist the    
strain imposed  by their own weight1    
they break across1 and discharge vast   
masses  into the ocean4 ,some of these  

run aground on the adjacent shores1  and
 often maintain themselves for years4   
,others escape southward1 to  be finally
 dissolved in the warm waters of the    
,atlantic4 ,the first  engraving on the 
opposite page is copied from a          
photograph taken by  ,mr4 ,bradford     
during a recent expedition to the       
,northern seas4 ,the  second represents 
a mass of ice upon the ,glacier des     
,bossons4 ,their  likeness suggests     
their common origin4    ,illustration   
,illustration       #ej4 ,the           
ggischhorn1 the ,mrgelin ,see and its   
,icebergs4    #cdf4 ,i am1 however1     
unwilling that you should quit          
,switzerland  without seeing such       
icebergs as it can show1 and indeed     
there are  other still nobler glaciers  
than the ,mer de ,glace with which you  
ought to be acquainted4 ,in tracing the 
,rhone to its source1 you have  already 
ascended the valley of the ,rhone4 ,let 
us visit it again  together2 halt at the
 little town of ,viesch1 and go from it 

straight  up to the excellent hostelry  
on the slope of the ggischhorn4 ,this   
we shall make our head-quarters while we
 explore that monarch of  ,european     
ice-streams1--the great ,aletsch        
glacier4    #cdg4 ,including the longest
 of its branches1 this noble ice-river  
is  about twenty miles long1 while at   
the middle of its trunk it measures     
nearly a mile and a quarter from side to
 side4 ,the grandest mountains  of the  
,bernese ,oberland1 the ,jungfrau1 the  
,monch1 the ,trugberg1 the              
,aletschhorn1 the ,breithorn1 the       
,gletscherhorn1 and many another noble  
peak and ridge1 are the collectors of   
its nvs4 ,from three great  valleys     
formed in the heart of the mountains    
these nvs are poured1  uniting together 
to form the trunk of the ,aletsch at a  
place named  by a witty mountaineer1 the
 ,place de la ,concorde of ,nature4 ,if 
the  phrase be meant to convey the ideas
 of tranquil grandeur1 beauty of  form1 
and purity of hue1 it is well bestowed4 

#cdh4 ,our hotel is not upon the peak of
 the ggischhorn1 but a brisk  morning   
walk soon places us upon the top4       
,thence we see the glacier  like a broad
 river stretching upwards to the roots  
of the ,jungfrau1  and downwards past   
the ,bel ,alp towards its end4          
,prolonging the vision  downwards1 we   
strike the noblest mountain group in all
 the ,alps1--the  ,dom and its attendant
 peaks1 the ,matterhorn and the         
,weisshorn4 ,the  scene indeed is one of
 impressive grandeur1 a multitude of    
peaks and  crests here unnamed          
contributing to its glory4    #cdi4 ,but
 low down to our right1 and surrounded  
by the sheltering  mountains1 is an     
object the beauty of which startles     
those who are  unprepared for it4       
,yonder we see the naked side of the    
glacier1  exposing glistening ice-cliffs
 sixty or seventy feet high4 ,it would  
seem as if the ,aletsch here were       
engaged in the vain attempt to  thrust  
an arm through a lateral valley4 ,it    

once did so2 but the arm  is now        
incessantly broken off close to the body
 of the glacier1 a  great space formerly
 covered by the ice being occupied by   
its water  of liquefaction4 ,a lake of  
the loveliest blue is thus formed1 which
  reaches quite to the base of the      
ice-cliffs1 saps them1 as the ,arctic   
waves sap the ,greenland glaciers1 and  
receives from them the broken  masses   
which it has undermined4 ,as we look    
down upon the lake1 small  icebergs sail
 over the tranquil surface1 each        
resembling a snowy swan  accompanied by 
its shadow4    #cej4 ,this is the       
beautiful little lake of ,mrgelin1 or1  
as the ,swiss  here call it1 the        
,mrgelin ,see4 ,you see that splash1 and
 immediately  afterwards hear the sound 
of the plunging ice4 ,the glacier has   
broken  before our eyes1 and dropped an 
iceberg into the lake4 ,all over the    
lake the water is set in commotion1 thus
 illustrating on a small  scale the     
swamping waves produced by the descent  

of vast islands of  ice from the ,arctic
 glaciers4 ,look to the end of the lake4
 ,it is  cumbered with the remnants of  
icebergs now aground1 which have been   
in part wafted thither by the wind1 but 
in part slowly borne by the  water which
 moves gently in this direction4        
#cea4 ,imagine us below upon the margin 
of the lake1 as ,i happened to  be on   
one occasion4 ,there is one large and   
lonely iceberg about the  middle4       
,suddenly a sound like that of a        
cataract is heard2 we look  towards the 
iceberg and see water teeming from its  
sides4 ,whence  comes the water8 the    
berg has become top-heavy through the   
melting  underneath2 it is in the act of
 performing a somersault1 and in        
rolling over carries with it a vast     
quantity of water1 which rushes  like a 
waterfall down its sides4 ,and notice   
that the iceberg1 which  a moment ago   
was snowy-white1 now exhibits the       
delicate blue colour  characteristic of 
compact ice4 ,it will soon1 however1 be 

rendered  white again by the action of  
the sun4 ,the vaster icebergs of the    
,northern seas sometimes roll over in   
the same fashion4 ,a week may be  spent 
with delight and profit at the          
ggischhorn4       #ea4 ,the ,bel ,alp4  
#ceb4 ,from the ggischhorn ,i might lead
 you along the mountain ridge  by the   
,betten ,see1 the fish of which we have 
already tasted1 to the  ,rieder ,alp1   
and thence across the ,aletsch to the   
,bel ,alp4 ,this is a  fine mountain    
ramble1 but you and ,i prefer making the
 glacier our  highway downwards4 ,easy  
at some places1 it is by no means       
child's  play at others to unravel its  
crevasses4 ,but the steady constancy and
  close observation which we have       
hitherto found availing in difficult    
places do not forsake us here4 ,we clear
 the fissures2 and1 after four  hours of
 exhilarating work1 we find ourselves   
upon the slope leading  up to the ,bel  
,alp hotel4    #cec4 ,this is one of the
 finest halting-places in the ,alps4    

,stretching  before us up to the        
ggischhorn and ,mrgelin ,see is the long
 last  reach of the ,aletsch1 with its  
great medial moraine running along its  
back4 ,at hand is the wild gorge of the 
,massa1 in which the snout of  the      
glacier lies couched like the head of a 
serpent4 ,the beautiful  system of the  
,oberaletsch glaciers is within easy    
reach4 ,above us  is a peak called the  
,sparrenhorn1 accessible to the most    
moderate  climber1 and on the summit of 
which little more than an hour's        
exertion will place you and me4 ,below  
us now is the ,oberaletsch  glacier1    
exhibiting the most perfect of medial   
moraines4 ,near us  is the great mass of
 the ,aletschhorn1 clasped by its nvs1  
and  culminating in brown rock4 ,it is  
supported by other peaks almost as      
noble as itself4 ,the ,nesthorn is at   
hand2 while sweeping round to the  west 
we strike the glorious triad already    
referred to1 the ,weisshorn1  the       
,matterhorn1 and the ,dom4 ,take one    

glance at the crevasses of the  glacier 
immediately below us4 ,it tumbles at its
 end down a steep  incline1 and is      
greatly riven4 ,but the crevasses open  
before the  steep part is reached1 and  
you notice the coalescence of marginal  
and  transverse crevasses1 producing a  
system of curved fissures with the      
convexities of the curves pointing      
upwards4 ,the mechanical reason of  this
 is now known to you4 ,the              
glacier-tables are also numerous and    
fine4 ,i should like to linger with you 
here for a week1 exploring the  existing
 glaciers1 and tracing out the evidences
 of others that have  passed away4      
#eb4 ,the ,riffelberg and ,grner        
,glacier4    #ced4 ,and though our      
measurements and observations on the    
,mer de ,glace  are more or less        
representative of all that can be made  
or solved  elsewhere1 ,i am unwilling to
 leave you unacquainted with the great  
system of glaciers which stream from the
 northern slopes of ,monte  ,rosa and   

the adjacent mountains4 ,from the ,bel  
,alp we can descend to  ,brieg1 and     
thence drive to ,visp2 but you and ,i   
prefer the breezy  heights1 so we sweep 
round the promontory of the ,nessel1    
until we  stand over the ,rhone valley1 
in front of ,visp4 ,from this village an
  hour's walking carries us to ,stalden1
 where the valley divides into  two     
branches3 the one leading through ,saas 
over the ,monte ,moro1 and  the other   
through ,st4 ,nicholas to ,zermatt4 ,the
 latter is our route4    #cee4 ,we reach
 ,zermatt1 but do not halt here4 ,on the
 mountain ridge1  #d1jjj feet above the 
valley1 we discern the ,riffelberg      
hotel4 ,this  we reach4 ,right in front 
of us is the pinnacle of the            
,matterhorn1  upon the top of which it  
must appear incredible to you that a    
human  foot could ever tread4 ,constancy
 and skill1 however1 accomplished  this1
 but in the first instance at a terrible
 price4 ,in the little  churchyard of   
,zermatt we have seen the graves of two 

of the greatest  mountaineers that      
,savoy and ,england have produced3 and  
who1 with two  gallant young companions1
 fell from the ,matterhorn in #ahfe4    
#cef4 ,at the ,riffelberg we are within 
an hour's walk of the famous  ,grner    
,grat1 which commands so grand a view of
 the glaciers of ,monte  ,rosa4 ,but    
yonder huge knob of perfectly bare rock1
 which is called  the ,riffelhorn1 must 
be our station4 ,what the ,cleft        
,station is to  the ,mer de ,glace1 the 
,riffelhorn is to the ,grner glacier and
 its  tributaries4 ,from its lower side 
the rock1 easy as it may seem1 is       
inaccessible4 ,here1 indeed1 in #ahfe1 a
 fifth good man met his end1  and he    
also lies beside his fellow countrymen  
in the churchyard of  ,zermatt4 ,passing
 a little tarn1 or lake1 called the     
,riffel ,see1 we  assail the ,riffelhorn
 on its upper side4 ,it is capital      
rock-practice  to reach the summit2 and 
from it we command a most extraordinary 
scene4    #ceg4 ,the huge and           

many-peaked mass of ,monte ,rosa faces  
us1 and we  scan its snows from bottom  
to top4 ,to the right is the mighty     
ridge  of the ,lyskamm1 also laden with 
snow2 and between both lies the         
,western ,glacier of ,monte ,rosa4 ,this
 glacier meets another from the  vast   
snow-fields of the ,cima di ,jazzi2 they
 join to form the ,grner  glacier1 and  
from their place of junction stretches  
the customary  medial moraine4 ,on this 
side of the ,lyskamm rise two           
beautifully  snowy eminences1 the ,twins
 ,castor and ,pollux2 then come the     
brown  crags of the ,breithorn1 then the
 ,little ,matterhorn1 and then the      
broad snow-field of the ,thodule1 out of
 which springs the ,great  ,matterhorn1 
and which you and ,i will cross         
subsequently into ,italy4    #ceh4 ,the 
valleys and depressions between these   
mountains are filled  with glaciers4    
,down the flanks of the ,twin ,castor   
comes the ,glacier  des ,jumeaux1 from  
,pollux comes the ,schwartze glacier1   

from the  ,breithorn the ,trifti        
glacier1 then come the ,little          
,matterhorn glacier  and the ,thodule   
glacier1 each1 as it welds itself to the
 trunk1  carrying with it its medial    
moraine4 ,we can count nine such        
moraines  from our present position4    
,and to a still more surprising degree  
than on the ,mer de ,glace1 we notice   
the power of the ice to yield to        
pressure2 the broad nvs being squeezed  
on the trunk of the ,grner  into white  
stripes1 which become ever narrower     
between the bounding  moraines1 and     
finally disappear under their own       
shingle4    ,illustration3 ,,the        
,g,,rner ,,glacier1 ,,with ,,monte      
,,rosa ,,in ,,the ,,distance1  ,,and    
,,the ,,riffelhorn ,,to ,,the ,,left4   
#cei4 ,on the two main tributaries we   
also notice moraines which seem  in each
 case to rise from the body of the      
glacier1 appearing in the  middle of the
 ice without any apparent origin higher 
up4 ,these at  their sources1 are       

sub-glacial moraines1 which have been   
rubbed away  from rocky promontories    
entirely covered with ice4 ,they lie    
hidden  for a time in the body of the   
glacier1 and appear at the surface      
where the ice above them has been melted
 away by the sun4    #cfj4 ,this is the 
place to mention a notion long          
entertained by the  inhabitants of the  
high ,alps1 that glaciers possess the   
power of  thrusting out all impurities  
from them4 ,on the ,mer de ,glace you   
and  ,i have noticed large patches of   
clay and black mud which evidently  came
 from the body of the glacier1 and we   
can therefore understand  how natural   
was this notion of extrusion to people  
unaccustomed to  close observation4 ,but
 the power of the glacier in this       
respect is  in reality the power of the 
sun1 which fuses the ice above concealed
  impurities1 and1 like the bodies of   
the guides on the ,glacier des  ,bossons
 7#adc71 brings them to the light of    
day4    #cfa4 ,on no other glacier will 

you find more objects of interest than  
on the ,grner4 ,sand-cones1             
glacier-tables1 deep ice-gorges cut by  
streams and bridged fantastically by    
boulders1 moulins1 sometimes  arched    
ice-caverns of extraordinary size and   
beauty4 ,on the lower  part of the      
glacier we notice the partial           
disappearance of the medial  moraine in 
the crevasses1 and its reappearance at  
the foot of the  incline4 ,for many     
years this glacier was steadily         
advancing on the  meadow in front of it1
 ploughing up the soil and overturning  
the  chalets in its way4 ,it now shares 
in the general retreat exhibited  during
 the last fifteen years among the       
glaciers of the ,alps4 ,as  usual1 a    
river1 the ,visp1 rushes from a vault at
 the extremity of the  ,grner glacier4  
#ec4 ,ancient ,glaciers of ,switzerland4
    #cfb4 ,you have not lost the memory 
of the old ,moraine1 which  interested  
us so much in our first ascent from the 
source of the  ,arveiron2 for it opened 

our minds to the fact that at one period
 of  its history the ,mer de ,glace     
attained far greater dimensions than it 
now exhibits4 ,our experience since that
 time has enabled us to pursue  these   
evidences of ice action to an extent of 
which we had then no  notion4    #cfc4  
,close to the existing glacier1 for     
example1 we have repeatedly  seen the   
mountain side laid bare by the retreat  
of the ice4 ,this is  especially        
conspicuous just now1 because for the   
last fifteen or  sixteen years the      
glaciers of the ,alps have been steadily
 shrinking2  so that it is no uncommon  
thing to see the marginal rocks laid    
bare  for a height of fifty1 sixty1     
eighty1 or even one hundred feet above  
the present glacier4 ,on the rocks thus 
exposed we see the evident  marks of the
 sliding2 and our eyes and minds have   
been so educated in  the observation of 
these appearances that we are now able  
to detect1  with certainty1 icemarks1 or
 moraines1 ancient or modern1 wherever  

they appear4    #cfd4 ,but the          
elevations at which we have found such  
evidence might  well shake belief in the
 conclusions to which they point4       
,beside  the ,massa ,gorge1 at #a1jjj   
feet above the present ,aletsch1 we     
found  a great old moraine4 ,descending 
the meadows between the ,bel ,alp  and  
,flatten1 we found another1 now clothed 
with grass1 and bearing  a village on   
its back4 ,but ,i wish to carry you to a
 region which  exhibits these evidences 
on a still grander and more impressive  
scale4 ,we have already taken a brief   
flight to the valley of  ,hasli and the 
,glacier of the ,aar4 ,let us make that 
glacier our  starting-point4 ,walking   
from it downwards towards the ,grimsel1 
we  pass everywhere over rocks          
singularly rounded1 and fluted1 and     
scarred4 ,these appearances are         
manifestly the work of the glacier in   
recent times4 ,but we approach the      
,grimsel1 and at the turning of the     
valley stand before the precipitous     

granite flank of the mountain4  ,the    
traces of the ancient ice are here as   
plain as they are amazing4  ,the rocks  
are so hard that not only the fluting   
and polishing1 but  even the fine       
scratches which date back unnamable     
thousands of years  are as evident as if
 they had been made yesterday4 ,we may  
trace these  evidences to a height of   
two thousand feet above the present     
valley  bed4 ,it is indubitable that an 
ice-river of this astounding depth  once
 flowed through the vale of ,hasli4     
#cfe4 ,yonder is the summit of the      
,siedelhorn2 and if we gain it1 the     
,unteraar glacier will lie like a map   
below us4 ,from this commanding  point  
we plainly see marked upon the mountain 
sides the height to  which the ancient  
ice extended4 ,the ice-ground part of   
the mountains  is clearly distinguished 
from the splintered crests which in     
those  distant days rose above the      
surface of the glacier1 and which must  
have then appeared as island peaks and  

crests in the midst of an  ocean of ice4
    #cff4 ,we now scamper down the      
,siedelhorn1 get once more into the     
valley of ,hasli1 along which we follow 
for more than twenty miles  the traces  
of the ice4 ,fluted precipices1 polished
 slabs1 and  beautifully-rounded granite
 domes4 ,right and left upon the        
mountain  flanks1 at great elevations1  
the evidences appear4 ,we follow the    
footsteps of the glacier to the ,lake of
 ,brientz2 and if we prolonged  our     
enquiries1 we should learn that all the 
lake beds of this region1  at the time  
now referred to1 bore the burden of     
immense masses of ice4    #cfg4 ,instead
 of the vale of ,hasli1 we might take   
the valley of the  ,rhone4 ,the traces  
of a mighty glacier1 which formerly     
filled it1  may be followed all the way 
to ,martigny1 which is #fj miles distant
  from the present ice4 ,at ,martigny   
the ,rhone glacier was reinforced  by   
another from ,mont ,blanc1 and the      
welded masses moved onward1  planing the

 mountains right and left1 to the ,lake 
of ,geneva1 the  basin of which they    
entirely filled4 ,other evidences prove 
that the  glacier did not end here1 but 
pushed across the low country until it  
encountered the limestone barrier of the
 ,jura ,mountains4       #ed4 ,erratic  
,blocks4    #cfh4 ,what are these other 
evidences8 ,we have seen mighty rocks   
poised  on the moraines of the ,mer de  
,glace1 and we now know that1 unless    
they are split and shattered by the     
frost1 these rocks will1 at  some       
distant day1 be landed bodily by the    
,glacier des ,bois in the  valley of    
,chamouni4 ,you have already learned    
that these boulders  often reveal the   
mineralogical nature of the mountains   
among which  the glacier has passed2    
that specimens are thus brought down of 
a  character totally different from the 
rocks among which they are  finally     
landed2 this is strikingly the case with
 the erratic blocks  stranded along the 
,jura4    #cfi4 ,for the ,jura itself1  

as already stated1 is limestone2 there  
is  no trace of native granite to be    
found amongst these hills4 ,still  along
 the breast of the mountain above the   
town of ,neufchtel1 and at  about #hjj  
feet above the lake of ,neufchtel1 we   
find stranded a belt  of granite        
boulders from ,mont ,blanc4 ,and when we
 clear the soil away  from the adjacent 
mountain side1 we find upon the         
limestone rocks the  scarrings of the   
ancient glacier which brought the       
boulders here4    #cgj4 ,the most famous
 of these rocks1 called the ,pierre     
,bt1  measures #ej feet in length1 #dj  
in height1 and #bj in width4            
,multiplying these three numbers        
together1 we obtain #dj1jjj cubic feet  
as the volume of the boulder4    #cga4  
,but this is small compared with some of
 the rocks which  constitute the freight
 of even recent glaciers4 ,let us visit 
another  of them4 ,we have already been 
to ,stalden1 where the valley divides   
into two branches1 the right branch     

running to ,st4 ,nicholas and  ,zermatt1
 and the left one to ,saas and the      
,monte ,moro4 ,three hours  above ,saas 
we come upon the end of the ,allelein   
glacier1 not filling  the main valley1  
but thrown athwart it so as to stop its 
drainage  like a dam4 ,above this       
ice-dam we have the ,mattmark ,lake1 and
 at the  head of the lake a small inn   
well known to travellers over the ,monte
  ,moro4    #cgb4 ,close to this inn is 
the greatest boulder that we have ever  
seen4 ,it measures #bdj1jjj cubic feet4 
,looking across the valley we  notice a 
glacier with its present end half a mile
 from the boulder4  ,the stone1 ,i      
believe1 is serpentine1 and were you and
 ,i to explore  the ,schwartzberg       
glacier to its upper fastnesses1 we     
should find  among them the birthplace  
of this gigantic stone4 ,four-and-twenty
  years ago1 when the glacier reached   
the place now occupied by the  boulder1 
it landed there its mighty freight1 and 
then retreated4  ,there is a second     

ice-borne rock at hand which would be   
considered  vast were it not dwarfed by 
the aspect of its huger neighbour4      
#cgc4 ,evidence of this kind might be   
multiplied to any extent4 ,in  fact1 at 
this moment1 distinguished men1 like    
,professor ,favre of  ,geneva1 are      
determining from the distribution of the
 erratic blocks  the extent of the      
ancient glaciers of ,switzerland4 ,it   
was1 however1  an engineer named ,venetz
 that first brought these evidences to  
light1  and announced to an incredulous 
world the vast extension of the  ancient
 ice4 ,m4 ,agassiz afterwards developed 
and wonderfully expanded  the discovery4
 ,perhaps the most interesting          
observation regarding  ancient glaciers 
is that of ,dr4 ,hooker1 who1 during a  
recent visit  to ,palestine1 found the  
celebrated ,cedars of ,lebanon growing  
upon  ancient moraines4       #ee4      
,ancient ,glaciers of ,england1         
,ireland1 ,scotland1 and ,wales4        
#cgd4 ,at the time the ice attained this

 extraordinary development in  the      
,alps1 many other portions of ,europe1  
where no glaciers now exist1  were      
covered with them4 ,in the ,highlands of
 ,scotland1 among the  mountains of     
,england1 ,ireland1 and ,wales1 the     
ancient glaciers have  written their    
story as plainly as in the ,alps        
themselves4 ,i should  like to wander   
with you through ,borrodale in          
,cumberland1 or through  the valleys    
near ,bethgellert in ,wales4 ,under all 
the beauty of the  present scenery we   
should discover the memorials of a time 
when the  whole region was locked in the
 embrace of ice4 ,professor ,ramsay is  
especially distinguished by his writings
 on the ancient glaciers of  ,wales4    
#cge4 ,we have made the acquaintance of 
the ,reeks of ,magillicuddy as  the     
great condensers of ,atlantic vapour4   
,at the time now referred to1  this     
moisture did not fall as soft and       
fructifying rain1 but as snow1  which   
formed the nutriment of great glaciers4 

,a chain of lakes now  constitutes the  
chief attraction of ,killarney1 the     
,lower1 the ,middle1  and the ,upper    
,lake4 ,let us suppose ourselves rowing 
towards the head  of the ,upper ,lake   
with the ,purple ,mountain to our left4 
,remembering  our travels in the ,alps1 
you would infallibly call my attention  
to  the planing of the rocks1 and       
declare the action to be unmistakably   
that of glaciers4 ,with our attention   
thus sharpened1 we land at  the head of 
the lake1 and walk up the ,black ,valley
 to the base of  ,magillicuddy's ,reeks4
 ,your conclusion would be1 that this   
valley  tells a tale as wonderful as    
that of ,hasli4    #cgf4 ,we reach our  
boat and row homewards along the ,upper 
,lake4 ,its  islands now possess a new  
interest for us4 ,some of them are bare1
  others are covered wholly or in part  
with luxuriant vegetation2 but  both the
 naked and clothed islands are          
glaciated4 ,the weathering of  ages has 
not altered their forms3 there are the  

,cannon ,rock1 the  ,giant's ,coffin1   
the ,man of ,war1 all sculptured as if  
the chisel had  passed over them in our 
own lifetime4 ,these lakes1 now fringed 
with  tender woodland beauty1 were all  
occupied by the ancient ice4 ,it has    
disappeared1 and seeds from other       
regions have been wafted thither  to sow
 the trees1 the shrubs1 the ferns1 and  
the grasses which now  beautify         
,killarney4 ,man himself1 they say1 has 
made his appearance in  the world since 
that time of ice2 but of the real period
 and manner  of man's introduction      
little is professed to be known since1  
to make  them square with science1 new  
meanings have been found for the        
beautiful myths and stories of the      
,bible4    #cgg4 ,it is the nature and  
tendency of the human mind to look      
backward  and forward2 to endeavour to  
restore the past and predict the future4
  ,thus endowed1 from data patiently and
 painfully won1 we recover in  idea a   
state of things which existed thousands1

 it may be millions1  of years before   
the history of the human race began4    
#ef4 ,the ,glacial ,epoch4    #cgh4     
,this period of ice-extension has been  
named the ,glacial ,epoch4  ,in         
accounting for it great minds have      
fallen into grave errors1 as we  shall  
presently see4    #cgi4 ,the substance  
on which we have thus far been working  
exists in  three different states3 as a 
solid in ice2 as a liquid in water2 as  
a gas in vapour4 ,to cause it to pass   
from one of these states to the  next   
following one1 heat is necessary4       
#chj4 ,dig a hole in the ice of the ,mer
 de ,glace in summer1 and place  a      
thermometer in the hole2 it will stand  
at #cb ,fahr4 ,dip your  thermometer    
into one of the glacier streams2 it will
 still mark #cb4  ,the water is         
therefore as cold as ice4    #cha4      
,hence the whole of the heat poured by  
the sun upon the glacier1  and which has
 been absorbed by the glacier1 is       
expended in simply  liquefying the ice1 

and not in rendering either ice or water
 a single  degree warmer4    #chb4      
,expose water to a fire2 it becomes     
hotter for a time4 ,it boils1  and from 
that moment it ceases to get hotter4    
,after it has begun to  boil1 all the   
heat communicated by the fire is carried
 away by the  steam1 though the steam   
itself is not the least fraction of a   
degree  hotter than the water4    #chc4 
,in fact1 simply to liquefy ice a large 
quantity of heat  is necessary1 and to  
vaporize water a still larger quantity  
is  necessary4 ,and inasmuch as this    
heat does not render the water warmer   
than the ice1 nor the steam warmer than 
the water1 it was at one time  supposed 
to be hidden in the water and in the    
steam4 ,and it was  therefore called    
latent heat4    #chd4 ,let us ask how   
much heat must the sun expend in order  
to convert  a pound weight of the       
tropical ocean into vapour8 ,this       
problem has  been accurately solved by  
experiment4 ,it would require in round  

numbers #a1jjj times the amount of heat 
necessary to raise one pound  of water  
one degree in temperature4    #che4 ,but
 the quantity of heat which would raise 
the temperature of a  pound of water one
 degree would raise the temperature of a
 pound of  iron ten degrees4 ,this has  
been also proved by experiment4 ,hence  
to convert one pound of the tropical    
ocean into vapour the sun must  expend  
#aj1jjj times as much heat as would     
raise one pound of iron one  degree in  
temperature4    #chf4 ,this quantity of 
heat would raise the temperature of #e  
lbs4 of  iron #b1jjj degrees1 which is  
the fusing point of cast iron2 at this  
temperature the metal would not only be 
white hot1 but would be  passing into   
the molten condition4    #chg4 ,consider
 the conclusions at which we have now   
arrived4 ,for every  pound of tropical  
vapour1 or for every pound of ,alpine   
ice produced  by the congelation of that
 vapour1 an amount of heat has been     
expended by the sun sufficient to raise 

#e lbs4 of cast iron to its             
melting-point4    #chh4 ,it would not be
 difficult to calculate approximately   
the weight  of the ,mer de ,glace and   
its tributaries--to say1 for example1   
that  they contained so many millions of
 millions of tons of ice and snow4  ,let
 the place of the ice be taken by a mass
 of white-hot iron of  quintuple the    
weight2 with such a picture before your 
mind you get  some notion of the        
enormous amount of heat paid out by the 
sun to  produce the present glacier4    
#chi4 ,you must think over this1 until  
it is as clear as sunshine4  ,for you   
must never henceforth fall into the     
error already referred  to1 and which   
has entangled so many4 ,so natural was  
the association  of ice and cold1 that  
even celebrated men assumed that all    
that is  needed to produce a great      
extension of our glaciers is a          
diminution  of the sun's temperature4   
,had they gone through the foregoing    
reflections and calculations1 they would

 probably have demanded more  heat      
instead of less for the production of a 
glacial epoch4 ,what  they really needed
 were condensers sufficiently powerful  
to congeal  the vapour generated by the 
heat of the sun4       #eg4 ,glacier    
,theories4    #cij4 ,you have not       
forgotten1 and hardly ever can forget1  
our climbs  to the ,cleft ,station4     
,thoughts were then suggested which we  
have not  yet discussed4 ,we saw the    
branch glaciers coming down from their  
nvs1 welding themselves together1       
pushing through ,trlaporte1 and         
afterwards moving through the sinuous   
valley of the ,mer de ,glace4  ,these   
appearances alone1 without taking into  
account subsequent  observations1 were  
sufficient to suggest the idea that     
glacier  ice1 however hard and brittle  
it may appear1 is really a viscous      
substance1 resembling treacle1 or honey1
 or tar1 or lava4       #eh4 ,dilatation
 and ,sliding ,theories4    #cia4 ,still
 this was not the notion expressed by   

the majority of  writers upon glaciers4 
,scheuchzer of ,zrich1 a great          
naturalist1  visited the glaciers in    
#agje1 and propounded a theory of their 
motion4 ,water1 he knew1 expands in     
freezing1 and the force of  expansion is
 so great1 that thick bombshells filled 
with water1 and  permitted to freeze1   
are1 as we know 7#cab71 shattered to    
pieces by  the ice within4 ,scheuchzer  
supposed that the water in the fissures 
of  the glaciers1 freezing there and    
expanding with resistless force1 was    
the power which urged the glacier       
downwards4 ,he added to this theory     
other notions of a less scientific kind4
    #cib4 ,many years subsequently1 ,de 
,charpentier of ,bex renewed and        
developed this theory with such ability 
and completeness1 that it was  long     
known as ,charpentier's ,theory of      
,dilatation4 ,m4 ,agassiz for a  time   
espoused this theory1 and it was also   
more or less distinctly  held by other  
writers4 ,the glacier1 in fact1 was     

considered to be a  magazine of cold1   
capable of freezing all water           
percolating through  it4 ,the theory was
 abandoned when this notion of glacier  
cold was  proved by ,m4 ,agassiz to be  
untenable4    #cic4 ,in #agfj1 ,altmann 
and ,grner propounded the view that     
glaciers  moved by sliding over their   
beds4 ,nearly forty years subsequently1 
this notion was revived by ,de          
,saussure1 and it has therefore been    
called ,de ,saussure's ,theory1 or the  
,sliding ,theory of glacier  motion4    
#cid4 ,there was1 however1 but little   
reason to connect the name of  ,de      
,saussure with this or any other theory 
of glaciers4 ,incessantly  occupied in  
observations of another kind1 this      
celebrated man devoted  very little time
 or thought to the question of glacier  
motion4 ,what  he has written upon the  
subject reads less like the elaboration 
of a  theory than the expression of an  
opinion4       #ei4 ,plastic ,theory4   
#cie4 ,by none of these writers is the  

property of viscosity or  plasticity    
ascribed to glacier ice2 the appearances
 of many glaciers  are1 however1 so     
suggestive of this idea that we may be  
sure it  would have found more frequent 
expression1 were it not in such         
apparent contradiction with our         
every-day experience of ice4    #cif4   
,still the idea found its advocates4 ,in
 a little book1 published  in #aggc1 and
 entitled ,picturesque ,journey to the  
,glaciers of ,savoy1  ,bordier of       
,geneva wrote thus3--,it is now time to 
look at all these  objects with the eyes
 of reason2 to study1 in the first      
place1 the  position and the progression
 of glaciers1 and to seek the solution  
of  their principal phenomena4 ,at the  
first aspect of the ice-mountains  an   
observation presents itself1 which      
appears sufficient to explain  all4 ,it 
is that the entire mass of ice is       
connected together1 and  presses from   
above downwards after the manner of     
fluids4 ,let us then  regard the ice1   

not as a mass entirely rigid and        
immobile1 but as a  heap of coagulated  
matter1 or as softened wax1 flexible and
 ductile  to a certain point4,f ,here   
probably for the first time the quality 
of plasticity is ascribed to the ice of 
glaciers4    ,f ,i am indebted to my    
distinguished friend ,prof4 ,studer of  
,berne  for directing my attention to   
,bordier's book1 and to my friends at   
the ,british ,museum for the great      
trouble they have taken to find it  for 
me4    #cig4 ,to us1 familiar with the  
aspect of the glaciers1 it must seem    
strange that this idea once expressed   
did not at once receive  recognition and
 development4 ,but in those early days  
explorers were  few1 and the            
,picturesque ,journey probably but      
little known1 so  that the notion of    
plasticity lay dormant for more than    
half a  century4 ,but ,bordier was at   
length succeeded by a man of far greater
  scientific grasp and insight than     
himself4 ,this was ,rendu1 a ,catholic  

priest and canon when he wrote1 and     
afterwards ,bishop of ,annecy4 ,in      
#ahda ,rendu laid before the ,royal     
,academy of ,sciences of ,savoy his     
,theory of the ,glaciers of ,savoy1 a   
contribution for ever memorable  in     
relation to this subject4,g    ,g       
,memoirs of the ,academy1 vol4 x4       
#cih4 ,rendu seized the idea of glacier 
plasticity with great power and         
clearness1 and followed it resolutely to
 its consequences4 ,it is not  known    
that he had ever seen the work of       
,bordier2 probably not1 as he  never    
mentions it4 ,let me quote for you some 
of ,rendu's expressions1  which1        
however1 fail to give an adequate idea  
of his insight and  precision of        
thought3--,between the ,mer de ,glace   
and a river there  is a resemblance so  
complete that it is impossible to find  
in the  glacier a circumstance which    
does not exist in the river4 ,in        
currents  of water the motion is not    
uniform either throughout their width or

  throughout their depth4 ,the friction 
of the bottom and of the sides1  with   
the action of local hindrances1 causes  
the motion to vary1 and  only towards   
the middle of the surface do we obtain  
the full motion4    #cii4 ,this reads   
like a prediction of what has since been
 established  by measurement4 ,looking  
at the glacier of ,mont ,dolent1 which  
resembles a sheaf in form1 wide at both 
ends and narrow in the  middle1 and     
reflecting that the upper wide part had 
become narrow1  and the narrow middle   
part again wide1 ,rendu observes1 ,there
 is a  multitude of facts which seem to 
necessitate the belief that glacier  ice
 enjoys a kind of ductility which       
enables it to mould itself to  its      
locality1 to thin out1 to swell1 and to 
contract as if it were a  soft paste4   
#djj4 ,to fully test his conclusions1   
,rendu required the accurate            
measurement of glacier motion4 ,had he  
added to his other endowments  the      
practical skill of a land-surveyor1 he  

would now be regarded as  the prince of 
glacialists4 ,as it was he was obliged  
to be content  with imperfect           
measurements4 ,in one of his excursions 
he examined the  guides regarding the   
successive positions of a vast rock     
which he  found upon the ice close to   
the side of the glacier4 ,the mean of   
five  years gave him a motion for this  
block of #dj feet a year4    #dja4      
,another block1 the transport of which  
he subsequently measured  more          
accurately1 gave him a velocity of #djj 
feet a year4 ,note his  explanation of  
this discrepancy3--,the enormous        
difference of these  two observations   
arises from the fact that one block     
stood near the  centre of the glacier1  
which moves most rapidly1 while the     
other  stood near the side1 where the   
ice is held back by friction4 ,so  clear
 and definite were ,rendu's ideas of the
 plastic motion of  glaciers1 that had  
the question of curvature occurred to   
him1 ,i  entertain no doubt that he     

would have enunciated beforehand the    
shifting of the point of maximum motion 
from side to side across the  axis of   
the glacier 7 #be74    #djb4 ,it is     
right that you should know that         
scientific men do not  always agree in  
their estimates of the comparative value
 of facts  and ideas2 and it is         
especially right that you should know   
that your  present tutor attaches a very
 high value to ideas when they spring   
from the profound and persistent        
pondering of superior minds1 and  are   
not1 as is too often the case1 thrown   
out without the warrant  of either deep 
thought or natural capacity4 ,it is     
because ,i believe  ,rendu's labours    
fulfil this condition1 that ,i ascribe  
to them so  high a value4 ,but when you 
become older and better informed1 you   
may  differ from me2 and ,i write these 
words lest you should too readily       
accept my opinion of ,rendu4 ,judge me1 
if you care to do so1 when your         
knowledge is matured4 ,i certainly shall

 not fear your verdict4    #djc4 ,but1  
much as ,i prize the prompting idea1 and
 thoroughly as  ,i believe that often in
 it the force of genius mainly lies1 it 
would1 in my opinion1 be an error of    
omission of the gravest kind1  and      
which1 if habitual1 would ensure the    
ultimate decay of natural  knowledge1 to
 neglect verifying our ideas1 and giving
 them outward  reality and substance    
when the means of doing so are at hand4 
,in  science thought1 as far as         
possible1 ought to be wedded to fact4   
,this was attempted by ,rendu1 and in   
part accomplished by ,agassiz and       
,forbes4       #fj4 ,viscous ,theory4   
#djd4 ,here indeed the merits of the    
distinguished glacialist last  named    
rise conspicuously to view4 ,from the   
able and earnest advocacy  of ,professor
 ,forbes1 the public knowledge of this  
doctrine of glacial  plasticity is      
almost wholly derived4 ,he gave the     
doctrine a more  distinctive form2 he   
first applied the term viscous to       

glacier ice1  and sought to found upon  
precise measurements a ,viscous ,theory 
of  glacier motion4    #dje4 ,i am here 
obliged to state facts in their historic
 sequence4  ,professor ,forbes when he  
began his investigations was acquainted 
with  the labours of ,rendu4 ,in his    
earliest work upon the ,alps he refers  
to those labours in terms of flattering 
recognition4 ,but though as  a matter of
 fact ,rendu's ideas were there to      
prompt him1 it would  be too much to say
 that he needed their inspiration4 ,had 
,rendu  not preceded him1 he might none 
the less have grasped the idea of       
viscosity1 executing his measurements   
and applying his knowledge to  maintain 
it4 ,be that as it may1 the appearance  
of ,professor ,forbes on  the ,unteraar 
glacier in #ahda1 and on the ,mer de    
,glace in #ahdb1 and  his labours then  
and subsequently1 have given him a name 
not to be  forgotten in the scientific  
history of glaciers4    #djf4 ,the      
theory advocated by ,professor ,forbes  

was enunciated by  himself in these     
words3--,a glacier is an imperfect      
fluid1 or viscous  body1 which is urged 
down slopes of certain inclination by   
the  natural pressure of its parts4 ,in 
#aggc ,bordier wrote thus3--,as the     
glaciers always advance upon the plain1 
and never disappear1 it is  absolutely  
essential that new ice shall perpetually
 take the place  of that which is       
melted3 it must therefore be pressed    
forward from  above4 ,one can hardly    
refuse then to accept the astonishing   
truth1  that this vast extent of hard   
and solid ice moves as a single piece   
downwards4 ,in the passage already      
quoted he speaks of the ice being       
pressed as a fluid from above4 ,these   
constitute1 ,i believe1 ,bordier's      
contributions to this subject4 ,the     
quotations show his sagacity at an      
early date2 but1 in point of            
completeness1 his views are not to be   
compared with those of ,rendu and       
,forbes4    #djg4 ,i must not omit to   

state here that though the idea of      
viscosity  has not been espoused by ,m4 
,agassiz1 his measurements1 and maps of 
measurements1 on the ,unteraar glacier  
have been recently cited as the  most   
clear and conclusive illustrations of a 
quality which1 at all  events1 closely  
resembles viscosity4    #djh4 ,but why1 
with proofs before him more copious and 
characteristic  than those of any other 
observer1 does ,m4 ,agassiz hesitate to 
accept  the idea of viscosity as applied
 to ice8 ,doubtless because he  believes
 the notion to be contradicted by our   
every-day experience of  the substance4 
#dji4 ,take a mass of ice ten or even   
fifteen cubic feet in volume2  draw a   
saw across it to a depth of half an inch
 or an inch2 and  strike a pointed      
pricker1 not thicker than a very small  
round file1  into the groove2 the       
substance will split from top to bottom 
with a  clean crystalline fracture4 ,how
 is this brittleness to be reconciled   
with the notion of viscosity8    #daj4  

,we have1 moreover1 been upon the       
glacier and have witnessed the  birth of
 crevasses4 ,we have seen them beginning
 as narrow cracks  suddenly formed1 days
 being required to open them a single   
inch4 ,in  many glaciers fissures may be
 traced narrow and profound for hundreds
  of yards through the ice4 ,what does  
this prove8 ,did the ice possess  even a
 very small modicum of that power of    
stretching1 which is  characteristic of 
a viscous substance1 such crevasses     
could not be  formed4    #daa4 ,still it
 is undoubted that the glacier moves    
like a viscous  body4 ,the centre flows 
past the sides1 the top flows over the  
bottom1 and the motion through a curved 
valley corresponds to fluid  motion4    
,mr4 ,mathews1 ,mr4 ,froude1 and above  
all ,signor ,bianconi1  have1 moreover1 
recently made experiments on ice which  
strikingly  illustrate the flexibility  
of the substance4 ,these experiments    
merit1  and will doubtless receive1 full
 attention at a future time4       #fa4 

,regelation ,theory4    #dab4 ,i will   
now describe to you an attempt that has 
been made of  late years to reconcile   
the brittleness of ice with1 its motion 
in  glaciers4 ,it is founded on the     
observation1 made by ,mr4 ,faraday in   
#ahej1 that when two pieces of thawing  
ice are placed together they  freeze    
together at the place of contact4       
#dac4 ,this fact may not surprise you2  
still it surprised ,mr4 ,faraday  and   
others1 and men of very great           
distinction in science have  differed in
 their interpretation of the fact4 ,the 
difficulty is to  explain where1 or how1
 in ice already thawing the cold is to  
be  found requisite to freeze the film  
of water between the two touching       
surfaces4    #dad4 ,the word ,regelation
 was proposed by ,dr4 ,hooker to express
 the  freezing together of two pieces of
 thawing ice observed by ,faraday2  and 
the memoir in which the term was first  
used was published by ,mr4  ,huxley and 
,mr4 ,tyndall in the ,philosophical     

,transactions for #aheg4    #dae4 ,the  
fact of regelation1 and its application 
irrespective of  the cause of           
regelation1 may be thus                 
illustrated3--,saw two slabs  from a    
block of ice1 and bring their flat      
surfaces into contact2 they  immediately
 freeze together4 ,two plates of ice1   
laid one upon the  other1 with flannel  
round them overnight1 are sometimes so  
firmly  frozen in the morning that they 
will rather break elsewhere than  along 
their surface of junction4 ,if you enter
 one of the dripping  ice-caves of      
,switzerland1 you have only to press for
 a moment a slab  of ice against the    
roof of the cave to cause it to freeze  
there and  stick to the roof4    #daf4  
,place a number of fragments of ice in a
 basin of water1 and  cause them to     
touch each other2 they freeze together  
where they  touch4 ,you can form a chain
 of such fragments2 and then1 by taking 
hold of one end of the chain1 you can   
draw the whole series after it4  ,chains

 of icebergs are sometimes formed in    
this way in the ,arctic  seas4    #dag4 
,consider what follows from these       
observations4 ,snow consists of  small  
particles of ice4 ,now if by pressure we
 squeeze out the air  entangled in      
thawing snow1 and bring the little      
ice-granules into  close contact1 they  
may be expected to freeze together2 and 
if the  expulsion of the air be         
complete1 the squeezed snow may be      
expected  to assume the appearance of   
compact ice4    #dah4 ,we arrive at this
 conclusion by reasoning2 let us now    
test it by  experiment1 employing a     
suitable hydraulic press1 and a mould to
 hold  the snow4 ,in exact accordance   
with our expectation1 we convert by     
pressure the snow into ice4,h    ,h ,a  
similar experiment was made by the      
,messrs4 ,schlagintweit prior  to the   
discovery which explains it1 and which  
therefore remained  unsolved4    #dai4  
,place a compact mass of ice in a proper
 mould1 and subject  it to pressure4 ,it

 breaks in pieces3 squeeze the pieces   
forcibly  together2 they re-unite by    
regelation1 and a compact piece of ice1 
totally different in shape from the     
first one1 is taken from the  press4 ,to
 produce this effect the ice must be in 
a thawing condition4  ,when its         
temperature is much below the melting   
point it is crushed  by pressure1 not   
into a pellucid mass of another shape1  
but into a  white powder4    #dbj4 ,by  
means of suitable moulds you may in this
 way change the shape  of ice to any    
extent1 turning out spheres1 and cups1  
and rings1 and  twisted ropes of the    
substance2 the change of form in these  
cases  being effected through rude      
fracture and regelation4    #dba4 ,by   
applying the pressure carefully1 rude   
fracture may be  avoided1 and the ice   
compelled slowly to change its form as  
if it  were a plastic body4    #dbb4    
,now our first experiment illustrates   
the consolidation of the  snows of the  
higher ,alpine regions4 ,the deeper     

layers of the nv  have to bear the      
weight of all above them1 and are       
thereby converted  into more or less    
perfect ice4 ,and our last experiment   
illustrates  the changes of form        
observed upon the glacier1 where1 by the
 slow and  constant application of      
pressure1 the ice gradually moulds      
itself to  the valley1 which it fills4  
#dbc4 ,in glaciers1 however1 we have    
also ample illustrations of  rude       
fracture and regelation4 ,the opening   
and closing of crevasses  illustrate    
this4 ,the glacier is broken on the     
cascades and mended  at their bases4    
,when two branch glaciers lay their     
sides together1  the regelation is so   
firm that they begin immediately to flow
 in  the trunk glacier as a single      
stream4 ,the medial moraine gives no    
indication by its slowness of motion    
that it is derived from the  sluggish   
ice of the sides of the branch glaciers4
    #dbd4 ,the gist of the ,regelation  
,theory is that the ice of glaciers     

changes its form and preserves its      
continuity under pressure which  keeps  
its particles together4 ,but when       
subjected to tension1 sooner  than      
stretch it breaks1 and behaves no longer
 as a viscous body4       #fb4 ,cause of
 ,regelation4    #dbe4 ,here the fact of
 regelation is applied to explain the   
plasticity  of glacier ice1 no attempt  
being made to assign the cause of       
regelation itself4 ,they are two        
entirely distinct questions4 ,but a     
little time will be well spent in       
looking more closely into the cause  of 
regelation4 ,you may feel some surprise 
that eminent men should  devote their   
attention to so small a point1 but we   
must not forget  that in nature nothing 
is small4 ,laws and principles interest 
the  scientific student most1 and these 
may be as well illustrated by  small    
things as by large ones4    #dbf4 ,the  
question of regelation immediately      
connects itself with that  of latent    
heat1 already referred to 7#chc71 but   

which we must now  subject to further   
examination4 ,to melt ice1 as already   
stated1 a  large amount of heat is      
necessary1 and in the case of the       
glaciers  this heat is furnished by the 
sun4 ,neither the ice so melted nor  the
 water which results from its           
liquefaction can fall below #cb         
,fahrenheit4 ,the freezing point of     
water and the melting point of ice      
touch each other1 as it were1 at this   
temperature4 ,a hair's-breadth  lower   
water freezes2 a hair's-breadth higher  
ice melts4    #dbg4 ,but if the ice     
could be caused to melt without this    
supply of  solar heat1 a temperature    
lower than that of ordinary thawing ice 
would result4 ,when snow and salt1 or   
pounded ice and salt1 are mixed         
together1 the salt causes the ice to    
melt1 and in this way a cold of  #bj or 
#cj degrees below the freezing point may
 be produced4 ,here1 in  fact1 the ice  
consumes its own warmth in the work of  
liquefaction4  ,such a mixture of ice   

and salt is called a freezing mixture4  
#dbh4 ,and if by any other means ice at 
the temperature of #cb  ,fahrenheit     
could be liquefied without access of    
heat from without1  the water produced  
would be colder than the ice4 ,now      
,professor ,james  ,thomson has proved  
that ice may be liquefied by mere       
pressure1 and  his brother1 ,sir        
,william ,thomson1 has also shown that  
water under  pressure requires a lower  
temperature to freeze it than when the  
pressure is removed4 ,professor ,mousson
 subsequently liquefied large  masses of
 ice by a hydraulic press2 and by a     
beautiful experiment  ,professor        
,helmholtz has proved that water in a   
vessel from which  the air has been     
removed1 and which is therefore relieved
 from the  pressure of the atmosphere1  
freezes and forms ice-crystals when     
surrounded by melting ice4 ,all these   
facts are summed up in the  brief       
statement that the freezing point of    
water is lowered by  pressure4,i    ,i  

,professor ,james ,thomson and          
,professor ,clausius proved this        
independently and almost                
contemporaneously4    #dbi4 ,for our own
 instruction we may produce the         
liquefaction of ice  by pressure in the 
following way3--,you remember the       
beautiful flowers  obtained when a      
sunbeam is sent through lake ice 7 #aa71
 and you have  not forgotten that the   
flowers always form parallel to the     
surface of  freezing4 ,let us cut a     
prism1 or small column of ice with the  
planes  of freezing running across it at
 right angles2 we place that prism      
between two slabs of wood1 and bring    
carefully to bear upon it the  squeezing
 force of a small hydraulic press4      
#dcj4 ,it is well to converge by means  
of a concave mirror a good light  upon  
the ice1 and to view it through a       
magnifying lens4 ,you already  see the  
result4 ,hazy surfaces are formed in the
 very body of the  ice1 which gradually 
expand as the pressure is slowly        

augmented4  ,here and there you notice  
something resembling crystallisation2   
fern-shaped figures run with            
considerable rapidity through the ice1  
and when you look carefully at their    
points and edges you find them  in      
visible motion4 ,these hazy surfaces are
 spaces of liquefaction1  and the motion
 you see is that of the ice falling to  
water under the  pressure4 ,that water  
is colder than the ice was before the   
pressure  was applied1 and if the       
pressure be relieved1 not only does the 
liquefaction cease1 but the water       
re-freezes4 ,the cold produced by  its  
liquefaction under pressure is          
sufficient to re-congeal it when  the   
pressure is removed4    #dca4 ,if       
instead of diffusing the pressure over  
surfaces of  considerable extent1 we    
concentrate it on a small surface1 the  
liquefaction will of course be more     
rapid1 and this is what ,mr4  ,bottomley
 has recently done in an experiment of  
singular beauty and  interest4 ,let us  

support on blocks of wood the two ends  
of a bar of  ice #aj inches long1 #d    
inches deep1 and #c wide1 and let us    
loop over  its middle a copper wire     
one-twentieth1 or even one-tenth1 of an 
inch in thickness4 ,connecting the two  
ends of the wire together1 and          
suspending from it a weight of #ab or   
#ad pounds1 the whole pressure  of this 
weight is concentrated on the ice which 
supports the wire4  ,what is the        
consequence8 ,the ice underneath the    
wire liquefies2 the  water of           
liquefaction escapes round the wire1 but
 the moment it is  relieved from the    
pressure it freezes1 and round about the
 wire1 even  before it has entered the  
ice1 you have a frozen casing4 ,the wire
  continues to sink in the ice2 the     
water incessantly escapes1 freezing  as 
it does so behind the wire4 ,in half an 
hour the weight falls2 the  wire has    
gone clean through the ice4 ,you can    
plainly see where it  has passed1 but   
the two severed pieces of ice are so    

firmly frozen  together that they will  
break elsewhere as soon as along the    
surface  of regelation4    #dcb4        
,another beautiful experiment bearing   
upon this point has  recently been made 
by ,m4 ,boussingault4 ,he filled a      
hollow steel  cylinder with water and   
chilled it4 ,in passing to ice1 water1  
as you  know1 expands 7 #de72 in fact1  
room for expansion is a necessary       
condition of solidification4 ,but in the
 present case the strong  steel resisted
 the expansion1 the water in consequence
 remaining  liquid at a temperature of  
more than #cj ,fahr4 below the ordinary 
freezing point4 ,a bullet within the    
cylinder rattled about at this          
temperature1 showing that the water was 
still liquid4 ,on opening the  tap the  
liquid1 relieved of the pressure1 was   
instantly converted  into ice4    #dcc4 
,it is only substances which expand on  
solidifying that behave  in this manner4
 ,the metal bismuth1 as we know1 is an  
example similar  to water2 while lead1  

wax1 or sulphur1 all of which contract  
on  solidifying1 have their point of    
fusion heightened by pressure4    #dcd4 
,and now you are prepared to understand 
,professor ,james ,thomson's  theory of 
regelation4 ,when two pieces of ice are 
pressed together  liquefaction1 he      
contends1 results4 ,the water spreads   
out around the  points of pressure1 and 
when released re-freezes1 thus forming a
 kind  of cement between the pieces of  
ice4       #fc4 ,faraday's ,view of     
,regelation4    #dce4 ,faraday's view of
 regelation is not so easily expressed1 
still  ,i will try to give you some     
notion of it1 dealing in the first place
  with admitted facts4 ,water1 even in  
open vessels1 may be lowered many       
degrees below its freezing temperature1 
and still remain liquid2  it may also be
 raised to a temperature far higher than
 its boiling  point1 and still resist   
boiling4 ,this is due to the mutual     
cohesion  of the water particles1 which 
resists the change of the liquid  either

 into the solid or the vaporous         
condition4    #dcf4 ,but if into the    
over-chilled water you throw a particle 
of ice1  the cohesion is ruptured1 and  
congelation immediately sets in4 ,and if
  into the superheated water you        
introduce a bubble of air or of steam1  
cohesion is likewise ruptured1 and      
ebullition immediately commences4       
#dcg4 ,faraday concluded that in the    
interior of any body1 whether  solid or 
liquid1 where every particle is grasped 
so to speak by the  surrounding         
particles1 and grasps them in turn1 the 
bond of cohesion  is so strong as to    
require a higher temperature to change  
the state  of aggregation than is       
necessary at the surface4 ,at the       
surface  of a piece of ice1 for example1
 the molecules are free on one side     
from the control of other molecules2 and
 they therefore yield to  heat more     
readily than in the interior4 ,the      
bubble of air or steam  in overheated   
water also frees the molecules on one   

side2 hence the  ebullition consequent  
upon its introduction4 ,practically     
speaking1  then1 the point of           
liquefaction of the interior ice is     
higher than  that of the superficial    
ice4 ,faraday also refers to the special
  solidifying power which bodies exert  
upon their own molecules4  ,camphor in a
 glass bottle fills the bottle with an  
atmosphere of  camphor4 ,in such an     
atmosphere large crystals of the        
substance may  grow by the incessant    
deposition of camphor molecules upon    
camphor1  at a temperature too high to  
permit of the slightest deposit upon    
the adjacent glass4 ,a similar remark   
applies to sulphur1 phosphorus1  and the
 metals in a state of fusion4 ,they are 
deposited upon solid  portions of their 
own substance at temperatures not low   
enough to  cause them to solidify       
against other substances4    #dch4      
,water furnishes an eminent example of  
this special solidifying  power4 ,it may
 be cooled ten degrees and more below   

its freezing  point without freezing4   
,but this is not possible if the        
smallest  fragment of ice be floating in
 the water4 ,it then freezes accurately 
at #cb ,fahr41 depositing itself1       
however1 not upon the sides of the      
containing vessel1 but upon the ice4    
,faraday observed in a freezing         
apparatus thin crystals of ice growing  
in ice-cold water to a length  of six1  
eight1 or ten inches1 at a temperature  
incompetent to produce  their deposition
 upon the sides of the containing       
vessel4    #dci4 ,and now we are        
prepared for ,faraday's view of         
regelation4  ,when the surfaces of two  
pieces of ice1 covered with a film of   
the water of liquefaction1 are brought  
together1 the covering  film is         
transferred from the surface to the     
centre of the ice1  where the point of  
liquefaction1 as before shown1 is higher
 than  at the surface4 ,the special     
solidifying power of ice upon water  is 
now brought into play on both sides of  

the film4 ,under these  circumstances1  
,faraday held that the film would       
congeal1 and freeze  the two surfaces   
together4    #ddj4 ,the lowering of the 
freezing point by pressure amounts to   
no more than one-seventieth of a degree 
,fahrenheit for a whole  atmosphere4    
,considering the infinitesimal fraction 
of this pressure  which is brought into 
play in some cases of regelation1       
,faraday  thought its effect insensible4
 ,he suspended pieces of ice1 and       
brought them into contact without       
sensible pressure1 still they  froze    
together4 ,professor ,james ,thomson1   
however1 considered that  even the      
capillary attraction exerted between two
 such masses would  be sufficient to    
produce regelation4 ,you may make the   
following  experiments1 in further      
illustration of this subject3--    #dda4
 ,place a small piece of ice in water1  
and press it underneath the  surface by 
a second piece4 ,the submerged piece may
 be so small as to  render the pressure 

infinitesimal2 still it will freeze to  
the under  surface of the superior      
piece4    #ddb4 ,place two pieces of ice
 in a basin of warm water1 and allow    
them  to come together2 they freeze     
together when they touch4 ,the parts    
surrounding the place of contact melt   
away1 but the pieces continue  for a    
time united by a narrow bridge of ice4  
,the bridge finally  melts1 and the     
pieces for a moment are separated4 ,but 
capillary  attraction immediately draws 
them together1 and regelation sets in   
once more4 ,a new bridge is formed1     
which in its turn is dissolved1  the    
separated pieces again closing up4 ,a   
kind of pulsation is thus  established  
between the two pieces of ice4 ,they    
touch1 they freeze1  a bridge is formed 
and melted2 and thus the rhythmic action
 continues  until the ice disappears4   
#ddc4 ,according to ,professor ,james   
,thomson's theory1 pressure is          
necessary to liquefy the ice4 ,the heat 
necessary for liquefaction  must be     

drawn from the ice itself1 and the cold 
water must escape  from the pressure to 
be re-frozen4 ,now in the foregoing     
experiments  the cold water1 instead of 
being allowed to freeze1 issues into    
the warm water1 still the floating      
fragments regelate in a moment4  ,the   
touching surfaces may1 moreover1 be     
convex2 they may be reduced  practically
 to points1 clasped all round by the    
warm water1 which  indeed rapidly       
dissolve them as they approach each     
other2 still they  freeze immediately   
when they touch4    #ddd4 ,you may learn
 from this discussion that in scientific
 matters1  as in all others1 there is   
room for differences of opinion4 ,the   
frame  of mind to be cultivated here is 
a suspension of judgment as long  as the
 meaning remains in doubt4 ,it may be   
that ,faraday's action  and ,thomson's  
action come both into play4 ,i cannot do
 better than  finish these remarks by   
quoting ,faraday's own concluding words1
  which show how in his mind scientific 

conviction dwelt apart from             
dogmatism3--,no doubt1 he says1 nice    
experiments will enable us  hereafter to
 criticise such results as these1 and   
separating the true  from the untrue    
will establish the correct theory of    
regelation4       #fd4 ,the ,blue ,veins
 of ,glaciers4    #dde4 ,we now approach
 the end1 one important question only   
remaining  to be discussed4 ,hitherto we
 have kept it back1 for a wide          
acquaintance with the glaciers was      
necessary to its solution4 ,we had  also
 to make ourselves familiar by actual   
experiment with the power  of ice1      
softened by thaw1 to yield to pressure1 
and to liquefy under  such pressure4    
#ddf4 ,snow is white4 ,but if you       
examine its individual particles you    
would call them transparent1 not white4 
,the whiteness arises from  the mixture 
of the ice particles with small spaces  
of air4 ,in the  case of all transparent
 bodies whiteness results from such a   
mixture4  ,the clearest glass or crystal

 when crushed becomes a white powder4   
,the foam of champagne is white through 
the intimate admixture of a  transparent
 liquid with transparent carbonic acid  
gas4 ,the whitest  paper1 moreover1 is  
composed of fibres which are            
individually  transparent4    #ddg4 ,it 
is not1 however1 the air or the gas1 but
 the optical  severance of the          
particles1 giving rise to a multitude of
 reflexions  of the white solar light at
 their surfaces1 that produces the      
whiteness4    #ddh4 ,the whiteness of   
the surface of a clean glacier 7#aab71  
and of  the icebergs of the ,mrgelin    
,see 7#ceg71 has been already referred  
to  a similar cause4 ,the surface is    
broken into innumerable fissures by  the
 solar heat1 the reflexion of solar     
light from the sides of the  little     
fissures producing the observed         
appearance4    #ddi4 ,in like manner if 
you freeze water in a test-tube by      
plunging it  into a freezing mixture1   
the ice produced is white4 ,for the most

 part  also the ice formed in freezing  
machines is white4 ,examine such1 ice1  
and you will find it filled with small  
air-bubbles4 ,when the freezing  is     
extremely slow the crystallising force  
pushes the air effectually  aside1 and  
the resulting ice is transparent2 when  
the freezing is  rapid1 the air is      
entangled before it can escape1 and the 
ice is  translucent4 ,but even in the   
case of quick freezing ,mr4 ,faraday    
obtained transparent ice by skilfully   
removing the air-bubbles as  fast as    
they appeared with a feather4    #dej4  
,in the case of lake ice the freezing is
 not uniform1 but  intermittent4 ,it is 
sometimes slow1 sometimes rapid4 ,when  
slow the  air dissolved in the water is 
effectually squeezed out and forms a    
layer of bubbles on the under-surface of
 the ice4 ,an act of sudden  freezing   
entangles the air1 and hence we find    
lake ice usually  composed of layers    
alternately clear1 and filled with      
bubbles4 ,such  layers render it easy to

 detect the planes of freezing in lake  
ice4    #dea4 ,and now for the bearing  
of these facts4 ,under the fall of the  
,gant1 at the base of the ,talfre       
cascade1 and lower down the ,mer  de    
,glace2 in the higher regions of the    
,grindelwald1 the ,aar1 the  ,aletsch   
and the ,grner glaciers1 the ice does   
not possess the  transparency which it  
exhibits near the ends of the glaciers4 
,it  is white1 or whitish4 ,why8        
,examination shows it to be filled with 
small air-bubbles2 and these1 as we now 
learn1 are the cause of its  whiteness4 
#deb4 ,they are the residue of the air  
originally entangled in the  snow1 and  
connected1 as before stated1 with the   
whiteness of the  snow4 ,during the     
descent of the glacier1 the bubbles are 
gradually  expelled by the enormous     
pressures brought to bear upon the ice4 
,not only is the expulsion caused by the
 mechanical yielding of the  soft       
thawing ice1 but the liquefaction of the
 substance at places of  violent        

pressure1 opening1 as it does1 fissures 
for the escape of the  air1 must play an
 important part in the consolidation of 
the glacier4    #dec4 ,the expulsion of 
the bubbles is1 however1 not uniform2   
for  neither ice nor any other substance
 offers an absolutely uniform           
resistance to pressure4 ,at the base of 
every cascade that we have  visited1 and
 on the walls of the crevasses there    
formed1 we have  noticed innumerable    
blue streaks drawn through the white    
translucent  ice1 and giving the whole  
mass the appearance of lamination4      
,these  blue veins turned out upon      
examination to be spaces from which the 
air-bubbles had been almost wholly      
expelled1 translucency being thus       
converted into transparency4    #ded4   
,this is the veined or ribboned         
structure of glaciers1  regarding the   
origin of which diverse opinions are now
 entertained4    #dee4 ,it is now our   
duty to take up the problem1 and to     
solve it if we  can4 ,on the nvs of the 

,col du ,gant1 and other glaciers1 we   
have  found great cracks1 and faults1   
and ,bergschrunds1 exposing deep        
sections of the nv2 and on these        
sections we have found marked the  edges
 of half-consolidated strata evidently  
produced by successive  falls of snow4  
,the nv is stratified because its supply
 of material  from the atmosphere is    
intermittent1 and when we first observed
  the blue veins we were disposed to    
regard them as due to this              
stratification4    #def4 ,but           
observation and reflexion soon dispelled
 this notion4 ,indeed  it could hardly  
stand in the presence of the single fact
 that at the  bases of the ice-falls the
 veins are always vertical1 or nearly   
so4  ,we saw no way of explaining how   
the horizontal strata of the nv  could  
be so tilted up at the base of the fall 
as to be set on edge4  ,nor is the      
aspect of the veins that of             
stratification4    #deg4 ,on the central
 portions of the cascades1 moreover1    

there are  no signs of the veins4 ,at   
the bases they first appear1 reaching in
  each case their maximum development a 
little below the base4 ,as you  and ,i  
stood upon the heights above the        
,zsenberg and scrutinised the  cascade  
of the ,strahleck branch of the         
,grindelwald glacier1 we could  not     
doubt that the base of the fall was the 
birthplace of the veins4  ,we called    
this portion of the glacier a ,structure
 ,mill1 intimating  that here1 and not  
on the nv1 the veined structure was     
manufactured4    ,illustration3         
,,section ,,of ,,icefall1 ,,and         
,,glacier ,,below ,,it1 ,,showing       
,,origin ,,of ,,veined ,,structure4     
#deh4 ,this1 however1 is1 at bottom1 the
 language of strong opinion  merely1 not
 that of demonstration2 and in science  
opinion ought to  content us only so    
long as positive proof is unattainable4 
,the love  of repose must not prevent us
 from seeking this proof4 ,there is no  
sterner conscience than the scientific  

conscience1 and it demands1  in every   
possible case1 the substitution for     
private conviction of  demonstration    
which shall be conclusive to all4       
#dei4 ,let us1 for example1 be shown a  
case in which the stratification  of the
 nv is prolonged into the glacier2 let  
us see the planes of  bedding and the   
planes of lamination existing side by   
side1 and still  indubitably distinct4  
,such an observation would effectually  
exclude  stratification from the problem
 of the veined structure1 and through   
the removal of this tempting source of  
error1 we should be rendered  more free 
to pursue the truth4    #dfj4 ,we sought
 for this conclusive test upon the ,mer 
de ,glace1  but did not find it4 ,we    
sought it on the ,grindelwald1 and the  
,aar  glaciers1,j with an equal want of 
success4 ,on the ,aletsch glacier1  for 
the first time1 we observed the apparent
 coexistence of bedding  and structure1 
the one cutting the other upon the walls
 of the same  crevasse4 ,still the case 

was not sufficiently pronounced to      
produce  entire conviction1 and we      
visited the ,grner glacier with the view
 of  following up our quest4    ,j ,m4  
,agassiz1 however1 reports a case of the
 kind upon the glacier  of the ,aar4    
,illustration3 ,,structure ,,and        
,,bedding ,,on ,,aletsch ,,glacier4     
#dfa4 ,here day after day added to the  
conviction that the bedding and  the    
structure were two different things4    
,still day after day passed  without    
revealing to us the final proof4 ,surely
 we have not let our  own ease stand in 
the way of its attainment1 and if we    
retire baffled  we shall do so with the 
consciousness of having done our best4  
,yonder1 however1 at the base of the    
,matterhorn1 is the ,furgge glacier     
that we have not yet explored4 ,upon it 
our final attempt must be made4    #dfb4
 ,we get upon the glacier near its end1 
and ascend it4 ,we are soon  fronted by 
a barrier composed of three successive  
walls of nv1 the  one rising above the  

other1 and each retreating behind the   
other4 ,the  bottom of each wall is     
separated from the top of the succeeding
 one  by a ledge1 on which threatening  
masses of broken nv now rest4 ,we  stand
 amid blocks and rubbish which have been
 evidently discharged  from these       
ledges1 on which other masses1 ready    
apparently to tumble1  are now poised4  
#dfc4 ,on the vertical walls of this    
barrier we see1 marked with the  utmost 
plainness1 the horizontal lines of      
stratification1 while  something        
exceedingly like the veined structure   
appears to cross the  lines of bedding  
at nearly a right angle4 ,the vertical  
surface is1  however weathered1 and the 
lines of structure1 if they be such1 are
  indistinct4 ,the problem now is to    
remove the surface1 and expose the  ice 
underneath4 ,it is one of the many cases
 that have come before  us1 where the   
value of an observation is to be        
balanced against the  danger which it   
involves4    #dfd4 ,we do nothing       

rashly2 but scanning the ledges and     
selecting a  point of attack1 we        
conclude that the danger is not too     
great to  be incurred4 ,we advance to   
the wall1 remove the surface1 and are   
rewarded by the discovery underneath it 
of the true blue veins4 ,they1          
moreover1 are vertical1 while the       
bedding is horizontal4 ,bruce1 as  you  
know1 was defeated in many a battle1 but
 he persisted and won at  last4 ,here1  
upon the ,furgge glacier1 you also have 
fought and won  your little             
,bannockburn4    ,illustration3         
,,structure ,,and ,,bedding ,,on        
,,furgge ,,glacier4    #dfe4 ,but let us
 not use the language of victory too    
soon4 ,the  stratification theory has   
been removed out of the field of        
explanation1 but nothing has as yet been
 offered in its place4       #fe4       
,relation of ,structure to ,pressure4   
#dff4 ,this veined structure was first  
described by the distinguished  ,swiss  
naturalist1 ,guyot1 now a resident in   

the ,united ,states4 ,from  the ,grimsel
 ,pass ,i have already pointed out to   
you the ,gries glacier  overspreading   
the mountains at the opposite side of   
the valley of the  ,rhone4 ,it was on   
this glacier that ,m4 ,guyot made his   
observation4    #dfg4 ,i saw1 he said1  
under my feet the surface of the entire 
glacier covered with regular furrows1   
from one to two inches wide1  hollowed  
out in a half-snowy mass1 and separated 
by protruding plates  of harder and more
 transparent ice4 ,it was evident that  
the glacier  here was composed of two   
kinds of ice1 one that of the furrows1  
snowy and more easily melted2 the other 
of the plates1 more perfect1            
crystalline1 glassy1 and resistant2 and 
that the unequal resistance  which the  
two kinds of ice presented to the       
atmosphere was the cause  of the ridges4
    #dfh4 ,after having followed them   
for several hundred yards1 ,i reached  a
 crevasse twenty or thirty feet wide1   
which1 as it cut the plates  and furrows

 at right angles1 exposed the interior  
of the glacier to  a depth of thirty or 
forty feet1 and gave a beautiful        
transverse  section of the structure4   
,as far as my eyes could reach1 ,i saw  
the mass of the glacier composed of     
layers of snowy ice1 each two  of which 
were separated by one of the hard plates
 of which ,i have  spoken1 the whole    
forming a regularly laminated mass1     
which resembled  certain calcareous     
slates4    #dfi4 ,i have not failed to  
point out to you upon all the glaciers  
that we have visited the little         
superficial furrows here described2  and
 you have1 moreover1 noticed that in the
 furrows mainly is lodged  the finer    
dirt which is scattered over the        
glacier4 ,they suggest  the passage of a
 rake over the ice4 ,and whenever these 
furrows were  interrupted by a crevasse1
 the veined structure invariably        
revealed  itself upon the walls of the  
fissure4 ,the surface grooving is indeed
  an infallible indication of the       

interior lamination of the ice4    #dgj4
 ,we have tracked the structure through 
the various parts of the  glaciers at   
which its appearance was most distinct2 
and we have  paid particular attention  
to the condition of the ice at these    
places4 ,the very fact of its cutting   
the crevasses at right angles  is       
significant4 ,we know the mechanical    
origin of the crevasses2 that  they are 
cracks formed at right angles to lines  
of tension4 ,but since  the crevasses   
are also perpendicular to the planes of 
structure1  these planes must be        
parallel to the lines of tension4       
#dga4 ,on the glaciers1 however1 tension
 rarely occurs alone4 ,at the  sides of 
the glacier1 for example1 where marginal
 crevasses are  formed1 the tension is  
always accompanied by pressure2 the one 
force acting at right angles to the     
other4 ,here1 therefore1 the  veined    
structure1 which is parallel to the     
lines of tension1 is  perpendicular to  
the lines of pressure4    #dgb4 ,that   

this is so will be evident to you in a  
moment4 ,let the  adjacent figure       
represent the channel of the glacier    
moving in the  direction of the arrow4  
,suppose three circles to be marked upon
 the  ice1 one at the centre and the two
 others at the sides4 ,in a glacier  of 
uniform inclination all these circles   
would move downward1 the  central one   
only remaining a circle4 ,by the        
retardation of the sides  the marginal  
circles would be drawn out to ovals4    
,the two circles  would be elongated in 
one direction1 and compressed in        
another4  ,across the long diameter1    
which is the direction of strain1 we    
have  the marginal crevasses2 across the
 short diameter m n1 which is the       
direction of pressure1 we have the      
marginal veined structure4              
,illustration    #dgc4 ,this association
 of pressure and structure is           
invariable4 ,at  the bases of the       
cascades1 where the inclination of the  
bed of the  glacier suddenly changes1   

the pressure in many cases suffices not 
only to close the crevasses but to      
violently squeeze the ice4 ,at  such    
places the structure always appears1    
sweeping quite across  the glacier4     
,when two branch glaciers unite1 their  
mutual thrust  intensifies the          
pre-existing marginal structure of the  
branches1  and developes new planes of  
lamination4 ,under the medial moraines1 
therefore1 we have usually a good       
development of the structure4 ,it  is   
finely displayed1 for example1 under the
 great medial moraine of  the glacier of
 the ,aar4    #dgd4 ,upon this glacier1 
indeed1 the blue veins were observed    
independently three years after ,m4     
,guyot had first described them4 ,i  say
 independently1 because ,m4 ,guyot's    
description1 though written in  #ahch1  
remained imprinted1 and was unknown in  
#ahda to the observers on  the ,aar4    
,these were ,m4 ,agassiz and ,professor 
,forbes4 ,to the question  of structure 
,professor ,forbes subsequently devoted 

much attention1  and it was mainly his  
observations and reasonings that gave it
 the  important position now assigned to
 it in the phenomena of glaciers4       
#dge4 ,thus without quitting the        
glaciers themselves1 we establish  the  
connexion between pressure and          
structure4 ,is there anything in  our   
previous scientific experience with     
which these facts may be  connected8    
,the new knowledge of nature must always
 strike its roots  into the old1 and    
spring from it as an organic growth4    
#ff4 ,slate ,cleavage and ,glacier      
,lamination4    #dgf4 ,m4 ,guyot threw  
out an exceedingly sagacious hint1 when 
he  compared the veined structure to the
 cleavage of slate rocks4 ,we must      
learn something of this cleavage1 for it
 really furnishes the key to  the       
problem which now occupies us4 ,let us  
go then to the quarries  of ,bangor or  
,cumberland1 and observe the quarrymen  
in their sheds  splitting the rocks4    
,with a sharp point struck skilfully    

into the  edge of the slate1 they cause 
it to divide into thin plates1 fit for  
roofing or ciphering1 as the case may   
be4 ,the surfaces along which  the rock 
cleaves are called its planes of        
cleavage4    #dgg4 ,all through the     
quarry you notice the direction of these
 planes  to be perfectly constant4 ,how 
is this laminated structure to be       
accounted for8    #dgh4 ,you might be   
disposed to consider that cleavage is a 
case of  stratification or bedding2 for 
it is true that in various parts of     
,england there are rocks which can be   
cloven into thin flags along the  planes
 of bedding4 ,but when we examine these 
slate rocks we verify  the observation1 
first ,i believe made by the eminent and
 venerable  ,professor ,sedgwick1 that  
the planes of bedding usually run across
 the  planes of cleavage4    #dgi4 ,we  
have here1 as you observe1 a case       
exactly similar to that of  glacier     
lamination1 which we were at first      
disposed to regard as due  to           

stratification4 ,we afterwards1 however1
 found planes of lamination  crossing   
the layers of the nv1 exactly as the    
planes of cleavage  cross the beds of   
slate rocks4    #dhj4 ,but the analogy  
extends further4 ,slate cleavage        
continued to  be a puzzle to geologists 
till the late ,mr4 ,daniel ,sharpe made 
the  discovery that shells and other    
fossils and bodies found in slate  rocks
 are invariably flattened out in the    
planes of cleavage4    #dha4 ,turn into 
any well-arranged museum--for example1  
into the ,school  of ,mines in ,jermyn  
,street1 and observe the evidence there 
collected4  ,look particularly to the   
fossil trilobites taken from the slate  
rock4  ,they are in some cases squeezed 
to one third of their primitive         
thickness4 ,numerous other specimens    
show in the most striking manner  the   
flattening out of shells4    #dhb4 ,to  
the evidence adduced by ,mr4 ,sharpe1   
,mr4 ,sorby added other  powerful       
evidence1 founded upon the microscopic  

examination of slate  rock4 ,taking both
 into account1 the conclusion is        
irresistible that  such rocks have      
suffered enormous pressure at right     
angles to the  planes of cleavage1      
exactly as the glacier has demonstrably 
suffered  great pressure at right angles
 to its planes of lamination4    #dhc4  
,the association of pressure and        
cleavage is thus demonstrated2  but the 
question arises1 do they stand to each  
other in the relation  of cause and     
effect8 ,the only way of replying to    
this question is to  combine            
artificially the conditions of nature1  
and see whether we  cannot produce her  
results4    #dhd4 ,the substance of     
slate rocks was once a plastic mud1 in  
which  fossils were embedded4 ,let us   
imitate the action of pressure upon     
such mud by employing1 instead of it1   
softened white wax4 ,placing a  ball of 
the wax between two glass plates1 wetted
 to prevent it from  sticking1 we apply 
pressure and flatten out the wax4       

#dhe4 ,the flattened mass is at first   
too soft to cleave sharply2 but  you can
 see1 by tearing1 that it is laminated4 
,let us chill it with  ice4 ,we find    
afterwards that no slate rock ever      
exhibited so fine a  cleavage4 ,the     
lamin1 it need hardly be said1 are      
perpendicular to  the pressure4    #dhf4
 ,one cause of this lamination is that  
the wax is an aggregate  of granules the
 surfaces of which are places of weak   
cohesion2 and  that by the pressure     
these granules are squeezed flat1 thus  
producing  planes of weakness at right  
angles to the pressure4    #dhg4 ,but   
the main cause of the cleavage ,i take  
to be the lateral  sliding of the       
particles of wax over each other4 ,old  
attachments  are thereby severed1 which 
the new ones fail to make good4 ,thus   
the  tangential sliding produces        
lamination1 as the rails near a station 
are caused to exfoliate by the gliding  
of the wheel4    #dhh4 ,instead of wax  
we may take the slate itself1 grind it  

to fine  powder1 add water1 and thus    
reproduce the pristine mud4 ,by the     
proper  compression of such mud1 in one 
direction1 the cleavage is restored4    
#dhi4 ,call now to mind the evidences we
 have had of the power of  thawing ice  
to yield to pressure4 ,recollect the    
shortening of the  ,glacier du ,gant1   
and the squeezing of the ,glacier de    
,lchaud1 at  ,trlaporte4 ,such a        
substance1 slowly acted upon by         
pressure1 will  yield laterally4 ,its   
particles will slide over each other1   
the  severed attachments being          
immediately made good by regelation4 ,it
  will not yield uniformly1 but along   
special planes4 ,it will also  liquefy1 
not uniformly1 but along special        
surfaces4 ,both the sliding  and the    
liquefaction will take place principally
 at right angles to  the pressure1 and  
glacier lamination is the result4       
#dij4 ,as long as it is sound the       
laminated glacier ice resists  cleavage4
 ,regelation1 as ,i have said1 makes the

 severed attachments  good4 ,but when   
such ice is exposed to the weather the  
structure is  revealed1 and the ice can 
then be cloven into tablets a square    
foot1  or even a square yard in area4   
#fg4 ,conclusion4    #dia4 ,here1 my    
friend1 our labours close4 ,it has been 
a true pleasure  to me to have you at my
 side so long4 ,in the sweat of our     
brows we  have often reached the heights
 where our work lay1 but you have been  
steadfast and industrious throughout1   
using in all possible cases  your own   
muscles instead of relying upon mine4   
,here and there ,i have  stretched an   
arm and helped you to a ledge1 but the  
work of climbing  has been almost       
exclusively your own4 ,it is thus that  
,i should like  to teach you all things2
 showing you the way to profitable      
exertion1  but leaving the exertion to  
you more anxious to bring out your      
manliness in the presence of difficulty 
than to make your way smooth  by toning 
difficulties down4    #dib4 ,steadfast1 

prudent1 without terror1 though not at  
all times  without awe1 ,i have found   
you on rock and ice1 and you have shown 
the still rarer quality of steadfastness
 in intellectual effort4 ,as  here set  
forth1 our task seems plain enough1 but 
you and ,i know how  often we have had  
to wrangle resolutely with the facts to 
bring out  their meaning4 ,the work1    
however1 is now done1 and you are master
 of  a fragment of that sure and certain
 knowledge which is founded on the      
faithful study of nature4 ,is it not    
worth the price paid for it8 ,or        
rather1 was not the paying of the price 
the healthful1 if sometimes  hard1      
exercise of mind and body1 upon alp and 
glacier--a portion of  our delight8     
#dic4 ,here then we part4 ,and should we
 not meet again1 the memory of  these   
days will still unite us4 ,give me your 
hand4 ,good bye4          ,,index4      
,a      ,accurate measurements of the   
motions of glaciers1 by ,agassiz and    
,forbes1 #fj-fb4    ggischhorn1 view    

from the1 #acg4    ,agassiz's           
measurements1 #fj2      conclusions1    
#ajg2      discovery by1 #aej2          
observations made by1 #ahg4    ,aiguille
 du ,dru1 pyramid of1 #dc2              
cloud-banner of1 #ij4    ---- des       
,charmoz1 #dc2      clouds about1 #ij4  
---- ,noire1 #ea4    ---- ,verte1 height
 of1 #ec    ---- du ,midi1 stone        
avalanches of1 #ef4    ,air1 its        
expansion1 #bd2      a chilling process1
 #be2      experiments illustrating1    
#be1 #bf4    ,aletsch glacier1 #acf2    
length of1 #acf2      arm of1 #acg4     
,alpine ice1 origin in the sun's heat1  
#g4    ,ancient glaciers of ,england1   
,ireland1 ,scotland1 and ,wales1 #aej1  
#aea4    ,architecture of snow1 #bi-cd1 
#ia2      of lake-ice1 #ce1 #afi4       
,arveiron1 vault of1 #ff2               
description and cause of1 #ib4      ,b  
,bel ,alp1 description of the1 #aci1    
#adj4    ,bergschrund1 formation of the1
 #ajb1 #ajc1 #agi4    ,blue veins of    
glaciers1 #agf2      whiteness of snow1 

#agf2      whiteness of ice1 #agg2      
freezing of lake-ice1 #agg2             
explanation of cause of whiteness of    
glaciers1 #agh2      translucency       
converted into transparency1 #agh2      
vertical veins1 #agi2      structure and
 bedding on glaciers1 #aha1 #ahb2       
stratification theory1 #ahc2            
observations1 #ahg4    ,bodies of guides
 found on ,glacier des ,bossons1 #eg1   
#add4    ,boulders1 size of1 #adh1 #adi4
      ,c      ,changes of volume        
resulting from heat and cold1 #aah-abb2 
illustrations of1 #aai1 #abj2           
consequences from1 #abb2      opinions  
of ,count ,rumford1 #ab1 #abd4          
,chapeau1 refreshment at1 #da4          
,cleavage and glacier lamination1 #ahg2 
analogy between1 #ahh1 #ahi2      planes
 of1 #ahh2      observations of ,prof4  
,sedgwick1 #ahh2      discovery by      
,daniel ,sharp1 #ahh2      additional   
evidence of ,mr4 ,sorby1 #ahi2          
association of pressure and cleavage    
established1 #ahi3      relation of     

cause and effect1 #ahi2      artificial 
conditions of ,nature combined1 #ahi1   
#aij4    ,clouds1 their formation1 #c-f2
      in tropical regions1 #be2         
illustration of the formation of1 #bf4  
,col du ,gant1 snows and ice-cascade of 
the1 #df1 #dg2      snow-fall on the    
plateau of1 #dh1 #di2      cracks on1   
#agi4    ,conclusion1 #aia1 #aib4       
,condensers needed1 #aed4    ,conditions
 necessary for the production of natural
 phenomena1 #ii4    ,conscience1        
scientific1 #ahj4    ,crevasses1 #da2   
work among the1 #eb2      widening of1  
#ed2      drifting of bodies buried in1 
#eg2      birth of1 #ih2      features  
of1 #ajj2      characteristic1 #ajb2    
transverse1 #ajc2      stalactites of   
,alpine1 #ajj2      marginal1 #aje-ajg2 
longitudinal1 #aji2      curvature of   
glacier related to number of1 #aaj-aab4 
,crystallization of metals1 #bi2      of
 sugar1 #cj2      of saltpetre1 #cj2    
of alum1 #cj2      of chalk1 #cj2       
of carbon1 #cj2      reversal of the    

process of1 #cf4      ,d      ,de       
,saussure's theory of glacier-motion1   
#aef4    ,dilatation theory1 #aee1 #aef4
    ,dirt-bands of ,mer de ,glace1      
observed by ,prof4 ,forbes1 #acj2       
description and explanation of1 #aca1   
#acb4    ,distillation1 oceanic1 #ah2   
ordinary1 #ba4    ,dme du ,got1 broken  
crags of1 #ej4    ,drifting of huts on  
ice1 #ei1 #fj4    ,dr4 ,william         
,hopkins's conclusions regarding the    
obliquity of the      lateral crevasses1
 #ajg4      ,e      gralets1 passage    
through the1 #ec4    ,electric light1   
dark waves of1 #ad4    ,equivalent      
points1 comparison of velocities of1    
#ge1 #gf1 #ajg4    ,erratic blocks1     
#adg-aej4    ,evaporation1 caused by the
 heat-rays of the sun1 #ac4             
,expansion of water1 #aba1 #aee4        
,experiments to show the heat-power of  
the dark rays1 #ad-ai2                  
illustrative1 #bb1 #bc1 #be1 #bj2       
,dr4 ,franklin's experiment1 #aab4      
,extract from ,bordier's book1 #aeg1    

#afb4      ,f      ,faraday's theory    
regarding regelation1 #aga2      special
 solidifying power exerted by substances
 upon their own        molecules1 #agb1 
#agc2      opinion of ,prof4 ,james     
,thomson1 #agd1 #age2      experiments  
illustrating the subject1 #agd2         
quotation from ,faraday1 #age4    ,fog1 
its formation in ball-rooms1 #e4        
,forces1 of crystallization1 #cj2       
of gravitation1 #cj2      of ,nature1   
#ca2      attractive and repulsive1     
#abg4    ,freezing mixture1 #abj1 #afh4 
,g      ,glacier1 the source of the     
,rhone1 #g2      fed by mountain-snow1  
#g1 #ba2      melted by the sun's dark  
rays1 #ac2      terminal moraines of1   
#ch2      questions regarding motions   
of1 #ed-eh2      action of the ends of1 
#eh2      motion at top and bottom of1  
#hj1 #ha2      lateral compression of1  
#ha1 #hb2      longitudinal compression 
of1 #hd1 #he2      slow movement in     
winter of1 #hg2      motion of          
,grindelwald1 #id2      motion of ,great

 ,aletsch1 #id2      motion of          
,morteratsch1 #ie2      crevasses at the
 side of1 #ajf2      action1 #adf1 #adg2
      ice1 #aee2      veined or ribboned
 structure of1 #agh2      blue veins of1
 #agj2      tables1 #aac1 #aad2         
mills1 #aaf-aah2      theory of         
,scheuchzer regarding1 #aee2            
ancient1 #ade-adg2      impurities      
thrust out by1 #add2      whiteness of a
 clean1 #dc1 #agj2      measurements by 
,hugi and ,agassiz of1 #ei1 #fj2        
epoch1 #aeb-afg4    ,glacier des ,bois1 
description of1 #ch-dc4    ---- des     
,bossons1 #ef2      mass of ice upon1   
#acd4    ---- of ,aletsch1 sand-cones   
of1 #aaf4    ---- des ,priades1 #ea4    
---- du ,talfre1 boundary of1 #ec2      
width of1 #ib2      chasms of the1 #ih4 
---- de ,lchaud1 motion of1 #hj2        
width of1 #hb2      compression of1     
#aij4    ---- du ,gant1 nv of the1 #di2 
motion of1 #gi2      width of1 #hb2     
cracks above the ice-falls of1 #aai2    
honey-combing of1 #aae2      shortening 

of1 #aij4    ---- ,unteraar1 movement   
of1 #fa2      appearance of ,prof4      
,forbes on1 #afa2      measurements by  
,agassiz on1 #afb4    ---- ,grner1      
sand-cones of1 #aaf2      description   
of1 #adj-add2      moraines of1 #adc2   
advance and retreat of1 #add2           
objects of interest on1 #add2           
structure and bedding on1 #aha4         
,grand ,plateau1 crevasse on1 #eg1 #aah4
    ,greenland's icy mountains1 #ba4    
,growth of knowledge1 #ei4    ,guesses  
in science1 #gd4      ,h      ,harmony  
of life and its conditions1 #abe4       
,heat1 waves of1 #ab2      invisible1   
#ad2      office of the invisible waves 
of1 #cf2      absorption of solar1 #ajj2
      demanded for the liquefaction of  
ice1 #aca2      latent1 #aec4           
,hoar-frost1 #e1 #f2      not melted by 
light-waves1 #ac1 #ah4    ,htel des     
,neuchtelois1 movements of1 at          
,riffelberg1 #ada4      ,i      ,ice1   
structure of1 #ce1 #cf1 #aai2           
towers of1 #ajd2      sea1 #acb-acd2    

retreat of1 #ade2      development in   
the ,alps of1 #aej2      freezing of    
pieces of1 #afd2      liquefaction by   
pressure of1 #ajh1 #afj2                
translucent1 #agg2      difference      
between hard and soft1 #hg4             
,icebergs1 of arctic seas1 #acc2        
described by ,sir ,leopold ,mc,clintock1
 #acc1 #acd2      drifting of1 #acd2    
origin of1 #acd2      of ,switzerland1  
#acf-ach2      colors of1 #ach2         
formation of chains of1 #afe4           
,ice-lens1 concentration of sun's rays  
by means of1 #cg4    ,ice-river through 
the vale of ,hasli1 #adf4    ,icicles1  
#ii2      how produced1 #ajj2      a    
theory of1 #ajj-ajb    ,imagination1    
scientific use of1 #cd4    ,impurities  
thrust out by glaciers1 #add4           
,infinite ,wisdom1 designs of1 #abd4    
,j      ,jardin1 description of1 #ec4   
,jungfrau1 #acf1 #acg4      ,k          
,killarney1 luxuriant vegetation of1    
#bg1 #aea4      ,l      ,la ,grande     
,jorasse1 crests of1 #dc2      roses of 

cloud about1 #ij4    ,lake of ,geneva1  
an expansion of the river ,rhone1 #f4   
,latent heat1 #aec1 #afg4    ,lateral   
moraines1 origin of1 #ed4    ,light1    
wave-theory of1 #aj1 #aa2      inference
 from the phenomena of1 #aa2      length
 of wave of1 #ab4    ,likeness of       
glacier-motion to river-motion1 #gb-gf4 
,liquefaction of ice1 #afh1 #afi2       
experiment by ,mr4 ,bottomley1 #agj2    
experiment by ,mr4 ,boussingault1 #agj1 
#aga4    ,locus of the point of swiftest
 motion1 #gf4    ,longitudinal          
crevasses1 how formed1 #aji2            
examples of1 #aaj4      ,m              
,magillicuddy's ,reeks1 #bg1 #aej1 #aea4
    ,magnet1 poles of1 #cb2             
repelling corners and ends of1 #abf4    
,mrgelin ,see1 #ach2 icebergs in the1   
#ach4    ,marginal crevasses1           
explanation of1 #ajf-aji4    ,mauvais   
,pas1 #da4    ,measurements of glaciers 
by ,hugi and ,agassiz1 #ei1 #fj4        
,medial moraines1 how accounted for1    
#ee4    ,mer de ,glace1 #da2      its   

sources1 #dc-de2      view of the1 #dd2 
branching of the1 #de2      medial      
moraines of the1 #ea1 #eb2              
triangulation of1 #fb2      motion of1  
#ff1 #gj2      daily motion of1 #fg2    
unequal motion of the two sides of1     
#gj-gb2      motion of axes of1 #gh2    
summer condition of1 #hg2      winter   
on1 #hh-ib2      dirt-bands of1 #abg2   
dimensions of1 #ade2      winter motion 
of1 #ic2      greater number of         
crevasses on eastern side of1 #aab2     
glacier tables of1 #aac2      grand     
moulin of1 #aag1 #aah2      approximate 
weight of1 #aed4    ,molecules1 of      
water1 #ca1 #cd2      expansion of1     
#abe2      forces acting upon1 #abg2    
exclusiveness of water1 #acb1 #acc4     
,montanvert1 auberge of the1 #da1 #dc2  
appearance in winter1 #hi4    ,moraine1 
lateral1 #da2      medial moraines of   
the ,mer de ,glace1 #ea1 #aab2          
cedars of ,lebanon growing on ancient1  
#aej2      explanation of the cause of  
ridges on1 #aab1 #aac4    ,morteratsch  

glacier1 cause of the widening of the   
medial        moraine of1 #ig2          
motion of1 #ie1 #if2      sand-cones of1
 #aaf4    ,motion1 of ,mer de ,glace1   
#ic2      of ,grindelwald1 #id2      of 
,great ,aletsch glacier1 #id2      of   
,morteratsch glacier1 #ie2              
sand-cones of1 #aaf4    ,moulins1       
description of1 #aaf2      dangers from1
 #aag2      sounding of1 #aah4          
,mountain condensers1 #bg1 #aej4      ,n
      ,nv1 explanation of term1 #di2    
stratification of the1 #agi4      ,o    
,obliquity of the lateral crevasses1    
#afg2      illustration1 #ajg1 #ajh4    
,p      ,petit ,plateau1 #ef4    ,piz   
,bernina1 route to1 #ie4    ,place de la
 ,concorde of ,nature1 #acf4    ,plastic
 theory1 #aef2      advocated by        
,bordier1 #aeg2      advocated by       
,rendu1 #aeh4    ,poles1 atomic1 #cb1   
#abf2      attractive and repellent1    
#cj4    ,pontresina1 village of1 #ie4   
,precious stones1 examples of           
crystallizing power1 #cj4               

,precipitation1 #bc1 #be2               
atmospheric1 #bg4    ,promontory of     
,trlaporte1 #dd2      of ,tacul1 #ea4   
,proofs of glacier-motions1 #eh4        
,pyramid of ,aiguille du ,dru1 #dc2     
of ,aiguille des ,charmoz1 #dc4      ,q 
,quotation from ,rendu1 #aeh4      ,r   
,rain1 its source1 #c2      tropical1   
#bc1 #be4    ,rainfall1 observations on 
amount of1 #bh4    ,regulation1 theory1 
#afc-afg2      observations made by ,mr4
 ,faraday1 #afd2      formation of chain
 of icebergs by1 #afe2      cause of1   
#afg2      ,faraday's view of1 #aga-agf4
    ,relation of structure to pressure1 
#ahc2      veined structure described by
 ,guyot1 #ahc-ahe2      illustration1   
#ahf2      connection established1 #ahg4
    ,retina1 how excited1 #h2           
theory of ,sir ,isaac ,newton1 #i4      
,riffelberg ,hotel1 location of1 #add4  
,rivers1 their sources1 #a1 #g1 #ai4    
,s      ,sand-cones1 #aaf4              
,scientific tacts1 connection of1 #gb4  
,siedelhorn1 view from the summit of1   

#adf4    ,snow1 its conversion into ice1
 #aef2      consolidation in ,alpine    
regions1 #aef2      line1 #di2      its 
formation in ,russian ball-rooms1 #e2   
in subterranean stables1 #e1 #ad2       
in polar regions1 #ba2      its         
architecture1 #bi-cb1 #cd1 #ia2         
absorbs solar heat1 #ajj4               
,solidifying power of camphor and       
metals1 #ag4    ,source of the ,severn1 
#b2      the ,thames1 #b2      the      
,danube1 #b2      the ,rhine1 #b2       
the ,rhone1 #b2      the ,gauges1 #b2   
the ,euphrates1 #b2      the ,garonne1  
#b2      the ,elbe1 #b2      the        
,missouri1 #b2      the ,amazon1 #b2    
,albula1 #b2      the ,arveiron1 #ch2   
the ,aar1 #ej4    ,stalactites of       
,alpine crevasses1 #ajj4    ,steam1 its 
condensation1 #c1 #d4    ,sunbeams1     
office of1 #aj-ba4    ,sun1 its heat the
 source of ,alpine ice1 #g2             
vibratory motion of the atoms of the1   
#aa2      position of1 #ai2             
indirect heat1 of the1 #bh4             

,switzerland1 ancient glaciers of1      
#ade-adg4      ,t      ,theodolite1     
description of1 #fc2      use of1 #fd1  
#fe4    ,theory1 of ,dilatation1 #aee2  
developed by ,de ,charpentier1 #aef2    
sliding1 #aef2      plastic1 #aef-afj2  
viscous1 #afa-ajc2      regulation1     
#afc-afg2      of glacial epoch1        
#aee-afg4    ,trade-winds1 #bj4         
,transverse crevasses1 formation of1    
#ajd1 #aje4    ,trlaporte1 promontory   
of1 #dd2      motion of the water       
through the narrows of1 #gi4      ,u    
,universe1 order of the1 #cb4      ,v   
,valley1 of ,hasli1 #adf1 #adg2         
,black1 #aea4    ,vapor1 in the         
atmosphere1 #e4    ,viscous theory1     
advocated by ,prof4 ,forbes1 #afa2      
rejected by ,m4 ,agassiz1 #afb4      ,w 
,water1 changes of volume of1 #aah-abb2 
maximum density of1 #abj2      effects  
of expansion of1 #aba2      not a       
solitary exception to general law1 #abd2
      molecular expansion of1 #abe-abg2 
temperature necessary to freeze the sea1

 #acb2      special solidifying power   
of1 #agc2      freezing-point of1 #afh4 
,waves1 of light1 #h-aa1 #abg2          
length of1 #ab2      of heat1 #ab4      
,whiteness of a clean glacier1 #dc1     
#agf2      of ,mrgelin ,see1 #ach1 #agf2
      of snow1 #agf2      of ice formed 
in freezing mixtures1 #agg4      ,,the  
,,end4             99       99       99 
99       99      ,transcriber ,note     
,on page #fa 7#aec71 ,principal was     
changed to ,professor4 ,minor typos were
  corrected4 ,some images were moved to 
avoid splitting paragraphs4