,illustration3 ,,the ,,mer ,,de ,,glace ,showing the ,cleft ,station at ,trelaporte1 les ,echelets1 the ,tacul1 the ,periades and the ,grande ,jorasse4 ,,the ,,glaciers ,,of ,,the ,,alps4 ,,being ,a ,,narrative ,,of ,,excursions ,,and ,,ascents1 ,,an ,,account ,,of ,,the ,,origin ,,and ,,phenomena ,,of ,,glaciers1 ,,and ,,an ,,exposition ,,of ,,the ,,physical ,,principles ,,to ,,which ,,they ,,are ,,related4 ,,by ,,john ,,tyndall1 ,f4,r4,s4 ,,with ,,illustrations4 ,,new ,,edition4 ,,longmans1 ,,green1 ,,and ,,co4 ,,london1 ,,new ,,york1 ,,and ,,bombay4 #ahif4 ,all rights reserved ,,to ,,michael ,,faraday1 ,,this ,,book ,,is ,,affectionately ,,inscribed4 #ahfj4 ,,preface4 ,in the following work ,i have not attempted to mix ,narrative and ,science1 believing that the mind once interested in the one1 cannot with satisfaction pass abruptly to the other4 ,the book is therefore divided into ,two ,parts3 the first chiefly narrative1 and the second chiefly scientific4 ,in ,part ,i4 ,i have sought to convey some notion of the life of an ,alpine explorer1 and of the means by which his knowledge is acquired4 ,in ,part ,,ii4 an attempt is made to classify such knowledge1 and to refer the observed phenomena to their physical causes4 ,the ,second ,part of the work is written with a desire to interest intelligent persons who may not possess any special scientific culture4 ,for their sakes ,i have dwelt more fully on principles than ,i should have done in presence of a purely scientific audience4 ,the brief sketch of the nature of ,light and ,heat1 with which ,part ,,ii4 is commenced1 will not1 ,i trust1 prove uninteresting to the reader for whom it is more especially designed4 ,should any obscurity exist as to the meaning of the terms ,structure1 ,dirt-bands1 ,regelation1 ,interference1 and others1 which occur in ,part ,i41 it will entirely disappear in the perusal of ,part ,,ii4 ,two ascents of ,mont ,blanc and two of ,monte ,rosa are recorded2 but the aspects of nature1 and other circumstances which attracted my attention1 were so different in the respective cases1 that repetition was scarcely possible4 ,the numerous interesting articles on glaciers which have been published during the last eighteen months1 and the various lively discussions to which the subject has given birth1 have induced me to make myself better acquainted than ,i had previously been with the historic aspect of the question4 ,in some important cases ,i have stated1 with the utmost possible brevity1 the results of my reading1 and thus1 ,i trust1 contributed to the formation of a just estimate of men whose labours in this field were long anterior to my own4 ,j4 ,t4 ,royal ,institution1 ,june1 #ahfj4 ,,prefatory ,,note4 ,glaciers of the ,alps was published nearly six and thirty years ago1 and has been long out of print1 its teaching in a condensed form having been embodied in the little book called ,forms of ,water4 ,the two books are1 however1 distinct in character2 each appears to me to supplement the other2 and as the older work is still frequently asked for1 ,i have1 at the suggestion of my husband's ,publishers1 consented to the present reprint1 which may be followed later on by a reprint of ,hours of ,exercise4 ,before reproducing a book written so long ago1 ,i sought to assure myself that it contained nothing touching the views of others which my husband might have wished at the present time to alter or omit4 ,with this object ,i asked ,lord ,kelvin to be good enough to read over for me the pages which deal with the history of the subject and with discussions in which he himself took an active part4 ,in kind response he writes3--444 ,after carefully going through all the passages relating to those old differences ,i could not advise the omission of any of them from the reprint4 ,there were1 no doubt1 some keen differences of opinion and judgement among us1 and other friends now gone from us1 but ,i think the statements on controversial points in this beautiful and interesting book of your husband's are all thoroughly courteous and considerate of feelings1 and have been felt to be so by those whose views were contested or criticised in them4 ,the current spelling of ,swiss names has changed considerably since ,glaciers of the ,alps was written1 but1 except in the very few cases where an obvious oversight called for correction1 the text has been left unaltered4 ,only the ,index has been made somewhat fuller than it was4 ,l4 ,c4 ,t4 ,january1 #ahif4 ,,contents4 ,,part ,i4 ,page #a4--;,introductory4 #a ,visit to ,penrhyn2 the ,cleavage of ,slate ,rocks2 ,sedgwick's theory--its difficulties2 ,sharpe's observations2 ,sorby's experiments2 ,lecture at the ,royal ,institution2 ,glacier ,lamination2 arrangement of an expedition to ,switzerland #b4--;,expedition of #ahef3 the ,oberland4 #i ,valley of ,lauterbrunnen2 ,pliability of rocks2 the ,wengern ,alp2 the ,jungfrau and ,silberhorn2 ,ice avalanches2 ,glaciers formed from them2 ,scene from the ,little ,scheideck2 the ,lower ,grindelwald ,glacier2 the ,heisse ,platte--its ,avalanches2 ,ice ,minarets and ,blocks2 ,echoes of the ,wetterhorn2 analogy with the ,reflection of ,light from angular mirrors2 the ,reichenbach ,cascade2 ,handeck ,fall2 the ,grimsel2 the ,unteraar ,glacier2 hut of ,m4 ,dollfuss2 ,hotel des ,neufchatelois2 the ,rhone glacier from the ,mayenwand2 expedition up the glacier2 ,coloured ,rings round the sun2 crevasses of the neve2 extraordinary meteorological phenomenon2 ,spirit of the ,brocken #c4--,the ,tyrol4 #bc ,kaunserthal and the ,gebatsch ,alp2 ,senner or ,cheesemakers2 ,gebatsch ,glacier2 a night in a cowshed2 passage to ,lantaufer2 a chamois on the rocks2 my ,guide2 the atmospheric snow-line2 passage of the ,stelvio2 ,colour of fresh snow2 ,bormio2 the pass recrossed by night2 aspect of the mountains2 ,meran to ,unserfrau2 passage of the ,hochjoch to ,fend2 singular hailstorm2 wild glacier region2 hidden crevasses2 ,first ,paper presented to the ,royal ,society #d4--;,expedition of #aheg3 the ,lake of ,geneva4 #cc ,blueness of the water2 the head of the ,lake2 appearance of the ,rhone2 subsidence of particles2 ,mirage #e4--;,chamouni and the ,montanvert4 #cg ,arrival2 ,coloured ,shadows on the snow2 ,source of the ,arveiron2 fall of the ,vault2 ,sunrise in the ,valley of ,chamouni2 ,scratched ,rocks2 quarters at the ,montanvert #f4--,the ,mer de ,glace4 #db ,not a ,sea but a ,river of ice2 ,wave-forms on its surface2 their explanation2 ,structure and ,strata2 ,glacier ,tables2 first view of the ,dirt ,bands2 influence of ,illumination in rendering them visible2 the ,eye incapable of detecting differences between intense lights #g4 #df ,measurements commenced2 the ,cleft ,station at ,trelaporte2 ,regelation of snow granules2 two chamois2 view of the ,mer de ,glace and its ,tributaries2 ,seracs of the ,col du ,geant2 ,sliding and ,viscous theories2 ,rending of the ice2 ,striae on its surface2 ,white ,ice-seams #h4 #eg ,alone upon the glacier2 ,lakes and ,rivulets2 parallel between ,glacier and ,geological disturbance2 splendid rainbow2 aspect of the glacier at the base of the ,seracs2 visit to the ,chief ,guide at ,chamouni2 ,liberties granted #i4--,the ,jardin4 #fa ,glacier du ,talefre2 ,jardin divides the neve2 ,blue ,veins near the summit2 surrounding scene2 ,moraines and ,avalanches2 ,cascade du ,talefre2 dangers on approaching it from above #aj4 #fd ,lightning and ,rain2 ,spherical hailstones2 an evening among the crevasses2 ,dangerous ,leap2 ice-practice2 preparations for an ascent of ,mont ,blanc #aa4--;,first ,ascent of ,mont ,blanc 7#aheg74 #fh ,across the mountain to the ,glacier des ,bossons2 its crevasses2 ,ladder left behind2 consequent difficulties2 the ,grands ,mulets2 ,twinkling and change of ,colour of the ,stars2 moonlight on the mountains2 start with one guide2 difficulties among the crevasses2 the ,petit ,plateau2 ,seracs of the ,dome du ,gouter2 bad condition of snow2 the ,grand ,plateau2 ,coloured ,spectra round the sun2 the lost ,guides2 the ,route missed2 dangerous ice-slope2 ,guide exhausted2 cutting steps2 cheerless prospect2 the ,corridor2 the ,mur de la ,cote2 the ,petits ,mulets2 food and drink disappear2 ,physiological experiences on the ,calotte2 ,summit attained2 the ,clouds and ,mountains2 experiment on ,sound2 colour of the snow2 the descent2 a solitary prisoner2 second night at the ,grands ,mulets2 ,inflammation of eyes2 a blind man among the crevasses2 descent to ,chamouni2 thunder on ,mont ,blanc #ab4 #hf ,life at the ,montanvert2 glacier ,blower2 ,cascade of the ,talefre2 difficulties in setting out lines2 departure from the ,montanvert2 my hosts2 prospect from the ,glacier des ,bois2 ,edouard ,simond #ac4--;,expedition of #aheh4 #ib ,origin and aim of the expedition2 ,laminated ,structure of the ice #ad4--,passage of the ,strahleck4 #ic ,unpromising weather2 appearance of the glacier and of the adjacent mountains2 ,transverse ,protuberances2 ,dirt ,bands2 ,structure2 a ,slip on a snow slope2 the ,finsteraarhorn2 the ,schreckhorn2 extraordinary ,atmospheric ,effects2 ,summit of the ,strahleck2 ,grand ,amphitheatre2 mutations of the clouds2 descent of the rocks2 a ,bergschrund2 fog in the valley2 descent to the ,grimsel #ae4 #ii ,ancient ,glaciers in the valley of ,hasli2 ,rounded1 ,polished1 and ,striated ,rocks2 level of the ancient ice2 ,groovings on the ,grimsel ,pass2 glacier of the ,rhone2 descent of the ,rhone valley2 the ,a,eggischhorn2 ,cloud ,iridescences2 the ,aletsch glacier2 the ,maerjelen ,see2 ,icebergs2 ,tributaries of the ,aletsch2 ,grand glacier-region2 crevasses2 a chamois deceived #af4--;,ascent of the ,finsteraarhorn4 #ajd ,character of my ,guide2 iridescent cloud2 evening on the ,faulberg2 the ,jungfrau and her neighbours2 a ,mountain ,cave2 the ,jungfrau before dawn2 contemplated visit2 the ,gruenhorn ,luecke2 ,magnificent ,corridor2 sunrise2 neve of the ,viesch glacier2 halt at the base of the ,finsteraarhorn2 ,spurs and ,couloirs of the mountain2 ,pyramidal ,crest2 scene of ,agassiz's observations2 a hard climb2 discipline of such an ascent2 ,boiling ,point2 ,registering ,thermometer1 its fate2 daring utterance2 descent by glissades2 the ,viesch glacier2 hidden crevasses2 a brave and competent guide #ag4 #aai ,subsequent days at the ,a,eggischhorn2 ,afloat on the ,icebergs2 ,bedding and ,structure2 ,ancient ,moraines of the ,aletsch2 ,scratched ,rocks2 passage of the mountains to the end of the glacier2 a wild gorge2 arrival at ,zermatt2 the ,riffelberg #ah4--;,first ,ascent of ,monte ,rosa4 #abb ,the ascent new to myself and my guide2 directions2 ,ulrich ,lauener2 ,ominous ,clouds2 passage of the ,goerner ,glacier2 ,roches ,moutonnees2 ,avalanche from the ,twins2 gradual advance of clouds2 bridged chasms2 ,scene from a cliff2 apparent atmospheric struggle2 ,sound of the snow2 ,dangerous ,edge2 ,overhanging ,cornice2 staff driven through it2 increased obscurity2 ,rocky ,crest2 loss of pocket-book2 ,summit attained2 ,boiling ,point2 fall of snow2 exquisite forms of the ,snow ,crystals2 a shower of frozen blossoms2 the descent2 mode of attachment2 ,startling ,avalanche2 ,blue ,light emitted from the fissures of the fresh snow2 ,stifling ,heat2 return to the ,riffel #ai4 #acc ,the ,rothe ,kumm2 pleasant companions2 difficult descent2 temperatures of rock1 air1 and grass2 ,singular ,cavern in the ice2 ,structure and ,stratification #bj4--,the ,goerner ,grat and the ,riffelhorn2 ,magnetic ,phenomena4 #acg ,formation and ,dissipation of clouds2 ,scene from the ,goerner ,grat2 ,magnetism of the ,rocks2 the ,compass and ,sun at variance2 ascent of the ,riffelhorn2 ,magnetic effects2 places of most intense action2 ,scratched and ,polished ,rocks2 ,exfoliation of crust produced by the sliding of ancient glaciers2 ,magnetic ,polarity2 ,consequent ,points2 ,bearings from the ,riffelhorn2 action on a ,distant ,needle #ba4 #ade ,fog on the ,riffelberg2 its dissipation2 ,sunset from the ,goerner ,grat2 ,cloud-wreaths on the ,matterhorn2 ,streamers of ,flame2 grand ,interference ,phenomenon2 investigation of ,structure2 the ,goernerhorn glacier2 ,western glacier of ,monte ,rosa2 the ,schwarze1 ,trifti1 and ,theodule glaciers2 welding of the ,tributaries to parallel ,strips2 ,temptation #bb4--,second ,ascent of ,monte ,rosa 7#aheh74 #aea ,a ,light ,scrip2 my ,guide lent2 a substitute2 a party on the mountain2 across the glacier and up the rocks2 the guide expostulates2 among the crevasses2 the guide halts2 left alone2 beauty of the mountain2 splendid effects of ,diffraction2 ,cheer from the summit2 on the ,kamm2 climbers meet2 among the rocks2 ,alone on the ,summit2 the ,axe slips2 the prospect2 the descent2 serious accident2 a word on climbing alone #bc4 #afj ,the ,furgge glacier2 thunder and lightning2 the ,weissthor given up2 excursion by ,stalden to ,saas2 ,herr ,imseng2 the ,mattmark ,see and ,hotel2 ascent of a boulder2 ,snow-storm2 cold quarters2 the ,monte ,moro2 the ,allalein glacier2 a noble vault2 ,structure and ,dirt-bands2 stormy weather2 ,avalanches at ,saas2 the ,fee glacier2 ,frozen dust on the ,mischabelhoerner2 ,snow1 ,vapour1 and ,cloud2 curious effect on the hearing2 a ,terrible ,hole2 singular group2 a ,song from ',the ,robbers' #bd4 #afh ,need of observations on ,alpine ,temperature2 ,balmat's intention2 aid from the ,royal ,society2 ,difficulties at ,chamouni in #aheh2 the ,intendant memorialised2 his response2 the ,seracs revisited2 ,crevasses and ,crumples2 bad weather2 thermometers placed at the ,jardin2 ,avalanches of the ,talefre2 wondrous sky #be4--,second ,ascent of ,mont ,blanc 7#aheh74 #agg ,shadows of the ,aiguilles2 ,silver ,trees at sunrise2 ,m4 ,necker's letter2 ,birds as ,sparks and ,stars against the sky2 crevasse bridged2 ladder rejected2 a hunt for a pont2 crevasses crossed2 ,magnificent ,sunset2 illuminated clouds2 ,storm on the ,grands ,mulets2 a ,comet discovered2 start by starlight2 the ,petit ,plateau a reservoir for avalanches2 ,balmat's warning2 the ,grand ,plateau at dawn2 blue of the ice2 ,balmat in danger2 ,clouds upon the ,calotte2 the ,summit2 wind and snow-dust2 ,balmat frostbitten2 halt on the ,calotte2 descent to ,chamouni2 good conduct of porters #bf4 #aib ,hostility of ,chief ,guide2 ,proces ,verbal2 the ,british ,association2 application to the ,sardinian authorities2 ,president's ,letter2 ,royal ,society2 ,testimonial to ,balmat #bg4--,winter ,expedition to the ,mer de ,glace1 #ahei4 #aie ,first defeat and fresh attempt2 ,geneva to ,chamouni2 deep snow2 ,desolation2 slow progress2 a horse in the snow2 a struggle2 ,chamouni on ,christmas night2 mountains hidden2 ,climb to the ,montanvert2 ,snow on the ,pines2 debris of avalanches2 ,breaking of snow2 ,atmospheric ,changes2 the mountains concealed and revealed2 colour of the snow2 the ,montanvert in ,winter2 footprints in the snow2 wonderful frost figures2 ,crystal ,curtain2 the ,mer de ,glace in ,winter2 the first night2 a rose of dawn2 ,crimson ,banners of the ,aiguilles2 the stakes fixed2 a ,hurricane on the glacier2 the second night2 ,wild ,snow-storm2 a man in a crevasse2 calm2 ,magnificent ,snow ,crystals2 ,sound through the falling snow2 swift descent2 ,source of the ,arveiron2 ,crystal ,cave2 appearance of water2 westward from the vault2 ,majestic ,scene2 ,farewell ,,part ,,ii4 #a4--,light and ,heat4 #bbc ,what is ,light8--notion of the ancients2 requires ,time to pass through ,space2 ,roemer1 ,bradley1 ,fizeau2 ,emission ,theory supported by ,newton1 opposed by ,huyghens2 the ,wave ,theory established by ,young and ,fresnel2 ,theory explained2 nature of ,sound2 of ,music2 of ,pitch2 nature of ,light2 of ,colour2 two sounds may produce silence2 two rays of light may produce darkness2 two rays of heat may produce cold2 ,length and ,number of waves of light2 ,liquid ,waves2 ,interference2 ,diffraction2 ,colours of ,thin ,plates2 applications of the foregoing to cloud iridescences1 luminous trees1 twinkling of stars1 the ,spirit of the ,brocken1 c4 #b4--,radiant ,heat4 #bci ,the ,sun emits a multitude of ,non-luminous ,rays2 ,rays of ,heat differ from rays of ,light as one colour differs from another2 the same ray may produce the sensations of light and heat #c4--,qualities of ,heat4 #bda ,heat a kind of ,motion2 system of exchanges2 ,luminous and ,obscure ,heat2 ,absorption by ,gases2 gases may be transparent to light1 but opaque to heat2 ,heat selected from luminous sources2 the ,atmosphere acts the part of a ,ratchet-wheel2 possible heat of a ,distant ,planet2 causes of ,cold in the upper strata of the ,earth's ,atmosphere #d4--,origin of ,glaciers4 #bdh ,application of principles2 the ,snow-line2 its meaning2 waters piled annually in a solid form on the summits of the hills2 the ,glaciers furnish the chief means of escape2 superior and inferior snow-line #e4 #bdi ,whiteness of snow2 whiteness of ice2 ,round air-bubbles2 melting and freezing2 ,conversion of snow into ice by ,pressure #f4--;,colour of ,water and ,ice4 #bec ,waves of ,ether not entangled2 they are separated in the prism2 they are differently absorbed2 ,colour due to this2 ,water and ,ice blue2 water and ice opaque to radiant heat2 ,long ,waves shivered on the molecules2 ,experiment2 ,grotto of ,capri2 the ,laugs of ,iceland #g4--;,colours of the ,sky4 #beg ,newton's idea2 ,goethe's ,theory2 ,clausius and ,bruecke2 ,suspended ,particles2 singular effect on a painting explained by ,goethe2 ,light separated without ,absorption2 ,reflected and ,transmitted light2 blueness of milk and juices2 the ,sun through ,london smoke2 ,experiments2 ,blue of the ,eye2 ,colours of ,steam2 the ,lake of ,geneva #h4--,the ,moraines4 #bfc ,glacier loaded along its edges by the ruins of the mountains2 ,lateral ,moraines2 ,medial ,moraines2 their number one less than the number of ,tributaries2 ,moraines of the ,mer de ,glace2 successive shrinkings2 ,glacier ,tables explained2 ',dip' of stones upon the glacier enables us to draw the ,meridian ,line2 type ',table2' ,sand ,cones2 moraines engulfed and disgorged2 transparency of ice under the moraines #i4--;,glacier ,motion1--,preliminary4 #bfi ,neve and ,glacier2 ,first ,measurements2 ,hugi and ,agassiz2 ,escher's defeat on the ,aletsch2 ,piles fixed across the ,aar glacier by ,agassiz in #ahda2 ,professor ,forbes invited by ,m4 ,agassiz2 ,forbes's first observations on the ,mer de ,glace in #ahdb2 motion of ,agassiz's piles measured by ,m4 ,wild2 ,centre of the glacier moves quickest2 ,state of the ,question #aj4--,motion of the ,mer de ,glace4 #bge ,the ,theodolite2 mode of measurement2 first line2 ,centre ,point not the quickest2 second line2 former result confirmed2 ,law of ,motion sought2 the glacier moves through a ,sinuous ,valley2 effect of ,flexure2 ,western half of glacier moves quickest2 ,point of ,maximum ,motion crosses axis2 ,eastern half moves quickest2 ,locus of ,point of ,maximum ,motion2 ,new ,law2 ,motion of the ,geant2 motion of the ,lechaud2 ,squeezing of the ,tributaries through the ,neck of the valley at ,trelaporte2 the ,lechaud a ,driblet #aa4--;,ice ,wall at the ,tacul1--,velocities of ,top and ,bottom4 #bhi ,first attempt by ,mr4 ,hirst2 second attempt1 stakes fixed at ,top1 ,bottom1 and ,centre2 dense fog2 the stakes lost2 process repeated2 ,velocities determined #ab4--,winter ,motion of the ,mer de ,glace4 #bid ,first line1 ,above the ,montanvert2 second line1 ,below the ,montanvert2 ,ratio of winter to summer motion #ac4--;,cause of ,glacier ,motion1--,de ,saussure's ,theory4 #bif ,first attempt at a ,theory by ,scheuchzer in #agje2 ,charpentier's theory1 or the ,theory of ,dilatation2 ,agassiz's theory2 ,altmann and ,gruener2 theory of ,de ,saussure1 or the ,sliding ,theory2 in part true2 strained interpretation of this theory #ad4--,rendu's ,theory4 #bii ,character of ,rendu2 his ,essay entitled ',theorie des ,glaciers de la ,savoie2' extracts from the essay2 he ascribes circulation to natural forces2 classifies glaciers2 assigns the cause of the conversion of snow into ice2 notices ,veined ,structure2 time and affinity2 notices ,regelation2 diminution of glaciers reservoirs2 ,remarkable ,passage2 announces ,swifter ,motion of ,centre2 ,north ,british ,review2 ,discrepancies explained by ,rendu2 ,liquid ,motion ascribed to glacier2 all the phenomena of a ,river reproduced upon the ,mer de ,glace2 ,ratio of ,side and ,central velocities2 ,errors removed #ae4 #cjh ,anticipations of ,rendu confirmed by ,agassiz and ,forbes2 analogies with ,liquid ,motion established by ,forbes2 his ,measurements in #ahdb2 measurements in #ahdd and #ahdf2 ,measurements of ,agassiz and ,wild in #ahdb1 #ahdc1 #ahdd1 and #ahde2 ,agassiz notices the migration of the ,point of ,swiftest ,motion2 true meaning of this observation2 ,summary of contributions on this part of the question #af4--;,forbes's ,theory4 #caa ,discussions as to its meaning2 ,facts and ,principles2 definition of theory2 ,some ,experiments on the ,mer de ,glace to test the ,viscosity of the ,ice #ag4--,the ,crevasses4 #cae ,caused by the ,motion2 ,ice ,sculpture2 ,fantastic ,figures2 beauty of the crevasses of the highest glaciers2 ,birth of a crevasse2 ,mechanical ,origin2 line of greatest strain2 ,marginal ,crevasses2 ,transverse ,crevasses2 ,longitudinal ,crevasses2 ,bergschrunds2 ,influence of ,flexure2 why the ,convex ,sides of glaciers are most crevassed #ah4 #cbe ,further considerations on ,viscosity2 ,numerical ,test2 formation of crevasses opposed to viscosity #ai4--;,heat and ,work4 #cbh ,connexion of ,natural ,forces2 ,equivalence of ,heat and ,work2 heat produced by ,mechanical ,action2 heat consumed in producing work2 ,chemical ,attractions2 ,attraction of ,gravitation2 amount of heat which would be produced by the stoppage of the ,earth in its ,orbit2 amount produced by the falling of the ,earth into the ,sun2 shifting of ,atoms2 heat consumed in ,molecular ,work2 ,specific ,heat2 ,latent ,heat2 'friability' of ice near its melting point2 ,rotten ,ice and softened ,wax #bj4 #ccd ,papers presented to the ,royal ,society by ,professor ,forbes in #ahdf2 ,capillary ,hypothesis of glacier motion2 hypothesis examined #ba4--,thomson's ,theory4 #cdj ,statement of theory2 influence of ,pressure on the ,melting ,point of ,ice2 difficulties of theory2 ,calculation of requisite ,pressure2 ,actual pressure insufficient #bb4--,pressure ,theory4 #cdf ,pressure and ,tension2 possible experiments2 ,ice may be moulded into ,vases and ,statuettes or coiled into ,knots2 this no proof of ,viscosity2 ,actual ,experiments2 a sphere of ice moulded to a lens2 a lens moulded to a cylinder2 a lump of ice moulded to a cup2 straight bars of ice bent2 ice thus moulded incapable of being sensibly stretched2 when ,tension is substituted for ,pressure1 analogy with viscous body breaks down #bc4--,regelation4 #cea ,faraday's first experiments2 ,freezing together of pieces of ice at #cb deg42 ,freezing in ,hot ,water2 ,faraday's recent experiments2 ,regelation not due to ,pressure nor to ,capillary ,attraction2 it takes place in vacuo2 fracture and regelation2 no viscidity discovered #bd4--;,crystallization and ,internal ,liquefaction4 #cec ,how crystals are 'nursed2' ,snow-,crystals2 ,crystal ,stars formed in ,water2 ,arrangement of ,atoms of ,lake ,ice2 dissection of ice by a sunbeam2 ,liquid ,flowers formed in ice2 associated ,vacuous ,spots2 curious sounds2 their explanation2 ,cohesion of water when free from air2 liquid snaps like a broken spring2 ,ebullition converted into ,explosion2 noise of crepitation2 ,water-cells in glacier ice2 ,vacuous ,spots mistaken for ,bubbles2 not ,flattened by ,pressure2 experiments2 ,cause of ,regelation #be4--,the ,moulins4 #cfb ,their character2 ,depth of ,moulin on ,grindelwald ,glacier2 ,explanation the ,grand ,moulin of the ,mer de ,glace2 ,motion of moulins #bf4--;,dirt-,bands of the ,mer de ,glace4 #cfg ,their discovery by ,professor ,forbes2 view of ,bands from a point near the ,flegere2 ,bands as seen from ,les ,charmoz2 ,skew ,surface of glacier2 aspect of ,bands from the ,cleft ,station2 ,origin of bands2 tendency to become straight2 differences between observers #bg4--,veined ,structure of ,glaciers4 #cgf ,general appearance2 ,grooves upon the glacier2 first observations2 description by ,m4 ,guyot2 observations of ,professor ,forbes2 ,structure and ,stratification2 subject examined2 ,marginal ,structure2 ,transverse ,structure2 ,longitudinal ,structure2 experimental illustrations2 the ,structure ,complementary to the ,crevasses2 glaciers of the ,oberland1 ,valais1 and ,savoy examined with reference to this question #bh4--,the ,veined ,structure and ,differential ,motion4 #cie ,marginal ,structure ,oblique to sides2 ,drag towards the centre2 difficulties of theory which ascribes the structure to ,differential ,sliding2 it persists across the lines of maximum sliding #bi4--,the ,ripple ,theory of the ,veined ,structure4 #cih ,ripples in ,water supposed to correspond to ,glacier ,structure2 analysis of theory2 observation of the ,,mm4 ,weber2 water dropping from an oar2 stream cleft by an obstacle2 ,two ,divergent lines of ,ripple2 ,single ,line produced by ,lateral ,obstacle2 ,direction of ripples compounded of ,river's motion and ,wave motion2 ,structure and ,ripples due to different causes2 their positions also different #cj4--,the ,veined ,structure and ,pressure4 #djd ,supposed case of pressed prism of glass2 ,experiments of ,nature2 ,quartz-pebbles flattened and indented2 ,pressure would produce ,lamination2 ,tangential ,action #ca4--,the ,veined ,structure and the ,liquefaction of ,ice by ,pressure4 #djh ,influence of pressure on ,melting and ,boiling points2 some substances swell1 others shrink in melting2 effects of pressure different on the two classes of bodies2 ,theoretic ,anticipation by ,mr4 ,james ,thomson2 ,melting point of ,ice lowered by pressure2 ,internal ,liquefaction of a prism of solid ice by pressure2 ,liquefaction in ,layers2 application to the ,veined ,structure #cb4--,white ,ice-,seams of the ,glacier du ,geant4 #dac ,aspect of ,seams2 they sweep across the glacier concentric with ,structure2 ,structure at the base of the ,talefre cascade2 ,crumples2 ,scaling off by pressure2 ,origin of seams of ,white ,ice #cc4 #dai ,glacier du ,geant in a state of ,longitudinal ,compression2 ,measurements which prove that its hinder parts are advancing upon those in front2 ,shortening of its ,undulations2 ,squeezing of white ,ice-seams2 development of ,veined ,structure ,summary #dbb ,appendix #dbg ,index #dda ,,illustrations4 ,the ,mer de ,glace4--,showing the ,cleft ,station at ,trelaporte1 the ,echelets1 the ,tacul1 the ,periades1 and the ,grand ,jorasse4 ,frontispiece ,fig4 ,page #a4 ,ice ,minaret #ad #b4 ,diagram of an angular reflector #af #c1 #d4 ,boats' sails inverted by ,atmospheric ,refraction #ce #e4 ,wave-like forms on the ,mer de ,glace #dc #f4 ,glacier ,table #dd #g4 ,tributaries of the ,mer de ,glace #ec #h4 ,magnetic ,boulder of the ,riffelhorn #adc #i1 #aj1 #aa1 #ab4 ,luminous ,trees projected against the sky at sunrise #ahj1 #aha #ac4 ,snow on the ,pines #bja #ad1 #ae4 ,snow ,crystals #bad #af4 ,chasing produced by waves #bcc #ag4 ,diagram explanatory of ,interference #bcd #ah4 ,interference ,spectra1 produced by ,diffraction ,to face #bce #ai4 ,moraines of the ,mer de ,glace #bfd #bj4 ,typical section of a glacier ,table #bff #ba4 ,locus of the ,point of ,maximum ,motion #bhf #bb4 ,inclinations of ice cascade of the ,glacier des ,bois #cac #bc4 ,inclinations of ,mer de ,glace above l',angle #cad #bd4 ,fantastic ,mass of ice #caf #be4 ,diagram explanatory of the mechanical origin of ,crevasses #cah #bf4 ,diagram showing the line of ,greatest ,strain #cai #bg;,a1 ,b4 ,section and ,plan of a portion of the ,lower ,grindelwald ,glacier #cbb #bh4 ,diagram illustrating the crevassing of ,convex ,sides of glacier #cbc #bi4 ,diagram illustrating test of viscosity #cbf #cj1 #ca1 #cb1 #cc4 ,moulds used in experiments with ice #cdf-cdh #cd4 ,liquid ,flowers in lake ice #cee #ce4 ,dirt-bands of the ,mer de ,glace1 as seen from a point near the ,flegere ,to face #cfg #cf4 ,ditto1 as seen from les ,charmoz #cfh #cg4 ,ditto1 as seen from the ,cleft ,station1 ,trelaporte #cfi #ch4 ,plan of ,dirt-bands taken from ,johnson's ',physical ,atlas' #cgd #ci4 ,veined ,structure on the walls of crevasses #cha #dj4 ,figure explanatory of the ,marginal ,structure #chc #da4 ,plan of part of ice-fall1 and of glacier below it 7,glacier of the ,rhone7 #chf #db4 ,section of ditto #chf #dc4 ,figure explanatory of ,longitudinal ,structure #chh #dd4 ,structure and bedding on the ,great ,aletsch ,glacier #cia #de1 #df4 ,structure and ,stratification on the ,furgge glacier #cid #dg4 ,diagram illustrating ,differential ,motion #cie #dh1 #di4 ,diagrams explanatory of the formation of ,ripples #djj1 #djc #ej1 #ea4 ,appearance of a prism of ice partially liquefied by ,pressure4 #daj #eb1 #ec4 ,figures illustrative of compression and liquefaction of ice4 #daa #ed1 #ee4 ,sections of ,white ,ice-seams #dad #ef1 #eg4 ,variations in the ,dip of the ,veined ,structure #dad1 #dae #eh4 ,section of three glacier ,crumples #daf #ei4 ,wall of a crevasse1 with incipient crumpling #daf #fj4 ,plan of a ,stream on the ,glacier du ,geant #dah #fa4 ,plan of a ,seam of ,white ,ice on ditto #dah ,,part ,i4 ,,chiefly ,,narrative4 ,ages are your days1 ,ye grand expressors of the present tense ,and types of permanence2 ,firm ensigns of the fatal ,being ,amid these coward shapes of joy and grief ,that will not bide the seeing4 ,hither we bring ,our insect miseries to the rocks1 ,and the whole flight with pestering wing ,vanish and end their murmuring1 ,vanish beside these dedicated blocks4 ,emerson ,,glaciers ,,of ,,the ,,alps4 ,,introductory4 7#a47 ,in the autumn of #ahed ,i attended the meeting of the ,british ,association at ,liverpool2 and1 after it was over1 availed myself of my position to make an excursion into ,north ,wales4 ,guided by a friend who knew the country1 ,i became acquainted with its chief beauties1 and concluded the expedition by a visit to ,bangor and the neighbouring slate quarries of ,penrhyn4 ,from my boyhood ,i had been accustomed to handle slates2 had seen them used as roofing materials1 and had worked the usual amount of arithmetic upon them at school2 but now1 as ,i saw the rocks blasted1 the broken masses removed to the sheds surrounding the quarry1 and there cloven into thin plates1 a new interest was excited1 and ,i could not help asking after the cause of this extraordinary property of cleavage4 ,it sufficed to strike the point of an iron instrument into the edge of a plate of rock to cause the mass to yield and open1 as wood opens in advance of a wedge driven into it4 ,i walked round the quarry and observed that the planes of cleavage were everywhere parallel2 the rock was capable of being split in one direction only1 and this direction remained perfectly constant throughout the entire quarry4 ,sidenote3 ,,cleavage ,,of ,,slate ,,rocks4 ,i was puzzled1 and1 on expressing my perplexity to my companion1 he suggested that the cleavage was nothing more than the layers in which the rock had been originally deposited1 and which1 by some subsequent disturbance1 had been set on end1 like the strata of the sandstone rocks and chalk cliffs of ,alum ,bay4 ,but though ,i was too ignorant to combat this notion successfully1 it by no means satisfied me4 ,i did not know that at the time of my visit this very question of slaty cleavage was exciting the greatest attention among ,english geologists1 and ,i quitted the place with that feeling of intellectual discontent which1 however unpleasant it may be for a time1 is very useful as a stimulant1 and perhaps as necessary to the true appreciation of knowledge as a healthy appetite is to the enjoyment of food4 ,on inquiry ,i found that the subject had been treated by three ,english writers1 ,professor ,sedgwick1 ,mr4 ,daniel ,sharpe1 and ,mr4 ,sorby4 ,from ,professor ,sedgwick ,i learned that cleavage and stratification were things totally distinct from each other2 that in many cases the strata could be observed with the cleavage passing through them at a high angle2 and that this was the case throughout vast areas in ,north ,wales and ,cumberland4 ,i read the lucid and important memoir of this eminent geologist with great interest3 it placed the data of the problem before me1 as far as they were then known1 and ,i found myself1 to some extent at least1 in a condition to appreciate the value of a theoretic explanation4 ,everybody has heard of the force of gravitation1 and of that of cohesion2 but there is a more subtle play of forces exerted by the molecules of bodies upon each other when these molecules possess sufficient freedom of action4 ,in virtue of such forces1 the ultimate particles of matter are enabled to build themselves up into those wondrous edifices which we call crystals4 ,a diamond is a crystal self-erected from atoms of carbon2 an amethyst is a crystal built up from particles of silica2 ,iceland spar is a crystal built by particles of carbonate of lime4 ,by artificial means we can allow the particles of bodies the free play necessary to their crystallization4 ,thus a solution of saltpetre exposed to slow evaporation produces crystals of saltpetre2 alum crystals of great size and beauty may be obtained in a similar manner2 and in the formation of a bit of common sugar-candy there are agencies at play1 the contemplation of which1 as mere objects of thought1 is sufficient to make the wisest philosopher bow down in wonder1 and confess himself a child4 ,sidenote3 ,,crystallization ,,theory4 ,the particles of certain crystalline bodies are found to arrange themselves in layers1 like courses of atomic masonry1 and along these layers such crystals may be easily cloven into the thinnest laminae4 ,some crystals possess one such direction in which they may be cloven1 some several2 some1 on the other hand1 may be split with different facility in different directions4 ,rock salt may be cloven with equal facility in three directions at right angles to each other2 that is1 it may be split into cubes2 calcspar may be cloven in three directions oblique to each other2 that is1 into rhomboids4 ,heavy spar may also be cloven in three directions1 but one cleavage is much more perfect1 or more eminent as it is sometimes called1 than the rest4 ,mica is a crystal which cleaves very readily in one direction1 and it is sufficiently tough to furnish films of extreme tenuity3 finally1 any boy1 with sufficient skill1 who tries a good crystal of sugar-candy in various directions with the blade of his penknife1 will find that it possesses one direction in particular1 along which1 if the blade of the knife be placed and struck1 the crystal will split into plates possessing clean and shining surfaces of cleavage4 ,sidenote3 ,,polar ,,forces4 ,professor ,sedgwick was intimately acquainted with all these facts1 and a great many more1 when he investigated the cleavage of slate rocks2 and seeing no other explanation open to him1 he ascribed to slaty cleavage a crystalline origin4 ,he supposed that the particles of slate rock were acted on1 after their deposition1 by polar forces1 which so arranged them as to produce the cleavage4 ,according to this theory1 therefore1 ,honister ,crag and the cliffs of ,penrhyn are to be regarded as portions of enormous crystals2 a length of time commensurate with the vastness of the supposed action being assumed to have elapsed between the deposition of the rock and its final crystallization4 ,when1 however1 we look closely into this bold and beautiful hypothesis1 we find that the only analogy which exists between the physical structure of slate rocks and of crystals is this single one of cleavage4 ,such a coincidence might fairly give rise to the conjecture that both were due to a common cause2 but there is great difficulty in accepting this as a theoretic truth4 ,when we examine the structure of a slate rock1 we find that the substance is composed of the debris of former rocks2 that it was once a fine mud1 composed of particles of sensible magnitude4 ,is it meant that these particles1 each taken as a whole1 were re-arranged after deposition8 ,if so1 the force which effected such an arrangement must be wholly different from that of crystallization1 for the latter is essentially molecular4 ,what is this force8 ,nature1 as far as we know1 furnishes none competent1 under the conditions1 to produce the effect4 ,is it meant that the molecules composing these sensible particles have re-arranged themselves8 ,we find no evidence of such an action in the individual fragments3 the mica is still mica1 and possesses all the properties of mica2 and so of the other ingredients of which the rock is composed4 ,independent of this1 that an aggregate of heterogeneous mineral fragments should1 without any assignable external cause1 so shift its molecules as to produce a plane of cleavage common to them all1 is1 in my opinion1 an assumption too heavy for any theory to bear4 ,nevertheless1 the paper of ,professor ,sedgwick invested the subject of slaty cleavage with an interest not to be forgotten1 and proved the stimulus to further inquiry4 ,the structure of slate rocks was more closely examined2 the fossils which they contained were subjected to rigid scrutiny1 and their shapes compared with those of the same species taken from other rocks4 ,thus proceeding1 the late ,mr4 ,daniel ,sharpe found that the fossils contained in slate rocks are distorted in shape1 being uniformly flattened out in the direction of the planes of cleavage4 ,here1 then1 was a fact of capital importance1--the shells became the indicators of an action to which the mass containing them had been subjected2 they demonstrated the operation of pressure acting at right angles to the planes of cleavage4 ,sidenote3 ,,mechanical ,,theory4 ,the more the subject was investigated1 the more clearly were the evidences of pressure made out4 ,subsequent to ,mr4 ,sharpe1 ,mr4 ,sorby entered upon this field of inquiry4 ,with great skill and patience he prepared sections of slate rock1 which he submitted to microscopic examination1 and his observations showed that the evidences of pressure could be plainly traced1 even in his minute specimens4 ,the subject has been since ably followed up by ,professors ,haughton1 ,harkness1 and others2 but to the two gentlemen first mentioned we are1 ,i think1 indebted for the prime facts on which rests the mechanical theory of slaty cleavage4,a ,sidenote3 ,,lecture ,,at ,,the ,,royal ,,institution4 ,the observations just referred to showed the co-existence of the two phenomena1 but they did not prove that pressure and cleavage stood to each other in the relation of cause and effect4 ,can the pressure produce the cleavage8 was still an open question1 and it was one which mere reasoning1 unaided by experiment1 was incompetent to answer4 ,sharpe despaired of an experimental solution1 regarding our means as inadequate1 and our time on earth too short to produce the result4 ,mr4 ,sorby was more hopeful4 ,submitting mixtures of gypsum and oxide of iron scales to pressure1 he found that the scales set themselves approximately at right angles to the direction in which the pressure was applied4 ,the position of the scales resembled that of the plates of mica which his researches had disclosed to him in slate rock1 and he inferred that the presence of such plates1 and of flat or elongated fragments generally1 lying all in the same general direction1 was the cause of slaty cleavage4 ,at the meeting of the ,british ,association at ,glasgow1 in #ahee1 ,i had the pleasure of seeing some of ,mr4 ,sorby's specimens1 and1 though the cleavage they exhibited was very rough1 still1 the tendency to yield at right angles to the direction in which the pressure had been applied1 appeared sufficiently manifest4 ,at the time now referred to ,i was engaged1 and had been for a long time previously1 in examining the effects of pressure upon the magnetic force1 and1 as far back as #ahea1 ,i had noticed that some of the bodies which ,i had subjected to pressure exhibited a cleavage of surpassing beauty and delicacy4 ,the bearing of such facts upon the present question now forcibly occurred to me4 ,i followed up the observations2 visited slate yards and quarries1 observed the exfoliation of rails1 the fibres of iron1 the structure of tiles1 pottery1 and cheese1 and had several practical lessons in the manufacture of puff-paste and other laminated confectionery4 ,my observations1 ,i thought1 pointed to a theory of slaty cleavage different from any previously given1 and which1 moreover1 referred a great number of apparently unrelated phenomena to a common cause4 ,on the #ajth of ,june1 #ahef1 ,i made them the subject of a ,friday evening's discourse at the ,royal ,institution4,b ,sidenote3 ,,origin ,,of ,,researches4 ,such are the circumstances1 apparently remote enough1 under which my connexion with glaciers originated4 ,my friend ,professor ,huxley was present at the lecture referred to3 he was well acquainted with the work of ,professor ,forbes1 entitled ',travels in the ,alps1' and he surmised that the question of slaty cleavage1 in its new aspect1 might have some bearing upon the laminated structure of glacier-ice discussed in the work referred to4 ,he therefore urged me to read the ',travels1' which ,i did with care1 and the book made the same impression upon me that it had produced upon my friend4 ,we were both going to ,switzerland that year1 and it required but a slight modification of our plans to arrange a joint excursion over some of the glaciers of the ,oberland1 and thus afford ourselves the means of observing together the veined structure of the ice4 ,had the results of this arrangement been revealed to me beforehand1 ,i should have paused before entering upon an investigation which required of me so long a renunciation of my old and more favourite pursuits4 ,but no man knows when he commences the examination of a physical problem into what new and complicated mental alliances it may lead him4 ,no fragment of nature can be studied alone2 each part is related to every other part2 and hence it is1 that1 following up the links of law which connect phenomena1 the physical investigator often finds himself led far beyond the scope of his original intentions1 the danger in this respect augmenting in direct proportion to the wish of the inquirer to render his knowledge solid and complete4 ,sidenote3 ,a ,,boy',s ,,book4 ,when the idea of writing this book first occurred to me1 it was not my intention to confine myself to the glaciers alone1 but to make the work a vehicle for the familiar explanation of such general physical phenomena as had come under my notice4 ,nor did ,i intend to address it to a cultured man of science1 but to a youth of average intelligence1 and furnished with the education which ,england now offers to the young4 ,i wished indeed to make it a boy's class-book1 which should reveal the mode of life1 as well as the scientific objects1 of an explorer of the ,alps4 ,the incidents of the past year have caused me to deviate1 in some degree1 from this intention1 but its traces will be sufficiently manifest2 and this reference to it will1 ,i trust1 excuse an occasional liberty of style and simplicity of treatment which would be out of place if intended for a reader of riper years4 ,,footnotes3 ,a ,mr4 ,sorby has drawn my attention to an able and interesting paper by ,m4 ,bauer1 in ,karsten's ',archiv' for #ahdf2 in which it is announced that cleavage is a tension of the mass produced by pressure4 ,the author refers to the experiments of ,mr4 ,hopkins as bearing upon the question4 ,b ,see ,appendix4 ,sidenote3 ,,the ,,oberland4 #ahef4 ,,expedition ,,of #ahef4 ,,the ,,oberland4 7#b47 ,on the #afth of ,august1 #ahef1 ,i received my ,alpenstock from the hands of ,dr4 ,hooker1 in the garden of the ,pension ,ober1 at ,interlaken4 ,it bore my name1 not marked1 however1 by the vulgar brands of the country1 but by the solar beams which had been converged upon it by the pocket lens of my friend4 ,i was the companion of ,mr4 ,huxley1 and our first aim was to cross the ,wengern ,alp4 ,light and shadow enriched the crags and green slopes as we advanced up the valley of ,lauterbrunnen1 and each occupied himself with that which most interested him4 ,my companion examined the drift1 ,i the cleavage1 while both of us looked with interest at the contortions of the strata to our left1 and at the shadowy1 unsubstantial aspect of the pines1 gleaming through the sunhaze to our right4 ,sidenote3 ,,folded ,,rocks4 #ahef4 ,what was the physical condition of the rock when it was thus bent and folded like a pliant mass8 ,was it necessarily softer than it is at present8 ,i do not think so4 ,the shock which would crush a railway carriage1 if communicated to it at once1 is harmless when distributed over the interval necessary for the pushing in of the buffer4 ,by suddenly stopping a cock from which water flows you may burst the conveyance pipe1 while a slow turning of the cock keeps all safe4 ,might not a solid rock by ages of pressure be folded as above8 ,it is a physical axiom that no body is perfectly hard1 none perfectly soft1 none perfectly elastic4 ,the hardest body subjected to pressure yields1 however little1 and the same body when the pressure is removed cannot return to its original form4 ,if it did not yield in the slightest degree it would be perfectly hard2 if it could completely return to its original shape it would be perfectly elastic4 ,let a pound weight be placed upon a cube of granite2 the cube is flattened1 though in an infinitesimal degree4 ,let the weight be removed1 the cube remains a little flattened2 it cannot quite return to its primitive condition4 ,let us call the cube thus flattened ,no4 #a4 ,starting with ,no4 #a as a new mass1 let the pound weight be laid upon it2 the mass yields1 and on removing the weight it cannot return to the dimensions of ,no4 #a2 we have a more flattened mass1 ,no4 #b4 ,proceeding in this manner1 it is manifest that by a repetition of the process we should produce a series of masses1 each succeeding one more flattened than the former4 ,this appears to be a necessary consequence of the physical axiom referred to above4 ,now if1 instead of removing and replacing the weight in the manner supposed1 we cause it to rest continuously upon the cube1 the flattening1 which above was intermittent1 will be continuous2 no matter how hard the cube may be1 there will be a gradual yielding of its mass under the pressure4 ,apply this to squeezed rocks--to those1 for example1 which form the base of an obelisk like the ,matterhorn2 that this base must yield1 seems a certain consequence of the physical constitution of matter3 the conclusion seems inevitable that the mountain is sinking by its own weight4 ,let two points be fixed1 one near the summit1 the other near the base of the obelisk2 next year these points will have approached each other4 ,whether the amount of approach in a human lifetime be measureable we know not2 but it seems certain that ages would leave their impress upon the mass1 and render visible to the eye an action which at present is appreciable by the imagination only4 ,sidenote3 ,,the ,,jungfrau ,,and ,,silberhorn4 #ahef4 ,we halted on the night of the #afth at the ,jungfrau ,hotel1 and next morning we saw the beams of the rising sun fall upon the peaked snow of the ,silberhorn4 ,slowly and solemnly the pure white cone appeared to rise higher and higher into the sunlight1 being afterwards mottled with gold and gloom1 as clouds drifted between it and the sun4 ,i descended alone towards the base of the mountain1 making my way through a rugged gorge1 the sides of which were strewn with pine-trees1 splintered1 broken across1 and torn up by the roots4 ,i finally reached the end of a glacier1 formed by the snow and shattered ice which fall from the shoulders of the ,jungfrau4 ,the view from this place had a savage magnificence such as ,i had not previously beheld1 and it was not without some slight feeling of awe that ,i clambered up the end of the glacier4 ,it was the first ,i had actually stood upon4 ,the loneliness of the place was very impressive1 the silence being only broken by fitful gusts of wind1 or by the weird rattle of the debris which fell at intervals from the melting ice4 ,sidenote3 ,,avalanches4 #ahef4 ,once ,i noticed what appeared to be the sudden and enormous augmentation of the waters of a cascade1 but the sound soon informed me that the increase was due to an avalanche which had chosen the track of the cascade for its rush4 ,soon afterwards my eyes were fixed upon a white slope some thousands of feet above me2 ,i saw the ice give way1 and1 after a sensible interval1 the thunder of another avalanche reached me4 ,a kind of zigzag channel had been worn on the side of the mountain1 and through this the avalanche rushed1 hidden at intervals1 and anon shooting forth1 and leaping like a cataract down the precipices4 ,the sound was sometimes continuous1 but sometimes broken into rounded explosions which seemed to assert a passionate predominance over the general level of the roar4 ,these avalanches1 when they first give way1 usually consist of enormous blocks of ice1 which are more and more shattered as they descend4 ,partly to the echoes of the first crash1 but mainly1 ,i think1 to the shock of the harder masses which preserve their cohesion1 the explosions which occur during the descent of the avalanche are to be ascribed4 ,much of the ice is crushed to powder2 and thus1 when an avalanche pours cataract-like over a ledge1 the heavier masses1 being less influenced by the atmospheric resistance1 shoot forward like descending rockets1 leaving the lighter powder in trains behind them4 ,such is the material of which a class of the smaller glaciers in the ,alps is composed4 ,they are the products of avalanches1 the crushed ice being recompacted into a solid mass1 which exhibits on a smaller scale most of the characteristics of the large glaciers4 ,after three hours' absence ,i reascended to the hotel1 breakfasted1 and afterwards returned with ,mr4 ,huxley to the glacier4 ,while we were engaged upon it the weather suddenly changed2 lightning flashed about the summits of the ,jungfrau1 and thunder leaped among her crags4 ,heavy rain fell1 but it cleared up afterwards with magical speed1 and we returned to our hotel4 ,heedless of the forebodings of many prophets of evil weather we set out for ,grindelwald4 ,the scene from the summit of the ,little ,scheideck was exceedingly grand4 ,the upper air exhibited a commotion which we did not experience2 clouds were wildly driven against the flanks of the ,eiger1 the ,jungfrau thundered behind1 while in front of us a magnificent rainbow1 fixing one of its arms in the valley of ,grindelwald1 and1 throwing the other right over the crown of the ,wetterhorn1 clasped the mountain in its embrace4 ,through jagged apertures in the clouds floods of golden light were poured down the sides of the mountain4 ,on the slopes were innumerable chalets1 glistening in the sunbeams1 herds browsing peacefully and shaking their mellow bells2 while the blackness of the pine-trees1 crowded into woods1 or scattered in pleasant clusters over alp and valley1 contrasted forcibly with the lively green of the fields4 ,sidenote3 ,,the ,,heisse ,,platte4 #ahef4 ,at ,grindelwald1 on the #ahth1 we engaged a strong and competent guide1 named ,christian ,kaufmann1 and proceeded to the ,lower ,glacier4 ,after a steep ascent1 we gained a point from which we could look down upon the frozen mass4 ,at first the ice presented an appearance of utter confusion1 but we soon reached a position where the mechanical conditions of the glacier revealed themselves1 and where we might learn1 had we not known it before1 that confusion is merely the unknown intermixture of laws1 and becomes order and beauty when we rise to their comprehension4 ,we reached the so-called ,eismeer--,ice ,sea4 ,in front of us was the range of the ,viescherhoerner1 and a vast snow slope1 from which one branch of the glacier was fed4 ,near the base of this neve1 and surrounded on all sides by ice1 lay a brown rock1 to which our attention was directed as a place noted for avalanches2 on this rock snow or ice never rests1 and it is hence called the ,heisse ,platte--the ,hot ,plate4 ,at the base of the rock1 and far below it1 the glacier was covered with clean crushed ice1 which had fallen from a crown of frozen cliffs encircling the brow of the rock4 ,one obelisk in particular signalised itself from all others by its exceeding grace and beauty4 ,its general surface was dazzling white1 but from its clefts and fissures issued a delicate blue light1 which deepened in hue from the edges inwards4 ,it stood upon a pedestal of its own substance1 and seemed as accurately fixed as if rule and plummet had been employed in its erection4 ,fig4 #a represents this beautiful minaret of ice4 ,sidenote3 ,,ice ,,minaret4 #ahef4 ,illustration3 ,fig4 #a4 ,ice ,minaret4 ,while we were in sight of the ,heisse ,platte1 a dozen avalanches rushed downwards from its summit4 ,in most cases we were informed of the descent of an avalanche by the sound1 but sometimes the white mass was seen gliding down the rock1 and scattering its smoke in the air1 long before the sound reached us4 ,it is difficult to reconcile the insignificant appearance presented by avalanches1 when seen from a distance1 with the volume of sound which they generate2 but on this day we saw sufficient to account for the noise4 ,one block of solid ice which we found below the ,heisse ,platte measured #g feet #f inches in length1 #e feet #h inches in height1 and #d feet #f inches in depth4 ,a second mass was #aj feet long1 #h feet high1 and #f feet wide4 ,it contained therefore #dhj cubic feet of ice1 which had been cast to a distance of nearly #ajjj yards down the glacier4 ,the shock of such hard and ponderous projectiles against rocks and ice1 reinforced by the echoes from the surrounding mountains1 will appear sufficient to account for the peals by which their descent is accompanied4 ,sidenote3 ,,echoes ,,of ,,the ,,wetterhorn4 #ahef4 ,a second day1 in company with ,dr4 ,hooker1 completed the examination of this glacier in #ahef2 after which ,i parted from my friends1 ,mr4 ,huxley intending to rejoin me at the ,grimsel4 ,on the morning of the #bjth of ,august ,i strapped on my knapsack and ascended the green slopes from ,grindelwald towards the ,great ,scheideck4 ,before reaching the summit ,i frequently heard the wonderful echoes of the ,wetterhorn4 ,some travellers were in advance of me1 and to amuse them an alpine horn was blown4 ,the direct sound was cut off from me by a hill1 but the echoes talked down to me from the mountain walls4 ,the sonorous waves arrived after one1 two1 three1 and more reflections1 diminishing gradually in intensity1 but increasing in softness1 as if in its wanderings from crag to crag the sound had undergone a kind of sifting process1 leaving all its grossness behind1 and returning in delightful flute notes to the ear4 ,let us investigate this point a little4 ,if two looking-glasses be placed perfectly parallel to each other1 with a lighted candle between them1 an infinite series of images of the candle will be seen at both sides1 the images diminishing in brightness the further they recede4 ,but if the looking-glasses1 instead of being parallel1 enclose an angle1 a limited number of images only will be seen4 ,the smaller the angle which the reflectors make with each other1 or1 in other words1 the nearer they approach parallelism1 the greater will be the number of images observed4 ,to find the number of images the following is the rule3--,divide #cfj1 or the number of degrees in a circle1 by the number of degrees in the angle enclosed by the two mirrors1 the quotient will be one more than the number of images2 or1 counting the object itself1 the quotient is always equal to the number of images plus the object4 ,in ,fig4 #b ,i have given the number and position of the images produced by two mirrors placed at an angle of #de deg4 ,a ,b and ,b ,c mark the edges of the mirrors1 and #j represents the candle1 which1 for the sake of simplicity1 ,i have placed midway between them4 ,fix one point of a pair of compasses at ,b1 and with the distance ,b #j sweep a circle3--all the images will be ranged upon the circumference of this circle4 ,the number of images found by the foregoing rule is #g1 and their positions are marked in the figure by the numbers #a1 #b1 #c1 c4 ,illustration3 ,fig4 #b4 ,diagram of an angular reflector4 ,sidenote3 ,,echoes ,,explained4 #ahef4 ,suppose the ear to occupy the place of the eye1 and that a sounding body occupies the place of the luminous one1 we should then have just as many echoes as we had images in the former case4 ,these echoes would diminish in loudness just as the images of the candle diminish in brightness4 ,at each reflection a portion both of sound and light is lost2 hence the oftener light is reflected the dimmer it becomes1 and the oftener sound is reflected the fainter it is4 ,now the cliffs of the ,wetterhorn are so many rough angular reflectors of the sound3 some of them send it back directly to the listener1 and we have a first echo2 some of them send it on to others from which it is again reflected1 forming a second echo4 ,thus1 by repeated reflection1 successive echoes are sent to the ear1 until1 at length1 they become so faint as to be inaudible4 ,the sound1 as it diminishes in intensity1 appears to come from greater and greater distances1 as if it were receding into the mountain solitudes2 the final echoes being inexpressibly soft and pure4 ,sidenote3 ,,reichenbach ,,and ,,handeck4 #ahef4 ,after crossing the ,scheideck ,i descended to ,meyringen1 visiting the ,reichenbach waterfall on my way4 ,a peculiarity of the descending water here is1 that it is broken up in one of the basins into nodular masses1 each of which in falling leaves the light foaming mass which surrounds it as a train in the air behind2 the effect exactly resembles that of the avalanches of the ,jungfrau1 in which the more solid blocks of ice shoot forward in advance of the lighter debris1 which is held back by the friction of the air4 ,next day ,i ascended the valley of ,hasli1 and observed upon the rocks and mountains the action of ancient glaciers which once filled the valley to the height of more than a thousand feet above its present level4 ,i paused1 of course1 at the waterfall of ,handeck1 and stood for a time upon the wooden bridge which spans the river at its top4 ,the ,aar comes gambolling down to the bridge from its parent glacier1 takes one short jump upon a projecting ledge1 boils up into foam1 and then leaps into a chasm1 from the bottom of which its roar ascends through the gloom4 ,a rivulet named the ,aarlenbach joins the ,aar from the left in the very jaws of the chasm3 falling1 at first1 upon a projection at some depth below the edge1 and1 rebounding from this1 it darts at the ,aar1 and both plunge together like a pair of fighting demons to the bottom of the gorge4 ,the foam of the ,aarlenbach is white1 that of the ,aar is yellow1 and this enables the observer to trace the passage of the one cataract through the other4 ,as ,i stood upon the bridge the sun shone brightly upon the spray and foam2 my shadow was oblique to the river1 and hence a symmetrical rainbow could not be formed in the spray1 but one half of a lovely bow1 with its base in the chasm1 leaned over against the opposite rocks1 the colours advancing and retreating as the spray shifted its position4 ,i had been watching the water intently for some time1 when a little ,swiss boy1 who stood beside me1 observed1 in his trenchant ,german1 ,there plunge stones ever downwards4 ,the stones were palpable enough1 carried down by the cataract1 and sometimes completely breaking loose from it1 but ,i did not see them until my attention was withdrawn from the water4 ,sidenote3 ,,hut ,,of ,m4 ,,dollfuss4 #ahef4 ,on my arrival at the ,grimsel ,i found ,mr4 ,huxley already there1 and1 after a few minutes' conversation1 we decided to spend a night in a hut built by ,m4 ,dollfuss in #ahdf1 beside the ,unteraar glacier1 about #bjjj feet above the ,hospice4 ,we hoped thus to be able to examine the glacier to its origin on the following day4 ,two days' food and some blankets were sent up from the ,hospice1 and1 accompanied by our guide1 we proceeded to the glacier4 ,sidenote3 ,,hotel ,,des ,,neufchatelois4 #ahef4 ,having climbed a great terminal moraine1 and tramped for a considerable time amid loose shingle and boulders1 we came upon the ice4 ,the finest specimens of tables which ,i have ever seen are to be found upon this glacier--huge masses of clean granite poised on pedestals of ice4 ,here are also dirt-cones of the largest size1 and numerous shafts1 the forsaken passages of ancient moulins1 some filled with water1 others simply with deep blue light4 ,i reserve the description and explanation of both cones and moulins for another place4 ,the surfaces of some of the small pools were sprinkled lightly over with snow1 which the water underneath was unable to melt2 a coating of snow granules was thus formed1 flexible as chain armour1 but so close that the air could not escape through it4 ,some bubbles which had risen through the water had lifted the coating here and there into little rounded domes1 which1 by gentle pressure1 could be shifted hither and thither1 and several of them collected into one4 ,we reached the hut1 the floor of which appeared to be of the original mountain slab2 there was a space for cooking walled off from the sleeping-room1 half of which was raised above the floor1 and contained a quantity of old hay4 ,the number #bdjd metres1 the height1 ,i suppose1 of the place above the sea1 was painted on the door1 behind which were also the names of several well-known observers--,agassiz1 ,forbes1 ,desor1 ,dollfuss1 ,ramsay1 and others--cut in the wood4 ,a loft contained a number of instruments for boring1 a surveyor's chain1 ropes1 and other matters4 ,after dinner ,i made my way alone towards the junction of the ,finsteraar and ,lauteraar glaciers1 which unite at the ,abschwung to form the trunk stream of the ,unteraar glacier4 ,upon the great central moraine which runs between the branches were perched enormous masses of rock1 and1 under the overhanging ledge of one of these1 ,m4 ,agassiz had his ,hotel des ,neufchatelois4 ,the rock is still there1 bearing traces of names now nearly obliterated by the weather1 while the fragments around also bear inscriptions4 ,there in the wilderness1 in the gray light of evening1 these blurred and faded evidences of human activity wore an aspect of sadness4 ,it was a temple of science now in ruins1 and ,i a solitary pilgrim to the desecrated blocks4 ,as the day declined1 rain began to fall1 and ,i turned my face towards my new home2 where in due time we betook ourselves to our hay1 and waited hopefully for the morning4 ,but our hopes were doomed to disappointment4 ,a vast quantity of snow fell during the night1 and1 when we arose1 we found the glacier covered1 and the air thick with the descending flakes4 ,we waited1 hoping that it might clear up1 but noon arrived and passed without improvement2 our fire-wood was exhausted1 the weather intensely cold1 and1 according to the men's opinion1 hopelessly bad2 they opposed the idea of ascending further1 and we had therefore no alternative but to pack up and move downwards4 ,what was snow at the higher elevations changed to rain lower down1 and drenched us completely before we reached the ,grimsel4 ,but though thus partially foiled in our design1 this visit taught us much regarding the structure and general phenomena of the glacier4 ,sidenote3 ,,the ,,rhone ,,glacier4 #ahef4 ,the morning of the #bdth was clear and calm3 we rose with the sun1 refreshed and strong1 and crossed the ,grimsel pass at an early hour4 ,the view from the summit of the pass was lovely in the extreme2 the sky a deep blue1 the surrounding summits all enamelled with the newly-fallen snow1 which gleamed with dazzling whiteness in the sunlight4 ,it was ,sunday1 and the scene was itself a ,sabbath1 with no sound to disturb its perfect rest4 ,in a lake which we passed the mountains were mirrored without distortion1 for there was no motion of the air to ruffle its surface4 ,from the summit of the ,mayenwand we looked down upon the ,rhone glacier1 and a noble object it seemed1--,i hardly know a finer of its kind in the ,alps4 ,forcing itself through the narrow gorge which holds the ice cascade in its jaws1 and where it is greatly riven and dislocated1 it spreads out in the valley below in such a manner as clearly to reveal to the mind's eye the nature of the forces to which it is subjected4 ,longfellow's figure is quite correct2 the glacier resembles a vast gauntlet1 of which the gorge represents the wrist2 while the lower glacier1 cleft by its fissures into finger-like ridges1 is typified by the hand4 ,furnishing ourselves with provisions at the adjacent inn1 we devoted some hours to the examination of the lower portion of the glacier4 ,the dirt upon its surface was arranged in grooves as fine as if produced by the passage of a rake1 while the laminated structure of the deeper ice always corresponded to the superficial grooving4 ,we found several shafts1 some empty1 some filled with water4 ,at one place our attention was attracted by a singular noise1 evidently produced by the forcing of air and water through passages in the body of the glacier2 the sound rose and fell for several minutes1 like a kind of intermittent snore1 reminding one of ,hugi's hypothesis that the glacier was alive4 ,sidenote3 ,,rings ,,around ,,the ,,sun4 #ahef4 ,we afterwards climbed to a point from which the whole glacier was visible to us from its origin to its end4 ,adjacent to us rose the mighty mass of the ,finsteraarhorn1 the monarch of the ,oberland4 ,the ,galenstock was also at hand1 while round about the neve of the glacier a mountain wall projected its jagged outline against the sky4 ,at a distance was the grand cone of the ,weisshorn1 then1 and ,i believe still1 unscaled2,a further to the left the magnificent peaks of the ,mischabel2 while between them1 in savage isolation1 stood the obelisk of the ,matterhorn4 ,near us was the chain of the ,furca1 all covered with shining snow1 while overhead the dark blue of the firmament so influenced the general scene as to inspire a sentiment of wonder approaching to awe4 ,we descended to the glacier1 and proceeded towards its source4 ,as we advanced an unusual light fell upon the mountains1 and looking upwards we saw a series of coloured rings1 drawn like a vivid circular rainbow quite round the sun4 ,between the orb and us spread a thin veil of cloud on which the circles were painted2 the western side of the veil soon melted away1 and with it the colours1 but the eastern half remained a quarter of an hour longer1 and then in its turn disappeared4 ,the crevasses became more frequent and dangerous as we ascended4 ,they were usually furnished with overhanging eaves of snow1 from which long icicles depended1 and to tread on which might be fatal4 ,we were near the source of the glacier1 but the time necessary to reach it was nevertheless indefinite1 so great was the entanglement of fissures4 ,we followed one huge chasm for some hundreds of yards1 hoping to cross it2 but after half an hour's fruitless effort we found ourselves baffled and forced to retrace our steps4 ,sidenote3 ,,spirit ,,of ,,the ,,brocken4 #ahef4 ,the sun was sloping to the west1 and we thought it wise to return2 so down the glacier we went1 mingling our footsteps with the tracks of chamois1 while the frightened marmots piped incessantly from the rocks4 ,we reached the land once more1 and halted for a time to look upon the scene within view4 ,the marvellous blueness of the sky in the earlier part of the day indicated that the air was charged1 almost to saturation1 with transparent aqueous vapour4 ,as the sun sank the shadow of the ,finsteraarhorn was cast through the adjacent atmosphere1 which1 thus deprived of the direct rays1 curdled up into visible fog4 ,the condensed vapour moved slowly along the flanks of the mountain1 and poured itself cataract-like into the valley of the ,rhone4 ,here it met the sun again1 which reduced it once more to the invisible state4 ,thus1 though there was an incessant supply from the generator behind1 the fog made no progress2 as in the case of the moving glacier1 the end of the cloud-river remained stationary where consumption was equal to supply4 ,proceeding along the mountain to the ,furca1 we found the valley at the further side of the pass also filled with fog1 which rose1 like a wall1 high above the region of actual shadow4 ,once on turning a corner an exclamation of surprise burst simultaneously from my companion and myself4 ,before each of us and against the wall of fog1 stood a spectral image of a man1 of colossal dimensions2 dark as a whole1 but bounded by a coloured outline4 ,we stretched forth our arms2 the spectres did the same4 ,we raised our alpenstocks2 the spectres also flourished their batons4 ,all our actions were imitated by these fringed and gigantic shades4 ,we had1 in fact1 the ,spirit of the ,brocken before us in perfection4 ,at the time here referred to ,i had had but little experience of alpine phenomena4 ,i had been through the ,oberland in #ahej1 but was then too ignorant to learn much from my excursion4 ,hence the novelty of this day's experience may have rendered it impressive3 still even now ,i think there was an intrinsic grandeur in its phenomena which entitles the day to rank with the most remarkable that ,i have spent among the ,alps4 ,at the ,furca1 to my great regret1 the joint ramblings of my friend and myself ended2 ,i parted from him on the mountain side1 and watched him descending1 till the gray of evening finally hid him from my view4 ,,footnotes3 ,a ,the ,weisshorn was first scaled1 by ,tyndall1 in #ahfa4--,l4 ,c4 ,t4 ,sidenote3 ,,the ,,tyrol4 #ahef4 ,,the ,,tyrol4 7#c47 ,my subsequent destination was ,vienna2 but ,i wished to associate with my journey thither a visit to some of the glaciers of the ,tyrol4 ,at ,landeck1 on the #bith of ,august1 ,i learned that the nearest glacier was that adjacent to the ,gebatsch ,alp1 at the head of the ,kaunserthal2 and on the following morning ,i was on my way towards this valley4 ,i sought to obtain a guide at ,kaltebrunnen1 but failed2 and afterwards walked to the little hamlet of ,feuchten1 where ,i put up at a very lonely inn4 ,my host1 ,i believe1 had never seen an ,englishman1 but he had heard of such1 and remarked to me in his patois with emphasis1 ,die ,englaender sind die kuehnsten ,leute in dieser ,welt4 ,through his mediation ,i secured a chamois-hunter1 named ,johann ,auer1 to be my guide1 and next morning ,i started with this man up the valley4 ,the sun1 as we ascended1 smote the earth and us with great power2 high mountains flanked us on either side1 while in front of us1 closing the view1 was the mass of the ,weisskugel1 covered with snow4 ,at three o'clock we came in sight of the glacier1 and soon afterwards ,i made the acquaintance of the ,senner or cheesemakers of the ,gebatsch ,alp4 ,sidenote3 ,,the ,,gebatsch ,,alp4 #ahef4 ,the chief of these was a fine tall fellow1 with free1 frank countenance1 which1 however1 had a dash of the mountain wildness in it4 ,his feet were bare1 he wore breeches1 and fragments of stockings partially covered his legs1 leaving a black zone between the upper rim of the sock and the breeches4 ,his feet and face were of the same swarthy hue2 still he was handsome1 and in a measure pleasant to look upon4 ,he asked me what he could cook for me1 and ,i requested some bread and milk2 the former was a month old1 the latter was fresh and delicious1 and on these ,i fared sumptuously4 ,i went to the glacier afterwards with my guide1 and remained upon the ice until twilight1 when we returned1 guided by no path1 but passing amid crags grasped by the gnarled roots of the pine1 through green dells1 and over bilberry knolls of exquisite colouring4 ,my guide kept in advance of me singing a ,tyrolese melody1 and his song and the surrounding scene revived and realised all the impressions of my boyhood regarding the ,tyrol4 ,milking was over when we returned to the chalet1 which now contained four men exclusive of myself and my guide4 ,a fire of pine logs was made upon a platform of stone1 elevated three feet above the floor2 there was no chimney1 as the smoke found ample vent through the holes and fissures in the sides and roof4 ,the men were all intensely sunburnt1 the legitimate brown deepening into black with beard and dirt4 ,the chief senner prepared supper1 breaking eggs into a dish1 and using his black fingers to empty the shell when the albumen was refractory4 ,a fine erect figure he was as he stood in the glowing light of the fire4 ,all the men were smoking1 and now and then a brand was taken from the fire to light a renewed pipe1 and a ruddy glare flung thereby over the wild countenance of the smoker4 ,in one corner of the chalet1 and raised high above the ground1 was a large bed1 covered with clothes of the most dubious black-brown hue2 at one end was a little water-wheel turned by a brook1 which communicated motion to a churndash which made the butter4 ,the beams and rafters were covered with cheeses1 drying in the warm smoke4 ,the senner1 at my request1 showed me his storeroom1 and explained to me the process of making cheese1 its interest to me consisting in its bearing upon the question of slaty cleavage4 ,three gigantic masses of butter were in the room1 and ,i amused my host by calling them butter-glaciers4 ,soon afterwards a bit of cotton was stuck in a lump of grease1 which was placed in a lantern1 and the wick ignited2 the chamois-hunter took it1 and led the way to our resting-place1 ,i having previously declined a good-natured invitation to sleep in the big black bed already referred to4 ,sidenote3 ,,an ,,alpine ,,chalet4 #ahef4 ,there was a cowhouse near the chalet1 and above it1 raised on pillars of pine1 and approached by a ladder1 was a loft1 which contained a quantity of dry hay3 this my guide shook to soften the lumps1 and erected an eminence for my head4 ,i lay down1 drawing my plaid over me1 but ,auer affirmed that this would not be a sufficient protection against the cold2 he therefore piled hay upon me to the shoulders1 and proposed covering up my head also4 ,this1 however1 ,i declined1 though the biting coldness of the air1 which sometimes blew in upon us1 afterwards proved to me the wisdom of the suggestion4 ,having set me right1 my chamois-hunter prepared a place for himself1 and soon his heavy breathing informed me that he was in a state of bliss which ,i could only envy4 ,one by one the stars crossed the apertures in the roof4 ,once the ,pleiades hung above me like a cluster of gems2 ,i tried to admire them1 but there was no fervour in my admiration4 ,sometimes ,i dozed1 but always as this was about to deepen into positive sleep it was rudely broken by the clamour of a group of pigs which occupied the ground-floor of our dwelling4 ,the object of each individual of the group was to secure for himself the maximum amount of heat1 and hence the outside members were incessantly trying to become inside ones4 ,it was the struggle of radical and conservative among the pachyderms1 the politics being determined by the accident of position4 ,sidenote3 ,,the ,,gebatsch ,,glacier4 #ahef4 ,i rose at five o'clock on the #ast of ,september1 and after a breakfast of black bread and milk ascended the glacier as far as practicable4 ,we once quitted it1 crossed a promontory1 and descended upon one of its branches1 which was flanked by some fine old moraines4 ,we here came upon a group of seven marmots1 which with yells of terror scattered themselves among the rocks4 ,the points of the glacier beyond my reach ,i examined through a telescope2 along the faces of the sections the lines of stratification were clearly shown2 and in many places where the mass showed manifest signs of lateral pressure1 ,i thought ,i could observe the cleavage passing though the strata4 ,the point1 however1 was too important to rest upon an observation made from such a distance1 and ,i therefore abstained from mentioning it subsequently4 ,i examined the fissures and the veining1 and noticed how the latter became most perfect in places where the pressure was greatest4 ,the effect of oblique pressure was also finely shown3 at one place the thrust of the descending glacier was opposed by the resistance offered by the side of the valley1 the direction of the force being oblique to the side2 the consequence was a structure nearly parallel to the valley1 and consequently oblique to the thrust which ,i believe to be its cause4 ,sidenote3 ,a ,,chamois ,,on ,,the ,,rocks4 #ahef4 ,after five hours' examination we returned to our chalet1 where we refreshed ourselves1 put our things in order1 and faced a nameless ,joch1 or pass2 our aim being to cross the mountains into the valley of ,lantaufer1 and reach ,graun that evening4 ,after a rough ascent over the alp we came to the dead crag1 where the weather had broken up the mountains into ruinous heaps of rock and shingle4 ,we reached the end of a glacier1 the ice of which was covered by sloppy snow1 and at some distance up it came upon an islet of stones and debris1 where we paused to rest ourselves4 ,my guide1 as usual1 ranged over the summits with his telescope1 and at length exclaimed1 ,i see a chamois4 ,the creature stood upon a cliff some hundreds of yards to our left1 and seemed to watch our movements4 ,it was a most graceful animal1 and its life and beauty stood out in forcible antithesis to the surrounding savagery and death4 ,on the steep slopes of the glacier ,i was assisted by the hand of my guide4 ,in fact1 on this day ,i deemed places dangerous1 and dreaded them as such1 which subsequent practice enabled me to regard with perfect indifference2 so much does what we call courage depend upon habit1 or on the fact of knowing that we have really nothing to fear4 ,doubtless there are times when a climber has to make up his mind for very unpleasant possibilities1 and even gather calmness from the contemplation of the worst2 but in most cases ,i should say that his courage is derived from the latent feeling that the chances of safety are immensely in his favour4 ,sidenote3 ,,passage ,,of ,a ,,joch4 #ahef4 ,after a tough struggle we reached the narrow row of crags which form the crest of the pass1 and looked into the world of mountain and cloud on the other side4 ,the scene was one of stern grandeur--the misty lights and deep cloud-glooms being so disposed as to augment the impression of vastness which the scene conveyed4 ,the breeze at the summit was exceedingly keen1 but it gave our muscles tone1 and we sprang swiftly downward through the yielding debris which here overlies the mountain1 and in which we sometimes sank to the knees4 ,lower down we came once more upon the ice4 ,the glacier had at one place melted away from its bounding cliff1 which rose vertically to our right1 while a wall of ice #fj or #hj feet high was on our left4 ,between the two was a narrow passage1 the floor of which was snow1 which ,i knew to be hollow beneath3 my companion1 however1 was in advance of me1 and he being the heavier man1 where he trod ,i followed without hesitation4 ,on turning an angle of the rock ,i noticed an expression of concern upon his countenance1 and he muttered audibly1 ,i did not expect this4 ,the snow-floor had1 in fact1 given way1 and exposed to view a clear green lake1 one boundary of which was a sheer precipice of rock1 and the other the aforesaid wall of ice2 the latter1 however1 curved a little at its base1 so as to form a short steep slope which overhung the water4 ,my guide first tried the slope alone2 biting the ice with his shoe-nails1 and holding on by the spike of his baton1 he reached the other side4 ,he then returned1 and1 divesting myself of all superfluous clothes1 as a preparation for the plunge which ,i fully expected1 ,i also passed in safety4 ,probably the consciousness that ,i had water to fall into instead of pure space1 enabled me to get across without anxiety or mischance2 but had ,i1 like my guide1 been unable to swim1 my feelings would have been far different4 ,this accomplished1 we went swiftly down the valley1 and the more ,i saw of my guide the more ,i liked him4 ,he might1 if he wished1 have made his day's journey shorter by stopping before he reached ,graun1 but he would not do so4 ,every word he said to me regarding distances was true1 and there was not the slightest desire shown to magnify his own labour4 ,i learnt by mere accident that the day's work had cut up his feet1 but his cheerfulness and energy did not bate a jot till he had landed me in the ,black ,eagle at ,graun4 ,next morning he came to my room1 and said that he felt sufficiently refreshed to return home4 ,i paid him what ,i owed him1 when he took my hand1 and1 silently bending down his head1 kissed it2 then1 standing erect1 he stretched forth his right hand1 which ,i grasped firmly in mine1 and bade him farewell2 and thus ,i parted from ,johann ,auer1 my brave and truthful chamois-hunter4 ,on the following day ,i met ,dr4 ,frankland in the ,finstermuntz pass1 and that night we bivouacked together at ,mals4 ,heavy rain fell throughout the night1 but it came from a region high above that of liquidity4 ,it was first snow1 which1 as it descended through the warmer strata of the atmosphere1 was reduced to water4 ,overhead1 in the air1 might be traced a surface1 below which the precipitate was liquid1 above which it was solid2 and this surface1 intersecting the mountains which surround ,mals1 marked upon them a beautifully-defined snow-line1 below which the pines were dark and the pastures green1 but above which pines and pastures and crags were covered with the freshly-fallen snow4 ,sidenote3 ,,the ,,stelvio4 #ahef4 ,sidenote3 ,,colour ,,of ,,fresh ,,snow4 #ahef4 ,on the #bnd of ,september we crossed the ,stelvio4 ,the brown cone of the well-known ,madatschspitze was clear1 but the higher summits were clouded1 and the fragments of sunshine which reached the lower world wandered like gleams of fluorescent light over the glaciers4 ,near the snow-line the partial melting of the snow had rendered it coarsely granular1 but as we ascended it became finer1 and the light emitted from its cracks and cavities a pure and deep blue4 ,when a staff was driven into the snow low down the mountain1 the colour of the light in the orifice was scarcely sensibly blue1 but higher up this increased in a wonderful degree1 and at the summit the effect was marvellous4 ,i struck my staff into the snow1 and turned it round and round2 the surrounding snow cracked repeatedly1 and flashes of blue light issued from the fissures4 ,the fragments of snow that adhered to the staff were1 by contrast1 of a beautiful pink yellow1 so that1 on moving the staff with such fragments attached to it up and down1 it was difficult to resist the impression that a pink flame was ascending and descending in the hole4 ,as we went down the other side of the pass1 the effect became more and more feeble1 until1 near the snow-line1 it almost wholly disappeared4 ,we remained that night at the baths of ,bormio1 but the following afternoon being fine we wished to avail ourselves of the fair weather to witness the scene from the summit of the pass4 ,twilight came on before we reached ,santa ,maria1 but a gorgeous orange overspread the western horizon1 from which we hoped to derive sufficient light4 ,it was a little too late when we reached the top1 but still the scene was magnificent4 ,a multitude of mountains raised their crowns towards heaven1 while above all rose the snow-white cone of the ,ortler4 ,far into the valley the giant stretched his granite limbs1 until they were hid from us by darkness4 ,as this deepened1 the heavens became more and more crowded with stars1 which blazed like gems over the heads of the mountains4 ,at times the silence was perfect1 unbroken save by the crackling of the frozen snow beneath our own feet2 while at other times a breeze would swoop down upon us1 keen and hostile1 scattering the snow from the roofs of the wooden galleries in frozen powder over us4 ,long after night had set in1 a ghastly gleam rested upon the summit of the ,ortler1 while the peaks in front deepened to a dusky neutral tint1 the more distant ones being lost in gloom4 ,we descended at a swift pace to ,trafoi1 which we reached before #aa ,p4,m4 ,sidenote3 ,,singular ,,hailstorm4 #ahef4 ,meran was our next resting-place1 whence we turned through the ,schnalzerthal to ,unserfrau1 and thence over the ,hochjoch to ,fend4 ,from a religious procession we took a guide1 who1 though partly intoxicated1 did his duty well4 ,before reaching the summit of the pass we were assailed by a violent hailstorm1 each hailstone being a frozen cone with a rounded end4 ,had not their motion through the air something to do with the shape of these hailstones8 ,the theory of meteorites now generally accepted is that they are small planetary bodies drawn to the earth by gravity1 and brought to incandescence by friction against the earth's atmosphere4 ,such a body moving through the atmosphere must have condensed hot air in front of it1 and rarefied cool air behind it2 and the same is true to a small extent of a hailstone4 ,this distribution of temperature must1 ,i imagine1 have some influence on the shape of the stone4 ,possibly also the stratified appearance of some hailstones may be connected with this action4,a ,sidenote3 ,,the ,,hochjoch ,,and ,,fend4 #ahef4 ,the hail ceased and the heights above us cleared as we ascended4 ,at the top of the pass we found ourselves on the verge of a great neve1 which lay between two ranges of summits1 sloping down to the base of each range from a high and rounded centre3 a wilder glacier scene ,i have scarcely witnessed4 ,wishing to obtain a more perfect view of the region1 ,i diverged from the track followed by ,dr4 ,frankland and the guide1 and climbed a ridge of snow about half a mile to the right of them4 ,a glorious expanse was before me1 stretching itself in vast undulations1 and heaping itself here and there into mountainous cones1 white and pure1 with the deep blue heaven behind them4 ,here ,i had my first experience of hidden crevasses1 and to my extreme astonishment once found myself in the jaws of a fissure of whose existence ,i had not the slightest notice4 ,such accidents have often occurred to me since1 but the impression made by the first is likely to remain the strongest4 ,it was dark when we reached the wretched ,wirthshaus at ,fend1 where1 badly fed1 badly lodged1 and disturbed by the noise of innumerable rats1 we spent the night4 ,thus ended my brief glacier expedition of #ahef2 and on the observations then made1 and on subsequent experiments1 was founded a paper presented to the ,royal ,society by ,mr4 ,huxley and myself4,b ,,footnotes3 ,a ,i take the following account of a grander storm of the above character from ,hooker's ',himalayan ,journals1' vol4 ii4 p4 #dje4 ,on the #bjth 7,march1 #ahdi7 we had a change in the weather3 a violent storm from the south-west occurred at noon1 with hail of a strange form1 the stones being sections of hollow spheres1 half an inch across and upwards1 formed of cones with truncated apices and convex bases3 these cones were aggregated together with their bases outwards4 ,the large masses were followed by a shower of the separate conical pieces1 and that by heavy rain4 ,on the mountains this storm was most severe3 the stones lay at ,darjeeling for seven days1 congealed into masses of ice several feet long and a foot thick in sheltered places3 at ,purneah1 fifty miles south1 stones one and two inches across fell1 probably as whole spheres4 ,b ',phil4 ,trans4' #aheg1 pp4 #cbg-cdf4--,l4 ,c4 ,t4 ,sidenote3 ,,the ,,lake ,,of ,,geneva4 #aheg4 ,,expedition ,,of #aheg4 ,,the ,,lake ,,of ,,geneva4 7#d47 ,the time occupied in the observations of #ahef embraced about five whole days2 and though these days were laborious and instructive1 still so short a time proved to be wholly incommensurate with the claims of so wide a problem4 ,during the subsequent experimental treatment of the subject1 ,i had often occasion to feel the incompleteness of my knowledge1 and hence arose the desire to make a second expedition to the ,alps1 for the purpose of expanding1 fortifying1 or1 if necessary1 correcting first impressions4 ,on ,thursday1 the #ith of ,july1 #aheg1 ,i found myself upon the ,lake of ,geneva1 proceeding towards ,vevey4 ,i had long wished to see the waters of this renowned inland sea1 the colour of which is perhaps more interesting to the man of science than to the poets who have sung about it4 ,long ago its depth of blue excited attention1 but no systematic examination of the subject has1 so far as ,i know1 been attempted4 ,it may be that the lake simply exhibits the colour of pure water4 ,ice is blue1 and it is reasonable to suppose that the liquid obtained from the fusion of ice is of the same colour2 but still the question presses--,is the blue of the ,lake of ,geneva to be entirely accounted for in this way8 ,the attempts which have been made to explain it otherwise show that at least a doubt exists as to the sufficiency of the above explanation4 ,sidenote3 ,,blueness ,,of ,,the ,,water4 #aheg4 ,it is only in its deeper portions that the colour of the lake is properly seen4 ,where the bottom comes into view the pure effect of the water is disturbed2 but where the water is deep the colour is deep3 between ,rolle and ,nyon for example1 the blue is superb4 ,where the blue was deepest1 however1 it gave me the impression of turbidity rather than of deep transparency4 ,at the upper portion of the lake the water through which the steamer passed was of a blue green4 ,wishing to see the place where the ,rhone enters the lake1 ,i walked on the morning of the #ajth from ,villeneuve to ,novelle1 and thence through the woods to the river side4 ,proceeding along an embankment1 raised to defend the adjacent land from the incursions of the river1 an hour brought me to the place where it empties itself into the lake4 ,the contrast between the two waters was very great3 the river was almost white with the finely divided matter which it held in suspension2 while the lake at some distance was of a deep ultramarine4 ,the lake in fact forms a reservoir where the particles held in suspension by the river have time to subside1 and its waters to become pure4 ,the subsidence of course takes place most copiously at the head of the lake2 and here the deposit continues to form new land1 adding year by year to the thousands of acres which it has already left behind it1 and invading more and more the space occupied by the water4 ,innumerable plates of mica spangled the fine sand which the river brought down1 and these1 mixing with the water1 and flashing like minute mirrors as the sun's rays fell upon them1 gave the otherwise muddy stream a silvery appearance4 ,had ,i an opportunity ,i would make the following experiments3-- 7a47 ,compare the colour of the light transmitted by a column of the lake water fifteen feet long with that transmitted by a second column1 of the same length1 derived from the melting of freshly fallen mountain snow4 7b47 ,compare in the same manner the colour of the ordinary water of the lake with that of the same water after careful distillation4 7c47 ,strictly examine whether the light transmitted by the ordinary water contains an excess of red over that transmitted by the distilled water3 this latter point1 as will be seen farther on1 is one of peculiar interest4 ,the length is fixed at fifteen feet1 because ,i have found this length extremely efficient in similar experiments4 ,illustration3 ,fig4 #c1 #d4 ,boats' sails inverted by ,atmospheric ,refraction4 ,sidenote3 ,,atmospheric ,,refraction4 #aheg4 ,on returning to the pier at ,villeneuve1 a peculiar flickering motion was manifest upon the surface of the distant portions of the lake1 and ,i soon noticed that the coast line was inverted by atmospheric refraction4 ,it required a long distance to produce the effect3 no trace of it was seen about the ,castle of ,chillon1 but at ,vevey and beyond it1 the whole coast was clearly inverted2 and the houses on the margin of the lake were also imaged to a certain height4 ,two boats at a considerable distance presented the appearance sketched in ,figs4 #c and #d2 the hull of each1 except a small portion at the end1 was invisible1 but the sails seemed lifted up high in the air1 with their inverted images below2 as the boats drew nearer the hulls appeared inverted1 the apparent height of the vessel above the surface of the lake being thereby nearly doubled1 while the sails and higher objects1 in these cases1 were almost completely cut away4 ,when viewed through a telescope the sensible horizon of the lake presented a billowy tumultuous appearance1 fragments being incessantly detached from it and suspended in the air4 ,sidenote3 ,,mirage4 #aheg4 ,the explanation of this effect is the same as that of the mirage of the desert1 which may be found in almost any book on physics1 and which so tantalized the ,french soldiers in ,egypt4 ,they often mistook this aerial inversion for the reflection from a lake1 and on trial found hot and sterile sand at the place where they expected refreshing waters4 ,the effect was shown by ,monge1 one of the learned men who accompanied the expedition1 to be due to the total reflection of very oblique rays at the upper surface of the layer of rarefied air which was nearest to the heated earth4 ,a sandy plain1 in the early part of the day1 is peculiarly favourable for the production of such effects2 and on the extensive flat strand which stretches between ,mont ,st4 ,michel and the coast adjacent to ,avranches in ,normandy1 ,i have noticed ,mont ,tombeline reflected as if glass instead of sand surrounded it and formed its mirror4 ,sidenote3 ,,chamouni ,,and ,,the ,,montanvert4 #aheg4 ,,chamouni ,,and ,,the ,,montanvert4 7#e47 ,on the evening of the #abth of ,july ,i reached ,chamouni2 the weather was not quite clear1 but it was promising2 white cumuli had floated round ,mont ,blanc during the day1 but these diminished more and more1 and the light of the setting sun was of that lingering rosy hue which bodes good weather4 ,two parallel beams of a purple tinge were drawn by the shadows of the adjacent peaks1 straight across the ,glacier des ,bossons1 and the ,glacier des ,pelerins was also steeped for a time in the same purple light4 ,once when the surrounding red illumination was strong1 the shadows of the ,grands ,mulets falling upon the adjacent snow appeared of a vivid green4 ,this green belonged to the class of subjective colours1 or colours produced by contrast1 about which a volume might be written4 ,the eye received the impression of green1 but the colour was not external to the eye4 ,place a red wafer on white paper1 and look at it intently1 it will be surrounded in a little time by a green fringe3 move the wafer bodily away1 and the entire space which it occupied upon the paper will appear green4 ,a body may have its proper colour entirely masked in this way4 ,let a red wafer be attached to a piece of red glass1 and from a moderately illuminated position let the sky be regarded through the glass2 the wafer will appear of a vivid green4 ,if a strong beam of light be sent through a red glass and caused to fall upon a screen1 which at the same time is moderately illuminated by a separate source of white light1 an opaque body placed in the path of the beam will cast a green shadow upon the screen which may be seen by several hundred persons at once4 ,if a blue glass be used1 the shadow will be yellow1 which is the complementary colour to blue4 ,sidenote3 ,,coloured ,,shadows4 #aheg4 ,when we suddenly pass from open sunlight to a moderately illuminated room1 it appears dark at first1 but after a little time the eye regains the power of seeing objects distinctly4 ,thus one effect of light upon the eye is to render it less sensitive1 and light of any particular colour falling upon the eye blunts its appreciation of that colour4 ,let us apply this to the shadow upon the screen4 ,this shadow is moderately illuminated by a jet of white light2 but the space surrounding it is red1 the effect of which upon the eye is to blind it in some degree to the perception of red4 ,hence1 when the feeble white light of the shadow reaches the eye1 the red component of this light is1 as it were1 abstracted from it1 and the eye sees the residual colour1 which is green4 ,a similar explanation applies to the shadows of the ,grands ,mulets4 ,on the #acth of ,july ,i was joined by my friend ,mr4 ,thomas ,hirst1 and on the #adth we examined together the end of the ,mer de ,glace4 ,in former times the whole volume of the ,arveiron escaped from beneath the ice at the end of the glacier1 forming a fine arch at its place of issue4 ,this year a fraction only of the water thus found egress2 the greater portion of it escaping laterally from the glacier at the summit of the rocks called ,les ,mottets1 down which it tumbled in a fine cascade4 ,the vault at the end of the glacier was nevertheless respectable1 and rather tempting to a traveller in search of information regarding the structure of the ice4 ,perhaps1 however1 ,nature meant to give me a friendly warning at the outset1 for1 while speculating as to the wisdom of entering the cavern1 it suddenly gave way1 and1 with a crash which rivalled thunder1 the roof strewed itself in ruins upon the floor4 ,sidenote3 ,,sunrise ,,at ,,chamouni4 #aheg4 ,many years ago ,i had read with delight ,coleridge's poem entitled ',sunrise in the ,valley of ,chamouni1' and to witness in all perfection the scene described by the poet1 ,i waited at ,chamouni a day longer than was otherwise necessary4 ,on the morning of ,wednesday1 the #aeth of ,july1 ,i rose before the sun2 ,mont ,blanc and his wondrous staff of ,aiguilles were without a cloud2 eastward the sky was of a pale orange which gradually shaded off to a kind of rosy violet1 and this again blended by imperceptible degrees with the deep zenithal blue4 ,the morning star was still shining to the right1 and the moon also turned a pale face towards the rising day4 ,the valley was full of music2 from the adjacent woods issued a gush of song1 while the sound of the ,arve formed a suitable bass to the shriller melody of the birds4 ,the mountain rose for a time cold and grand1 with no apparent stain upon his snows4 ,suddenly the sunbeams struck his crown and converted it into a boss of gold4 ,for some time it remained the only gilded summit in view1 holding communion with the dawn while all the others waited in silence4 ,these1 in the order of their heights1 came afterwards1 relaxing1 as the sunbeams struck each in succession1 into a blush and smile4 ,sidenote3 ,,glacier ,,des ,,bois4 #aheg4 ,on the same day we had our luggage transported to the ,montanvert1 while we clambered along the lateral moraine of the glacier to the ,chapeau4 ,the rocks alongside the glacier were beautifully scratched and polished1 and ,i paid particular attention to them1 for the purpose of furnishing myself with a key to ancient glacier action4 ,the scene to my right was one of the most wonderful ,i had ever witnessed4 ,along the entire slope of the ,glacier des ,bois1 the ice was cleft and riven into the most striking and fantastic forms4 ,it had not yet suffered much from the wasting influence of the summer weather1 but its towers and minarets sprang from the general mass with clean chiselled outlines4 ,some stood erect1 others leaned1 while the white debris1 strewn here and there over the glacier1 showed where the wintry edifices had fallen1 breaking themselves to pieces1 and grinding the masses on which they fell to powder4 ,some of them gave way during our inspection of the place1 and shook the valley with the reverberated noise of their fall4 ,i endeavoured to get near them1 but failed2 the chasms at the margin of the glacier were too dangerous1 and the stones resting upon the heights too loosely poised to render persistence in the attempt excusable4 ,we subsequently crossed the glacier to the ,montanvert1 and ,i formally took up my position there4 ,the rooms of the hotel were separated from each other by wooden partitions merely1 and thus the noise of early risers in one room was plainly heard in the next4 ,for the sake of quiet1 therefore1 ,i had my bed placed in the chateau next door1--a little octagonal building erected by some kind and sentimental ,frenchman1 and dedicated a la ,nature4 ,my host at first demurred1 thinking the place not propre1 but ,i insisted1 and he acquiesced4 ,true the stone floor was dark with moisture1 and on the walls a glistening was here and there observable1 which suggested rheumatism1 and other penalties1 but ,i had had no experience of rheumatism1 and trusted to the strength which mountain air and exercise were sure to give me1 for power to resist its attacks4 ,moreover1 to dispel some of the humidity1 it was agreed that a large pine fire should be made there on necessary occasions4 ,sidenote3 ,,quarters ,,at ,,the ,,montanvert4 #aheg4 ,though singularly favoured on the whole1 still our residence at the ,montanvert was sufficiently long to give us specimens of all kinds of weather2 and thus my chateau derived an interest from the mutations of external nature4 ,sometimes no breath disturbed the perfect serenity of the night1 and the moon1 set in a black-blue sky1 turned a face of almost supernatural brightness to the mountains1 while in her absence the thick-strewn stars alone flashed and twinkled through the transparent air4 ,sometimes dull dank fog choked the valley1 and heavy rain plashed upon the stones outside4 ,on two or three occasions we were favoured by a thunderstorm1 every peal of which broke into a hundred echoes1 while the seams of lightning which ran through the heavens produced a wonderful intermittence of gloom and glare4 ,and as ,i sat within1 musing on the experiences of the day1 with my pine logs crackling1 and the ruddy fire-light gleaming over the walls1 and lending animation to the visages sketched upon them with charcoal by the guides1 ,i felt that my position was in every way worthy of a student of nature4 ,,the ,,mer ,,de ,,glace4 7#f47 ,sidenote3 ,a ,,river ,,of ,,ice4 #aheg4 ,the name ,mer de ,glace has doubtless led many who have never seen this glacier to a totally erroneous conception of its character4 ,misled probably by this term1 a distinguished writer1 for example1 defines a glacier to be a sheet of ice spread out upon the slope of a mountain2 whereas the ,mer de ,glace is indeed a river1 and not a sea of ice4 ,but certain forms upon its surface1 often noticed and described1 and which ,i saw for the first time from the window of our hotel on the morning of the #afth of ,july1 suggest at once the origin of the name4 ,the glacier here has the appearance of a sea which1 after it had been tossed by a storm1 had suddenly stiffened into rest4 ,the ridges upon its surface accurately resemble waves in shape1 and this singular appearance is produced in the following way3-- ,some distance above the ,montanvert--opposite to the ,echelets--the glacier1 in passing down an incline1 is rent by deep fissures1 between each two of which a ridge of ice intervenes4 ,at first the edges of these ridges are sharp and angular1 but they are soon sculptured off by the action of the sun4 ,the bearing of the ,mer de ,glace being approximately north and south1 the sun at mid-day shines down the glacier1 or rather very obliquely across it2 and the consequence is1 that the fronts of the ridges1 which look downward1 remain in shadow all the day1 while the backs of the ridges1 which look up the glacier1 meet the direct stroke of the solar rays4 ,the ridges thus acted upon have their hindmost angles wasted off and converted into slopes which represent the back of a wave1 while the opposite sides of the ridges1 which are protected from the sun1 preserve their steepness1 and represent the front of the wave4 ,fig4 #e will render my meaning at once plain4 ,sidenote3 ,,frozen ,,waves4 #aheg4 ,illustration3 ,fig4 #e4 ,wave-like forms on the ,mer de ,glace4 ,the dotted lines are intended to represent three of the ridges into which the glacier is divided1 with their interposed fissures2 the dots representing the boundaries of the ridges when the glacier is first broken4 ,the parallel shading lines represent the direction of the sun's rays1 which1 falling obliquely upon the ridges1 waste away the right-hand corners1 and finally produce wave-like forms4 ,we spent a day or two in making the general acquaintance of the glacier4 ,on the #afth we ascended till we came to the rim of the ,talefre basin1 from which we had a good view of the glacier system of the region4 ,the laminated structure of the ice was a point which particularly interested me2 and as ,i saw the exposed sections of the neve1 counted the lines of stratification1 and compared these with the lines upon the ends of the secondary glaciers1 ,i felt the absolute necessity either of connecting the veined structure with the strata by a continuous chain of observations1 or of proving by ocular evidence that they were totally distinct from each other4 ,i was well acquainted with the literature of the subject1 but nothing that ,i had read was sufficient to prove what ,i required4 ,strictly speaking1 nothing that had been written upon the subject rose above the domain of opinion1 while ,i felt that without absolute demonstration the question would never be set at rest4 ,illustration3 ,fig4 #f4 ,glacier ,table4 ,sidenote3 ,,glacier ,,tables4 #aheg4 ,on this day we saw some fine glacier tables2 flat masses of rock1 raised high upon columns of ice3 ,fig4 #f is a sketch of one of the finest of them4 ,some of them fell from their pedestals while we were near them1 and the clean ice-surfaces which they left behind sparkled with minute stars as the small bubbles of air ruptured the film of water by which they were overspread4 ,i also noticed that petit bruit de crepitation1 to which ,m4 ,agassiz alludes1 and which he refers to the rupture of the ice by the expansion of the air-bubbles contained within it4 ,when ,i first read ,agassiz's account of it1 ,i thought it might be produced by the rupture of the minute air-bubbles which incessantly escape from the glacier4 ,this1 doubtless1 produces an effect1 but there is something in the character of the sound to be referred1 ,i think1 to a less obvious cause1 which ,i shall notice further on4 ,sidenote3 ,,first ,,sight ,,of ,,the ,,dirt-,,bands4 #aheg4 ,at six ,p4,m4 this day ,i reached the ,montanvert2 and the same evening1 wrapping my plaid around me1 ,i wandered up towards ,charmoz1 and from its heights observed1 as they had been observed fifteen years previously by ,professor ,forbes1 the dirt-bands of the ,mer de ,glace4 ,they were different from any ,i had previously seen1 and ,i felt a strong desire to trace them to their origin4 ,content1 however1 with the performance of the day1 and feeling healthily tired by it1 ,i lay down upon the bilberry bushes and fell asleep4 ,it was dark when ,i awoke1 and ,i experienced some difficulty and risk in getting down from the petty eminence referred to4 ,the illumination of the glacier1 as remarked by ,professor ,forbes1 has great influence upon the appearance of the bands2 they are best seen in a subdued light1 and ,i think for the following reasons3-- ,the dirt-bands are seen simply because they send less light to the eye than the cleaner portions of the glacier which lie between them2 two surfaces1 differently illuminated1 are presented to the eye1 and it is found that this difference is more observable when the light is that of evening than when it is that of noon4 ,it is only within certain limits that the eye is able to perceive differences of intensity in different lights2 beyond a certain intensity1 if ,i may use the expression1 light ceases to be light1 and becomes mere pain4 ,the naked eye can detect no difference in brightness between the electric light and the lime light1 although1 when we come to strict measurement1 the former may possess many times the intensity of the latter4 ,it follows from this that we might reduce the ordinary electric light to a fraction of its intensity1 without any perceptible change of brightness to the naked eye which looks at it4 ,but if we reduce the lime light in the same proportion the effect would be very different4 ,this light lies much nearer to the limit at which the eye can appreciate differences of brightness1 and its reduction might bring it quite within this limit1 and make it sensibly dimmer than before4 ,hence we see that when two sources of intense light are presented to the eye1 by reducing both the lights in the same proportion1 the difference between them may become more perceptible4 ,sidenote3 ,,bands ,,seen ,,best ,,by ,,twilight4 #aheg4 ,now the dirt-bands and the spaces between them resemble1 in some measure1 the two lights above mentioned4 ,by the full glare of noon both are so strongly illuminated that the difference which the eye perceives is very small2 as the evening advances the light of both is lowered in the same proportion1 but the differential effect upon the eye is thereby augmented1 and the bands are consequently more clearly seen4 7#g47 ,on ,friday1 the #agth of ,july1 we commenced our measurements4 ,through the kindness of ,sir ,roderick ,murchison1 ,i found myself in the possession of an excellent five-inch theodolite1 an instrument with the use of which both my friend ,hirst and myself were perfectly familiar4 ,we worked in concert for a few days to familiarize our assistant with the mode of proceeding1 but afterwards it was my custom to simply determine the position where a measurement was to be made1 and to leave the execution of it entirely to ,mr4 ,hirst and our guide4 ,on the #bjth of ,july ,i made a long excursion up the glacier1 examining the moraines1 the crevasses1 the structure1 the moulins1 and the disintegration of the surface4 ,i was accompanied by a boy named ,edouard ,balmat1,a and found him so good an iceman that ,i was induced to take him with me on the following day also4 ,sidenote3 ,,the ,,cleft ,,station4 #aheg4 ,looking upwards from the ,montanvert to the left of the ,aiguille de ,charmoz1 a singular gap is observed in the rocky mountain wall1 in the centre of which stands a detached column of granite4 ,both cleft and pillar are shown in the frontispiece1 to the right4 ,the eminence to the left of this gap is signalised by ,professor ,forbes as one of the best stations from which to view the ,mer de ,glace1 and this point1 which ,i shall refer to hereafter as the ,cleft ,station1 it was now my desire to attain4 ,from the ,montanvert side a steep gully leads to the cleft2 up this couloir we proposed to try the ascent4 ,at a considerable height above the ,mer de ,glace1 and closely hugging the base of the ,aiguille de ,charmoz1 is the small ,glacier de ,tendue1 shown in the frontispiece1 and from which a steep slope stretches down to the ,mer de ,glace4 ,this ,tendue is the most talkative glacier ,i have ever known2 the clatter of the small stones which fall from it is incessant4 ,huge masses of granite also frequently fall upon the glacier from the cliffs above it1 and1 being slowly borne downwards by the moving ice1 are at length seen toppling above the terminal face of the glacier4 ,the ice which supports them being gradually melted1 they are at length undermined1 and sent bounding down the slope with peal and rattle1 according as the masses among which they move are large or small4 ,the space beneath the glacier is cumbered with blocks thus sent down2 some of them of enormous size4 ,sidenote3 ,,rough ,,ascent4 #aheg4 ,the danger arising from this intermittent cannonade1 though in reality small1 has caused the guides to swerve from the path which formerly led across the slope to the promontory of ,trelaporte4 ,i say small1 because1 even should a rock choose the precise moment at which a traveller is passing to leap down1 the boulders at hand are so large and so capable of bearing a shock that the least presence of mind would be sufficient to place him in safety4 ,but presence of mind is not to be calculated on under such circumstances1 and hence the guides were right to abandon the path4 ,reaching the mouth of our gully after a rough ascent1 we took to the snow1 instead of climbing the adjacent rocks4 ,it was moist and soft1 in fact in a condition altogether favourable for the regelation of its granules4 ,as the foot pressed upon it the particles became cemented together4 ,a portion of the pressure was transmitted laterally1 which produced attachments beyond the boundary of the foot2 thus as the latter sank1 it pressed upon a surface which became continually wider and more rigid1 and at length sufficiently strong to bear the entire weight of the body2 the pressed snow formed in fact a virtual camel's foot1 which soon placed a limit to the sinking4 ,it is this same principle of regelation which enables men to cross snow bridges in safety4 ,by gentle cautious pressure the loose granules of the substance are cemented into a continuous mass1 all sudden shocks which might cause the frozen surfaces to snap asunder being avoided4 ,in this way an arch of snow fifteen or twenty inches in thickness may be rendered so firm that a man will cross it1 although it may span a chasm one hundred feet in depth4 ,as we ascended1 the incline became very steep1 and once or twice we diverged from the snow to the adjacent rocks2 these were disintegrated1 and the slightest disturbance was sufficient to bring them down2 some fell1 and from one of them ,i found it a little difficult to escape2 for it grazed my leg1 inflicting a slight wound as it passed4 ,just before reaching the cleft at which we aimed1 the snow for a short distance was exceedingly steep1 but we surmounted it2 and ,i sat for a time beside the granite pillar1 pleased to find that ,i could permit my legs to dangle over a precipice without prejudice to my head4 ,sidenote3 ,,chamois ,,on ,,the ,,mountains4 #aheg4 ,while we remained here a chamois made its appearance upon the rocks above us4 ,deeming itself too near1 it climbed higher1 and then turned round to watch us4 ,it was soon joined by a second1 and the two formed a very pretty picture3 their attitudes frequently changed1 but they were always graceful2 with head erect and horns curved back1 a light limb thrown forward upon a ledge of rock1 looking towards us with wild and earnest gaze1 each seemed a type of freedom and agility4 ,turning now to the left1 we attacked the granite tower1 from which we purposed to scan the glacier1 and were soon upon its top4 ,my companion was greatly pleased--he was tres-content to have reached the place--he felt assured that many old guides would have retreated from that ugly gully1 with its shifting shingle and debris1 and his elation reached its climax in the declaration that1 if ,i resolved to ascend ,mont ,blanc without a guide1 he was willing to accompany me4 ,sidenote3 ,,scene ,,from ,,the ,,station4 #aheg4 ,from the position which we had attained1 the prospect was exceedingly fine1 both of the glaciers and of the mountains4 ,beside us was the ,aiguille de ,charmoz1 piercing with its spikes of granite the clear air4 ,to my mind it is one of the finest of the ,aiguilles1 noble in mass1 with its summits singularly cleft and splintered4 ,in some atmospheric colourings it has the exact appearance of a mountain of cast copper1 and the manner in which some of its highest pinnacles are bent1 suggesting the idea of ductility1 gives strength to the illusion that the mass is metallic4 ,at the opposite side of the glacier was the ,aiguille ,verte1 with a cloud poised upon its point3 it has long been the ambition of climbers to scale this peak1 and on this day it was attempted by a young ,french count with a long retinue of guides4 ,he had not fair play1 for before we quitted our position we heard the rumble of thunder upon the mountain1 which indicated the presence of a foe more terrible than the avalanches themselves4 ,higher to the right1 and also at the opposite side of the glacier1 rose the ,aiguille du ,moine2 and beyond was the basin of the ,talefre1 the ice cascade issuing from which appeared1 from our position1 like the foam of a waterfall4 ,then came the ,aiguille de ,lechaud1 the ,petite ,jorasse1 the ,grande ,jorasse1 and the ,mont ,tacul2 all of which form a cradle for the ,glacier de ,lechaud4 ,mont ,mallet1 the ,periades1 and the ,aiguille ,noire1 came next1 and then the singular obelisk of the ,aiguille du ,geant1 from which a serrated edge of cliff descends to the summit of the ,col4 ,sidenote3 ,,seracs ,,of ,,the ,,col ,,du ,,geant4 #aheg4 ,over the slopes of the ,col du ,geant was spread a coverlet of shining snow1 at some places apparently as smooth as polished marble1 at others broken so as to form precipices1 on the pale blue faces of which the horizontal lines of bedding were beautifully drawn4 ,as the eye approaches the line which stretches from the ,rognon to the ,aiguille ,noire1 the repose of the neve becomes more and more disturbed4 ,vast chasms are formed1 which however are still merely indicative of the trouble in advance4 ,if the glacier were lifted off we should probably see that the line just referred to would lie along the summit of a steep gorge2 over this summit the glacier is pushed1 and has its back periodically broken1 thus forming vast transverse ridges which follow each other in succession down the slope4 ,at the summit these ridges are often cleft by fissures transverse to them1 thus forming detached towers of ice of the most picturesque and imposing character4,b ,these towers often fall2 and while some are caught upon the platforms of the cascade1 others struggle with the slow energy of a behemoth through the debris which opposes them1 reach the edges of the precipices which rise in succession along the fall1 leap over1 and1 amid ice-smoke and thunder-peals1 fight their way downwards4 ,sidenote3 ,,glacier ,,motion4 #aheg4 ,a great number of secondary glaciers were in sight hanging on the steep slopes of the mountains1 and from them streams sped downwards1 falling over the rocks1 and filling the valley with a low rich music4 ,in front of me1 for example1 was the ,glacier du ,moine1 and ,i could not help feeling as ,i looked at it1 that the arguments drawn from the deportment of such glaciers against the sliding theory1 and which are still repeated in works upon the ,alps1 militate just as strongly against the viscous theory4 ,how1 demands the antagonist of the sliding theory1 can a secondary glacier exist upon so steep a slope8 why does it not slide down as an avalanche8 ,but how1 the person addressed may retort1 can a mass which you assume to be viscous exist under similar conditions8 ,if it be viscous1 what prevents it from rolling down8 ,the sliding theory assumes the lubrication of the bed of the glacier1 but on this cold height the quantity melted is too small to lubricate the bed1 and hence the slow motion of these glaciers4 ,thus a sliding-theory man might reason1 and1 if the external deportment of secondary glaciers were to decide the question1 ,de ,saussure might perhaps have the best of the argument4 ,and with regard to the current idea1 originated by ,m4 de ,charpentier1 and adopted by ,professor ,forbes1 that if a glacier slides it must slide as an avalanche1 it may be simply retorted that1 in part1 it does so2 but if it be asserted that an accelerated motion is the necessary motion of an avalanche1 the statement needs qualification4 ,an avalanche on passing through a rough couloir soon attains a uniform velocity--its motion being accelerated only up to the point when the sum of the resistances acting upon it is equal to the force drawing it downwards4 ,these resistances are furnished by the numberless asperities which the mass encounters1 and which incessantly check its descent1 and render an accumulation of motion impossible4 ,the motion of a man walking down stairs may be on the whole uniform1 but it is really made up of an aggregate of small motions1 each of which is accelerated2 and it is easy to conceive how a glacier moving over an uneven bed1 when released from one opposing obstacle will be checked by another1 and its motion thus rendered sensibly uniform4 ,sidenote3 ,,moraines4 #aheg4 ,sidenote3 ,,tributaries ,,of ,,the ,,mer ,,de ,,glace4 #aheg4 ,illustration3 ,fig4 #g4 ,tributaries of the ,mer de ,glace4 ,from the ,aiguille du ,geant and ,les ,periades a glacier descended1 which was separated by the promontory of ,la ,noire from the glacier proceeding from the ,col du ,geant4 ,a small moraine was formed between them1 which is marked a upon the diagram1 ,fig4 #g4 ,the great mass of the glacier descending from the ,col du ,geant came next1 and this was bounded on the side nearest to ,trelaporte by a small moraine b1 the origin of which ,i could not see1 its upper portion being shut out by a mountain promontory4 ,between the moraine b and the actual side of the valley was another little glacier1 derived from some of the lateral tributaries4 ,it was1 however1 between the moraines a and b that the great mass of the ,glacier du ,geant really lay4 ,at the promontory of the ,tacul the lateral moraines of the ,glacier des ,periades and of the ,glacier de ,lechaud united to form the medial moraine c of the ,mer de ,glace4 ,carrying the eye across the ,lechaud1 we had the moraine d formed by the union of the lateral moraines of the ,lechaud and ,talefre2 further to the left was the moraine e1 which came from the ,jardin1 and beyond it was the second lateral moraine of the ,talefre4 ,the ,mer de ,glace is formed by the confluence of the whole of the glaciers here named2 being forced at ,trelaporte through a passage1 the width of which appears considerably less than that of the single tributary1 the ,glacier du ,geant4 ,in the ice near ,trelaporte the blue veins of the glacier are beautifully shown2 but they vary in distinctness according to the manner in which they are looked at4 ,when regarded obliquely their colour is not so pronounced as when the vision plunges deeply into them4 ,the weathered ice of the surface near ,trelaporte could be cloven with great facility2 ,i could with ease obtain plates of it a quarter of an inch thick1 and possessing two square feet of surface4 ,on the #bhth of ,july ,i followed the veins several times from side to side across the ,geant portion of the ,mer de ,glace2 starting from one side1 and walking along the veins1 my route was directed obliquely downwards towards the axis of the tributary4 ,at the axis ,i was forced to turn1 in order to keep along the veins1 and now ascended along a line which formed nearly the same angle with the axis at the other side4 ,thus the veins led me as it were along the two sides of a triangle1 the vertex of which was near the centre of the glacier4 ,the vertex was1 however1 in reality rounded off1 and the figure rather resembled a hyperbola1 which tended to coincidence with its asymptotes4 ,this observation corroborates those of ,professor ,forbes with regard to the position of the veins1 and1 like him1 ,i found that at the centre the veining1 whose normal direction would be transverse to the glacier1 was contorted and confused4 ,sidenote3 ,,wasting ,,of ,,ice4 #aheg4 ,near the side of the ,glacier du ,geant1 above the promontory of ,trelaporte1 the ice is rent in a remarkable manner4 ,looking upwards from the lower portions of the glacier1 a series of vertical walls1 rising apparently one above the other1 face the observer4 ,i clambered up among these singular terraces1 and now recognise1 both from my sketch and memory1 that their peculiar forms are due to the same action as that which has given their shape to the billows of the ,mer de ,glace4 ,a series of profound crevasses is first formed4 ,the ,glacier du ,geant deviates #ad deg4 from the meridian line1 and hence the sun shines nearly down it during the middle portion of each day4 ,the backs of the ridges between the crevasses are thus rounded off1 one boundary of each fissure is destroyed1 or at least becomes a mere steep declivity1 while the other boundary being shaded from the sun preserves its verticality2 and thus a very curious series of precipices is formed4 ,through all this dislocation1 the little moraine on which ,i have placed the letter b in the sketch maintains its right to existence1 and under it the laminated structure of this portion of the glacier appears to reach its most perfect development4 ,the moraine was generally a mere dirt track1 but one or two immense blocks of granite were perched upon it4 ,i examined the ice underneath one of these1 being desirous of seeing whether the pressure resulting from its enormous weight would produce a veining1 but the result was not satisfactory4 ,veins were certainly to be seen in directions different from the normal ones1 but whether they were due to the bending of the latter1 or were directly owing to the pressure of the block1 ,i could not say4 ,the sides of a stream which had cut a deep gorge in the clean ice of the ,glacier du ,geant afforded a fine opportunity of observing the structure4 ,it was very remarkable--highly significant indeed in a theoretic point of view4 ,two long and remarkably deep blue veins traversed the bottom of the stream1 and bending upwards at a place where the rivulet curved1 drew themselves like a pair of parallel lines upon the clean white ice4 ,but the general structure was of a totally different character2 it did not consist of long bars1 but approximated to the lenticular form1 and was1 moreover1 of a washy paleness1 which scarcely exceeded in depth of colouring the whitish ice around4 ,sidenote3 ,,grooves ,,on ,,the ,,surface4 #aheg4 ,to the investigator of the structure nothing can be finer than the appearance of the glacier from one of the ice terraces cut in the ,glacier du ,geant by its passage round ,trelaporte4 ,as far as the vision extended the dirt upon the surface of the ice was arranged in striae4 ,these striae were not always straight lines1 nor were they unbroken curves4 ,within slight limits the various parts into which a glacier is cut up by its crevasses enjoy a kind of independent motion4 ,the grooves1 for example1 on two ridges which have been separated by a small fissure1 may one day have their striae perfect continuations of each other1 but in a short time this identity of direction may be destroyed by a difference of motion between the ridges4 ,thus it is that the grooves upon the surface above ,trelaporte are bent hither and thither1 a crack or seam always marking the point where their continuity is ruptured4 ,this bending occurs1 however1 within limits sufficiently small to enable the striae to preserve the same general direction4 ,sidenote3 ,,seams ,,of ,,white ,,ice4 #aheg4 ,my attention had often been attracted this day by projecting masses of what at first appeared to be pure white snow1 rising in seams above the general surface of the glacier4 ,on examination1 however1 ,i found them to be compact ice1 filled with innumerable air-cells1 and so resistant as to maintain itself in some places at a height of four feet above the general level4 ,when amongst the ridges they appeared discontinuous and confused1 being scattered apparently at random over the glacier2 but when viewed from a sufficient distance1 the detached parts showed themselves to belong to a system of white seams which swept quite across the ,glacier du ,geant1 in a direction concentric with the structure4 ,unable to account for these singular seams1 ,i climbed up among the tributary glaciers on the ,rognon side of the ,glacier du ,geant1 and remained there until the sun sank behind the neighbouring peaks1 and the fading light warned me that it was time to return4 ,,footnotes3 ,a ,le petit ,balmat my host always called him4 ,b ,to such towers the name ,seracs is applied4 ,in the chalets of ,savoy1 after the richer curd has been precipitated by rennet1 a stronger acid is used to throw down what remains2 an inferior kind of cheese called ,serac is thus formed1 the shape and colour of which have suggested the application of the term to the cubical masses of ice4 7#h47 ,early on the following day ,i was again upon the ice4 ,i first confined myself to the right side of the ,glacier du ,geant1 and found that the veins of white ice which ,i had noticed on the previous day were exclusively confined to this glacier1 or to the space between the moraines a and b 7,fig4 #g71 bending up so that the moraine a between the ,glacier du ,geant and the ,glacier des ,periades was tangent to them4 ,at a good distance up the glacier ,i encountered a considerable stream rushing across it almost from side to side4 ,i followed the rivulet1 examining the sections which it exposed4 ,at a certain point three other streams united1 and formed at their place of confluence a small green lake4 ,from this a rivulet rushed1 which was joined by the stream whose track ,i had pursued1 and at this place of junction a second green lake was formed1 from which flowed a stream equal in volume to the sum of all the tributaries4 ,it entered a crevasse1 and took the bottom of the fissure for its bed4 ,standing at the entrance of the chasm1 a low muffled thunder resounding through the valley attracted my attention4 ,i followed the crevasse1 which deepened and narrowed1 and1 by the blue light of the ice1 could see the stream gambolling along its bottom1 and flashing as it jumped over the ledges which it encountered in its way4 ,the fissure at length came to an end3 placing a foot on each side of it1 and withholding the stronger light from my eyes1 ,i looked down between its shining walls1 and saw the stream plunge into a shaft which carried it to the bottom of the glacier4 ,slowly1 and in zigzag fashion1 as the crevasses demanded1 ,i continued to ascend1 sometimes climbing vast humps of ice from which good views of the surrounding glacier were obtained2 sometimes hidden in the hollows between the humps1 in which also green glacier tarns were often formed1 very lonely and very beautiful4 ,sidenote3 ,a ,,lake ,,set ,,free4 #aheg4 ,while standing beside one of these1 and watching the moving clouds which it faithfully mirrored1 ,i heard the sound of what appeared to be a descending avalanche1 but the time of its continuance surprised me4 ,looking through my opera-glass in the direction of the sound1 ,i saw issuing from the end of a secondary glacier on the ,tacul side a torrent of what appeared to me to be stones and mud4 ,i could see the stones and finer debris jumping down the declivities1 and shaping themselves into singular cascades4 ,the noise continued for a quarter of an hour1 after which the torrent rapidly diminished1 until1 at length1 the ordinary little stream due to the melting of the glacier alone remained4 ,a subglacial lake had burst its boundary1 and carried along with it in its rush downwards the debris which it met with in its course4 ,sidenote3 ,,impressive ,,scene4 #aheg4 ,in some places ,i found the crevasses difficult1 the ice being split in a very singular manner4 ,vast plates of it not more than a foot in thickness were sometimes detached from the sides of the crevasses1 and stood alone4 ,i was now approaching the base of the seracs1 and the glacier around me still retained a portion of the turbulence of the cascade4 ,i halted at times amid the ruin and confusion1 and examined with my glass the cascade itself4 ,it was a wild and wonderful scene1 suggesting throes of spasmodic energy1 though1 in reality1 all its dislocation had been slowly and gradually produced4 ,true1 the stratified blocks which here and there cumbered the terraces suggested debacles1 but these were local and partial1 and did not affect the general question4 ,there is scarcely a case of geological disturbance which could not be matched with its analogue upon the glaciers1--contortions1 faults1 fissures1 joints1 and dislocations1--but in the case of the ice we can prove the effects to be due to slowly-acting causes2 how reasonable is it then to ascribe to the operation of similar causes1 which have had an incomparably longer time to work1 many geological effects which at first sight might suggest sudden convulsion6 ,wandering slowly upwards1 successive points of attraction drawing me almost unconsciously on1 ,i found myself as the day was declining deep in the entanglements of the ice4 ,a shower commenced1 and a splendid rainbow threw an oblique arch across the glacier4 ,i was quite alone2 the scene was exceedingly impressive1 and the possibility of difficulties on which ,i had not calculated intervening between me and the lower glacier1 gave a tinge of anxiety to my position4 ,i turned towards home2 crossed some bosses of ice and rounded others2 ,i followed the tracks of streams which were very irregular on this portion of the glacier1 bending hither and thither1 rushing through deep-cut channels1 falling in cascades and expanding here and there to deep green lakes2 they often plunged into the depths of the ice1 flowed under it with hollow gurgle1 and reappeared at some distant point4 ,i threaded my way cautiously amid systems of crevasses1 scattering with my axe1 to secure a footing1 the rotten ice of the sharper crests1 which fell with a ringing sound into the chasms at either side4 ,strange subglacial noises were sometimes heard1 as if caverns existed underneath1 into which blocks of ice fell at intervals1 transmitting the shock of their fall with a dull boom to the surface of the glacier4 ,by the steady surmounting of difficulties one after another1 ,i at length placed them all behind me1 and afterwards hastened swiftly along the glacier to my mountain home4 ,sidenote3 ,,chamouni ,,rules4 #aheg4 ,on the #cjth incessant rain confined us to indoor work2 on the #cast we determined the velocity with which the glacier is forced through the entrance of the trunk valley at ,trelaporte1 and also the motion of the ,grand ,moulin4 ,we also determined both the velocity and the width of the ,glacier du ,geant4 ,the #ast of ,august was spent by me at the cascade of the ,talefre1 examining the structure1 crumpling1 and scaling off of the ice4 ,finding that the rules at ,chamouni put an unpleasant limit to my demands on my guide ,simond1 ,i visited the ,guide ,chef on the #bnd of ,august1 and explained to him the object of my expedition1 pointing out the inconvenience which a rigid application of the rules made for tourists would impose upon me4 ,he had then the good sense to acknowledge the reasonableness of my remarks1 and to grant me the liberty ,i requested4 ,the #crd of ,august was employed in determining the velocity and width of the ,glacier de ,lechaud1 and in observations on the lamination of the glacier4 ,sidenote3 ,,the ,,jardin4 #aheg4 ,,the ,,jardin4 7#i47 ,sidenote3 ,a ,,reservoir ,,of ,,ice4 #aheg4 ,on the #dth of ,august1 with a view of commencing a series of observations on the inclinations of the ,mer de ,glace and its tributaries1 we had our theodolite transported to the ,jardin1 which1 as is well known1 lies like an island in the middle of the ,glacier du ,talefre4 ,we reached the place by the usual route1 and found some tourists reposing on the soft green sward which covers the lower portion1 and to which1 and the flowers which spangle it1 the place owes its name4 ,towards the summit of the ,jardin1 a rock jutted forward1 apparently the very apex of the place1 or at least hiding by its prominence everything that might exist behind it2 leaving our guide with the instrument1 we aimed at this1 and soon left the grass and flowers behind us4 ,stepping amid broken fragments of rock1 along slopes of granite1 with fat felspar crystals which gave the boots a hold1 and crossing at intervals patches of snow1 which continued still to challenge the summer heat1 ,i at length found myself upon the peak referred to2 and1 although it was not the highest1 the unimpeded view which it commanded induced me to get astride it4 ,the ,jardin was completely encircled by the ice of the glacier1 and this was held in a mountain basin1 which was bounded all round by a grand and cliffy rim4 ,the outline of the dark brown crags--a deeply serrated and irregular line--was forcibly drawn against the blue heaven1 and still more strongly against some white and fleecy clouds which lay here and there behind it2 while detached spears and pillars of rock1 sculptured by frost and lightning1 stood like a kind of defaced statuary along the ridge4 ,all round the basin the snow reared itself like a buttress against the precipitous cliffs1 being streaked and fluted by the descent of blocks from the summits4 ,this mighty tub is the collector of one of the tributaries of the ,mer de ,glace4 ,according to ,professor ,forbes1 its greatest diameter is #dbjj yards1 and out of it the half-formed ice is squeezed through a precipitous gorge about #gjj yards wide1 forming there the ice cascade of the ,talefre4 ,bounded on one side by the ,grande ,jorasse1 and on the other by ,mont ,mallet1 the principal tributary of the ,glacier de ,lechaud lay white and pure upon the mountain slope4 ,round further to the right we had the vast plateau whence the ,glacier du ,geant is fed1 fenced on the left by the ,aiguille du ,geant and the ,aiguille ,noire1 and on the right by the ,monts ,maudits and ,mont ,blanc4 ,the scene was a truly majestic one4 ,the mighty ,aiguilles piercing the sea of air1 the soft white clouds floating here and there behind them2 the shining snow with its striped faults and precipices2 the deep blue firmament overhead2 the peals of avalanches and the sound of water2--all conspired to render the scene glorious1 and our enjoyment of it deep4 ,a voice from above hailed me as ,i moved from my perch2 it was my friend1 who had found a lodgment upon the edge of a rock which was quite detached from the ,jardin1 being the first to lift its head in opposition to the descending neve4 ,making a detour round a steep concave slope of the glacier1 ,i reached the flat summit of the rock4 ,the end of a ridge of ice abutted against it1 which was split and bent by the pressure so as to form a kind of arch4 ,i cut steps in the ice1 and ascended until ,i got beneath the azure roof4 ,innumerable little rills of pellucid water descended from it4 ,some came straight down1 clear for a time1 and apparently motionless1 rapidly tapering at first1 and more slowly afterwards1 until1 at the point of maximum contraction1 they resolved themselves into strings of liquid pearls which pattered against the ice floor underneath4 ,others again1 owing to the directions of the little streamlets of which they were constituted1 formed spiral figures of great beauty3 one liquid vein wound itself round another1 forming a spiral protuberance1 and owing to the centrifugal motion thus imparted1 the vein1 at its place of rupture1 scattered itself laterally in little liquid spherules4,a ,even at this great elevation the structure of the ice was fairly developed1 not with the sharpness to be observed lower down1 but still perfectly decided4 ,blue bands crossed the ridge of ice to which ,i have referred1 at right angles to the direction of the pressure4 ,sidenote3 ,,moraines ,,of ,,the ,,talefre4 #aheg4 ,i descended1 and found my friend beneath an overhanging rock4 ,immediately afterwards a peal like that of thunder shook the air1 and right in front of us an avalanche darted down the brown cliffs1 then along a steep slope of snow which reared itself against the mountain wall1 carrying with it the debris of the rocks over which it passed1 until it finally lay a mass of sullied rubbish at the base of the incline3 the whole surface of the ,talefre is thus soiled4 ,another peal was heard immediately afterwards1 but the avalanche which caused it was hidden from us by a rocky promontory4 ,from this same promontory the greater portion of the medial moraine which descends the cascade of the ,talefre is derived1 forming at first a gracefully winding curve1 and afterwards stretching straight to the summit of the fall4 ,in the chasms of the cascade its boulders are engulfed1 but the lost moraine is restored below the fall1 as if disgorged by the ice which had swallowed it4 ,from the extremity of the ,jardin itself a mere driblet of a moraine proceeds1 running parallel to the former1 and like it disappearing at the summit of the cascade4 ,sidenote3 ,,among ,,the ,,crevasses4 #aheg4 ,we afterwards descended towards the cascade1 but long before this is attained the most experienced iceman would find himself in difficulty4 ,transverse crevasses are formed1 which follow each other so speedily as to leave between them mere narrow ridges of ice1 along which we moved cautiously1 jumping the adjacent fissures1 or getting round them1 as the case demanded4 ,as we approached the jaws of the gorge1 the ridges dwindled to mere plates and wedges1 which being bent and broken by the lateral pressure1 added to the confusion1 and warned us not to advance4 ,the position was in some measure an exciting one4 ,our guide had never been here before2 we were far from the beaten track1 and the riven glacier wore an aspect of treacherous hostility4 ,as at the base of the seracs1 a subterranean noise sometimes announced the falling of ice-blocks into hollows underneath1 the existence of which the resonant concussion of the fallen mass alone revealed4 ,there was thus a dash of awe mingled with our thoughts2 a stirring up of the feelings which troubled the coolness of the intellect4 ,we finally swerved to the right1 and by a process the reverse of straightforward reached the ,couvercle4 ,nightfall found us at the threshold of our hotel4 ,,footnotes3 ,a ,the recent hydraulic researches of ,professor ,magnus furnish some beautiful illustrations of this action4 7#aj47 ,sidenote3 ,,round ,,hailstones4 #aheg4 ,sidenote3 ,a ,,dangerous ,,leap4 #aheg4 ,on the #eth we were engaged for some time in an important measurement at the ,tacul4 ,we afterwards ascended towards the seracs1 and determined the inclinations of the ,glacier du ,geant downwards4 ,dense cloud-masses gathered round the points of the ,aiguilles1 and the thunder bellowed at intervals from the summit of ,mont ,blanc4 ,as we descended the ,mer de ,glace the valley in front of us was filled with a cloud of pitchy darkness4 ,suddenly from side to side this field of gloom was riven by a bar of lightning of intolerable splendour2 it was followed by a peal of commensurate grandeur1 the echoes of which leaped from cliff to cliff long after the first sound had died away4 ,the discharge seemed to unlock the clouds above us1 for they showered their liquid spheres down upon us with a momentum like that of swan-shot3 all the way home we were battered by this pellet-like rain4 ,on the #fth the rain continued with scarcely any pause2 on the #gth ,i was engaged all day upon the ,glacier du ,geant2 on the morning of the #hth heavy hail had fallen there1 the stones being perfect spheres2 the rounded rain-drops had solidified during their descent without sensible change of form4 ,when this hail was squeezed together1 it exactly resembled a mass of oolitic limestone which ,i had picked up in #ahec near ,blankenburg in the ,hartz4 ,mr4 ,hirst and myself were engaged together this day taking the inclinations3 he struck his theodolite at the ,angle1 and went home accompanied by ,simond1 and the evening being extremely serene1 ,i pursued my way down the centre of the glacier towards the ,echelets4 ,the crevasses as ,i advanced became more deep and frequent1 the ridges of ice between them becoming gradually narrower4 ,they were very fine1 their downward faces being clear cut1 perfectly vertical1 and in many cases beautifully veined4 ,vast plates of ice moreover often stood out midway between the walls of the chasms1 as if cloven from the glacier and afterwards set on edge4 ,the place was certainly one calculated to test the skill and nerve of an iceman2 and as the day drooped1 and the shadow in the valley deepened1 a feeling approaching to awe took possession of me4 ,my route was an exaggerated zigzag2 right and left amid the chasms wherever a hope of progress opened2 and here ,i made the experience which ,i have often repeated since1 and laid to heart as regards intellectual work also1 that enormous difficulties may be overcome when they are attacked in earnest4 ,sometimes ,i found myself so hedged in by fissures that escape seemed absolutely impossible2 but close and resolute examination so often revealed a means of exit1 that ,i felt in all its force the brave verity of the remark of ,mirabeau1 that the word impossible is a mere blockhead of a word4 ,it finally became necessary to reach the shore1 but ,i found this a work of extreme difficulty4 ,at length1 however1 it became pretty evident that1 if ,i could cross a certain crevasse1 my retreat would be secured4 ,the width of the fissure seemed to be fairly within jumping distance1 and if ,i could have calculated on a safe purchase for my foot ,i should have thought little of the spring2 but the ice on the edge from which ,i was to leap was loose and insecure1 and hence a kind of nervous thrill shot through me as ,i made the bound4 ,the opposite side was fairly reached1 but an involuntary tremor shook me all over after ,i felt myself secure4 ,i reached the edge of the glacier without further serious difficulty1 and soon after found myself steeped in the creature comforts of our hotel4 ,on ,monday1 ,august #ajth1 ,i had the great pleasure of being joined by my friend ,huxley2 and though the weather was very unpromising1 we started together up the glacier1 he being desirous to learn something of its general features1 and1 if possible1 to reach the ,jardin4 ,we reached the ,couvercle1 and squeezed ourselves through the ,egralets2 but here the rain whizzed past us1 and dense fog settled upon the cascade of the ,talefre1 obscuring all its parts4 ,we met ,mr4 ,galton1 the ,african traveller1 returning from an attempt upon the ,jardin2 and learning that his guides had lost their way in the fog1 we deemed it prudent to return4 ,the foregoing brief notes will have informed the reader that at the period of ,mr4 ,huxley's arrival ,i was not without due training upon the ice2 ,i may also remark1 that on the #beth of ,july ,i reached the summit of the ,col du ,geant1 accompanied by the boy ,balmat1 and returned to the ,montanvert on the same day4 ,my health was perfect1 and incessant practice had taught me the art of dealing with the difficulties of the ice4 ,from the time of my arrival at the ,montanvert the thought of ascending ,mont ,blanc1 and thus expanding my knowledge of the glaciers1 had often occurred to me1 and ,i think ,i was justified in feeling that the discipline which both my friend ,hirst and myself had undergone ought to enable us to accomplish the journey in a much more modest way than ordinary4 ,i thought a single guide sufficient for this purpose1 and ,i was strengthened in this opinion by the fact that ,simond1 who was a man of the strictest prudence1 and who at first declared four guides to be necessary1 had lowered his demand first to two1 and was now evidently willing to try the ascent with us alone4 ,sidenote3 ,,preparations ,,for ,a ,,climb4 #aheg4 ,on mentioning the thing to ,mr4 ,huxley he at once resolved to accompany us4 ,on the #aath of ,august the weather was exceedingly fine1 though the snow which had fallen during the previous days lay thick upon the glacier4 ,at noon we were all together at the ,tacul1 and the subject of attempting ,mont ,blanc was mooted and discussed4 ,my opinion was that it would be better to wait until the fresh snow which loaded the mountain had disappeared2 but the weather was so exquisite that my friends thought it best to take advantage of it4 ,we accordingly entered into an agreement with our guide1 and immediately descended to make preparations for commencing the expedition on the following morning4 ,,first ,,ascent ,,of ,,mont ,,blanc1 #aheg4 7#aa47 ,sidenote3 ,,scene ,,from ,,the ,,charmoz4 #aheg4 ,on ,wednesday1 the #abth of ,august1 we rose early1 after a very brief rest on my part4 ,simond had proposed to go down to ,chamouni1 and commence the ascent in the usual way1 but we preferred crossing the mountains from the ,montanvert1 straight to the ,glacier des ,bossons4 ,at eight o'clock we started1 accompanied by two porters who were to carry our provisions to the ,grands ,mulets4 ,slowly and silently we climbed the hill-side towards ,charmoz4 ,we soon passed the limits of grass and rhododendrons1 and reached the slabs of gneiss which overspread the summit of the ridge1 lying one upon the other like coin upon the table of a money-changer4 ,from the highest-point ,i turned to have a last look at the ,mer de ,glace2 and through a pair of very dark spectacles ,i could see with perfect distinctness the looped dirt-bands of the glacier1 which to the naked eye are scarcely discernible except by twilight4 ,flanking our track to the left rose a series of mighty ,aiguilles--the ,aiguille de ,charmoz1 with its bent and rifted pinnacles2 the ,aiguille du ,grepon1 the ,aiguille de ,blaitiere1 the ,aiguille du ,midi1 all piercing the heavens with their sharp pyramidal summits4 ,far in front of us rose the grand snow-cone of the ,dome du ,gouter1 while1 through a forest of dark pines which gathered like a cloud at the foot of the mountain1 gleamed the white minarets of the ,glacier des ,bossons4 ,below us lay the ,valley of ,chamouni1 beyond which were the ,brevent and the chain of the ,aiguilles ,rouges2 behind us was the granite obelisk of the ,aiguille du ,dru1 while close at hand science found a corporeal form in a pyramid of stones used as a trigonometrical station by ,professor ,forbes4 ,sound is known to travel better up hill than down1 because the pulses transmitted from a denser medium to a rarer1 suffer less loss of intensity than when the transmission is in the opposite direction2 and now the mellow voice of the ,arve came swinging upwards from the heavier air of the valley to the lighter air of the hills in rich deep cadences4 ,sidenote3 ,,passage ,,to ,,the ,,pierre ,a ,l',,echelle4 #aheg4 ,the way for a time was excessively rough1 our route being overspread with the fragments of peaks which had once reared themselves to our left1 but which frost and lightning had shaken to pieces1 and poured in granite avalanches down the mountain4 ,we were sometimes among huge angular boulders1 and sometimes amid lighter shingle1 which gave way at every step1 thus forcing us to shift our footing incessantly4 ,escaping from these1 we crossed the succession of secondary glaciers which lie at the feet of the ,aiguilles1 and having secured firewood found ourselves after some hours of hard work at the ,pierre a l',echelle4 ,here we were furnished with leggings of coarse woollen cloth to keep out the snow2 they were tied under the knees and quite tightly again over the insteps1 so that the legs were effectually protected4 ,we had some refreshment1 possessed ourselves of the ladder1 and entered upon the glacier4 ,sidenote3 ,,ladder ,,left ,,behind4 #aheg4 ,sidenote3 ,,difficult ,,crevasses4 #aheg4 ,the ice was excessively fissured3 we crossed crevasses and crept round slippery ridges1 cutting steps in the ice wherever climbing was necessary4 ,this rendered our progress very slow4 ,once1 with the intention of lending a helping hand1 ,i stepped forward upon a block of granite which happened to be poised like a rocking stone upon the ice1 though ,i did not know it2 it treacherously turned under me2 ,i fell1 but my hands were in instant requisition1 and ,i escaped with a bruise1 from which1 however1 the blood oozed angrily4 ,we found the ladder necessary in crossing some of the chasms1 the iron spikes at its end being firmly driven into the ice at one side1 while the other end rested on the opposite side of the fissure4 ,the middle portion of the glacier was not difficult4 ,mounds of ice rose beside us right and left1 which were sometimes split into high towers and gaunt-looking pyramids1 while the space between was unbroken4 ,twenty minutes' walking brought us again to a fissured portion of the glacier1 and here our porter left the ladder on the ice behind him4 ,for some time ,i was not aware of this1 but we were soon fronted by a chasm to pass which we were in consequence compelled to make a long and dangerous circuit amid crests of crumbling ice4 ,this accomplished1 we hoped that no repetition of the process would occur1 but we speedily came to a second fissure1 where it was necessary to step from a projecting end of ice to a mass of soft snow which overhung the opposite side4 ,simond could reach this snow with his long-handled axe2 he beat it down to give it rigidity1 but it was exceedingly tender1 and as he worked at it he continued to express his fears that it would not bear us4 ,i was the lightest of the party1 and therefore tested the passage1 first2 being partially lifted by ,simond on the end of his axe1 ,i crossed the fissure1 obtained some anchorage at the other side1 and helped the others over4 ,we afterwards ascended until another chasm1 deeper and wider than any we had hitherto encountered1 arrested us4 ,we walked alongside of it in search of a snow bridge1 which we at length found1 but the keystone of the arch had unfortunately given way1 leaving projecting eaves of snow at both sides1 between which we could look into the gulf1 till the gloom of its deeper portions cut the vision short4 ,both sides of the crevasse were sounded1 but no sure footing was obtained2 the snow was beaten and carefully trodden down as near to the edge as possible1 but it finally broke away from the foot and fell into the chasm4 ,one of our porters was short-legged and a bad iceman2 the other was a daring fellow1 and he now threw the knapsack from his shoulders1 came to the edge of the crevasse1 looked into it1 but drew back again4 ,after a pause he repeated the act1 testing the snow with his feet and staff4 ,i looked at the man as he stood beside the chasm manifestly undecided as to whether he should take the step upon which his life would hang1 and thought it advisable to put a stop to such perilous play4 ,i accordingly interposed1 the man withdrew from the crevasse1 and he and ,simond descended to fetch the ladder4 ,while they were away ,huxley sat down upon the ice1 with an expression of fatigue stamped upon his countenance3 the spirit and the muscles were evidently at war1 and the resolute will mixed itself strangely with the sense of peril and feeling of exhaustion4 ,he had been only two days with us1 and1 though his strength is great1 he had had no opportunity of hardening himself by previous exercise upon the ice for the task which he had undertaken4 ,the ladder now arrived1 and we crossed the crevasse4 ,i was intentionally the last of the party1 ,huxley being immediately in front of me4 ,the determination of the man disguised his real condition from everybody but myself1 but ,i saw that the exhausting journey over the boulders and debris had been too much for his ,london limbs4 ,converting my waterproof haversack into a cushion1 ,i made him sit down upon it at intervals1 and by thus breaking the steep ascent into short stages we reached the cabin of the ,grands ,mulets together4 ,here ,i spread a rug on the boards1 and placing my bag for a pillow1 he lay down1 and after an hour's profound sleep he rose refreshed and well2 but still he thought it wise not to attempt the ascent farther4 ,our porters left us3 a baton was stretched across the room over the stove1 and our wet socks and leggings were thrown across it to dry2 our boots were placed around the fire1 and we set about preparing our evening meal4 ,a pan was placed upon the fire1 and filled with snow1 which in due time melted and boiled2 ,i ground some chocolate and placed it in the pan1 and afterwards ladled the beverage into the vessels we possessed1 which consisted of two earthen dishes and the metal cases of our brandy flasks4 ,after supper ,simond went out to inspect the glacier1 and was observed by ,huxley1 as twilight fell1 in a state of deep contemplation beside a crevasse4 ,sidenote3 ,,star ,,twinkling4 #aheg4 ,gradually the stars appeared1 but as yet no moon4 ,before lying down we went out to look at the firmament1 and noticed1 what ,i suppose has been observed to some extent by everybody1 that the stars near the horizon twinkled busily1 while those near the zenith shone with a steady light4 ,one large star in particular excited our admiration2 it flashed intensely1 and changed colour incessantly1 sometimes blushing like a ruby1 and again gleaming like an emerald4 ,a determinate colour would sometimes remain constant for a sensible time1 but usually the flashes followed each other in very quick succession4 ,three planks were now placed across the room near the stove1 and upon these1 with their rugs folded round them1 ,huxley and ,hirst stretched themselves1 while ,i nestled on the boards at the most distant end of the room4 ,we rose at eleven o'clock1 renewed the fire and warmed ourselves1 after which we lay down again4 ,i at length observed a patch of pale light upon the wooden wall of the cabin1 which had entered through a hole in the end of the edifice1 and rising found that it was past one o'clock4 ,the cloudless moon was shining over the wastes of snow1 and the scene outside was at once wild1 grand1 and beautiful4 ,sidenote3 ,,start ,,from ,,the ,,grands ,,mulets4 #aheg4 ,breakfast was soon prepared1 though not without difficulty2 we had no candles1 they had been forgotten2 but ,i fortunately possessed a box of wax matches1 of which ,huxley took charge1 patiently igniting them in succession1 and thus giving us a tolerably continuous light4 ,we had some tea1 which had been made at the ,montanvert1 and carried to the ,grands ,mulets in a bottle4 ,my memory of that tea is not pleasant2 it had been left a whole night in contact with its leaves1 and smacked strongly of tannin4 ,the snow-water1 moreover1 with which we diluted it was not pure1 but left a black residuum at the bottom of the dishes in which the beverage was served4 ,the few provisions deemed necessary being placed in ,simond's knapsack1 at twenty minutes past two o'clock we scrambled down the rocks1 leaving ,huxley behind us4 ,the snow was hardened by the night's frost1 and we were cheered by the hope of being able to accomplish the ascent with comparatively little labour4 ,we were environed by an atmosphere of perfect purity2 the larger stars hung like gems above us1 and the moon1 about half full1 shone with wondrous radiance in the dark firmament4 ,one star in particular1 which lay eastward from the moon1 suddenly made its appearance above one of the ,aiguilles1 and burned there with unspeakable splendour4 ,we turned once towards the ,mulets1 and saw ,huxley's form projected against the sky as he stood upon a pinnacle of rock2 he gave us a last wave of the hand and descended1 while we receded from him into the solitudes4 ,the evening previous our guide had examined the glacier for some distance1 his progress having been arrested by a crevasse4 ,beside this we soon halted3 it was spanned at one place by a bridge of snow1 which was of too light a structure to permit of ,simond's testing it alone2 we therefore paused while our guide uncoiled a rope and tied us all together4 ,the moment was to me a peculiarly solemn one4 ,our little party seemed so lonely and so small amid the silence and the vastness of the surrounding scene4 ,we were about to try our strength under unknown conditions1 and as the various possibilities of the enterprise crowded on the imagination1 a sense of responsibility for a moment oppressed me4 ,but as ,i looked aloft and saw the glory of the heavens1 my heart lightened1 and ,i remarked cheerily to ,hirst that ,nature seemed to smile upon our work4 ,yes1 he replied1 in a calm and earnest voice1 and1 ,god willing1 we shall accomplish it4 ,sidenote3 ,a ,,wrong ,,turn4 #aheg4 ,a pale light now overspread the eastern sky1 which increased1 as we ascended1 to a daffodil tinge2 this afterwards heightened to orange1 deepening at one extremity into red1 and fading at the other into a pure ethereal hue to which it would be difficult to assign a special name4 ,higher up the sky was violet1 and this changed by insensible degrees into the darkling blue of the zenith1 which had to thank the light of moon and stars alone for its existence4 ,we wound steadily for a time through valleys of ice1 climbed white and slippery slopes1 crossed a number of crevasses1 and after some time found ourselves beside a chasm of great depth and width1 which extended right and left as far as we could see4 ,we turned to the left1 and marched along its edge in search of a pont2 but matters became gradually worse3 other crevasses joined on to the first one1 and the further we proceeded the more riven and dislocated the ice became4 ,at length we reached a place where further advance was impossible4 ,simond in his difficulty complained of the want of light1 and wished us to wait for the advancing day2 ,i1 on the contrary1 thought that we had light enough and ought to make use of it4 ,here the thought occurred to me that ,simond1 having been only once before to the top of the mountain1 might not be quite clear about the route2 the glacier1 however1 changes within certain limits from year to year1 so that a general knowledge was all that could be expected1 and we trusted to our own muscles to make good any mistake in the way of guidance4 ,we now turned and retraced our steps along the edges of chasms where the ice was disintegrated and insecure1 and succeeded at length in finding a bridge which bore us across the crevasse4 ,this error caused us the loss of an hour1 and after walking for this time we could cast a stone from the point we had attained to the place whence we had been compelled to return4 ,sidenote3 ,,seracs ,,of ,,the ,,dome ,,du ,,gouter4 #aheg4 ,our way now lay along the face of a steep incline of snow1 which was cut by the fissure we had just passed1 in a direction parallel to our route4 ,on the heights to our right1 loose ice-crags seemed to totter1 and we passed two tracks over which the frozen blocks had rushed some short time previously4 ,we were glad to get out of the range of these terrible projectiles1 and still more so to escape the vicinity of that ugly crevasse4 ,to be killed in the open air would be a luxury1 compared with having the life squeezed out of one in the horrible gloom of these chasms4 ,the blush of the coming day became more and more intense2 still the sun himself did not appear1 being hidden from us by the peaks of the ,aiguille du ,midi1 which were drawn clear and sharp against the brightening sky4 ,right under this ,aiguille were heaps of snow smoothly rounded and constituting a portion of the sources whence the ,glacier du ,geant is fed2 these1 as the day advanced1 bloomed with a rosy light4 ,we reached the ,petit ,plateau1 which we found covered with the remains of ice avalanches2 above us upon the crest of the mountain rose three mighty bastions1 divided from each other by deep vertical rents1 with clean smooth walls1 across which the lines of annual bedding were drawn like courses of masonry4 ,from these1 which incessantly renew themselves1 and from the loose and broken ice-crags near them1 the boulders amid which we now threaded our way had been discharged4 ,when they fall their descent must be sublime4 ,sidenote3 ,,the ,,lost ,,guides4 #aheg4 ,the snow had been gradually getting deeper1 and the ascent more wearisome1 but superadded to this at the ,petit ,plateau was the uncertainty of the footing between the blocks of ice4 ,in many places the space was merely covered by a thin crust1 which1 when trod upon1 instantly yielded1 and we sank with a shock sometimes to the hips4 ,our way next lay up a steep incline to the ,grand ,plateau1 the depth and tenderness of the snow augmenting as we ascended4 ,we had not yet seen the sun1 but1 as we attained the brow which forms the entrance to the ,grand ,plateau1 he hung his disk upon a spike of rock to our left1 and1 surrounded by a glory of interference spectra of the most gorgeous colours1 blazed down upon us4 ,on the ,grand ,plateau we halted and had our frugal refreshment4 ,at some distance to our left was the crevasse into which ,dr4 ,hamel's three guides were precipitated by an avalanche in #ahbj2 they are still entombed in the ice1 and some future explorer may perhaps see them disgorged lower down1 fresh and undecayed4 ,they can hardly reach the surface until they pass the snow-line of the glacier1 for above this line the quantity of snow that annually falls being in excess of the quantity melted1 the tendency would be to make the ice-covering above them thicker4 ,but it is also possible that the waste of the ice underneath may have brought the bodies to the bed of the glacier1 where their very bones may have been ground to mud by an agency which the hardest rocks cannot withstand4 ,sidenote3 ,,the ,,guide ,,tired4 #aheg4 ,sidenote3 ,a ,,perilous ,,slope4 #aheg4 ,as the sun poured his light upon the ,plateau the little snow-facets sparkled brilliantly1 sometimes with a pure white light1 and at others with prismatic colours4 ,contrasted with the white spaces above and around us were the dark mountains on the opposite side of the valley of ,chamouni1 around which fantastic masses of cloud were beginning to build themselves4 ,mont ,buet1 with its cone of snow1 looked small1 and the ,brevent altogether mean2 the limestone bastions of the ,fys1 however1 still presented a front of gloom and grandeur4 ,we traversed the ,grand ,plateau1 and at length reached the base of an extremely steep incline which stretched upwards towards the ,corridor4 ,here1 as if produced by a fault1 consequent upon the sinking of the ice in front1 rose a vertical precipice1 from the coping of which vast stalactites of ice depended4 ,previous to reaching this place ,i had noticed a haggard expression upon the countenance of our guide1 which was now intensified by the prospect of the ascent before him4 ,hitherto he had always been in front1 which was certainly the most fatiguing position4 ,i felt that ,i must now take the lead1 so ,i spoke cheerily to the man and placed him behind me4 ,marking a number of points upon the slope as resting places1 ,i went swiftly from one to the other4 ,the surface of the snow had been partially melted by the sun and then refrozen1 thus forming a superficial crust1 which bore the weight up to a certain point1 and then suddenly gave way1 permitting the leg to sink to above the knee4 ,the shock consequent on this1 and the subsequent effort necessary to extricate the leg1 were extremely fatiguing4 ,my motion was complained of as too quick1 and my tracks as imperfect2 ,i moderated the former1 and1 to render my footholes broad and sure1 ,i stamped upon the frozen crust1 and twisted my legs in the soft mass underneath1--a terribly exhausting process4 ,i thus led the way to the base of the ,rochers ,rouges1 up to which the fault already referred to had prolonged itself as a crevasse1 which was roofed at one place by a most dangerous-looking snow-bridge4 ,simond came to the front2 ,i drew his attention to the state of the snow1 and proposed climbing the ,rochers ,rouges2 but1 with a promptness unusual with him1 he replied that this was impossible2 the bridge was our only means of passing1 and we must try it4 ,we grasped our ropes1 and dug our feet firmly into the snow to check the man's descent if the pont gave way1 but to our astonishment it bore him1 and bore us safely after him4 ,the slope which we had now to ascend had the snow swept from its surface1 and was therefore firm ice4 ,it was most dangerously steep1 and1 its termination being the fretted coping of the precipice to which ,i have referred1 if we slid downwards we should shoot over this and be dashed to pieces upon the ice below4,a ,simond1 who had come to the front to cross the crevasse1 was now engaged in cutting steps1 which he made deep and large1 so that they might serve us on our return4 ,but the listless strokes of his axe proclaimed his exhaustion2 so ,i took the implement out of his hands1 and changed places with him4 ,step after step was hewn1 but the top of the ,corridor appeared ever to recede from us4 ,hirst was behind unoccupied1 and could thus turn his thoughts to the peril of our position3 he felt the angle on which we hung1 and saw the edge of the precipice1 to which less than a quarter of a minute's slide would carry us1 and for the first time during the journey he grew giddy4 ,a cigar which he lighted for the purpose tranquilized him4 ,sidenote3 ,,will ,,and ,,muscle4 #aheg4 ,i hewed sixty steps upon this slope1 and each step had cost a minute1 by ,hirst's watch4 ,the ,mur de la ,cote was still before us1 and on this the guide-books informed us two or three hundred steps were sometimes found necessary4 ,if sixty steps cost an hour1 what would be the cost of two hundred8 ,the question was disheartening in the extreme1 for the time at which we had calculated on reaching the summit was already passed1 while the chief difficulties remained unconquered4 ,having hewn our way along the harder ice we reached snow4 ,i again resorted to stamping to secure a footing1 and while thus engaged became1 for the first time1 aware of the drain of force to which ,i was subjecting myself4 ,the thought of being absolutely exhausted had never occurred to me1 and from first to last ,i had taken no care to husband my strength4 ,i always calculated that the will would serve me even should the muscles fail1 but ,i now found that mechanical laws rule man in the long run2 that no effort of will1 no power of spirit1 can draw beyond a certain limit upon muscular force4 ,the soul1 it is true1 can stir the body to action1 but its function is to excite and apply force1 and not to create it4 ,while stamping forward through the frozen crust ,i was compelled to pause at short intervals2 then would set out again apparently fresh1 to find1 however1 in a few minutes that my strength was gone1 and that ,i required to rest once more4 ,in this way ,i gained the summit of the ,corridor1 when ,hirst came to the front1 and ,i felt some relief in stepping slowly after him1 making use of the holes into which his feet had sunk4 ,he thus led the way to the base of the ,mur de la ,cote1 the thought of which had so long cast a gloom upon us2 here we left our rope behind us1 and while pausing ,i asked ,simond whether he did not feel a desire to go to the summit--,bien sur1 was his reply1 mais6 ,our guide's mind was so constituted that the mais seemed essential to its peace4 ,i stretched my hand towards him1 and said1 ,simond1 we must do it4 ,one thing alone ,i felt could defeat us3 the usual time of the ascent had been more than doubled1 the day was already far spent1 and if the ascent would throw our subsequent descent into night it could not be contemplated4 ,sidenote3 ,a ,,doze ,,on ,,the ,,calotte4 #aheg4 ,we now faced the ,mur1 which was by no means so bad as we had expected4 ,driving the iron claws of our boots into the scars made by the axe1 and the spikes of our batons into the slope above our feet1 we ascended steadily until the summit was attained1 and the top of the mountain rose clearly above us4 ,we congratulated ourselves upon this2 but ,simond1 probably fearing that our joy might become too full1 remarked1 ,mais le sommet est encore bien loin6 ,it was1 alas6 too true4 ,the snow became soft again1 and our weary limbs sank in it as before4 ,our guide went on in front1 audibly muttering his doubts as to our ability to reach the top1 and at length he threw himself upon the snow1 and exclaimed1 ,il faut y renoncer6 ,hirst now undertook the task of rekindling the guide's enthusiasm1 after which ,simond rose1 exclaiming1 ,ah6 comme ca me fait mal aux genoux1 and went forward4 ,two rocks break through the snow between the summit of the ,mur and the top of the mountain2 the first is called the ,petits ,mulets1 and the highest the ,derniers ,rochers4 ,at the former of these we paused to rest1 and finished our scanty store of wine and provisions4 ,we had not a bit of bread nor a drop of wine left2 our brandy flasks were also nearly exhausted1 and thus we had to contemplate the journey to the summit1 and the subsequent descent to the ,grands ,mulets1 without the slightest prospect of physical refreshment4 ,the almost total loss of two nights' sleep1 with two days' toil superadded1 made me long for a few minutes' doze1 so ,i stretched myself upon a composite couch of snow and granite1 and immediately fell asleep4 ,my friend1 however1 soon aroused me4 ,you quite frighten me1 he said2 ,i have listened for some minutes1 and have not heard you breathe once4 ,i had1 in reality1 been taking deep draughts of the mountain air1 but so silently as not to be heard4 ,i now filled our empty wine-bottle with snow and placed it in the sunshine1 that we might have a little water on our return4 ,we then rose2 it was half-past two o'clock2 we had been upwards of twelve hours climbing1 and ,i calculated that1 whether we reached the summit or not1 we could at all events work towards it for another hour4 ,to the sense of fatigue previously experienced1 a new phenomenon was now added--the beating of the heart4 ,we were incessantly pulled up by this1 which sometimes became so intense as to suggest danger4 ,i counted the number of paces which we were able to accomplish without resting1 and found that at the end of every twenty1 sometimes at the end of fifteen1 we were compelled to pause4 ,at each pause my heart throbbed audibly1 as ,i leaned upon my staff1 and the subsidence of this action was always the signal for further advance4 ,my breathing was quick1 but light and unimpeded4 ,i endeavoured to ascertain whether the hip-joint1 on account of the diminished atmospheric pressure1 became loosened1 so as to throw the weight of the leg upon the surrounding ligaments1 but could not be certain about it4 ,i also sought a little aid and encouragement from philosophy1 endeavouring to remember what great things had been done by the accumulation of small quantities1 and ,i urged upon myself that the present was a case in point1 and that the summation of distances twenty paces each must finally place us at the top4 ,still the question of time left the matter long in doubt1 and until we had passed the ,derniers ,rochers we worked on with the stern indifference of men who were doing their duty1 and did not look to consequences4 ,here1 however1 a gleam of hope began to brighten our souls2 the summit became visibly nearer1 ,simond showed more alacrity2 at length success became certain1 and at half-past three ,p4,m4 my friend and ,i clasped hands upon the top4 ,sidenote3 ,,the ,,summit ,,attained4 #aheg4 ,the summit of the mountain is an elongated ridge1 which has been compared to the back of an ass4 ,it was perfectly manifest that we were dominant over all other mountains2 as far as the eye could range ,mont ,blanc had no competitor4 ,the summits which had looked down upon us in the morning were now far beneath us4 ,the ,dome du ,gouter1 which had held its threatening seracs above us so long1 was now at our feet4 ,the ,aiguille du ,midi1 ,mont ,blanc du ,tacul1 and the ,monts ,maudits1 the ,talefre with its surrounding peaks1 the ,grand ,jorasse1 ,mont ,mallet1 and the ,aiguille du ,geant1 with our own familiar glaciers1 were all below us4 ,and as our eye ranged over the broad shoulders of the mountain1 over ice hills and valleys1 plateaux and far-stretching slopes of snow1 the conception of its magnitude grew upon us1 and impressed us more and more4 ,sidenote3 ,,clouds ,,from ,,the ,,summit4 #aheg4 ,the clouds were very grand--grander indeed than anything ,i had ever before seen4 ,some of them seemed to hold thunder in their breasts1 they were so dense and dark2 others1 with their faces turned sunward1 shone with the dazzling whiteness of the mountain snow2 while others again built themselves into forms resembling gigantic elm trees1 loaded with foliage4 ,towards the horizon the luxury of colour added itself to the magnificent alternations of light and shade4 ,clear spaces of amber and ethereal green embraced the red and purple cumuli1 and seemed to form the cradle in which they swung4 ,closer at hand squally mists1 suddenly engendered1 were driven hither and thither by local winds2 while the clouds at a distance lay like angels sleeping on the wing1 with scarcely visible motion4 ,mingling with the clouds1 and sometimes rising above them1 were the highest mountain heads1 and as our eyes wandered from peak to peak1 onwards to the remote horizon1 space itself seemed more vast from the manner in which the objects which it held were distributed4 ,sidenote3 ,,intensity ,,of ,,sound4 #aheg4 ,i wished to repeat the remarkable experiment of ,de ,saussure upon sound1 and for this purpose had requested ,simond to bring a pistol from ,chamouni2 but in the multitude of his cares he forgot it1 and in lieu of it my host at the ,montanvert had placed in two tin tubes1 of the same size and shape1 the same amount of gunpowder1 securely closing the tubes afterwards1 and furnishing each of them with a small lateral aperture4 ,we now planted one of them upon the snow1 and bringing a strip of amadou into communication with the touchhole1 ignited its most distant end3 it failed2 we tried again1 and were successful1 the explosion tearing asunder the little case which contained the powder4 ,the sound was certainly not so great as ,i should have expected from an equal quantity of powder at the sea level4,b ,the snow upon the summit was indurated1 but of an exceedingly fine grain1 and the beautiful effect already referred to as noticed upon the ,stelvio was strikingly manifest4 ,the hole made by driving the baton into the snow was filled with a delicate blue light2 and1 by management1 its complementary pinky yellow could also be produced4 ,even the iron spike at the end of the baton made a hole sufficiently deep to exhibit the blue colour1 which certainly depends on the size and arrangement of the snow crystals4 ,the firmament above us was without a cloud1 and of a darkness almost equal to that which surrounded the moon at #b ,a4,m4 ,still1 though the sun was shining1 a breeze1 whose tooth had been sharpened by its passage over the snow-fields1 searched us through and through4 ,the day was also waning1 and1 urged by the warnings of our ever prudent guide1 we at length began the descent4 ,sidenote3 ,,an ,,unexpected ,,glissade4 #aheg4 ,gravity was now in our favour1 but gravity could not entirely spare our wearied limbs1 and where we sank in the snow we found our downward progress very trying4 ,i suffered from thirst1 but after we had divided the liquefied snow at the ,petits ,mulets amongst us we had nothing to drink4 ,i crammed the clean snow into my mouth1 but the process of melting was slow and tantalizing to a parched throat1 while the chill was painful to the teeth4 ,we marched along the ,corridor1 and crossed cautiously the perilous slope on which we had cut steps in the morning1 breathing more freely after we had cleared the ice-precipice before described4 ,along the base of this precipice we now wound1 diverging from our morning's track1 in order to get surer footing in the snow2 it was like flour1 and while descending to the ,grand ,plateau we sometimes sank in it nearly to the waist4 ,when ,i endeavoured to squeeze it1 so as to fill my flask1 it at first refused to cling together1 behaving like so much salt2 the heat of the hand1 however1 soon rendered it a little moist1 and capable of being pressed into compact masses4 ,the sun met us here with extraordinary power2 the heat relaxed my muscles1 but when fairly immersed in the shadow of the ,dome du ,gouter1 the coolness restored my strength1 which augmented as the evening advanced4 ,simond insisted on the necessity of haste1 to save us from the perils of darkness4 ,on peut perir was his repeated admonition1 and he was quite right4 ,we reached the region of ponts1 more weary1 but1 in compensation1 more callous1 than we had been in the morning1 and moved over the soft snow of the bridges as if we had been walking upon eggs4 ,the valley of ,chamouni was filled with brown-red clouds1 which crept towards us up the mountain2 the air around and above us was1 however1 clear1 and the chastened light told us that day was departing4 ,once as we hung upon a steep slope1 where the snow was exceedingly soft1 ,hirst omitted to make his footing sure2 the soft mass gave way1 and he fell1 uttering a startled shout as he went down the declivity4 ,i was attached to him1 and1 fixing my feet suddenly in the snow1 endeavoured to check his fall1 but ,i seemed a mere feather in opposition to the force with which he descended4,c ,i fell1 and went down after him2 and we carried quite an avalanche of snow along with us1 in which we were almost completely hidden at the bottom of the slope4 ,all further dangers1 however1 were soon past1 and we went at a headlong speed to the base of the ,grands ,mulets2 the sound of our batons against the rocks calling ,huxley forth4 ,a position more desolate than his had been can hardly be imagined4 ,for seventeen hours he had been there4 ,he had expected us at two o'clock in the afternoon2 the hours came and passed1 and till seven in the evening he had looked for us4 ,to the end of my life1 he said1 ,i shall never forget the sound of those batons4 ,it was his turn now to nurse me1 which he did1 repaying my previous care of him with high interest4 ,we were all soon stretched1 and1 in spite of cold and hard boards1 ,i slept at intervals2 but the night1 on the whole1 was a weary one1 and we rose next morning with muscles more tired than when we lay down4 ,sidenote3 ,,blind ,,amid ,,the ,,crevasses4 #aheg4 ,friday1 #adth ,august4--,hirst was almost blind this morning2 and our guide's eyes were also greatly inflamed4 ,we gathered our things together1 and bade the ,grands ,mulets farewell4 ,it had frozen hard during the night1 and this1 on the steeper slopes1 rendered the footing very insecure4 ,simond1 moreover1 appeared to be a little bewildered1 and ,i sometimes preceded him in cutting the steps1 while ,hirst moved among the crevasses like a blind man2 one of us keeping near him1 so that he might feel for the actual places where our feet had rested1 and place his own in the same position4 ,it cost us three hours to cross from the ,grands ,mulets to the ,pierre a l',echelle1 where we discarded our leggings1 had a mouthful of food1 and a brief rest4 ,once upon the safe earth ,simond's powers seemed to be restored1 and he led us swiftly downwards to the little auberge beside the ,cascade du ,tard1 where we had some excellent lemonade1 equally choice cognac1 fresh strawberries and cream4 ,how sweet they were1 and how beautiful we thought the peasant girl who served them6 ,our guide kept a little hotel1 at which we halted1 and found it clean and comfortable4 ,we were1 in fact1 totally unfit to go elsewhere4 ,my coat was torn1 holes were kicked through my boots1 and ,i was altogether ragged and shabby4 ,a warm bath before dinner refreshed all mightily4 ,dense clouds now lowered upon ,mont ,blanc1 and we had not been an hour at ,chamouni when the breaking up of the weather was announced by a thunder-peal4 ,we had accomplished our journey just in time4 ,,footnotes3 ,a ,those acquainted with the mountain will at once recognise the grave error here committed4 ,in fact on starting from the ,grands ,mulets we had crossed the glacier too far1 and throughout were much too close to the ,dome du ,gouter4 ,b ,i fired the second case in a field in ,hampshire1 and1 as far as my memory enabled me to make the comparison1 found its sound considerably denser1 if ,i may use the expression4 ,in #ahei ,i had a pistol fired at the summit of ,mont ,blanc3 its sound was sensibly feebler and shorter than in the valley2 it resembled somewhat the discharge of a cork from a champagne bottle1 though much louder1 but it could not be at all compared to the sound of a common cracker4 ,c ,i believe that ,i could stop him now 7#ahfj74 7#ab47 ,sidenote3 ,,happy ,,evenings4 #aheg4 ,after our return we spent every available hour upon the ice1 working at questions which shall be treated under their proper heads1 each day's work being wound up by an evening of perfect enjoyment4 ,roast mutton and fried potatoes were our incessant fare1 for which1 after a little longing for a change at first1 we contracted a final and permanent love4 ,as the year advanced1 moreover1 and the grass sprouted with augmented vigour on the slopes of the ,montanvert1 the mutton1 as predicted by our host1 became more tender and juicy4 ,we had also some capital ,sallenches beer1 cold as the glacier water1 but effervescent as champagne4 ,such were our food and drink4 ,after dinner we gathered round the pine-fire1 and ,i can hardly think it possible for three men to be more happy than we then were4 ,it was not the goodness of the conversation1 nor any high intellectual element1 which gave the charm to our gatherings2 the gladness grew naturally out of our own perfect health1 and out of the circumstances of our position4 ,every fibre seemed a repository of latent joy1 which the slightest stimulus sufficed to bring into conscious action4 ,sidenote3 ,a ,,glacier ,,blower4 #aheg4 ,on the #agth ,i penetrated with ,simond through thick gloom to the ,tacul2 on the #ahth we set stakes at the same place3 on the same day1 while crossing the medial moraine of the ,talefre1 a little below the cascade1 a singular noise attracted my attention2 it seemed at first as if a snake were hissing about my feet4 ,on changing my position the sound suddenly ceased1 but it soon recommenced4 ,there was some snow upon the glacier1 which ,i removed1 and placed my ear close to the ice1 but it was difficult to fix on the precise spot from which the sound issued4 ,i cut away the disintegrated portion of the surface1 and at length discovered a minute crack1 from which a stream of air issued1 which ,i could feel as a cold blast against my hand4 ,while cutting away the surface further1 ,i stopped the little blower4 ,a marmot screamed near me1 and while ,i paused to look at the creature scampering up the crags1 the sound commenced again1 changing its note variously--hissing like a snake1 singing like a kettle1 and sometimes chirruping intermittently like a bird4 ,on passing my fingers to and fro over the crack1 ,i obtained a succession of audible puffs2 the current was sufficiently strong to blow away the corner of a gauze veil held over the fissure4 ,still the crack was not wide enough to permit of the entrance of my finger nail2 and to issue with such force from so minute a rent the air must have been under considerable pressure4 ,the origin of the blower was in all probability the following3--,when the ice is recompacted after having descended a cascade1 it is next to certain that chambers of air will be here and there enclosed1 which1 being powerfully squeezed afterwards1 will issue in the manner described whenever a crack in the ice furnishes it with a means of escape4 ,in my experiments on flowing mud1 for example1 the air entrapped in the mass while descending from the sluice into the trough1 bursts in bubbles from the surface at a short distance downwards4 ,sidenote3 ,a ,,difficult ,,line4 #aheg4 ,i afterwards examined the ,talefre cascade from summit to base1 with reference to the structure1 until at the close of the day thickening clouds warned me off4 ,i went down the glacier at a trot1 guided by the boulders capped with little cairns which marked the route4 ,the track which ,i had pursued for the last five weeks amid the crevasses near l',angle was this day barely passable4 ,the glacier had changed1 my work was drawing to a close1 and1 as ,i looked at the objects which had now become so familiar to me1 ,i felt that1 though not viscous1 the ice did not lack the quality of adhesiveness1 and ,i felt a little sad at the thought of bidding it so soon farewell4 ,at some distance below the ,montanvert the ,mer de ,glace is riven from side to side by transverse crevasses3 these fissures indicate that the glacier where they occur is in a state of longitudinal strain which produces transverse fracture4 ,i wished to ascertain the amount of stretching which the glacier here demanded1 and which the ice was not able to give2 and for this purpose desired to compare the velocity of a line set out across the fissured portion with that of a second line staked out across the ice before it had become thus fissured4 ,a previous inspection of the glacier through the telescope of our theodolite induced us to fix on a place which1 though much riven1 still did not exclude the hope of our being able to reach the other side4 ,each of us was1 as usual1 armed with his own axe2 and carrying with us suitable stakes1 my guide and myself entered upon this portion of the glacier on the morning of the #aith of ,august4 ,sidenote3 ,,nous ,,nous ,,trouverons ,,perdus6 #aheg4 ,i was surprised on entering to find some veins of white ice1 which from their position and aspect appeared to be derived from the ,glacier du ,geant2 but to these ,i shall subsequently refer4 ,our work was extremely difficult2 we penetrated to some distance along one line1 but were finally forced back1 and compelled to try another4 ,right and left of us were profound fissures1 and once a cone of ice forty feet high leaned quite over our track4 ,in front of us was a second leaning mass borne by a mere stalk1 and so topheavy that one wondered why the slight pedestal on which it rested did not suddenly crack across4 ,we worked slowly forwards1 and soon found ourselves in the shadow of the topheavy mass above referred to2 and from which ,i escaped with a wounded hand1 caused by over-haste4 ,simond surmounted the next ridge and exclaimed1 ,nous nous trouverons perdus6 ,i reached his side1 and on looking round the place saw that there was no footing for man4 ,the glacier here1 as shown in the frontispiece1 was cut up into thin wedges1 separated from each other by profound chasms1 and the wedges were so broken across as to render creeping along their edges quite impossible4 ,thus brought to a stand1 ,i fixed a stake at the point where we were forced to halt1 and retreated along edges of detestable granular ice1 which fell in showers into the crevasses when struck by the axe4 ,at one place an exceedingly deep fissure was at our left1 which was joined1 at a sharp angle1 by another at our right1 and we were compelled to cross at the place of intersection3 to do this we had to trust ourselves to a projecting knob of that vile rotten ice which ,i had learned to fear since my experience of it on the ,col du ,geant4 ,we finally escaped1 and set out our line at another place1 where the glacier1 though badly cut1 was not impassable4 ,sidenote3 ,,farewell ,,to ,,the ,,montanvert4 #aheg4 ,on the #bjth we made a series of final measurements at the ,tacul1 and determined the motion of two lines which we had set out the previous day4 ,on the #bast we quitted the ,montanvert2 ,i had been there from the #aeth of ,july1 and the longer ,i remained the better ,i liked the establishment and the people connected with it4 ,it was then managed by ,joseph ,tairraz and ,jules ,charlet1 both of whom showed us every attention4 ,in #aheh and #ahei ,i had occasion to revisit the establishment1 which was then managed by ,jules and his brother1 and found in it the same good qualities4 ,during my winter expedition of #ahei ,i also found the same readiness to assist me in every possible way2 honest ,jules expressing his willingness to ascend through the snow to the auberge if ,i thought his presence would in any degree contribute to my comfort4 ,we crossed the glacier1 and descended by the ,chapeau to the ,cascade des ,bois1 the inclination of which and of the lower portion of the glacier we then determined4 ,the day was magnificent4 ,looking upwards1 the ,aiguilles de ,charmoz and du ,dru rose right and left like sentinels of the valley1 while in front of us the ice descended the steep1 a bewildering mass of crags and chasms4 ,at the other side was the pine-clad slope of the ,montanvert4 ,further on the ,aiguille du ,midi threw its granite pyramid between us and ,mont ,blanc2 on the ,dome du ,gouter the seracs of the mountain were to be seen1 while issuing as if from a cleft in the mountain side the ,glacier des ,bossons thrust through the black pines its snowy tongue4 ,below us was the beautiful valley of ,chamouni itself1 through which the ,arve and ,arveiron rushed like enlivening spirits4 ,we finally examined a grand old moraine produced by a ,mer de ,glace of other ages1 when the ice quite crossed the valley of ,chamouni and abutted against the opposite mountain-wall4 ,sidenote3 ,,edouard ,,simond4 #aheg4 ,simond had proved himself a very valuable assistant2 he was intelligent and perfectly trustworthy2 and though the peculiar nature of my work sometimes caused me to attempt things against which his prudence protested1 he lacked neither strength nor courage4 ,on reaching ,chamouni and adding up our accounts1 ,i found that ,i had not sufficient cash to pay him2 money was waiting for me at the post-office in ,geneva1 and thither it was arranged that my friend ,hirst should proceed next morning1 while ,i was to await the arrival of the money at ,chamouni4 ,my guide heard of this arrangement1 and divined its cause3 he came to me1 and in the most affectionate manner begged of me to accept from him the loan of #ejj francs4 ,though ,i did not need the loan1 the mode in which it was offered to me augmented the kindly feelings which ,i had long entertained towards ,simond1 and ,i may add that my intercourse with him since has served only to confirm my first estimate of his worthiness4 ,,expedition ,,of #aheh4 7#ac47 ,sidenote3 ,,doubts ,,regarding ,,structure4 #aheh4 ,i had confined myself during the summer of #aheg to the ,mer de ,glace and its tributaries1 desirous to make my knowledge accurate rather than extensive4 ,i had made the acquaintance of all accessible parts of the glacier1 and spared no pains to master both the details and the meaning of the laminated structure of the ice1 but ,i found no fact upon which ,i could take my stand and say to an advocate of an opposing theory1 ,this is unassailable4 ,in experimental science we have usually the power of changing the conditions at pleasure2 if ,nature does not reply to a question we throw it into another form2 a combining of conditions is1 in fact1 the essence of experiment4 ,to meet the requirements of the present question1 ,i could not twist the same glacier into various shapes1 and throw it into different states of strain and pressure2 but ,i might1 by visiting many glaciers1 find all needful conditions fulfilled in detail1 and by observing these ,i hoped to confer upon the subject the character and precision of a true experimental inquiry4 ,the summer of #aheh was accordingly devoted to this purpose1 when ,i had the good fortune to be accompanied by ,professor ,ramsay1 the author of some extremely interesting papers upon ancient glaciers4 ,taking ,zuerich1 ,schaffhausen1 and ,lucerne in our way1 we crossed the ,bruenig on the #bbnd of ,july1 and met my guide1 ,christian ,lauener1 at ,meyringen4 ,on the #bcrd we visited the glacier of ,rosenlaui1 and the glacier of the ,schwartzwald1 and reached ,grindelwald in the evening of the same day4 ,my expedition with ,mr4 ,huxley had taught me that the ,lower ,grindelwald ,glacier was extremely instructive1 and ,i was anxious to see many parts of it once more2 this ,i did1 in company with ,ramsay1 and we also spent a day upon the upper glacier1 after which our path lay over the ,strahleck to the glaciers of the ,aar and of the ,rhone4 ,,passage ,,of ,,the ,,strahleck4 7#ad47 ,sidenote3 ,a ,,gloomy ,,prospect4 #aheh4 ,on ,monday1 the #bfth of ,july1 we were called at #d ,a4,m41 and found the weather very unpromising1 but the two mornings which preceded it had also been threatening without any evil result4 ,there was1 it is true1 something more than usually hostile in the aspect of the clouds which sailed sullenly from the west1 and smeared the air and mountains as if with the dirty smoke of a manufacturing town4 ,we despatched our coffee1 went down to the bottom of the ,grindelwald valley1 up the opposite slope1 and were soon amid the gloom of the pines which partially cover it4 ,on emerging from these1 a watery gleam on the mottled head of the ,eiger was the only evidence of direct sunlight in that direction4 ,to our left was the ,wetterhorn surrounded by wild and disorderly clouds1 through the fissures of which the morning light glared strangely4 ,for a time the ,heisse ,platte was seen1 a dark brown patch amid the ghastly blue which overspread the surrounding slopes of snow4 ,the clouds once rolled up1 and revealed for a moment the summits of the ,viescherhoerner2 but they immediately settled down again1 and hid the mountains from top to base4 ,soon afterwards they drew themselves partially aside1 and a patch of blue over the ,strahleck gave us hope and pleasure4 ,as we ascended1 the prospect in front of us grew better1 but that behind us--and the wind came from behind--grew worse4 ,slowly and stealthily the dense neutral-tint masses crept along the sides of the mountains1 and seemed to dog us like spies2 while over the glacier hung a thin veil of fog1 through which gleamed the white minarets of the ice4 ,sidenote3 ,,ice ,,cascade ,,and ,,protuberances4 #aheh4 ,sidenote3 ,,dirt-,,bands ,,of ,,the ,,strahleck ,,branch4 #aheh4 ,when we first spoke of crossing the ,strahleck1 ,lauener said it would be necessary to take two guides at least2 but after a day's performance on the ice he thought we might manage very well by taking1 in addition to himself1 the herd of the alp1 over the more difficult part of the pass4 ,he had further experience of us on the second day1 and now1 as we approached the herd's hut1 ,i was amused to hear him say that he thought any assistance beside his own unnecessary4 ,relying upon ourselves1 therefore1 we continued our route1 and were soon upon the glacier1 which had been rendered smooth and slippery through the removal of its disintegrated surface by the warm air4 ,crossing the ,strahleck branch of the glacier to its left side1 we climbed the rocks to the grass and flowers which clothe the slopes above them4 ,our way sometimes lay over these1 sometimes along the beds of streams1 across turbulent brooks1 and once around the face of a cliff1 which afforded us about an inch of ledge to stand upon1 and some protruding splinters to lay hold of by the hands4 ,having reached a promontory which commanded a fine view of the glacier1 and of the ice cascade by which it was fed1 ,i halted1 to check the observations already made from the side of the opposite mountain4 ,here1 as there1 cliffy ridges were seen crossing the cascade of the glacier1 with interposed spaces of dirt and debris--the former being toned down1 and the latter squeezed towards the base of the fall1 until finally the ridges swept across the glacier1 in gentle swellings1 from side to side2 while the valleys between them1 holding the principal share of the superficial impurity1 formed the cradles of the so-called ,dirt-,bands4 ,these swept concentric with the protuberances across the glacier1 and remained upon its surface even after the swellings had disappeared4 ,the swifter flow of the centre of the glacier tends of course incessantly to lengthen the loops of the bands1 and to thrust the summits of the curves which they form more and more in advance of their lateral portions4 ,the depressions between the protuberances appeared to be furrowed by minor wrinkles1 as if the ice of the depressions had yielded more than that of the protuberances4 ,this1 ,i think1 is extremely probable1 though it has never yet been proved4 ,three stakes1 placed1 one on the summit1 another on the frontal slope1 and another at the base of a protuberance1 would1 ,i think1 move with unequal velocities4 ,they would1 ,i think1 show that1 upon the large and general motion of the glacier1 smaller motions are superposed1 as minor oscillations are known to cover parasitically the large ones of a vibrating string4 ,possibly1 also1 the dirt-bands may owe something to the squeezing of impurities out of the glacier to its surface in the intervals between the swellings4 ,from our present position we could also see the swellings on the ,viescherhoerner branch of the glacier1 in the valleys between which coarse shingle and debris were collected1 which would form dirt-bands if they could4 ,on neither branch1 however1 do the bands attain the definition and beauty which they possess upon the ,mer de ,glace4 ,after an instructive lesson we faced our task once more1 passing amid crags and boulders1 and over steep moraines1 from which the stones rolled down upon the slightest disturbance4 ,while crossing a slope of snow with an inclination of #de deg41 my footing gave way1 ,i fell1 but turned promptly on my face1 dug my staff deeply into the snow1 and arrested the motion before ,i had slid a dozen yards4 ,ramsay was behind me1 speculating whether he should be able to pass the same point without slipping2 before he reached it1 however1 the snow yielded1 he fell1 and slid swiftly downwards4 ,lauener1 whose attention had been aroused by my fall1 chanced to be looking round when ,ramsay's footing yielded4 ,with the velocity of a projectile he threw himself upon my companion1 seized him1 and brought him to rest before he had reached the bottom of the slope4 ,the act made a very favourable impression upon me1 it was so prompt and instinctive4 ,an eagle could not swoop upon its prey with more directness of aim and swiftness of execution4 ,sidenote3 ,,ice ,,cliffs ,,through ,,the ,,fog4 #aheh4 ,while this went on the clouds were playing hide and seek with the mountains4 ,the ice-crags and pinnacles to our left1 looming through the haze1 seemed of gigantic proportions1 reminding one of the ,hades of ,byron's ',cain4' ,how sunless and how vast are these dim realms6 ,we climbed for some time along the moraine which flanks the cascade1 and on reaching the level of the brow ,lauener paused1 cast off his knapsack1 and declared for breakfast4 ,while engaged with it the dense clouds which had crammed the gorge and obscured the mountains1 all melted away1 and a scene of indescribable magnificence was revealed4 ,overhead the sky suddenly deepened to dark blue1 and against it the ,finsteraarhorn projected his dark and mighty mass4 ,brown spurs jutted from the mountain1 and between them were precipitous snow-slopes1 fluted by the descent of rocks and avalanches1 and broken into ice-precipices lower down4 ,right in front of us1 and from its proximity more gigantic to the eye1 was the ,schreckhorn1 while from couloirs and mountain-slopes the matter of glaciers yet to be was poured into the vast basin on the rim of which we now stood4 ,sidenote3 ,,mutations ,,of ,,the ,,clouds4 #aheh4 ,this it was next our object to cross2 our way lying in part through deep snow-slush1 the scene changing perpetually from blue heaven to gray haze which massed itself at intervals in dense clouds about the mountains4 ,after crossing the basin our way lay partly over slopes of snow1 partly over loose shingle1 and at one place along the edge of a formidable precipice of rock4 ,we sat down sometimes to rest1 and during these pauses1 though they were very brief1 the scene had time to go through several of its ,protean mutations4 ,at one moment all would be perfectly serene1 no cloud in the transparent air to tell us that any portion of it was in motion1 while the blue heaven threw its flattened arch over the magnificent amphitheatre4 ,then in an instant1 from some local cauldron1 the vapour would boil up suddenly1 eddying wildly in the air1 which a moment before seemed so still1 and enveloping the entire scene4 ,thus the space enclosed by the ,finsteraarhorn1 the ,viescherhoerner1 and the ,schreckhorn1 would at one moment be filled with fog to the mountain heads1 every trace of which a few minutes sufficed to sweep away1 leaving the unstained blue of heaven behind it1 and the mountains showing sharp and jagged outlines in the glassy air4 ,one might be almost led to imagine that the vapour molecules endured a strain similar to that of water cooled below its freezing point1 or heated beyond its boiling point2 and that1 on the strain being relieved by the sudden yielding of the opposing force1 the particles rushed together1 and thus filled in an instant the clear atmosphere with aqueous precipitation4 ,i had no idea that the ,strahleck was so fine a pass4 ,whether it is the quality of my mind to take in the glory of the present so intensely as to make me forgetful of the glory of the past1 ,i know not1 but it appeared to me that ,i had never seen anything finer than the scene from the summit4 ,the amphitheatre formed by the mountains seemed to me of exceeding magnificence2 nor do ,i think that my feeling was subjective merely2 for the simple magnitude of the masses which built up the spectacle would be sufficient to declare its grandeur4 ,looking down towards the ,glacier of the ,aar1 a scene of wild beauty and desolation presented itself4 ,not a trace of vegetation could be seen along the whole range of the bounding mountains2 glaciers streamed from their shoulders into the valley beneath1 where they welded themselves to form the ,finsteraar affluent of the ,unteraar glacier4 ,sidenote3 ,,descent ,,of ,,the ,,crags4 #aheh4 ,after a brief pause1 ,lauener again strapped on his knapsack1 and tempered both will and muscles by the remark1 that our worst piece of work was now before us4 ,from the place where we sat1 the mountain fell precipitously for several hundred feet2 and down the weathered crags1 and over the loose shingle which encumbered their ledges1 our route now lay4 ,lauener was in front1 cool and collected1 lending at times a hand to ,ramsay1 and a word of encouragement to both of us1 while ,i brought up the rear4 ,i found my full haversack so inconvenient that ,i once or twice thought of sending it down the crags in advance of me1 but ,lauener assured me that it would be utterly destroyed before reaching the bottom4 ,my complaint against it was1 that at critical places it sometimes came between me and the face of the cliff1 pushing me away from the latter so as to throw my centre of gravity almost beyond the base intended to support it4 ,we came at length upon a snow-slope1 which had for a time an inclination of #ej deg42 then once more to the rocks2 again to the snow1 which was both steep and deep4 ,our batons were at least six feet long3 we drove them into the snow to secure an anchorage1 but they sank to their very ends1 and we merely retained a length of them sufficient for a grasp4 ,this slope was intersected by a so-called ,bergschrund1 the lower portion of the slope being torn away from its upper portion so as to form a crevasse that extended quite round the head of the valley4 ,we reached its upper edge2 the chasm was partially filled with snow1 which brought its edges so near that we cleared it by a jump4 ,the rest of the slope was descended by a glissade4 ,each sat down upon the snow1 and the motion1 once commenced1 swiftly augmented to the rate of an avalanche1 and brought us pleasantly to the bottom4 ,sidenote3 ,,through ,,gloom ,,to ,,the ,,grimsel4 #aheh4 ,as we looked from the heights1 we could see that the valley through which our route lay was filled with gray fog3 into this we soon plunged1 and through it we made our way towards the ,abschwung4 ,the inclination of the glacier was our only guide1 for we could see nothing4 ,reaching the confluence of the ,finsteraar and ,lauteraar branches1 we went downwards with long swinging strides1 close alongside the medial moraine of the trunk glacier4 ,the glory of the morning had its check in the dull gloom of the evening4 ,across streams1 amid dirt-cones and glacier-tables1 and over the long reach of shingle which covers the end of the glacier1 we plodded doggedly1 and reached the ,grimsel at #g ,p4,m41 the journey having cost a little more than #ad hours4 7#ae47 ,sidenote3 ,,ancient ,,glacier ,,action4 #aheh4 ,we made the ,grimsel our station for a day1 which was spent in examining the evidences of ancient glacier action in the valley of ,hasli4 ,near the ,hospice1 but at the opposite side of the ,aar1 rises a mountain-wall of hard granite1 on which the flutings and groovings are magnificently preserved4 ,after a little practice the eye can trace with the utmost precision the line which marks the level of the ancient ice3 above this the crags are sharp and rugged2 while below it the mighty grinder has rubbed off the pinnacles of the rocks and worn their edges away4 ,the height to which this action extends must be nearly two thousand feet above the bed of the present valley4 ,it is also easy to see the depth to which the river has worked its channel into the ancient rocks4 ,in some cases the road from ,guttanen to the ,grimsel lay right over the polished rocks1 asperities being supplied by the chisel of man in order to prevent travellers from slipping on their slopes4 ,here and there also huge protuberant crags were rounded into domes almost as perfect as if chiselled by art4 ,to both my companion and myself this walk was full of instruction and delight4 ,on the #bhth of ,july we crossed the ,grimsel pass1 and traced the scratchings to the very top of it4 ,ramsay remarked that their direction changed high up the pass1 as if a tributary from the summit had produced them1 while lower down they merged into the general direction of the glacier which had filled the principal valley4 ,from the summit of the ,mayenwand we had a clear view of the glacier of the ,rhone2 and to see the lower portion of this glacier to advantage no better position can be chosen4 ,the dislocation of its cascade1 the spreading out of the ice below1 its system of radial crevasses1 and the transverse sweep of its structural groovings1 may all be seen4 ,a few hours afterwards we were among the wild chasms at the brow of the ice-fall1 where we worked our way to the centre of the ice1 but were unable to attain the opposite side4 ,having examined the glacier both above and below the cascade1 we went down the valley to ,viesch1 and ascended thence1 on the #cjth of ,july1 to the ,hotel ,jungfrau on the slopes of the ,a,eggischhorn4 ,on the following day we climbed to the summit of the mountain1 and from a sheltered nook enjoyed the glorious prospect which it commands4 ,the wind was strong1 and fleecy clouds flew over the heavens2 some of which1 as they formed and dispersed themselves about the flanks of the ,aletschhorn1 showed extraordinary iridescences4 ,sidenote3 ,,the ,m,ae,r,j,e,l,e,n ,,see4 #aheh4 ,the sunbeams called us early on the morning of the #ast of ,august4 ,no cloud rested on the opposite range of the ,valais mountains1 but on looking towards the ,a,eggischhorn we found a cap upon its crest2 we looked again--the cap had disappeared and a serene heaven stretched overhead4 ,as we breasted the alp the moon was still in the sky1 paling more and more before the advancing day2 a single hawk swung in the atmosphere above us2 clear streams babbled from the hills1 the louder sounds reposing on a base of music2 while groups of cows with tinkling bells browsed upon the green alp4 ,here and there the grass was dispossessed1 and the flanks of the mountain were covered by the blocks which had been cast down from the summit4 ,on reaching the plateau at the base of the final pyramid1 we rounded the mountain to the right and came over the lonely and beautiful ,maerjelen ,see4 ,no doubt the hollow which this lake fills had been scooped out in former ages by a branch of the ,aletsch glacier2 but long ago the blue ice gave place to blue water4 ,the glacier bounds it at one side by a vertical wall of ice sixty feet in height3 this is incessantly undermined1 a roof of crystal being formed over the water1 till at length the projecting mass1 becoming too heavy for its own rigidity1 breaks and tumbles into the lake4 ,here1 attacked by sun and air1 its blue surface is rendered dazzlingly white1 and several icebergs of this kind now floated in the sunlight2 the water was of a glassy smoothness1 and in its blue depths each ice mass doubled itself by reflection4,a ,sidenote3 ,,the ,,aletsch ,,glacier4 #aheh4 ,the ,aletsch is the grandest glacier in the ,alps3 over it we now stood1 while the bounding mountains poured vast feeders into the noble stream4 ,the ,jungfrau was in front of us without a cloud1 and apparently so near that ,i proposed to my guide to try it without further preparation4 ,he was enthusiastic at first1 but caution afterwards got the better of his courage4 ,at some distance up the glacier the snow-line was distinctly drawn1 and from its edge upwards the mighty shoulders of the hills were heavy laden with the still powdery material of the glacier4 ,amid blocks and debris we descended to the ice3 the portion of it which bounded the lake had been sapped1 and a space of a foot existed between ice and water3 numerous chasms were formed here1 the mass being thus broken1 preparatory to being sent adrift upon the lake4 ,we crossed the glacier to its centre1 and looking down it the grand peaks of the ,mischabel1 the noble cone of the ,weisshorn1 and the dark and stern obelisk of the ,matterhorn1 formed a splendid picture4 ,looking upwards1 a series of most singularly contorted dirt-bands revealed themselves upon the surface of the ice4 ,i sought to trace them to their origin1 but was frustrated by the snow which overspread the upper portion of the glacier4 ,along this we marched for three hours1 and came at length to the junction of the four tributary valleys which pour their frozen streams into the great trunk valley4 ,the glory of the day1 and that joy of heart which perfect health confers1 may have contributed to produce the impression1 but ,i thought ,i had never seen anything to rival in magnificence the region in the heart of which we now found ourselves4 ,we climbed the mountain on the right-hand side of the glacier1 where1 seated amid the riven and weather-worn crags1 we fed our souls for hours on the transcendent beauty of the scene4 ,sidenote3 ,a ,,chamois ,,deceived4 #aheh4 ,we afterwards redescended to the glacier1 which at this place was intersected by large transverse crevasses1 many of which were apparently filled with snow1 while over others a thin and treacherous roof was thrown4 ,in some cases the roof had broken away1 and revealed rows of icicles of great length and transparency pendent from the edges4 ,we at length turned our faces homewards1 and looking down the glacier ,i saw at a great distance something moving on the ice4 ,i first thought it was a man1 though it seemed strange that a man should be there alone4 ,on drawing my guide's attention to it he at once pronounced it to be a chamois1 and ,i with my telescope immediately verified his statement4 ,the creature bounded up the glacier at intervals1 and sometimes the vigour of its spring showed that it had projected itself over a crevasse4 ,it approached us sometimes at full gallop3 then would stop1 look toward us1 pipe loudly1 and commence its race once more4 ,it evidently made the reciprocal mistake to my own1 imagining us to be of its own kith and kin4 ,we sat down upon the ice the better to conceal our forms1 and to its whistle our guide whistled in reply4 ,a joyous rush was the creature's first response to the signal2 but it afterwards began to doubt1 and its pauses became more frequent4 ,its form at times was extremely graceful1 the head erect in the air1 its apparent uprightness being augmented by the curvature which threw its horns back4 ,i watched the animal through my glass until ,i could see the glistening of its eyes2 but soon afterwards it made a final pause1 assured itself of its error1 and flew with the speed of the wind to its refuge in the mountains4 ,,footnotes3 ,a ,a painting of this exquisite lake has been recently executed by ,mr4 ,george ,barnard4 ,,ascent ,,of ,,the ,,finsteraarhorn1 #aheh4 7#af47 ,sidenote3 ,,my ,,guide4 #aheh4 ,since my arrival at the hotel on the #cjth of ,july ,i had once or twice spoken about ascending the ,finsteraarhorn1 and on the #bnd of ,august my host advised me to avail myself of the promising weather4 ,a guide1 named ,bennen1 was attached to the hotel1 a remarkable-looking man1 between #cj and #dj years old1 of middle stature1 but very strongly built4 ,his countenance was frank and firm1 while a light of good-nature at times twinkled in his eye4 ,altogether the man gave me the impression of physical strength1 combined with decision of character4 ,the proprietor had spoken to me many times of the strength and courage of this man1 winding up his praises of him by the assurance that if ,i were killed in ,bennen's company there would be two lives lost1 for that the guide would assuredly sacrifice himself in the effort to save his ,herr4 ,he was called1 and ,i asked him whether he would accompany me alone to the top of the ,finsteraarhorn4 ,to this he at first objected1 urging the possibility of his having to render me assistance1 and the great amount of labour which this might entail upon him2 but this was overruled by my engaging to follow where he led1 without asking him to render me any help whatever4 ,he then agreed to make the trial1 stipulating1 however1 that he should not have much to carry to the cave of the ,faulberg1 where we were to spend the night4 ,to this ,i cordially agreed1 and sent on blankets1 provisions1 wood1 and hay1 by two porters4 ,sidenote3 ,,iridescent ,,cloud4 #aheh4 ,my desire1 in part1 was to make a series of observations at the summit of the mountain1 while a similar series was made by ,professor ,ramsay in the valley of the ,rhone1 near ,viesch1 with a view to ascertaining the permeability of the lower strata of the atmosphere to the radiant heat of the sun4 ,during the forenoon of the #bnd ,i occupied myself with my instruments1 and made the proper arrangements with ,ramsay4 ,i tested a mountain-thermometer which ,mr4 ,casella had kindly lent me1 and found the boiling point of water on the dining-room table of the hotel to be #aii4bi deg4 ,fahrenheit4 ,at about three o'clock in the afternoon we quitted the hotel1 and proceeded leisurely with our two guides up the slope of the ,a,eggischhorn4 ,we once caught a sight of the topmost pinnacle of the ,finsteraarhorn2 beside it was the ,rothhorn1 and near this again the ,oberaarhorn1 with the ,viescher glacier streaming from its shoulders4 ,on the opposite side we could see1 over an oblique buttress of the mountain on which we stood1 the snowy summit of the ,weisshorn2 to the left of this was the ever grim and lonely ,matterhorn2 and farther to the left1 with its numerous snow-cones1 each with its attendant shadow1 rose the mighty ,mischabel4 ,we descended1 and crossed the stream which flows from the ,maerjelen ,see1 into which a large mass of the glacier had recently fallen1 and was now afloat as an iceberg4 ,we passed along the margin of the lake1 and at the junction of water and ice ,i bade ,ramsay good-bye4 ,at the commencement of our journey upon the ice1 whenever we crossed a crevasse1 ,i noticed ,bennen watching me2 his vigilance1 however1 soon diminished1 whence ,i gathered that he finally concluded that ,i was able to take care of myself4 ,clouds hovered in the atmosphere throughout the whole time of our ascent2 one smoky-looking mass marred the glory of the sunset1 but at some distance was another which exhibited colours almost as rich and varied as those of the solar spectrum4 ,i took the glorious banner thus unfurled as a sign of hope1 to check the despondency which its gloomy neighbour was calculated to produce4 ,sidenote3 ,,evening ,,near ,,the ,,jungfrau4 #aheh4 ,two hours' walking brought us near our place of rest2 the porters had already reached it1 and were now returning4 ,we deviated to the right1 and1 having crossed some ice-ravines1 reached the lateral moraine of the glacier1 and picked our way between it and the adjacent mountain-wall4 ,we then reached a kind of amphitheatre1 crossed it1 and climbing the opposite slope1 came to a triple grotto formed by clefts in the mountain4 ,in one of these a pine-fire was soon blazing briskly1 and casting its red light upon the surrounding objects1 though but half dispelling the gloom from the deeper portions of the cell4 ,i left the grotto1 and climbed the rocks above it to look at the heavens4 ,the sun had quitted our firmament1 but still tinted the clouds with red and purple2 while one peak of snow in particular glowed like fire1 so vivid was its illumination4 ,during our journey upwards the ,jungfrau never once showed her head1 but1 as if in ill temper1 had wrapped her vapoury veil around her4 ,she now looked more good-humoured1 but still she did not quite remove her hood2 though all the other summits1 without a trace of cloud to mask their beautiful forms1 pointed heavenward4 ,the calmness was perfect2 no sound of living creature1 no whisper of a breeze1 no gurgle of water1 no rustle of debris1 to break the deep and solemn silence4 ,surely1 if beauty be an object of worship1 those glorious mountains1 with rounded shoulders of the purest white--snow-crested and star-gemmed--were well calculated to excite sentiments of adoration4 ,sidenote3 ,,the ,,cave ,,of ,,the ,,faulberg4 #aheh4 ,i returned to the grotto1 where supper was prepared and waiting for me4 ,the boiling point of water1 at the level of the kitchen floor1 ,i found to be #aif deg4 ,fahr4 ,nothing could be more picturesque than the aspect of the cave before we went to rest4 ,the fire was gleaming ruddily4 ,i sat upon a stone bench beside it1 while ,bennen was in front with the red light glimmering fitfully over him4 ,my boiling-water apparatus1 which had just been used1 was in the foreground2 and telescopes1 opera-glasses1 haversacks1 wine-keg1 bottles1 and mattocks1 lay confusedly around4 ,the heavens continued to grow clearer1 the thin clouds1 which had partially overspread the sky1 melting gradually away4 ,the grotto was comfortable2 the hay sufficient materially to modify the hardness of the rock1 and my position at least sheltered and warm4 ,one possibility remained that might prevent me from sleeping--the snoring of my companion2 he assured me1 however1 that he did not snore1 and we lay down side by side4 ,the good fellow took care that ,i should not be chilled2 he gave me the best place1 by far the best part of the clothes1 and may have suffered himself in consequence2 but1 happily for him1 he was soon oblivious of this4 ,physiologists1 ,i believe1 have discovered that it is chiefly during sleep that the muscles are repaired2 and ere long the sound ,i dreaded announced to me at once the repair of ,bennen's muscles and the doom of my own4 ,the hollow cave resounded to the deep-drawn snore4 ,i once or twice stirred the sleeper1 breaking thereby the continuity of the phenomenon2 but it instantly pieced itself together again1 and went on as before4 ,i had not the heart to wake him1 for ,i knew that upon him would devolve the chief labour of the coming day4 ,at half-past one he rose and prepared coffee1 and at two o'clock ,i was engaged upon the beverage4 ,we afterwards packed up our provisions and instruments4 ,bennen bore the former1 ,i the latter1 and at three o'clock we set out4 ,sidenote3 ,,shall ,,we ,,try ,,the ,,jungfrau8 #aheh4 ,we first descended a steep slope to the glacier1 along which we walked for a time4 ,a spur of the ,faulberg jutted out between us and the ice-laden valley through which we must pass2 this we crossed in order to shorten our way and to avoid crevasses4 ,loose shingle and boulders overlaid the mountain2 and here and there walls of rock opposed our progress1 and rendered the route far from agreeable4 ,we then descended to the ,gruenhorn tributary1 which joins the trunk glacier at nearly a right angle1 being terminated by a saddle which stretches across from mountain to mountain1 with a curvature as graceful and as perfect as if drawn by the instrument of a mathematician4 ,the unclouded moon was shining1 and the ,jungfrau was before us so pure and beautiful1 that the thought of visiting the ,maiden without further preparation occurred to me4 ,i turned to ,bennen1 and said1 ,shall we try the ,jungfrau8 ,i think he liked the idea well enough1 though he cautiously avoided incurring any responsibility4 ,if you desire it1 ,i am ready1 was his reply4 ,he had never made the ascent1 and nobody knew anything of the state of the snow this year2 but ,lauener had examined it through a telescope on the previous day1 and pronounced it dangerous4 ,in every ascent of the mountain hitherto made1 ladders had been found indispensable1 but we had none4 ,i questioned ,bennen as to what he thought of the probabilities1 and tried to extract some direct encouragement from him2 but he said that the decision rested altogether with myself1 and it was his business to endeavour to carry out that decision4 ,we will attempt it1 then1 ,i said1 and for some time we actually walked towards the ,jungfrau4 ,a gray cloud drew itself across her summit1 and clung there4 ,i asked myself why ,i deviated from my original intention8 ,the ,finsteraarhorn was higher1 and therefore better suited for the contemplated observations4 ,i could in no wise justify the change1 and finally expressed my scruples4 ,a moment's further conversation caused us to right about1 and front the saddle of the ,gruenhorn4 ,sidenote3 ,,magnificent ,,scene4 #aheh4 ,the dawn advanced4 ,the eastern sky became illuminated and warm1 and high in the air across the ridge in front of us stretched a tongue of cloud like a red flame1 and equally fervid in its hue4 ,looking across the trunk glacier1 a valley which is terminated by the ,loetsch saddle was seen in a straight line with our route1 and ,i often turned to look along this magnificent corridor4 ,the mightiest mountains in the ,oberland form its sides2 still1 the impression which it makes is not that of vastness or sublimity1 but of loveliness not to be described4 ,the sun had not yet smitten the snows of the bounding mountains1 but the saddle carved out a segment of the heavens which formed a background of unspeakable beauty4 ,over the rim of the saddle the sky was deep orange1 passing upwards through amber1 yellow1 and vague ethereal green to the ordinary firmamental blue4 ,right above the snow-curve purple clouds hung perfectly motionless1 giving depth to the spaces between them4 ,there was something saintly in the scene4 ,anything more exquisite ,i had never beheld4 ,we marched upwards over the smooth crisp snow to the crest of the saddle1 and here ,i turned to take a last look along that grand corridor1 and at that wonderful daffodil sky4 ,the sun's rays had already smitten the snows of the ,aletschhorn2 the radiance seemed to infuse a principle of life and activity into the mountains and glaciers1 but still that holy light shone forth1 and those motionless clouds floated beyond1 reminding one of that eastern religion whose essence is the repression of all action and the substitution for it of immortal calm4 ,the ,finsteraarhorn now fronted us2 but clouds turbaned the head of the giant1 and hid it from our view4 ,the wind1 however1 being north1 inspired us with a strong hope that they would melt as the day advanced4 ,i have hardly seen a finer ice-field than that which now lay before us4 ,considering the neve which supplies it1 it appeared to me that the ,viescher glacier ought to discharge as much ice as the ,aletsch2 but this is an error due to the extent of neve which is here at once visible3 since a glance at the map of this portion of the ,oberland shows at once the great superiority of the mountain treasury from which the ,aletsch glacier draws support4 ,still1 the ice-field before us was a most noble one4 ,the surrounding mountains were of imposing magnitude1 and loaded to their summits with snow4 ,down the sides of some of them the half-consolidated mass fell in a state of wild fracture and confusion4 ,in some cases the riven masses were twisted and overturned1 the ledges bent1 and the detached blocks piled one upon another in heaps2 while in other cases the smooth white mass descended from crown to base without a wrinkle4 ,the valley now below us was gorged by the frozen material thus incessantly poured into it4 ,we crossed it1 and reached the base of the ,finsteraarhorn1 ascended the mountain a little way1 and at six o'clock paused to lighten our burdens and to refresh ourselves4 ,sidenote3 ,,the ,,mountain ,,assailed4 #aheh4 ,the north wind had freshened1 we were in the shade1 and the cold was very keen4 ,placing a bottle of tea and a small quantity of provisions in the knapsack1 and a few figs and dried prunes in our pockets1 we commenced the ascent4 ,the ,finsteraarhorn sends down a number of cliffy buttresses1 separated from each other by wide couloirs filled with ice and snow4 ,we ascended one of these buttresses for a time1 treading cautiously among the spiky rocks2 afterwards we went along the snow at the edge of the spine1 and then fairly parted company with the rock1 abandoning ourselves to the neve of the couloir4 ,the latter was steep1 and the snow was so firm that steps had to be cut in it4 ,once ,i paused upon a little ledge1 which gave me a slight footing1 and took the inclination4 ,the slope formed an angle of #de deg4 with the horizon2 and across it1 at a little distance below me1 a gloomy fissure opened its jaws4 ,the sun now cleared the summits which had before cut off his rays1 and burst upon us with great power1 compelling us to resort to our veils and dark spectacles4 ,two years before1 ,bennen had been nearly blinded by inflammation brought on by the glare from the snow1 and he now took unusual care in protecting his eyes4 ,the rocks looking more practicable1 we again made towards them1 and clambered among them till a vertical precipice1 which proved impossible of ascent1 fronted us4 ,bennen scanned the obstacle closely as we slowly approached it1 and finally descended to the snow1 which wound at a steep angle round its base3 on this the footing appeared to me to be singularly insecure1 but ,i marched without hesitation or anxiety in the footsteps of my guide4 ,sidenote3 ,,the ,,crest ,,of ,,rocks4 #aheh4 ,we ascended the rocks once more1 continued along them for some time1 and then deviated to the couloir on our left4 ,this snow-slope is much dislocated at its lower portion1 and above its precipices and crevasses our route now lay4 ,the snow was smooth1 and sufficiently firm and steep to render the cutting of steps necessary4 ,bennen took the lead3 to make each step he swung his mattock once1 and his hindmost foot rose exactly at the moment the mattock descended2 there was thus a kind of rhythm in his motion1 the raising of the foot keeping time to the swing of the implement4 ,in this manner we proceeded till we reached the base of the rocky pyramid which caps the mountain4 ,sidenote3 ,,the ,,summit ,,gained4 #aheh4 ,one side of the pyramid had been sliced off1 thus dropping down almost a sheer precipice for some thousands of feet to the ,finsteraar glacier4 ,a wall of rock1 about #aj or #ae feet high1 runs along the edge of the mountain1 and this sheltered us from the north wind1 which surged with the sound of waves against the tremendous barrier at the other side4 ,our hardest work is now before us1 said my guide4 ,our way lay up the steep and splintered rocks1 among which we sought out the spikes which were closely enough wedged to bear our weight4 ,each had to trust to himself1 and ,i fulfilled to the letter my engagement with ,bennen to ask no help4 ,my boiling-water apparatus and telescope were on my back1 much to my annoyance1 as the former was heavy1 and sometimes swung awkwardly round as ,i twisted myself among the cliffs4 ,bennen offered to take it1 but he had his own share to carry1 and ,i was resolved to bear mine4 ,sometimes the rocks alternated with spaces of ice and snow1 which we were at intervals compelled to cross2 sometimes1 when the slope was pure ice and very steep1 we were compelled to retreat to the highest cliffs4 ,the wall to which ,i have referred had given way in some places1 and through the gaps thus formed the wind rushed with a loud1 wild1 wailing sound4 ,through these spaces ,i could see the entire field of ,agassiz's observations2 the junction of the ,lauteraar and ,finsteraar glaciers at the ,abschwung1 the medial moraine between them1 on which stood the ,hotel des ,neufchatelois1 and the pavilion built by ,m4 ,dollfuss1 in which ,huxley and myself had found shelter two years before4 ,bennen was evidently anxious to reach the summit1 and recommended all observations to be postponed until after our success had been assured4 ,i agreed to this1 and kept close at his heels4 ,strong as he was1 he sometimes paused1 laid his head upon his mattock1 and panted like a chased deer4 ,he complained of fearful thirst1 and to quench it we had only my bottle of tea3 this we shared loyally1 my guide praising its virtues1 as well he might4 ,still the summit loomed above us2 still the angry swell of the north wind1 beating against the torn battlements of the mountain1 made wild music4 ,upward1 however1 we strained2 and at last1 on gaining the crest of a rock1 ,bennen exclaimed1 in a jubilant voice1 ,die hoechste ,spitze6--the highest point4 ,in a moment ,i was at his side1 and saw the summit within a few paces of us4 ,a minute or two placed us upon the topmost-pinnacle1 with the blue dome of heaven above us1 and a world of mountains1 clouds1 and glaciers beneath4 ,a notion is entertained by many of the guides that if you go to sleep at the summit of any of the highest mountains1 you will ,sleep the sleep that knows no waking4 ,sidenote3 ,,thermometer ,,placed4 #aheh4 ,bennen did not appear to entertain this superstition2 and before starting in the morning1 ,i had stipulated for ten minutes' sleep on reaching the summit1 as part compensation for the loss of the night's rest4 ,my first act1 after casting a glance over the glorious scene beneath us1 was to take advantage of this agreement2 so ,i lay down and had five minutes' sleep1 from which ,i rose refreshed and brisk4 ,the sun at first beat down upon us with intense force1 and ,i exposed my thermometers2 but thin veils of vapour soon drew themselves before the sun1 and denser mists spread over the valley of the ,rhone1 thus destroying all possibility of concert between ,ramsay and myself4 ,i turned therefore to my boiling-water apparatus1 filled it with snow1 melted the first charge1 put more in1 and boiled it2 ascertaining the boiling point to be #ahg deg4 ,fahrenheit4 ,on a sheltered ledge1 about two or three yards south of the highest point1 ,i placed a minimum-thermometer1 in the hope that it would enable us in future years to record the lowest winter temperatures at the summit of the mountain4,a ,sidenote3 ,,scene ,,from ,,the ,,summit4 #aheh4 ,it is difficult to convey any just impression of the scene from the summit of the ,finsteraarhorn3 one might1 it is true1 arrange the visible mountains in a list1 stating their heights and distances1 and leaving the imagination to furnish them with peaks and pinnacles1 to build the precipices1 polish the snow1 rend the glaciers1 and cap the highest summits with appropriate clouds4 ,but if imagination did its best in this way1 it would hardly exceed the reality1 and would certainly omit many details which contribute to the grandeur of the scene itself4 ,the various shapes of the mountains1 some grand1 some beautiful1 bathed in yellow sunshine1 or lying black and riven under the frown of impervious cumuli2 the pure white peaks1 cornices1 bosses1 and amphitheatres2 the blue ice rifts1 the stratified snow-precipices1 the glaciers issuing from the hollows of the eternal hills1 and stretching like frozen serpents through the sinuous valleys2 the lower cloud field--itself an empire of vaporous hills--shining with dazzling whiteness1 while here and there grim summits1 brown by nature1 and black by contrast1 pierce through it like volcanic islands through a shining sea1--add to this the consciousness of one's position which clings to one unconsciously1 that undercurrent of emotion which surrounds the question of one's personal safety1 at a height of more than #ad1jjj feet above the sea1 and which is increased by the weird strange sound of the wind surging with the full deep boom of the distant sea against the precipice behind1 or rising to higher cadences as it forces itself through the crannies of the weatherworn rocks1--all conspire to render the scene from the ,finsteraarhorn worthy of the monarch of the ,bernese ,alps4 ,sidenote3 ,,have ,,no ,,fear4 #aheh4 ,sidenote3 ,,discipline4 #aheh4 ,my guide at length warned me that we must be moving2 repeating the warning more impressively before ,i attended to it4 ,we packed up1 and as we stood beside each other ready to march he asked me whether we should tie ourselves together1 at the same time expressing his belief that it was unnecessary4 ,up to this time we had been separate1 and the thought of attaching ourselves had not occurred to me till he mentioned it4 ,i thought it1 however1 prudent to accept the suggestion1 and so we united our destinies by a strong rope4 ,now1 said ,bennen1 have no fear2 no matter how you throw yourself1 ,i will hold you4 ,afterwards1 on another perilous summit1 ,i repeated this saying of ,bennen's to a strong and active guide1 but his observation was that it was a hardy untruth1 for that in many places ,bennen could not have held me4 ,nevertheless a daring word strengthens the heart1 and1 though ,i felt no trace of that sentiment which ,bennen exhorted me to banish1 and was determined1 as far as in me lay1 to give him no opportunity of trying his strength in saving me1 ,i liked the fearless utterance of the man1 and sprang cheerily after him4 ,our descent was rapid1 apparently reckless1 amid loose spikes1 boulders1 and vertical prisms of rock1 where a false step would assuredly have been attended with broken bones2 but the consciousness of certainty in our movements never forsook us1 and proved a source of keen enjoyment4 ,the senses were all awake1 the eye clear1 the heart strong1 the limbs steady1 yet flexible1 with power of recovery in store1 and ready for instant action should the footing give way4 ,such is the discipline which a perilous ascent imposes4 ,sidenote3 ,,descent ,,by ,,glissades4 #aheh4 ,we finally quitted the crest of rocks1 and got fairly upon the snow once more4 ,we first went downwards at a long swinging trot4 ,the sun having melted the crust which we were compelled to cut through in the morning1 the leg at each plunge sank deeply into the snow2 but this sinking was partly in the direction of the slope of the mountain1 and hence assisted our progress4 ,sometimes the crust was hard enough to enable us to glide upon it for long distances while standing erect2 but the end of these glissades was always a plunge and tumble in the deeper snow4 ,once upon a steep hard slope ,bennen's footing gave way2 he fell1 and went down rapidly1 pulling me after him4 ,i fell also1 but turning quickly1 drove the spike of my hatchet into the ice1 got good anchorage1 and held both fast2 my success assuring me that ,i had improved as a mountaineer since my ascent of ,mont ,blanc4 ,we tumbled so often in the soft snow1 and our clothes and boots were so full of it1 that we thought we might as well try the sitting posture in gliding down4 ,we did so1 and descended with extraordinary velocity1 being checked at intervals by a bodily immersion in the softer and deeper snow4 ,i was usually in front of ,bennen1 shooting down with the speed of an arrow and feeling the check of the rope when the rapidity of my motion exceeded my guide's estimate of what was safe4 ,sometimes ,i was behind him1 and darted at intervals with the swiftness of an avalanche right upon him2 sometimes in the same transverse line with him1 with the full length of the rope between us2 and here ,i found its check unpleasant1 as it tended to make me roll over4 ,my feet were usually in the air1 and it was only necessary to turn them right or left1 like the helm of a boat1 to change the direction of motion and avoid a difficulty1 while a vigorous dig of leg and hatchet into the snow was sufficient to check the motion and bring us to rest4 ,swiftly1 yet cautiously1 we glided into the region of crevasses1 where we at last rose1 quite wet1 and resumed our walking1 until we reached the point where we had left our wine in the morning1 and where ,i squeezed the water from my wet clothes1 and partially dried them in the sun4 ,sidenote3 ,,the ,,viesch ,,glacier4 #aheh4 ,we had left some things at the cave of the ,faulberg1 and it was ,bennen's first intention to return that way and take them home with him4 ,finding1 however1 that we could traverse the ,viescher glacier almost to the ,a,eggischhorn1 ,i made this our highway homewards4 ,at the place where we entered it1 and for an hour or two afterwards1 the glacier was cut by fissures1 for the most part covered with snow4 ,we had packed up our rope1 and ,bennen admonished me to tread in his steps4 ,three or four times he half disappeared in the concealed fissures1 but by clutching the snow he rescued himself and went on as swiftly as before4 ,once my leg sank1 and the ring of icicles some fifty feet below told me that ,i was in the jaws of a crevasse2 my guide turned sharply--it was the only time that ,i had seen concern on his countenance3-- ,gott's ,donner6 ,sie haben meine ,tritte nicht gefolgt4 ,doch6 was my only reply1 and we went on4 ,he scarcely tried the snow that he crossed1 as from its form and colour he could in most cases judge of its condition4 ,for a long time we kept at the left-hand side of the glacier1 avoiding the fissures which were now permanently open4 ,we came upon the tracks of a herd of chamois1 which had clambered from the glacier up the sides of the ,oberaarhorn1 and afterwards crossed the glacier to the right-hand side1 my guide being perfect master of the ground4 ,his eyes went in advance of his steps1 and his judgment was formed before his legs moved4 ,the glacier was deeply fissured1 but there was no swerving1 no retreating1 no turning back to seek more practicable routes2 each stride told1 and every stroke of the axe was a profitable investment of labour4 ,we left the glacier for a time1 and proceeded along the mountain side1 till we came near the end of the ,trift glacier1 where we let ourselves down an awkward face of rock along the track of a little cascade1 and came upon the glacier once more4 ,here again ,i had occasion to admire the knowledge and promptness of my guide4 ,the glacier1 as is well known1 is greatly dislocated1 and has once or twice proved a prison to guides and travellers1 but ,bennen led me through the confusion without a pause4 ,we were sometimes in the middle of the glacier1 sometimes on the moraine1 and sometimes on the side of the flanking mountain4 ,towards the end of the day we crossed what seemed to be the consolidated remains of a great avalanche2 on this my foot slipped1 there was a crevasse at hand1 and a sudden effort was necessary to save me from falling into it4 ,in making this effort the spike of my axe turned uppermost1 and the palm of my hand came down upon it1 thus receiving a very ugly wound4 ,we were soon upon the green alp1 having bidden a last farewell to the ice4 ,another hour's hard walking brought us to our hotel4 ,no one seeing us crossing the alp would have supposed that we had laid such a day's work behind us2 the proximity of home gave vigour to our strides1 and our progress was much more speedy than it had been on starting in the morning4 ,i was affectionately welcomed by ,ramsay1 had a warm bath1 dined1 went to bed1 where ,i lay fast locked in sleep for eight hours1 and rose next morning as fresh and vigorous as if ,i had never scaled the ,finsteraarhorn4 ,,footnotes3 ,a ,the following note describes the single observation made with this thermometer4 ,mr4 ,b4 informs me that on finding the instrument ,bennen swung it in triumph round his head4 ,i fear1 therefore1 that the observation gives us no certain information regarding the minimum winter-temperature4 ,st4 ,nicholas1 #ahei1 ,aug4 #be4 ,sir1--,on ,tuesday last 7the #bcrd inst47 a party1 consisting of ,messrs4 ,b41 ,h41 ,r4 ,l41 and myself1 succeeded in reaching the summit of the ,finsteraarhorn under the guidance of ,bennen and ,melchior ,anderegg4 ,we made it an especial object to observe and reset the minimum-thermometer which you left there last year4 ,on reaching the summit1 before ,i had time to stop him1 ,bennen produced the instrument1 and it is just possible that in moving it he may have altered the position of the index4 ,however1 as he held the instrument horizontally1 and did not1 as far as ,i saw1 give it any sensible jerk1 ,i have great confidence that the index remained unmoved4 ,the reading of the index was -#cb deg4 ,cent4 ,a portion of the spirit extending over about #aj-a_/b deg4 7and standing tween #cc deg4 and #dc-a_/b deg47 was separated from the rest1 but there appeared to be no data for determining when the separation had taken place4 ,as it appeared desirable to unite the two portions of spirit before again setting the index to record the cold of another winter1 we endeavoured to effect this by heating the bulb1 but unfortunately1 just as we were expecting to see them coalesce1 the bulb burst1 and ,i have now to express my great regret that my clumsiness or ignorance of the proper mode of setting the instrument in order should have interfered with the continuance of observations of so much interest4 ,the remains of the instrument1 together with a note of the accident1 ,i have left in the charge of ,wellig1 the landlord of the hotel on the ,a,eggischhorn4 ,we reached the summit about #aj4dj ,a4,m4 and remained there till noon2 the reading of a pocket thermometer in the shade was #da deg4 ,f4 ,should there be any further details connected with our ascent on which you would like to have information1 ,i shall be happy to supply them to the best of my recollection4 ,meanwhile1 with a farther apology for my clumsiness1 ,i beg to subscribe myself yours respectfully1 ,h4 ,professor ,tyndall4 7#ag47 ,sidenote3 ,a ,,rotating ,,iceberg4 #aheh4 ,on the #fth of ,august there was a long fight between mist and sunshine1 each triumphing by turns1 till at length the orb gained the victory and cleansed the mountains from every trace of fog4 ,we descended to the ,maerjelen ,see1 and1 wishing to try the floating power of its icebergs1 at a place where masses sufficiently large approached near to the shore1 ,i put aside a portion of my clothes1 and retaining my boots stepped upon the floating ice4 ,it bore me for a time1 and ,i hoped eventually to be able to paddle myself over the water4 ,on swerving a little1 however1 from the position in which ,i first stood1 the mass turned over and let me into the lake4 ,i tried a second one1 which served me in the same manner2 the water was too cold to continue the attempt1 and there was also some risk of being unpleasantly ground between the opposing surfaces of the masses of ice4 ,a very large iceberg which had been detached some short time previously from the glacier lay floating at some distance from us4 ,suddenly a sound like that of a waterfall drew our attention towards it4 ,we saw it roll over with the utmost deliberation1 while the water which it carried along with it rushed in cataracts down its sides4 ,its previous surface was white1 its present one was of a lovely blue1 the submerged crystal having now come to the air4 ,the summerset of this iceberg produced a commotion all over the lake2 the floating masses at its edge clashed together1 and a mellow glucking sound1 due to the lapping of the undulations against the frozen masses1 continued long afterwards4 ,we subsequently spent several hours upon the glacier2 and on this day ,i noticed for the first time a contemporaneous exhibition of bedding and structure to which ,i shall refer at another place4 ,we passed finally to the left bank of the glacier1 at some distance below the base of the ,a,eggischhorn1 and traced its old moraines at intervals along the flanks of the bounding mountain4 ,at the summit of the ridge we found several fine old roches moutonnees1 on some of which the scratchings of a glacier long departed were well preserved2 and from the direction of the scratchings it might be inferred that the ice moved down the mountain towards the valley of the ,rhone4 ,a plunge into a lonely mountain lake ended the day's excursion4 ,sidenote3 ,,end ,,of ,,the ,,aletsch ,,glacier4 #aheh4 ,on the #gth of ,august we quitted this noble station4 ,sending our guide on to ,viesch to take a conveyance and proceed with our luggage down the valley1 ,ramsay and myself crossed the mountains obliquely1 desiring to trace the glacier to its termination4 ,we had no path1 but it was hardly possible to go astray4 ,we crossed spurs1 climbed and descended pleasant mounds1 sometimes with the soft grass under our feet1 and sometimes knee-deep in rhododendrons4 ,it took us several hours to reach the end of the glacier1 and we then looked down upon it merely4 ,it lay couched like a reptile in a wild gorge1 as if it had split the mountain by its frozen snout4 ,we afterwards descended to ,moerill1 where we met our guide and driver2 thence down the valley to ,visp2 and the following evening saw us lodged at the ,monte ,rosa hotel in ,zermatt4 ,the boiling point of water on the table of the salle a manger1 ,i found to be #bjb4eh deg4 ,fahr4 ,sidenote3 ,,meadows ,,invaded ,,by ,,ice4 #aheh4 ,on the following morning ,i proceeded without my friend to the ,goerner glacier4 ,as is well known1 the end of this glacier has been steadily advancing for several years1 and when ,i saw it1 the meadow in front of it was partly shrivelled up by its irresistible advance4 ,i was informed by my host that within the last sixty years forty-four chalets had been overturned by the glacier1 the ground on which they stood being occupied by the ice2 at present there are others for which a similar fate seems imminent4 ,in thus advancing the glacier merely takes up ground which belonged to it in former ages1 for the rounded rocks which rise out of the adjacent meadow show that it once passed over them4 ,i had arranged to meet ,ramsay this morning on the road to the ,riffelberg4 ,the meeting took place1 but ,i then learned that a minute or two after my departure he had received intelligence of the death of a near relative4 ,thus was our joint expedition terminated1 for he resolved to return at once to ,england4 ,at my solicitation he accompanied me to the ,riffel hotel4 ,we had planned an ascent of ,monte ,rosa together1 but the arrangement thus broke down1 and ,i was consequently thrown upon my own resources4 ,lauener had never made the ascent1 but he nevertheless felt confident that we should accomplish it together4 ,,first ,,ascent ,,of ,,monte ,,rosa1 #aheh4 7#ah47 ,sidenote3 ,,the ,,riffelberg4 #aheh4 ,sidenote3 ,,sounds ,,on ,,the ,,glacier4 #aheh4 ,on ,monday1 the #ith of ,august1 we reached the ,riffel1 and1 by good fortune1 on the evening of the same day1 my guide's brother1 the well-known ,ulrich ,lauener1 also arrived at the hotel on his return from ,monte ,rosa4 ,from him we obtained all the information possible respecting the ascent1 and he kindly agreed to accompany us a little way the next morning1 to put us on the right track4 ,at three ,a4,m4 the door of my bedroom opened1 and ,christian ,lauener announced to me that the weather was sufficiently good to justify an attempt4 ,the stars were shining overhead2 but ,ulrich afterwards drew our attention to some heavy clouds which clung to the mountains on the other side of the valley of the ,visp2 remarking that the weather might continue fair throughout the day1 but that these clouds were ominous4 ,at four o'clock we were on our way1 by which time a gray stratus cloud had drawn itself across the neck of the ,matterhorn1 and soon afterwards another of the same nature encircled his waist4 ,we proceeded past the ,riffelhorn to the ridge above the ,goerner glacier1 from which ,monte ,rosa was visible from top to bottom1 and where an animated conversation in ,swiss patois commenced4 ,ulrich described the slopes1 passes1 and precipices1 which were to guide us2 and ,christian demanded explanations1 until he was finally able to declare to me that his knowledge was sufficient4 ,we then bade ,ulrich good-bye1 and went forward4 ,all was clear about ,monte ,rosa1 and the yellow morning light shone brightly upon its uppermost snows4 ,beside the ,queen of the ,alps was the huge mass of the ,lyskamm1 with a saddle stretching from the one to the other2 next to the ,lyskamm came two white rounded mounds1 smooth and pure1 the ,twins ,castor and ,pollux1 and further to the right again the broad brown flank of the ,breithorn4 ,behind us ,mont ,cervin gathered the clouds more thickly round him1 until finally his grand obelisk was totally hidden4 ,we went along the mountain-side for a time1 and then descended to the glacier4 ,the surface was hard frozen1 and the ice crunched loudly under our feet4 ,there was a hollowness and volume in the sound which require explanation2 and this1 ,i think1 is furnished by the remarks of ,sir ,john ,herschel on those hollow sounds at the ,solfaterra1 near ,naples1 from which travellers have inferred the existence of cavities within the mountain4 ,at the place where these sounds are heard the earth is friable1 and1 when struck1 the concussion is reinforced and lengthened by the partial echoes from the surfaces of the fragments4 ,the conditions for a similar effect exist upon the glacier1 for the ice is disintegrated to a certain depth1 and from the innumerable places of rupture little reverberations are sent1 which give a length and hollowness to the sound produced by the crushing of the fragments on the surface4 ,we looked to the sky at intervals1 and once a meteor slid across it1 leaving a train of sparks behind4 ,the blue firmament1 from which the stars shone down so brightly when we rose1 was more and more invaded by clouds1 which advanced upon us from our rear1 while before us the solemn heights of ,monte ,rosa were bathed in rich yellow sunlight4 ,as the day advanced the radiance crept down towards the valleys2 but still those stealthy clouds advanced like a besieging army1 taking deliberate possession of the summits1 one after the other1 while gray skirmishers moved through the air above us4 ,the play of light and shadow upon ,monte ,rosa was at times beautiful1 bars of gloom and zones of glory shifting and alternating from top to bottom of the mountain4 ,sidenote3 ,,advance ,,of ,,the ,,clouds4 #aheh4 ,at five o'clock a gray cloud alighted on the shoulder of the ,lyskamm1 which had hitherto been warmed by the lovely yellow light4 ,soon afterwards we reached the foot of ,monte ,rosa1 and passed from the glacier to a slope of rocks1 whose rounded forms and furrowed surfaces showed that the ice of former ages had moved over them2 the granite was now coated with lichens1 and between the bosses where mould could rest were patches of tender moss4 ,as we ascended1 a peal to the right announced the descent of an avalanche from the ,twins2 it came heralded by clouds of ice-dust1 which resembled the sphered masses of condensed vapour which issue from a locomotive4 ,a gentle snow-slope brought us to the base of a precipice of brown rocks1 round which we wound2 the snow was in excellent order1 and the chasms were so firmly bridged by the frozen mass that no caution was necessary in crossing them4 ,surmounting a weathered cliff to our left1 we paused upon the summit to look upon the scene around us4 ,the snow gliding insensibly from the mountains1 or discharged in avalanches from the precipices which it overhung1 filled the higher valleys with pure white glaciers1 which were rifted and broken here and there1 exposing chasms and precipices from which gleamed the delicate blue of the half-formed ice4 ,sometimes1 however1 the neves spread over wide spaces without a rupture or wrinkle to break the smoothness of the superficial snow4 ,the sky was now for the most part overcast1 but through the residual blue spaces the sun at intervals poured light over the rounded bosses of the mountain4 ,sidenote3 ,,monte ,,rosa ,,capped4 #aheh4 ,at half-past seven o'clock we reached another precipice of rock1 to the left of which our route lay1 and here ,lauener proposed to have some refreshment2 after which we went on again4 ,the clouds spread more and more1 leaving at length mere specks and patches of blue between them4 ,passing some high peaks1 formed by the dislocation of the ice1 we came to a place where the neve was rent by crevasses1 on the walls of which the stratification due to successive snow-falls was shown with great beauty and definition4 ,between two of these fissures our way now lay3 the wall of one of them was hollowed out longitudinally midway down1 thus forming a roof above and a ledge below1 and from roof to ledge stretched a railing of cylindrical icicles1 as if intended to bolt them together4 ,a cloud now for the first time touched the summit of ,monte ,rosa1 and sought to cling to it1 but in a minute it dispersed in shattered fragments1 as if dashed to pieces for its presumption4 ,the mountain remained for a time clear and triumphant1 but the triumph was short-lived3 like suitors that will not be repelled1 the dusky vapours came2 repulse after repulse took place1 and the sunlight gushed down upon the heights1 but it was manifest that the clouds gained ground in the conflict4 ,until about a quarter past nine o'clock our work was mere child's play1 a pleasant morning stroll along the flanks of the mountain2 but steeper slopes now rose above us1 which called for more energy1 and more care in the fixing of the feet4 ,looked at from below1 some of these slopes appeared precipitous2 but we were too well acquainted with the effect of fore-shortening to let this daunt us4 ,at each step we dug our batons into the deep snow4 ,when first driven in1 the batons,a dipped from us1 but were brought1 as we walked forward1 to the vertical1 and finally beyond it at the other side4 ,the snow was thus forced aside1 a rubbing of the staff against it1 and of the snow-particles against each other1 being the consequence4 ,we had thus perpetual rupture and regelation2 while the little sounds consequent upon rupture1 reinforced by the partial echoes from the surfaces of the granules1 were blended together to a note resembling the lowing of cows4 ,hitherto ,i had paused at intervals to make notes1 or to take an angle2 but these operations now ceased1 not from want of time1 but from pure dislike2 for when the eye has to act the part of a sentinel who feels that at any moment the enemy may be upon him2 when the body must be balanced with precision1 and legs and arms1 besides performing actual labour1 must be kept in readiness for possible contingencies2 above all1 when you feel that your safety depends upon yourself alone1 and that1 if your footing gives way1 there is no strong arm behind ready to be thrown between you and destruction2 under such circumstances the relish for writing ceases1 and you are willing to hand over your impressions to the safe keeping of memory4 ,sidenote3 ,,the ,,comb ,,of ,,the ,,mountain4 #aheh4 ,sidenote3 ,,ascent ,,along ,a ,,cornice4 #aheh4 ,from the vast boss which constitutes the lower portion of ,monte ,rosa cliffy edges run upwards to the summit4 ,were the snow removed from these we should1 ,i doubt not1 see them as toothed or serrated crags1 justifying the term kamm1 or comb1 applied to such edges by the ,germans4 ,our way now lay along such a kamm1 the cliffs of which had1 however1 caught the snow1 and been completely covered by it1 forming an edge like the ridge of a house-roof1 which sloped steeply upwards4 ,on the ,lyskamm side of the edge there was no footing1 and1 if a human body fell over here1 it would probably pass through a vertical space of some thousands of feet1 falling or rolling1 before coming to rest4 ,on the other side the snow-slope was less steep1 but excessively perilous-looking1 and intersected by precipices of ice4 ,dense clouds now enveloped us1 and made our position far uglier than if it had been fairly illuminated4 ,the valley below us was one vast cauldron1 filled with precipitated vapour1 which came seething at times up the sides of the mountain4 ,sometimes this fog would partially clear away1 and the light would gleam upwards from the dislocated glaciers4 ,my guide continually admonished me to make my footing sure1 and to fix at each step my staff firmly in the consolidated snow4 ,at one place1 for a short steep ascent1 the slope became hard ice1 and our position a very ticklish one4 ,we hewed our steps as we moved upwards1 but were soon glad to deviate from the ice to a position scarcely less awkward4 ,the wind had so acted upon the snow as to fold it over the edge of the kamm1 thus causing it to form a kind of cornice1 which overhung the precipice on the ,lyskamm side of the mountain4 ,this cornice now bore our weight3 its snow had become somewhat firm1 but it was yielding enough to permit the feet to sink in it a little way1 and thus secure us at least against the danger of slipping4 ,here also at each step we drove our batons firmly into the snow1 availing ourselves of whatever help they could render4 ,once1 while thus securing my anchorage1 the handle of my hatchet went right through the cornice on which we stood1 and1 on withdrawing it1 ,i could see through the aperture into the cloud-crammed gulf below4 ,we continued ascending until we reached a rock protruding from the snow1 and here we halted for a few minutes4 ,lauener looked upwards through the fog4 ,according to all description1 he observed1 this ought to be the last kamm of the mountain2 but in this obscurity we can see nothing4 ,snow began to fall1 and we recommenced our journey1 quitting the rocks and climbing again along the edge4 ,another hour brought us to a crest of cliffs1 at which1 to our comfort1 the kamm appeared to cease1 and other climbing qualities were demanded of us4 ,sidenote3 ,,die ,h,oe,c,h,s,t,e ,,spitze4 #aheh4 ,on the ,lyskamm side1 as ,i have said1 rescue would be out of the question1 should the climber go over the edge4 ,on the other side of the edge rescue seemed possible1 though the slope1 as stated already1 was most dangerously steep4 ,i now asked ,lauener what he would have done1 supposing my footing to have failed on the latter slope4 ,he did not seem to like the question1 but said that he should have considered well for a moment and then have sprung after me2 but he exhorted me to drive all such thoughts away4 ,i laughed at him1 and this did more to set his mind at rest than any formal profession of courage could have done4 ,we were now among rocks3 we climbed cliffs and descended them1 and advanced sometimes with our feet on narrow ledges1 holding tightly on to other ledges by our fingers2 sometimes1 cautiously balanced1 we moved along edges of rock with precipices on both sides4 ,once1 in getting round a crag1 ,lauener shook a book from his pocket2 it was arrested by a rock about sixty or eighty feet below us4 ,he wished to regain it1 but ,i offered to supply its place1 if he thought the descent too dangerous4 ,he said he would make the trial1 and parted from me4 ,i thought it useless to remain idle4 ,a cleft was before me1 through which ,i must pass2 so1 pressing my knees and back against its opposite sides1 ,i gradually worked myself to the top4 ,i descended the other face of the rock1 and then1 through a second ragged fissure1 to the summit of another pinnacle4 ,the highest point of the mountain was now at hand1 separated from me merely by a short saddle1 carved by weathering out of the crest of the mountain4 ,i could hear ,lauener clattering after me1 through the rocks behind4 ,i dropped down upon the saddle1 crossed it1 climbed the opposite cliff1 and die hoechste ,spitze of ,monte ,rosa was won4 ,sidenote3 ,,gloom ,,on ,,the ,,summit4 #aheh4 ,lauener joined me immediately1 and we mutually congratulated each other on the success of the ascent4 ,the residue of the bread and meat was produced1 and a bottle of tea was also appealed to4 ,mixed with a little cognac1 ,lauener declared that he had never tasted anything like it4 ,snow fell thickly at intervals1 and the obscurity was very great2 occasionally this would lighten and permit the sun to shed a ghastly dilute light upon us through the gleaming vapour4 ,i put my boiling-water apparatus in order1 and fixed it in a corner behind a ledge2 the shelter was1 however1 insufficient1 so ,i placed my hat above the vessel4 ,the boiling point was #ahd4ib deg4 ,fahr41 the ledge on which the instrument stood being #e feet below the highest point of the mountain4 ,the ascent from the ,riffel hotel occupied us about seven hours1 nearly two of which were spent upon the kamm and crest4 ,neither of us felt in the least degree fatigued2 ,i1 indeed1 felt so fresh1 that had another ,monte ,rosa been planted on the first1 ,i should have continued the climb without hesitation1 and with strong hopes of reaching the top4 ,i experienced no trace of mountain sickness1 lassitude1 shortness of breath1 heart-beat1 or headache2 nevertheless the summit of ,monte ,rosa is #ae1bhd feet high1 being less than #ejj feet lower than ,mont ,blanc4 ,it is1 ,i think1 perfectly certain1 that the rarefaction of the air at this height is not sufficient of itself to produce the symptoms referred to2 physical exertion must be superadded4 ,sidenote3 ,,frozen ,,flowers4 #aheh4 ,after a few fitful efforts to dispel the gloom1 the sun resigned the dominion to the dense fog and the descending snow1 which now prevented our seeing more than #ae or #bj paces in any direction4 ,the temperature of the crags at the summit1 which had been shone upon by the unclouded sun during the earlier portion of the day1 was #fj deg4 ,fahr42 hence the snow melted instantly wherever it came in contact with the rock4 ,but some of it fell upon my felt hat1 which had been placed to shelter the boiling-water apparatus1 and this presented the most remarkable and beautiful appearance4 ,the fall of snow was in fact a shower of frozen flowers4 ,all of them were six-leaved2 some of the leaves threw out lateral ribs like ferns1 some were rounded1 others arrowy and serrated1 some were close1 others reticulated1 but there was no deviation from the six-leaved type4 ,nature seemed determined to make us some compensation for the loss of all prospect1 and thus showered down upon us those lovely blossoms of the frost2 and had a spirit of the mountain inquired my choice1 the view1 or the frozen flowers1 ,i should have hesitated before giving up that exquisite vegetation4 ,it was wonderful to think of1 as well as beautiful to behold4 ,let us imagine the eye gifted with a microscopic power sufficient to enable it to see the molecules which composed these starry crystals2 to observe the solid nucleus formed and floating in the air2 to see it drawing towards it its allied atoms1 and these arranging themselves as if they moved to music1 and ended by rendering that music concrete4 ,surely such an exhibition of power1 such an apparent demonstration of a resident intelligence in what we are accustomed to call brute matter1 would appear perfectly miraculous4 ,and yet the reality would1 if we could see it1 transcend the fancy4 ,if the ,houses of ,parliament were built up by the forces resident in their own bricks and lithologic blocks1 and without the aid of hodman or mason1 there would be nothing intrinsically more wonderful in the process than in the molecular architecture which delighted us upon the summit of ,monte ,rosa4 ,sidenote3 ,,startling ,,avalanche4 #aheh4 ,twice or thrice had my guide warned me that we must think of descending1 for the snow continued to fall heavily1 and the loss of our track would be attended with imminent peril4 ,we therefore packed up1 and clambered downward among the crags of the summit4 ,we soon left these behind us1 and as we stood once more upon the kamm1 looking into the gloom beneath1 an avalanche let loose from the side of an adjacent mountain shook the air with its thunder4 ,we could not see it1 could form no estimate of its distance1 could only hear its roar1 which coming to us through the darkness1 had an undefinable element of horror in it4 ,lauener remarked1 ,i never hear those things without a shudder2 the memory of my brother comes back to me at the same time4 ,his brother1 who was the best climber in the ,oberland1 had been literally broken to fragments by an avalanche on the slopes of the ,jungfrau4 ,we had been separate coming up1 each having trusted to himself1 but the descent was more perilous1 because it is more difficult to fix the heel of the boot than the toe securely in the ice4 ,lauener was furnished with a rope1 which he now tied round my waist1 and forming a noose at the other end1 he slipped it over his arm4 ,this to me was a new mode of attachment4 ,hitherto my guides in dangerous places had tied the ropes round their waists also4 ,simond had done it on ,mont ,blanc1 and ,bennen on the ,finsteraarhorn1 proving thus their willingness to share my fate whatever that might be4 ,but here ,lauener had the power of sending me adrift at any moment1 should his own life be imperilled4 ,i told him that his mode of attachment was new to me1 but he assured me that it would give him more power in case of accident4 ,i did not see this at the time2 but neither did ,i insist on his attaching himself in the usual way4 ,it could neither be called anger nor pride1 but a warm flush ran through me as ,i remarked1 that ,i should take good care not to test his power of holding me4 ,i believe ,i wronged my guide by the supposition that he made the arrangement with reference to his own safety1 for all ,i saw of him afterwards proved that he would at any time have risked his life to save mine4 ,the flush however did me good1 by displacing every trace of anxiety1 and the rope1 ,i confess1 was also a source of some comfort to me4 ,we descended the kamm1 ,i going first4 ,secure your footing before you move1 was my guide's constant exhortation1 and make your staff firm at each step4 ,we were sometimes quite close upon the rim of the kamm on the ,lyskamm side1 and we also followed the depressions which marked our track along the cornice4 ,this ,i now tried intentionally1 and drove the handle of my axe through it once or twice4 ,at two places in descending we were upon the solid ice1 and these were some of the steepest portions of the kamm4 ,they were undoubtedly perilous1 and the utmost caution was necessary in fixing the staff and securing the footing4 ,these however once past1 we felt that the chief danger was over4 ,we reached the termination of the edge1 and although the snow continued to fall heavily1 and obscure everything1 we knew that our progress afterwards was secure4 ,there was pleasure in this feeling2 it was an agreeable variation of that grim mental tension to which ,i had been previously wound up1 but which in itself was by no means disagreeable4 ,sidenote3 ,,splendid ,,blue ,,of ,,the ,,snow4 #aheh4 ,sidenote3 ,,stifling ,,heat4 #aheh4 ,i have already noticed the colour of the fresh snow upon the summit of the ,stelvio pass4 ,since ,i observed it there it has been my custom to pay some attention to this point at all great elevations4 ,this morning1 as ,i ascended ,monte ,rosa1 ,i often examined the holes made in the snow by our batons1 but the light which issued from them was scarcely perceptibly blue4 ,now1 however1 a deep layer of fresh snow overspread the mountain1 and the effect was magnificent4 ,along the kamm ,i was continually surprised and delighted by the blue gleams which issued from the broken or perforated stratum of new snow2 each hole made by the staff was filled with a light as pure1 and nearly as deep1 as that of the unclouded firmament4 ,when we reached the bottom of the kamm1 ,lauener came to the front1 and tramped before me4 ,as his feet rose out of the snow1 and shook the latter off in fragments1 sudden and wonderful gleams of blue light flashed from them4 ,doubtless the blue of the sky has much to do with mountain colouring1 but in the present instance not only was there no blue sky1 but the air was so thick with fog and descending snow-flakes1 that we could not see twenty yards in advance of us4 ,a thick fog1 which wrapped the mountain quite closely1 now added its gloom to the obscurity caused by the falling snow4 ,before we reached the base of the mountain the fog became thin1 and the sun shone through it4 ,there was not a breath of air stirring1 and1 though we stood ankle-deep in snow1 the heat surpassed anything of the kind ,i had ever felt3 it was the dead suffocating warmth of the interior of an oven1 which encompassed us on all sides1 and from which there seemed no escape4 ,our own motion through the air1 however1 cooled us considerably4 ,we found the snow-bridges softer than in the morning1 and consequently needing more caution2 but we encountered no real difficulty among them4 ,indeed it is amusing to observe the indifference with which a snow-roof is often broken through1 and a traveller immersed to the waist in the jaws of a fissure4 ,the effort at recovery is instantaneous2 half instinctively hands and knees are driven into the snow1 and rescue is immediate4 ,fair glacier work was now before us2 after which we reached the opposite mountain-slope1 which we ascended1 and then went down the flank of the ,riffelberg to our hotel4 ,the excursion occupied us eleven and a half hours4 ,,footnotes3 ,a ,my staff was always the handle of an axe an inch or two longer than an ordinary walking-stick4 7#ai47 ,on the afternoon of the #aath ,i made an attempt alone to ascend the ,riffelhorn1 and attained a considerable height2 but ,i attacked it from the wrong side1 and the fading light forced me to retreat4 ,i found some agreeable people at the hotel on my return4 ,one clergyman especially1 with a clear complexion1 good digestion1 and bad lungs--of free1 hearty1 and genial manner--made himself extremely pleasant to us all4 ,he appeared to bubble over with enjoyment1 and with him and others on the morning of the #acth ,i walked to the ,goerner ,grat1 as it lay on the way to my work4 ,we had a glorious prospect from the summit3 indeed the assemblage of mountains1 snow1 and ice1 here within view is perhaps without a rival in the world4,a ,i shouldered my axe1 and saying good-bye moved away from my companions4 ,are you going8 exclaimed the clergyman4 ,give me one grasp of your hand before we part4 ,this was the signal for a grasp all round2 and the hearty human kindness which thus showed itself contributed that day to make my work pleasant to me4 ,sidenote3 ,a ,,difficult ,,descent4 #aheh4 ,we proceeded along the ridge of the ,rothe ,kumme to a point which commanded a fine view of the glacier4 ,the ice had been over these heights in ages past1 for1 although lichens covered the surfaces of the old rocks1 they did not disguise the grooves and scratchings4 ,the surface of the glacier was now about a thousand feet below us1 and this it was our desire to attain4 ,to reach it we had to descend a succession of precipices1 which in general were weathered and rugged1 but here and there1 where the rock was durable1 were fluted and grooved4 ,once or twice indeed we had nothing to cling to but the little ridges thus formed4 ,we had to squeeze ourselves through narrow fissures1 and often to get round overhanging ledges1 where our main trust was in our feet1 but where these had only ledges an inch or so in width to rest upon4 ,these cases were to me the most unpleasant of all1 for they compelled the arms to take a position which1 if the footing gave way1 would necessitate a wrench1 for which ,i entertain considerable abhorrence4 ,we came at length to a gorge by which the mountain is rent from top to bottom1 and into which we endeavoured to descend4 ,we worked along its rim for a time1 but found its smooth faces too deep4 ,we retreated2 ,lauener struck into another track1 and while he tested it ,i sat down near some grass tufts1 which flourished on one of the ledges1 and found the temperature to be as follows3-- ,temperature of rock #db deg4 ,c4 ,of air an inch above the rock #cb ,of air a foot from rock #bb ,of grass #be ,the first of these numbers does not fairly represent the temperature of the rock1 as the thermometer could be in contact with it only at one side at a time4 ,it was differences such as these between grass and stone1 producing a mixed atmosphere of different densities1 that weakened the sound of the falls of the ,orinoco1 as observed and explained by ,humboldt4 ,sidenote3 ,,singular ,,ice-,,cave4 #aheh4 ,by a process of trial and error we at length reached the ice1 after two hours had been spent in the effort to disentangle ourselves from the crags4 ,the glacier is forcibly thrust at this place against the projecting base of the mountain1 and the structure of the ice correspondingly developed4 ,crevasses also intersect the ice1 and the blue veins cross them at right angles4 ,i ascended the glacier to a region where the ice was compressed and greatly contorted1 and thought that in some cases ,i could see the veins crossing the lines of stratification4 ,once my guide drew my attention to what he called ein sonderbares ,loch4 ,on one of the slopes an archway was formed which appeared to lead into the body of the glacier4 ,we entered it1 and explored the cavern to its end4 ,the walls were of transparent blue ice1 singularly free from air-bubbles2 but where the roof of the cavern was thin enough to allow the sun to shine feebly through it1 the transmitted light was of a pink colour4 ,my guide expressed himself surprised at den roethlichen ,schein4 ,at one place a plate of ice had been placed like a ceiling across the cavern2 but owing to lateral squeezing it had been broken so as to form a ,v4 ,i found some air-bubbles in this ice1 and in all cases they were associated with blebs of water4 ,a portion of the ceiling1 indeed1 was very full of bubbles1 and was at some places reduced1 by internal liquefaction1 to a mere skeleton of ice1 with water-cells between its walls4 ,sidenote3 ,,structure ,,and ,,strata4 #aheh4 ,high up the glacier 7towards the old ,weissthor7 the horizontal stratification is everywhere beautifully shown4 ,i drew my guide's attention to it1 and he made the remark that the perfection of the lower ice was due to the pressure of the layers above it4 ,the snow by degrees compressed itself to glacier4 ,as we approached one of the tributaries on the ,monte ,rosa side1 where great pressure came into play1 the stratification appeared to yield and the true structure to cross it at those places where it had yielded most4 ,as the place of greatest pressure was approached1 the bedding disappeared more and more1 and a clear vertical structure was finally revealed4 ,,footnotes3 ,a ,in #aheh ,mr4 ,e4 ,w4 ,cooke made a pencil-sketch of this splendid panorama1 which is the best and truest that ,i have yet seen4 ,,the ,g,oe,r,n,e,r ,,grat ,,and ,,the ,,riffelhorn4 ,,magnetic ,,phenomena4 7#bj47 ,at an early hour on ,saturday1 the #adth of ,august1 ,i heard the servant exclaim1 ,das ,wetter ist wunderschoen6 which good news caused me to spring from my bed and prepare to meet the morn4 ,the range of summits at the opposite side of the valley of ,st4 ,nicholas was at first quite clear1 but as the sun ascended light cumuli formed round them1 increasing in density up to a certain point2 below these clouds the air of the valley was transparent2 above them the air of heaven was still more so2 and thus they swung midway between heaven and earth1 ranging themselves in a level line along the necks of the mountains4 ,sidenote3 ,,generation ,,of ,,clouds4 #aheh4 ,it might be supposed that the presence of the sun heating the air would tend to keep it more transparent1 by increasing its capacity to dissolve all visible cloud2 and this indeed is the true action of the sun4 ,but it is not the only action4 ,his rays1 as he climbed the eastern heaven1 shot more and more deeply into the valley of ,st4 ,nicholas1 the moisture of which rose as invisible vapour1 remaining unseen as long as the air possessed sufficient warmth to keep it in the vaporous state4 ,high up1 however1 the cold crags which had lost their heat by radiation the night before1 acted like condensers upon the ascending vapour1 and caused it to curdle into visible fog4 ,the current1 however1 continued ascensional1 and the clouds were slowly lifted above the tallest peaks1 where they arranged themselves in fantastic forms1 shifting and changing shape as they gradually melted away4 ,one peak stood like a field-officer with his cap raised above his head1 others sent straggling cloud-balloons upwards2 but on watching these outliers they were gradually seen to disappear4 ,at first they shone like snow in the sunlight1 but as they became more attenuated they changed colour1 passing through a dull red to a dusky purple hue1 until finally they left no trace of their existence4 ,sidenote3 ,,the ,,rocks ,,warmed4 #aheh4 ,sidenote3 ,,scene ,,from ,,the ,g,oe,r,n,e,r ,,grat4 #aheh4 ,as the day advanced1 warming the rocks1 the clouds wholly disappeared1 and a hyaline air formed the setting of both glaciers and mountains4 ,i climbed to the ,goerner ,grat to obtain a general view of the surrounding scene4 ,looking towards the origin of the ,goerner glacier the view was bounded by a wide col1 upon which stood two lovely rounded eminences enamelled with snow of perfect purity4 ,they shone like burnished silver in the sunlight1 as if their surfaces had been melted and recongealed to frosted mirrors from which the rays were flung4 ,to the right of these were the bounding crags of ,monte ,rosa1 and then the body of the mountain itself1 with its crest of crag and coat of snows4 ,to the right of ,monte ,rosa1 and almost rivalling it in height1 was the vast mass of the ,lyskamm1 a rough and craggy mountain1 to whose ledges clings the snow which cannot grasp its steeper walls1 sometimes leaning over them in impending precipices1 which often break1 and send wild avalanches into the space below4 ,between the ,lyskamm and ,monte ,rosa lies a large wide valley into which both mountains pour their snows1 forming there the ,western glacier of ,monte ,rosa,a--a noble ice stream1 which from its magnitude and permanence deserves to impose its name upon the trunk glacier4 ,it extends downwards from the col which unites the two mountains2 riven and broken at some places1 but at others stretching white and pure down to its snow-line1 where the true glacier emerges from the neve4 ,from the rounded shoulders of the ,twin ,castor a glacier descends1 at first white and shining1 then suddenly broken into faults1 fissures1 and precipices1 which are afterwards repaired1 and the glacier joins that of ,monte ,rosa before the junction of the latter with the trunk stream4 ,next came a boss of rock1 with a secondary glacier clinging to it as if plastered over it1 and after it the ,schwarze glacier1 bounded on one side by the ,breithorn1 and on the other by the ,twin ,pollux4 ,this glacier is of considerable magnitude4 ,over its upper portion rise the ,twin eminences1 pure and white2 then follows a smooth and undulating space1 after passing which the neve is torn up into a collection of peaks and chasms2 these1 however1 are mended lower down1 and the glacier moves smoothly and calmly to meet its brothers in the main valley4 ,next comes the ,trifti glacier1,b embraced on all sides by the rocky arms of the ,breithorn2 its mass is not very great1 but it descends in a graceful sweep1 and exhibits towards its extremity a succession of beautiful bands4 ,afterwards we have the glacier of the ,petit ,mont ,cervin and those of ,st4 ,theodule1 which latter are the last that empty their frozen cargoes into the valley of the ,goerner4 ,all the glaciers here mentioned are welded together to a common trunk which squeezes itself through the narrow defile at the base of the ,riffelhorn4 ,soon afterwards the moraines become confused1 the glacier drops steeply to its termination1 and ploughs up the meadows in front of it with its irresistible share4 ,in a line with the ,riffelhorn1 and rising over the latter so high as to make it almost vanish by comparison1 was the ,titan obelisk of the ,matterhorn1 from the base of which the ,furgge glacier struggles downwards4 ,on the other side are the ,zmutt glacier1 the ,schoenbuehl1 and the ,hochwang1 from the ,dent ,blanche2 the ,gabelhorn and ,trift glaciers1 from the summits which bear those names4 ,then come the glaciers of the ,weisshorn4 ,describing a curve still farther to the right we alight on the peaks of the ,mischabel1 dark and craggy precipices from this side1 though from the ,a,eggischhorn they appear as cones of snow4 ,sweeping by the ,alphubel1 the ,allaleinhorn1 the ,rympfischorn1 and ,strahlhorn--all of them majestic--we reach the pass of the ,weissthor1 and the ,cima di ,jazzi4 ,this completes the glorious circuit within the observer's view4 ,sidenote3 ,,compass ,,at ,,fault4 #aheh4 ,i placed my compass upon a piece of rock to find the bearing of the ,goerner glacier1 and was startled at seeing the sun and it at direct variance4 ,what the sun declared to be north1 the needle affirmed to be south4 ,i at first supposed that the maker had placed the ,s where the ,n ought to be1 and vice versa4 ,on shifting my position1 however1 the needle shifted also1 and ,i saw immediately that the effect was due to the rock of the ,grat4 ,sometimes one end of the needle dipped forcibly1 at other places it whirled suddenly round1 indicating an entire change of polarity4 ,the rock was evidently to be regarded as an assemblage of magnets1 or as a single magnet full of consequent points4 ,a distance of transport not exceeding an inch was1 in some cases1 sufficient to reverse the position of the needle4 ,i held the needle between the two sides of a long fissure a foot wide4 ,the needle set along the fissure at some places1 while at others it set across it4 ,sometimes a little jutting knob would attract the north end of the needle1 while a closely adjacent little knob would forcibly repel it1 and attract the south end4 ,one extremity of a ledge three feet long was north magnetic1 the other end was south magnetic1 while a neutral point existed midway between the two1 the ledge having therefore the exact polar arrangement of an ordinary bar-magnet4 ,at the highest point of the rock the action appeared to be most intense1 but ,i also found an energetic polarity in a mass at some distance below the summit4 ,sidenote3 ,,magnetism ,,of ,,rocks4 #aheh4 ,remembering that ,professor ,forbes had noticed some peculiar magnetic effect upon the ,riffelhorn1 ,i resolved to ascend it4 ,descending from the ,grat we mounted the rocks which form the base of the horn2 these are soft and soapy from the quantity of mica which they contain2 the higher rocks of the horn are1 however1 very dense and hard4 ,the ascent is a pleasant bit of mountain practice4 ,we climbed the walls of rock1 and wound round the ledges1 seeking the assailable points4 ,i tried the magnetic condition of the rocks as we ascended1 and found it in general feeble4 ,in other respects the ,riffelhorn is a most remarkable mass4 ,the ice of the ,goerner glacier of former ages1 which rose hundreds1 perhaps thousands of feet above its present level1 encountered the horn in its descent1 and was split by the latter1 a diversion of the ice along the sides of the peak being the consequence4 ,portions of the vertical walls of the horn are polished by this action as if they had come from the hands of a lapidary1 and the scratchings are as sharp and definite as if drawn by points of steel4 ,i never saw scratchings so perfectly preserved3 the finest lines are as clear as the deepest1 a consequence of the great density and durability of the rock4 ,the latter evidently contains a good deal of iron1 and its surface near the summit is of the rich brown red due to the peroxide of the metal4 ,when we fairly got among the precipices we left our hatchets behind us1 trusting subsequently to our hands and feet alone4 ,squeezing1 creeping1 clinging1 and climbing1 in due time we found ourselves upon the summit of the horn4 ,sidenote3 ,,ascent ,,of ,,the ,,riffelhorn4 #aheh4 ,a pile of stones had been erected near the point where we gained the top4 ,i examined the stones of this pile1 and found them strongly polar4 ,the surrounding rocks also showed a violent action1 the needle oscillating quickly1 and sometimes twirling swiftly round upon a slight change of position4 ,the fragments of rock scattered about were also polar4 ,long ledges showed north magnetism for a considerable length1 and again for an equal length south magnetism4 ,two parallel masses separated from each other by a fissure1 showed the same magnetic distribution4 ,while ,i was engaged at one end of the horn1 ,lauener wandered to the other1 on which stood two or three hommes de pierres4 ,he was about disturbing some of the stones1 when a yell from me surprised him4 ,in fact1 the thought had occurred to me that the magnetism of the horn had been developed by lightning striking upon it1 and my desire was to examine those points which were most exposed to the discharge of the atmospheric electricity2 hence my shout to my guide to let the stones alone4 ,i worked towards the other end of the horn1 examining the rocks in my way4 ,two weathered prominences1 which seemed very likely recipients of the lightning1 acted violently upon the needle4 ,i sometimes descended a little way1 and found that among the rocks below the summit the action was greatly enfeebled4 ,on reaching another very prominent point1 ,i found its extremity all north polar1 but at a little distance was a cluster of consequent points1 among which the transport of a few inches was sufficient to turn the needle round and round4 ,sidenote3 ,,magnetism ,,of ,,the ,,horn4 #aheh4 ,the piles of stone at the ,zermatt end of the horn did not seem so strongly polar as the pile at the other end1 which was higher2 still a strong polar action was manifested at many points of the surrounding rocks4 ,having completed the examination of the summit1 ,i descended the horn1 and examined its magnetic condition as ,i went along4 ,it seemed to me that the jutting prominences always exhibited the strongest action4 ,i do not indeed remember any case in which a strong action did not exhibit itself at the ends of the terraces which constitute the horn4 ,in all cases1 however1 the rock acted as a number of magnets huddled confusedly together1 and not as if its entire mass was endowed with magnetism of one kind4 ,illustration3 ,fig4 #h4 ,magnetic ,boulder of the ,riffelhorn4 ,on the evening of the same day ,i examined the lower spur of the ,riffelhorn4 ,amid its fissures and gullies one feels as if wandering through the ruins of a vast castle or fortification2 the precipices are so like walls1 and the scratching and polishing so like what might be done by the hands of man4 ,i found evidences of strong polar action in some of the rocks low down4 ,in the same continuous mass the action would sometimes exhibit itself over an area of small extent1 while the remainder of the rock showed no appreciable action4 ,some of the boulders cast down from the summit exhibited a strong and varied polarity4 ,fig4 #h is a sketch of one of these2 the barbed end of each arrow represents the north end of the needle1 which assumed the various positions shown in the figure4 ,midway down the spur ,i lighted upon a transverse wall of rock1 which formed in earlier ages the boundary of a lateral outlet of the ,goerner glacier4 ,it was red and hard1 weathered rough at some places1 and polished smooth at others4 ,the lines were drawn finely upon it1 but its outer surface appeared to be peeling off like a crust2 the polished layer rested upon the rock like a kind of enamel4 ,the action of the glacier appeared to resemble that of the break of a locomotive upon rails1 both being cases of exfoliation brought about by pressure and friction4 ,this wall measured twenty-eight yards across1 and one end of it1 for a distance of ten or twelve yards1 was all north polar2 the other end for a similar distance was south polar1 but there was a pair of consequent points at its centre4 ,sidenote3 ,,the ,,magnetic ,,force4 #ahfh4 ,to meet the case of my young readers1 ,i will here say a few words about the magnetic force4 ,the common magnetic needle points nearly north and south2 and if a bit of iron be brought near to either end of the needle1 they will mutually attract each other4 ,a piece of lead will not show this effect1 nor will copper1 gold1 nor silver4 ,iron1 in fact1 is a magnetic metal1 which the others are not4 ,it is to be particularly observed1 that the bit of iron attracts both ends of the needle when it is presented to them in succession2 and if a common steel sewing needle be substituted for the iron it will be seen that it also has the power of attracting both ends of the magnetic needle4 ,but if the needle be rubbed once or twice along one end of a magnet1 it will be found that one of its ends will afterwards repel a certain end of the magnetic needle and attract the other4 ,by rubbing the needle on the magnet1 we thus develop both attraction and repulsion1 and this double action of the magnetic force is called its polarity2 thus the steel which was at first simply magnetic1 is now magnetic and polar4 ,it is the aim of persons making magnets1 that each magnet should have but two poles1 at its two ends2 it is1 however1 easy to develop in the same piece of steel several pairs or poles2 and if the magnetization be irregular1 this is sometimes done when we wish to avoid it4 ,these irregular poles are called consequent points4 ,now ,i want my young reader to understand that it is not only because the rocks of the ,goerner ,grat and ,riffelhorn contain iron1 that they exhibit the action which ,i have described4 ,they are not only magnetic1 as common iron is1 but1 like the magnetized steel needle1 they are magnetic and polar4 ,and these poles are irregularly distributed like the consequent points to which ,i have referred1 and this is the reason why ,i have used the term4 ,sidenote3 ,,bearings ,,from ,,the ,,riffelhorn4 #aheh4 ,professor ,forbes1 as ,i have already stated1 was the first to notice the effect of the ,riffelhorn upon the magnetic needle1 but he seems to have supposed that the entire mass of the mountain exercised a local attraction upon the needle2 7upon which end he does not say74 ,to enable future observers to allow for this attraction1 he took the bearing of several of the surrounding mountains from the ,riffelhorn2 but it is very probable that had he changed his position a few inches1 and perfectly certain had he changed it a few yards1 he would have found a set of bearings totally different from those which he has recorded4 ,the close proximity and irregular distribution of its consequent points would prevent the ,riffelhorn from exerting any appreciable influence on a distant needle1 as in this case the local poles would effectually neutralize each other4 ,,footnotes3 ,a ,now called1 in the ,federal map1 the ',grenz glacier4'--,l4 ,c4 ,t4 ,b ,i take this name from ,studer's map4 ,sometimes1 however1 ,i have called it the ,breithorn glacier4 7#ba47 ,sidenote3 ,,mont ,,cervin ,,as ,,cloud-,,maker4 #aheh4 ,on the morning of the #aeth the ,riffelberg was swathed in a dense fog1 through which heavy rain showered incessantly4 ,towards one o'clock the continuity of the gray mass was broken1 and sky-gleams of the deepest blue were seen through its apertures2 these would close up again1 and others open elsewhere1 as if the fog were fighting for existence with the sun behind it4 ,the sun1 however1 triumphed1 the mountains came more and more into view1 and finally the entire air was swept clear4 ,i went up to the ,goerner ,grat in the afternoon1 and examined more closely the magnetism of its rocks2 here1 as on the ,riffelhorn1 ,i found it most pronounced at the jutting prominences of the ,grat4 ,can it be that the superior exposure is more favourable to the formation of the magnetic oxide of iron8 ,i secured a number of fragments1 which ,i still possess1 and which act forcibly upon a magnetic needle4 ,the sun was near the western horizon1 and ,i remained alone upon the ,grat to see his last beams illuminate the mountains1 which1 with one exception1 were without a trace of cloud4 ,this exception was the ,matterhorn1 the appearance of which was extremely instructive4 ,the obelisk appeared to be divided in two halves by a vertical line drawn from its summit half way down1 to the windward of which we had the bare cliffs of the mountain2 and to the left of it a cloud which appeared to cling tenaciously to the rocks4 ,in reality1 however1 there was no clinging2 the condensed vapour incessantly got away1 but it was ever renewed1 and thus a river of cloud had been sent from the mountain over the valley of ,aosta4 ,the wind in fact blew lightly up the valley of ,st4 ,nicholas charged with moisture1 and when the air that held it rubbed against the cold cone of the ,matterhorn the vapour was chilled and precipitated in his lee4 ,the summit seemed to smoke sometimes like a burning mountain2 for immediately after its generation1 the fog was drawn away in long filaments by the wind4 ,as the sun sank lower the ruddiness of his light augmented1 until these filaments resembled streamers of flame4 ,the sun sank deeper1 the light was gradually withdrawn1 and where it had entirely vanished it left the mountain like a desolate old man whose hoary hair ,stream'd like a meteor in the troubled air4 ,for a moment after the sun had disappeared the scene was amazingly grand4 ,the distant west was ruddy1 copious gray smoke-wreaths were wafted from the mountains1 while high overhead1 in an atmospheric region which seemed perfectly motionless1 floated a broad thin cloud1 dyed with the richest iridescences4 ,the colours were of the same character as those which ,i had seen upon the ,aletschhorn1 being due to interference1 and in point of splendour and variety far exceeded anything ever produced by the mere coloured light of the setting sun4 ,sidenote3 ,,cells ,,in ,,the ,,ice4 #aheh4 ,on the #afth ,i was early upon the glacier4 ,it had frozen hard during the night1 and the partially liberated streams flowed1 in many cases1 over their own ice4 ,i took some clear plates from under the water1 and found in them numerous liquid cells1 each associated with an air-bubble or a vacuous spot4 ,the most common shape of the cells was a regular hexagon1 but there were all forms between the perfect hexagon and the perfect circle4 ,many cells had also crimped borders1 intimating that their primitive form was that of a flower with six leaves4 ,a plate taken from ice which was defended from the sunbeams by the shadow of a rock had no such cells2 so that those that ,i observed were probably due to solar radiation4 ,my first aim was to examine the structure of the ,goernerhorn glacier1,a which descends the breast of ,monte ,rosa until it is abruptly cut off by the great ,western glacier of the mountain4,b ,between them is a moraine which is at once terminal as regards the former1 and lateral as regards the latter4 ,the ice is veined vertically along the moraine1 the direction of the structure being parallel to the latter4 ,i ascended the glacier1 and found1 as ,i retreated from the place where the thrust was most violent1 that the structure became more feeble4 ,from the glacier ,i passed to the rocks called auf der ,platte1 so as to obtain a general view of its terminal portion4 ,the gradual perfecting of the structure as the region of pressure was approached was very manifest3 the ice at the end seemed to wrinkle up in obedience to the pressure1 the structural furrows1 from being scarcely visible1 became more and more decided1 and the lamination underneath correspondingly pronounced1 until it finally attained a state of great perfection4 ,sidenote3 ,,structure ,,of ,,the ,,ice4 #aheh4 ,i now quitted the rocks and walked straight across the ,western glacier of ,monte ,rosa to its centre1 where ,i found the structure scarcely visible4 ,i next faced the ,goerner ,grat1 and walked down the glacier towards the moraine which divides it from the ,goerner glacier4 ,the mechanical conditions of the ice here are quite evident2 each step brought me to a place of greater pressure1 and also to a place of more highly developed structure1 until finally near to the moraine itself1 and running parallel to it1 a magnificent lamination was developed4 ,here the superficial groovings could be traced to great distances1 and beside the moraine were boulders poised on pedestals of ice through which the blue veins ran4 ,at some places the ice had been weathered into laminae not more than a line in thickness4 ,i now recrossed the ,monte ,rosa glacier to its junction with the ,schwartze glacier1 which descends between the ,twins and ,breithorn4 ,the structure of the ,monte ,rosa glacier is here far less pronounced than at the other side1 and the pressure which it endures is also manifestly less2 the structure of the ,schwartze glacier is fairly developed1 being here parallel to its moraine4 ,the cliffs of the ,breithorn are much exposed to weathering action1 and boulders are copiously showered down upon the adjacent ice4 ,between the ,schwartze glacier and the glacier which descends from the breast of the ,breithorn itself these blocks ride upon a spine of ice1 and form a moraine of grand proportions4 ,from it a fine view of the glacier is attainable1 and the gradual development of its structure as the region of maximum pressure is approached is very plain4 ,a number of gracefully curved undulations sweep across the ,breithorn glacier1 which are squeezed more closely together as the moraine is approached4 ,all the glaciers that descend from the flanking mountains of the ,goerner valley are suddenly turned aside where they meet the great trunk stream1 and are reduced by the pressure to narrow stripes of ice separated from each other by parallel moraines4 ,sidenote3 ,,tributaries ,,explored4 #aheh4 ,i ascended the ,breithorn glacier to the base of an ice-fall1 on one side of which ,i found large crumples produced by the pressure1 the veined structure being developed at right angles to the direction of the latter4 ,no such structure was visible above this place4 ,the crumples were cut by fissures1 perpendicular to which the blue veins ran4 ,i now quitted the glacier1 and clambered up the adjacent alp1 from which a fine view of the general surface was attainable4 ,as in the case of the ,goernerhorn glacier1 the gradual perfecting of the structure was very manifest2 the dirt1 which first irregularly scattered over the surface1 gradually assumed a striated appearance1 and became more and more decided as the moraine was approached4 ,descending from the alp1 ,i endeavoured to measure some of the undulations2 proceeding afterwards to the junction of the ,breithorn glacier with that of ,st4 ,theodule4 ,the end of the latter appears to be crumpled by its thrust against the former1 and the moraine between them1 instead of being raised1 runs along a hollow which is flanked by the crumples on either side4 ,the ,breithorn glacier became more and more attenuated1 until finally it actually vanished under its own moraines4 ,on the sides of the crevasses1 by which the ,theodule glacier is here intersected1 ,i thought ,i could plainly see two systems of veins cutting each other at an angle of fifteen or twenty degrees4 ,reaching the ,goerner glacier1 at a place where its dislocation was very great1 ,i proceeded down it past the ,riffelhorn1 to a point where it seemed possible to scale the opposite mountain wall4 ,here ,i crossed the glacier1 treading with the utmost caution along the combs of ice1 and winding through the entanglement of crevasses until the spur of the ,riffelhorn was reached2 this ,i climbed to its summit1 and afterwards crossed the green alp to our hotel4 ,sidenote3 ,,temptation4 #aheh4 ,the foregoing good day's work was rewarded by a sound sleep at night4 ,the tourists were called in succession next morning1 but after each call ,i instantly subsided into deep slumber1 and thus healthily spaced out the interval of darkness4 ,day at length dawned and gradually brightened4 ,i looked at my watch and found it twenty minutes to six4 ,my guide had been lent to a party of gentlemen who had started at three o'clock for the summit of ,monte ,rosa1 and he had left with me a porter who undertook to conduct me to one of the adjacent glaciers4 ,but as ,i looked from my window the unspeakable beauty of the morning filled me with a longing to see the world from the top of ,monte ,rosa4 ,i was in exceedingly good condition--could ,i not reach the summit alone8 ,trained and indurated as ,i had been1 ,i felt that the thing was possible2 at all events ,i could try1 without attempting anything which was not clearly within my power4 ,,footnotes3 ,a ,now called1 in the ,federal map1 the ,monte ,rosa glacier4 ,goernerhorn is an old local name for the central mass of ,monte ,rosa4--,l4 ,c4 ,t4 ,b ,see p4 #ach1 footnote4 ,,second ,,ascent ,,of ,,monte ,,rosa1 #aheh4 7#bb47 ,sidenote3 ,a ,,light ,,scrip4 #aheh4 ,whether my exercise be mental or bodily1 ,i am always most vigorous when cool4 ,during my student life in ,germany1 the friends who visited me always complained of the low temperature of my room1 and here among the ,alps it was no uncommon thing for me to wander over the glaciers from morning till evening in my shirt-sleeves4 ,my object now was to go as light as possible1 and hence ,i left my coat and neckcloth behind me1 trusting to the sun and my own motion to make good the calorific waste4 ,after breakfast ,i poured what remained of my tea into a small glass bottle1 an ordinary demi-bouteille1 in fact2 the waiter then provided me with a ham sandwich1 and1 with my scrip thus frugally furnished1 ,i thought the heights of ,monte ,rosa might be won4 ,i had neither brandy nor wine1 but ,i knew the immense amount of mechanical force represented by four ounces of bread and ham1 and ,i therefore feared no failure from lack of nutriment4 ,indeed1 ,i am inclined to think that both guides and travellers often impair their vigour and render themselves cowardly and apathetic by the incessant refreshing which they deem it necessary to indulge in on such occasions4 ,sidenote3 ,,the ,,guide ,,expostulates4 #aheh4 ,sidenote3 ,,the ,,guide ,,halts4 #aheh4 ,the guide whom ,lauener intended for me was at the door2 ,i passed him and desired him to follow me4 ,this he at first refused to do1 as he did not recognise me in my shirt-sleeves2 but his companions set him right1 and he ran after me4 ,i transferred my scrip to his shoulders1 and led the way upward4 ,once or twice he insinuated that that was not the way to the ,schwarze-,see1 and was probably perplexed by my inattention4 ,from the summit of the ridge which bounds the ,goerner glacier the whole grand panorama revealed itself1 and on the higher slopes of ,monte ,rosa--so high1 indeed1 as to put all hope of overtaking them1 or even coming near them1 out of the question--a row of black dots revealed the company which had started at three o'clock from the hotel4 ,they had made remarkably good use of their time1 and ,i was afterwards informed that the cause of this was the intense cold1 which compelled them to keep up the proper supply of heat by increased exertion4 ,i descended swiftly to the glacier1 and made for the base of ,monte ,rosa1 my guide following at some distance behind me4 ,one of the streams1 produced by superficial melting1 had cut for itself a deep wide channel in the ice2 it was not too wide for a spring1 and with the aid of a run ,i cleared it and went on4 ,some minutes afterwards ,i could hear the voice of my companion exclaiming1 in a tone of expostulation1 ,no1 no1 ,i won't follow you there4 ,he however made a circuit1 and crossed the stream2 ,i waited for him at the place where the ,monte ,rosa glacier joins the rock1 auf der ,platte1 and helped him down the ice-slope4 ,at the summit of these rocks ,i again waited for him4 ,he approached me with some excitement of manner1 and said that it now appeared plain to him that ,i intended to ascend ,monte ,rosa1 but that he would not go with me4 ,i asked him to accompany me to the summit of the next cliff1 which he agreed to do2 and ,i found him of some service to me4 ,he discovered the faint traces of the party in advance1 and1 from his greater experience1 could keep them better in view than ,i could4 ,we lost them1 however1 near the base of the cliff at which we aimed1 and ,i went on1 choosing as nearly as ,i could remember the route followed by ,lauener and myself a week previously1 while my guide took another route1 seeking for the traces4 ,the glacier here is crevassed1 and ,i was among the fissures some distance in advance of my companion4 ,fear was manifestly getting the better of him1 and he finally stood still1 exclaiming1 ,no man can pass there4 ,at the same moment ,i discovered the trace1 and drew his attention to it2 he approached me submissively1 said that ,i was quite right1 and declared his willingness to go on4 ,we climbed the cliff1 and discovered the trace in the snow above it4 ,here ,i transferred the scrip and telescope to my own shoulders1 and gave my companion a cheque for five francs4 ,he returned1 and ,i went on alone4 ,the sun and heaven were glorious1 but the cold was nevertheless intense1 for it had frozen bitterly the night before4 ,the mountain seemed more noble and lovely than when ,i had last ascended it2 and as ,i climbed the slopes1 crossed the shining cols1 and rounded the vast snow-bosses of the mountain1 the sense of being alone lent a new interest to the glorious scene4 ,i followed the track of those who preceded me1 which was that pursued by ,lauener and myself a week previously4 ,once ,i deviated from it to obtain a glimpse of ,italy over the saddle which stretches from ,monte ,rosa to the ,lyskamm4 ,deep below me was the valley1 with its huge and dislocated neve1 and the slope on which ,i hung was just sufficiently steep to keep the attention aroused without creating anxiety4 ,i prefer such a slope to one on which the thought of danger cannot be entertained4 ,i become more weary upon a dead level1 or in walking up such a valley as that which stretches between ,visp and ,zermatt1 than on a steep mountain side4 ,the sense of weariness is often no index to the expenditure of muscular force3 the muscles may be charged with force1 and1 if the nervous excitant be feeble1 the strength lies dormant1 and we are tired without exertion4 ,but the thought of peril keeps the mind awake1 and spurs the muscles into action2 they move with alacrity and freedom1 and the time passes swiftly and pleasantly4 ,sidenote3 ,,left ,,alone4 #aheh4 ,occupied with my own thoughts as ,i ascended1 ,i sometimes unconsciously went too quickly1 and felt the effects of the exertion4 ,i then slackened my pace1 allowing each limb an instant of repose as ,i drew it out of the snow1 and found that in this way walking became rest4 ,this is an illustration of the principle which runs throughout nature--to accomplish physical changes1 time is necessary4 ,different positions of the limb require different molecular arrangements2 and to pass from one to the other requires time4 ,by lifting the leg slowly and allowing it to fall forward by its own gravity1 a man may get on steadily for several hours1 while a very slight addition to this pace may speedily exhaust him4 ,of course the normal pace differs in different persons1 but in all the power of endurance may be vastly augmented by the prudent outlay of muscular force4 ,the sun had long shone down upon me with intense fervour1 but ,i now noticed a strange modification of the light upon the slopes of snow4 ,i looked upwards1 and saw a most gorgeous exhibition of interference-colours4 ,a light veil of clouds had drawn itself between me and the sun1 and this was flooded with the most brilliant dyes4 ,orange1 red1 green1 blue--all the hues produced by diffraction were exhibited in the utmost splendour4 ,there seemed a tendency to form circular zones of colour round the sun1 but the clouds were not sufficiently uniform to permit of this1 and they were consequently broken into spaces1 each steeped with the colour due to the condition of the cloud at the place4 ,three times during my ascent similar veils drew themselves across the sun1 and at each passage the splendid phenomena were renewed4 ,as ,i reached the middle of the mountain an avalanche was let loose from the sides of the ,lyskamm2 the thunder drew my eyes to the place2 ,i saw the ice move1 but it was only the tail of the avalanche2 still the volume of sound told me that it was a huge one4 ,suddenly the front of it appeared from behind a projecting rock1 hurling its ice-masses with fury into the valley1 and tossing its rounded clouds of ice-dust high into the atmosphere4 ,a wild long-drawn sound1 multiplied by echoes1 now descended from the heights above me4 ,it struck me at first as a note of lamentation1 and ,i thought that possibly one of the party which was now near the summit had gone over the precipice4 ,on listening more attentively ,i found that the sound shaped itself into an ,english hurrah6 ,i was evidently nearing the party1 and on looking upwards ,i could see them1 but still at an immense height above me4 ,the summit still rose before them1 and ,i therefore thought the cheer premature4 ,a precipice of ice was now in front of me1 around which ,i wound to the right1 and in a few minutes found myself fairly at the bottom of the ,kamm4 ,sidenote3 ,,giddiness ,,on ,,the ,,kamm4 #aheh4 ,sidenote3 ,,scrip ,,left ,,behind4 #aheh4 ,i paused here for a moment1 and reflected on the work before me4 ,my head was clear1 my muscles in perfect condition1 and ,i felt just sufficient fear to render me careful4 ,i faced the ,kamm1 and went up slowly but surely1 and soon heard the cheer which announced the arrival of the party at the summit of the mountain4 ,it was a wild1 weird1 intermittent sound1 swelling or falling as the echoes reinforced or enfeebled it4 ,in getting through the rocks which protrude from the snow at the base of the last spur of the mountain1 ,i once had occasion to stoop my head1 and1 on suddenly raising it1 my eyes swam as they rested on the unbroken slope of snow at my left4 ,the sensation was akin to giddiness1 but ,i believe it was chiefly due to the absence of any object upon the snow upon which ,i could converge the axes of my eyes4 ,up to this point ,i had eaten nothing4 ,i now unloosed my scrip1 and had two mouthfuls of sandwich and nearly the whole of the tea that remained4 ,i found here that my load1 light as it was1 impeded me4 ,when fine balancing is necessary1 the presence of a very light load1 to which one is unaccustomed1 may introduce an element of danger1 and for this reason ,i here left the residue of my tea and sandwich behind me4 ,a long1 long edge was now in front of me1 sloping steeply upwards4 ,as ,i commenced the ascent of this1 the foremost of those whose cheer had reached me from the summit some time previously1 appeared upon the top of the edge1 and the whole party was seen immediately afterwards dangling on the ,kamm4 ,we mutually approached each other4 ,peter ,bohren1 a well-known ,oberland guide1 came first1 and after him came the gentleman in his immediate charge4 ,then came other guides with other gentlemen1 and last of all my guide1 ,lauener1 with his strong right arm round the youngest of the party4 ,we met where a rock protruded through the snow4 ,the cold smote my naked throat bitterly1 so to protect it ,i borrowed a handkerchief from ,lauener1 bade my new acquaintances good bye1 and proceeded upwards4 ,i was soon at the place where the snow-ridge joins the rocks which constitute the crest of the mountain2 through these my way lay1 every step ,i took augmenting my distance from all life1 and increasing my sense of solitude4 ,i went up and down the cliffs as before1 round ledges1 through fissures1 along edges of rock1 over the last deep and rugged indentation1 and up the rocks at its opposite side1 to the summit4 ,sidenote3 ,,alone ,,on ,,the ,,summit4 #aheh4 ,sidenote3 ,,the ,,axe ,,slips4 #aheh4 ,a world of clouds and mountains lay beneath me4 ,switzerland1 with its pomp of summits1 was clear and grand2 ,italy was also grand1 but more than half obscured4 ,dark cumulus and dark crag vied in savagery1 while at other places white snows and white clouds held equal rivalry4 ,the scooped valleys of ,monte ,rosa itself were magnificent1 all gleaming in the bright sunlight--tossed and torn at intervals1 and sending from their rents and walls the magical blue of the ice4 ,ponderous neves lay upon the mountains1 apparently motionless1 but suggesting motion--sluggish1 but indicating irresistible dynamic energy1 which moved them slowly to their doom in the warmer valleys below4 ,i thought of my position3 it was the first time that a man had stood alone upon that wild peak1 and were the imagination let loose amid the surrounding agencies1 and permitted to dwell upon the perils which separated the climber from his kind1 ,i dare say curious feelings might have been engendered4 ,but ,i was prompt to quell all thoughts which might lessen my strength1 or interfere with the calm application of it4 ,once indeed an accident made me shudder4 ,while taking the cork from a bottle which is deposited on the top1 and which contains the names of those who have ascended the mountain1 my axe slipped out of my hand1 and slid some thirty feet away from me4 ,the thought of losing it made my flesh creep1 for without it descent would be utterly impossible4 ,i regained it1 and looked upon it with an affection which might be bestowed upon a living thing1 for it was literally my staff of life under the circumstances4 ,one look more over the cloud-capped mountains of ,italy1 and ,i then turned my back upon them1 and commenced the descent4 ,the brown crags seemed to look at me with a kind of friendly recognition1 and1 with a surer and firmer feeling than ,i possessed on ascending1 ,i swung myself from crag to crag and from ledge to ledge with a velocity which surprised myself4 ,i reached the summit of the ,kamm1 and saw the party which ,i had passed an hour and a half before1 emerging from one of the hollows of the mountain2 they had escaped from the edge which now lay between them and me4 ,the thought of the possible loss of my axe at the summit was here forcibly revived1 for without it ,i dared not take a single step4 ,my first care was to anchor it firmly in the snow1 so as to enable it to bear at times nearly the whole weight of my body4 ,in some places1 however1 the anchor had but a loose hold2 the cornice to which ,i have already referred became granular1 and the handle of the axe went through it up to the head1 still1 however1 remaining loose4 ,some amount of trust had thus to be withdrawn from the staff and placed in the limbs4 ,a curious mixture of carelessness and anxiety sometimes fills the mind on such occasions4 ,i often caught myself humming a verse of a frivolous song1 but this was mechanical1 and the substratum of a man's feelings under such circumstances is real earnestness4 ,the precipice to my left was a continual preacher of caution1 and the slope to my right was hardly less impressive4 ,i looked down the former but rarely1 and sometimes descended for a considerable time without looking beyond my own footsteps4 ,the power of a thought was illustrated on one of these occasions4 ,i had descended with extreme slowness and caution for some time1 when looking over the edge of the cornice ,i saw a row of pointed rocks at some distance below me4 ,these ,i felt must receive me if ,i slipped over1 and ,i thought how before reaching them ,i might so break my fall as to arrive at them unkilled4 ,this thought enabled me to double my speed1 and as long as the spiky barrier ran parallel to my track ,i held my staff in one hand1 and contented myself with a slight pressure upon it4 ,i came at length to a place where the edge was solid ice1 which rose to the level of the cornice1 the latter appearing as if merely stuck against it4 ,a groove ran between the ice and snow1 and along this groove ,i marched until the cornice became unsafe1 and ,i had to betake myself to the ice4 ,the place was really perilous1 but1 encouraging myself by the reflection that it would not last long1 ,i carefully and deliberately hewed steps1 causing them to dip a little inward1 so as to afford a purchase for the heel of my boot1 never forsaking one till the next was ready1 and never wielding my hatchet until my balance was secured4 ,i was soon at the bottom of the ,kamm1 fairly out of danger1 and full of glad vigour ,i bore swiftly down upon the party in advance of me4 ,it was an easy task to me to fuse myself amongst them as if ,i had been an old acquaintance1 and we joyfully slid1 galloped1 and rolled together down the residue of the mountain4 ,sidenote3 ,,accident ,,on ,,the ,,kamm4 #aheh4 ,the only exception was the young gentleman in ,lauener's care4 ,a day or two previously he had1 ,i believe1 injured himself in crossing the ,gemmi1 and long before he reached the summit of ,monte ,rosa his knee swelled1 and he walked with great difficulty4 ,but he persisted in ascending1 and ,lauener1 seeing his great courage1 thought it a pity to leave him behind4 ,i have stated that a portion of the ,kamm was solid ice4 ,on descending this1 ,mr4 ,f4's footing gave way1 and he slipped forward4 ,lauener was forced to accompany him1 for the place was too steep and slippery to permit of their motion being checked4 ,both were on the point of going over the ,lyskamm side of the mountain1 where they would have indubitably been dashed to pieces4 ,there was no escape there1 said ,lauener1 in describing the incident to me subsequently1 but ,i saw a possible rescue at the other side1 so ,i sprang to the right1 forcibly swinging my companion round2 but in doing so1 the baton tripped me up2 we both fell1 and rolled rapidly over each other down the incline4 ,i knew that some precipices were in advance of us1 over which we should have gone1 so1 releasing myself from my companion1 ,i threw myself in front of him1 stopped myself with my axe1 and thus placed a barrier before him4 ,after some vain efforts at sliding down the slopes on a baton1 in which practice ,i was fairly beaten by some of my new friends1 ,i attached myself to the invalid1 and walked with him and ,lauener homewards4 ,had ,i gone forward with the foremost of the party1 ,i should have completed the expedition to the summit and back in a little better than nine hours4 ,sidenote3 ,,danger ,,of ,,climbing ,,alone4 #aheh4 ,i think it right to say one earnest word in connexion with this ascent2 and the more so as ,i believe a notion is growing prevalent that half what is said and written about the dangers of the ,alps is mere humbug4 ,no doubt exaggeration is not rare1 but ,i would emphatically warn my readers against acting upon the supposition that it is general4 ,the dangers of ,mont ,blanc1 ,monte ,rosa1 and other mountains1 are real1 and1 if not properly provided against1 may be terrible4 ,i have been much accustomed to be alone upon the glaciers1 but sometimes1 even when a guide was in front of me1 ,i have felt an extreme longing to have a second one behind me4 ,less than two good ones ,i think an arduous climber ought not to have2 and if climbing without guides were to become habitual1 deplorable consequences would assuredly sooner or later ensue4 7#bc47 ,the #ahth of ,august ,i spent upon the ,furgge glacier at the base of ,mont ,cervin1 and what it taught me shall be stated in another place4 ,the evening of this day was signalised by the pleasant acquaintances which it gave me4 ,it was my intention to cross the ,weissthor on the morning of the #aith1 but thunder1 lightning1 and heavy rain opposed the project1 and with two friends ,i descended1 amid pitiless rain1 to ,zermatt4 ,next day ,i walked by way of ,stalden to ,saas1 where ,i made the acquaintance of ,herr ,imseng1 the ,cure1 and on the #bast ascended to the ,distel ,alp4 ,near to this place the ,allalein glacier pushes its huge terminus right across the valley and dams up the streams descending from the mountains higher up1 thus giving birth to a dismal lake4 ,at one end of this stands the ,mattmark hotel1 which was to be my headquarters for a few days4 ,sidenote3 ,,ascent ,,of ,a ,,boulder4 #aheh4 ,i reached the place in good company4 ,near to the hotel are two magnificent boulders of green serpentine1 which have been lodged there by one of the lateral glaciers2 and two of the ladies desiring to ascend one of these rocks1 a friend and myself helped them to the top4 ,the thing was accomplished in a very spirited way4 ,indeed the general contrast1 in regard to energy1 between the maidens of the ,british ,isles and those of the ,continent and of ,america is extraordinary4 ,surely those who talk of this country being in its old age overlook the physical vigour of its sons and daughters4 ,they are strong1 but from a combination of the greatest forces we may obtain a small resultant1 because the forces may act in opposite directions and partly neutralize each other4 ,herein1 in fact1 lies ,britain's weakness2 it is strength ill-directed2 and is indicative rather of the perversity of young blood than of the precision of mature years4 ,sidenote3 ,,dismal ,,quarters4 #aheh4 ,immediately after this achievement ,i was forsaken by my friends1 and remained the only visitor in the hotel4 ,a dense gray cloud gradually filled the entire atmosphere1 from which the rain at length began to gush in torrents4 ,the scene from the windows of the hotel was of the most dismal character2 the rain also came through the roof1 and dripped from the ceiling to the floor4 ,i endeavoured to make a fire1 but the air would not let the smoke of the pine-logs ascend1 and the biting of the hydrocarbons was excruciating to the eyes4 ,on the whole1 the cold was preferable to the smoke4 ,during the night the rain changed to snow1 and on the morning of the #bbnd all the mountains were thickly covered4 ,the gray delta through which a river of many arms ran into the ,mattmark ,see was hidden2 against some of the windows of the salle a manger the snow was also piled1 obscuring more than half their light4 ,i had sent my guide to ,visp1 and two women and myself were the only occupants of the place4 ,it was extremely desolate--,i felt1 moreover1 the chill of ,monte ,rosa in my throat1 and the conditions were not favourable to the cure of a cold4 ,on the #bcrd the ,allalein glacier was unfit for work2 ,i therefore ascended to the summit of the ,monte ,moro1 and found the ,valaisian side of the pass in clear sunshine1 while impenetrable fog met us on the ,italian side4 ,i examined the colour of the freshly fallen snow2 it was not an ordinary blue1 and was even more transparent than the blue of the firmament4 ,when the snow was broken the light flashed forth2 when the staff was dug into the snow and withdrawn1 the blue gleam appeared2 when the staff lay in a hole1 although there might be a sufficient space all round it1 the coloured light refused to show itself4 ,my cough kept me awake on the night of the #bcrd1 and my cold was worse next day4 ,i went upon the ,allalein glacier1 but found myself by no means so sure a climber as usual4 ,the best guides find that their powers vary2 they are not equally competent on all days4 ,i have heard a celebrated ,chamouni guide assert that a man's morale is different on different days4 ,the morale in my case had a physical basis1 and it probably has so in all4 ,the ,allalein glacier1 as ,i have said1 crosses the valley and abuts against the opposite mountain2 here it is forced to turn aside1 and in consequence of the thrust and bending it is crumpled and crevassed4 ,the wall of the ,mattmark ,see is a fine glacier section3 looked at from a distance1 the ridges and fissures appear arranged like a fan4 ,the structure of the crumpled ice varies from the vertical to the horizontal1 and the ridges are sometimes split along the planes of structure4 ,the aspect of this portion of the glacier from some of the adjacent heights is exceedingly interesting4 ,sidenote3 ,,the ,,vault ,,of ,,the ,,allalein4 #aheh4 ,on the morning of the #beth ,i had two hours' clambering over the mountains before breakfast1 and traced the action of ancient glaciers to a great height4 ,the valley of ,saas in this respect rivals that of ,hasli2 the flutings and polishings being on the grandest scale4 ,after breakfast ,i went to the end of the ,allalein glacier1 where the ,saas ,visp river rushes from it3 the vault was exceedingly fine1 being composed of concentric arches of clear blue ice4 ,i spent several hours here examining the intimate structure of the ice1 and found the vacuum disks which ,i shall describe at another place1 of the greatest service to me4 ,as at ,rosenlaui and elsewhere1 they here taught me that the glacier was composed of an aggregate of small fragments1 each of which had a definite plane of crystallization4 ,where the ice was partially weathered the surfaces of division between the fragments could be traced through the coherent mass1 but on crossing these surfaces the direction of the vacuum disks changed1 indicating a similar change of the planes of crystallization4 ,the blue veins of the glacier went through its component fragments irrespective of these planes4 ,sometimes the vacuum disks were parallel to the veins1 sometimes across them1 sometimes oblique to them4 ,several fine masses of ice had fallen from the arch upon its floor1 and these were disintegrated to the core4 ,a kick1 or a stroke of an axe1 sufficed to shake masses almost a cubic yard in size into fragments varying not much on either side of a cubic inch4 ,the veining was finely preserved on the concentric arches of the vault1 and some of them apparently exhibited its abolition1 or at least confusion1 and fresh development by new conditions of pressure4 ,the river being deep and turbulent this day1 to reach its opposite side ,i had to climb the glacier and cross over the crown of its highest arch2 this enabled me to get quite in front of the vault1 to enter it1 and closely inspect those portions where the structure appeared to change4 ,i afterwards ascended the steep moraine which lies between the ,allalein and the smaller glacier to the left of it2 passing to the latter at intervals to examine its structure4 ,i was at length stopped by the dislocated ice2 and from the heights ,i could count a system of seven dirt-bands1 formed by the undulations on the surface of the glacier4 ,on my return to the hotel ,i found there a number of well-known ,alpine men who intended to cross the ,adler pass on the following day4 ,herr ,imseng was there3 he came to me full of enthusiasm1 and asked me whether ,i would join him in an ascent of the ,dom3 we might immediately attack it2 and he felt sure that we should succeed4 ,the ,dom is the highest of the ,mischabel peaks1 and is one of the grandest of the ,alps4 ,i agreed to join the ,cure1 and with this understanding we parted for the night4 ,sidenote3 ,,avalanche ,,at ,,saas4 #aheh4 ,thursday1 #bfth ,august4--,a wild stormy morning after a wild and rainy night3 the ,adler pass being impassable1 the mountaineers returned1 and ,imseng informed me that the ,dom must be abandoned4 ,he gave me the statistics of an avalanche which had fallen in the valley some years before4 ,within the memory of man ,saas had never been touched by an avalanche1 but a tradition existed that such a catastrophe had once occurred4 ,on the #adth of ,march1 #ahdh1 at eight o'clock in the morning1 the ,cure was in his room2 when he heard the cracking of pine-branches1 and inferred from the sound that an avalanche was descending upon the village4 ,it dashed in the windows of his house and filled his rooms with snow2 the sound it produced being sufficient to mask the crashing of the timbers of an adjacent house4 ,three persons were killed4 ,on the #crd of ,april1 #ahdi1 heavy snow fell at ,saas2 the ,cure waited until it had attained a depth of four feet1 and then retreated to ,fee4 ,that night an avalanche descended1 and in the line of its rush was a house in which five or six and twenty people had collected for safety3 nineteen of them were killed4 ,the ,cure afterwards showed me the site of the house1 and the direction of the avalanche4 ,it passed through a pine wood2 and on expressing my surprise that the trees did not arrest it1 he replied that the snow was quite like dust1 and rushed among the trees like so much water4 ,to return from ,fee to ,saas on the day following he found it necessary to carry two planks4 ,kneeling upon one of them1 he pushed the other forward1 and transferred his weight to it1 drawing the other after him and repeating the same act4 ,the snow was like flour1 and would not otherwise bear his weight4 ,seeing no prospect of fine weather1 ,i descended to ,saas on the afternoon of the #bfth4 ,i was the only guest at the hotel2 but during the evening ,i was gratified by the unexpected arrival of my friend ,hirst1 who was on his way over the ,monte ,moro to ,italy4 ,sidenote3 ,,the ,,fee ,,glacier4 #aheh4 ,sidenote3 ,,snow1 ,,vapour ,,and ,,cloud4 #aheh4 ,for the last five days it had been a struggle between the north wind and the south1 each edging the other by turns out of its atmospheric bed1 and producing copious precipitation2 but now the conflict was decided--the north had prevailed1 and an almost unclouded heaven overspread the ,alps4 ,the few white fleecy masses that remained were good indications of the swift march of the wind in the upper air4 ,my friend and ,i resolved to have at least one day's excursion together1 and we chose for it the glacier of the ,fee4 ,ascending the mountain by a well-beaten path1 we passed a number of ,calvaries filled with tattered saints and ,virgins1 and soon came upon the rim of a flattened bowl quite clasped by the mountains4 ,in its centre was the little hamlet of ,fee1 round which were fresh green pastures1 and beyond it the perpetual ice and snow4 ,it was exceedingly picturesque--a scene of human beauty and industry where savagery alone was to be expected4 ,the basin had been scooped by glaciers1 and as we paused at its entrance the rounded and fluted rocks were beneath our feet4 ,the ,alphubel and the ,mischabel raised their crowns to heaven in front of us2 the newly fallen snow clung where it could to the precipitous crags of the ,mischabel1 but on the summits it was the sport of the wind4 ,sometimes it was borne straight upwards in long vertical striae2 sometimes the fibrous columns swayed to the right1 sometimes to the left2 sometimes the motion on one of the summits would quite subside2 anon the white peak would appear suddenly to shake itself to dust1 which it yielded freely to the wind4 ,i could see the wafted snow gradually melt away1 and again curdle up into true white cloud by precipitation2 this in its turn would be pulled asunder like carded wool1 and reduced a second time to transparent vapour4 ,in the middle of the ice of the ,fee stands a green alp1 not unlike the ,jardin2 up this we climbed1 halting at intervals upon its grassy knolls to inspect the glacier4 ,i aimed at those places where on a priori grounds ,i should have thought the production of the veined structure most likely1 and reached at length the base of a wall of rock from the edge of which long spears of ice depended4 ,here my friend halted1 while ,lauener and myself climbed the precipice1 and ascended to the summit of the alp4 ,the snow was deep at many places1 and our immersions in unseen holes very frequent4 ,from the peak of the ,fee ,alp a most glorious view is obtained2 in point of grandeur it will bear comparison with any in the ,alps1 and its seclusion gives it an inexpressible charm4 ,we remained for half an hour upon the warm rock1 and then descended4 ,it was our habit to jump from the higher ledges into the deep snow below them1 in which we wallowed as if it were flour2 but on one of these occasions ,i lighted on a stone1 and the shock produced a curious effect upon my hearing4 ,i appeared suddenly to lose the power of appreciating deep sounds1 while the shriller ones were comparatively unimpaired4 ,after ,i rejoined my friend it required attention on my part to hear him when he spoke to me4 ,this continued until ,i approached the end of the glacier1 when suddenly the babblement of streams1 and a world of sounds to which ,i had been before quite deaf burst in upon me4 ,the deafness was probably due to a strain of the tympanum1 such as we can produce artificially1 and thus quench low sounds1 while shrill ones are scarcely affected4 ,sidenote3 ,a ,,terrible ,,hole4 #aheh4 ,i was anxious to quit ,saas early next morning1 but the ,cure expressed so strong a wish to show us what he called a schauderhaftes ,loch--a terrible hole--which he had himself discovered1 that ,i consented to accompany him4 ,we were joined by his assistant and the priest of ,fee4 ,the stream from the ,fee glacier has cut a deep channel through the rocks1 and along the right-hand bank of the stream we ascended4 ,it was very rough with fallen crags and fallen pines amid which we once or twice lost our way4 ,at length we came to an aperture just sufficient to let a man's body through1 and were informed by our conductor that our route lay along the little tunnel3 he lay down upon his stomach and squeezed himself through it like a marmot4 ,i followed him2 a second tunnel1 in which1 however1 we could stand upright1 led into a spacious cavern1 formed by the falling together of immense slabs of rock which abutted against each other so as to form a roof4 ,it was the very type of a robber den2 and when ,i remarked this1 it was at once proposed to sing a verse from ,schiller's play4 ,the young priest had a powerful voice--he led and we all chimed in4 ,sidenote3 ,,song ,,of ,,the ,,robbers4 #aheh4 ,ein frohes ,leben fuehren wir1 ,ein ,leben voller ,wonne4 ,der ,wald ist unser ,nachtquartier1 ,bei ,sturm und ,wind hanthieren wir1 ,der ,mond ist unsre ,sonne4 ,herr ,imseng wore his black coat2 the others had taken theirs off1 but they wore their clerical hats1 black breeches and stockings4 ,we formed a singular group in a singular place1 and the echoed voices mingled strangely with the gusts of the wind and the rush of the river4 ,soon afterwards ,i parted from my friend1 and descended the valley to ,visp1 where ,i also parted with my guide4 ,he had been with me from the #bbnd of ,july to the #bith of ,august1 and did his duty entirely to my satisfaction4 ,he is an excellent iceman1 and is well acquainted both with the glaciers of the ,oberland and of the ,valais4 ,he is strong and good-humoured1 and were ,i to make another expedition of the kind ,i don't think that ,i should take any guide in the ,oberland in preference to ,christian ,lauener4 7#bd47 ,sidenote3 ,,climbers ,,and ,,science4 #aheh4 ,it is a singular fact that as yet we know absolutely nothing of the winter temperature of any one of the high ,alpine summits4 ,no doubt it is a sufficient justification of our ,alpine men1 as regards their climbing1 that they like it4 ,this plain reason is enough2 and no man who ever ascended that bad eminence ,primrose ,hill1 or climbed to ,hampstead ,heath for the sake of a freer horizon1 can consistently ask a better4 ,as regards physical science1 however1 the contributions of our mountaineers have as yet been nil1 and hence1 when we hear of the scientific value of their doings1 it is simply amusing to the climbers themselves4 ,i do not fear that ,i shall offend them in the least by my frankness in stating this4 ,their pleasure is that of overcoming acknowledged difficulties1 and of witnessing natural grandeur4 ,but ,i would venture to urge that our ,alpine men will not find their pleasure lessened by embracing a scientific object in their doings4 ,they have the strength1 the intelligence1 and let them add to these the accuracy which physical science now demands1 and they may contribute work of enduring value4 ,mr4 ,casella will gladly teach them the use of his minimum-thermometers2 and ,i trust that the next seven years will not pass without making us acquainted with the winter temperature of every mountain of note in ,switzerland4,a ,i had thought of this subject since ,i first read the conjectures of ,de ,saussure on the temperature of ,mont ,blanc2 but in #aheg ,i met ,auguste ,balmat at the ,jardin1 and there learned from him that he entertained the idea of placing a self-registering thermometer at the summit of the mountain4 ,balmat was personally a stranger to me at the time1 but ,professor ,forbes's writings had inspired me with a respect for him1 which this unprompted idea of his augmented4 ,he had procured a thermometer1 the graduation of which1 however1 he feared was not low enough4 ,as an encouragement to ,balmat1 and with the view of making his laudable intentions known1 ,i communicated them to the ,royal ,society1 and obtained from the ,council a small grant of money to purchase thermometers and to assist in the expenses of an ascent4 ,i had now the thermometers in my possession2 and having completed my work at ,zermatt and ,saas1 my next desire was to reach ,chamouni and place the instruments on the top of ,mont ,blanc4 ,i accordingly descended the valley of the ,rhone to ,martigny1 crossed the ,tete ,noire1 and arrived at ,chamouni on the #bith of ,august1 #aheh4 ,sidenote3 ,,difficulties ,,at ,,chamouni4 #aheh4 ,balmat was engaged at this time as the guide of ,mr4 ,alfred ,wills1 who1 however1 kindly offered to place him at my disposal2 and also expressed a desire to accompany me himself and assist me in my observations4 ,i gladly accepted a proposal which gave me for companion so determined a climber and so estimable a man4 ,but ,chamouni was rife with difficulties4 ,in #aheg the ,guide ,chef had the good sense to give me considerable liberty of action4 ,now his mood was entirely changed3 he had been molested for giving me so much freedom4 ,i wished to have a boy to carry a small instrument for me up the ,mer de ,glace--he would not allow it2 ,i must take a guide4 ,if ,i ascended ,mont ,blanc he declared that ,i must take four guides2 that1 in short1 ,i must in all respects conform to the rules made for ordinary tourists4 ,i endeavoured to explain to him the advantages which ,chamouni had derived from the labours of men of science2 it was such men who had discovered it when it was unknown1 and it was by their writings that the attention of the general public had been called towards it4 ,it was a bad recompense1 ,i urged1 to treat a man of science as he was treating me4 ,this was urged in vain2 he shrugged his shoulders1 was very sorry1 but the thing could not be changed4 ,i then requested to know his superior1 that ,i might apply to him2 he informed me that there were a ,president and ,commission of guides at ,chamouni1 who were the proper persons to decide the question1 and he proposed to call them together on the #cast of ,august1 at seven ,p4,m41 on condition that ,i was to be present to state my own case4 ,to this ,i agreed4 ,i spent that day quite alone upon the ,mer de ,glace1 and climbed amid a heavy snow-storm to the ,cleft station over ,trelaporte4 ,when ,i reached the ,montanvert ,i was wet and weary1 and would have spent the night there were it not for my engagement with the ,guide ,chef4 ,i descended amid the rain1 and at the appointed hour went to his bureau4 ,he met me with a polite sympathetic shrug2 explained to me that he had spoken to the ,commission1 but that it could not assemble pour une chose comma ca2 that the rules were fixed1 and ,i must abide by them4 ,well1 ,i responded1 you think you have done your duty2 it is now my turn to perform mine4 ,if no other means are available ,i will have this transaction communicated to the ,sardinian ,government1 and ,i don't think that it will ratify what you have done4 ,the ,guide ,chef evidently did not believe a word of it4 ,previous to taking any further step ,i thought it right to see the ,president of the ,commission of ,guides1 who was also ,syndic of the commune4 ,i called upon him on the morning of the #ast of ,september1 and1 assuming that he knew all about the transaction1 spoke to him accordingly4 ,he listened to me for a time1 but did not seem to understand me1 which ,i ascribed partly to my defective ,french pronunciation4 ,i expressed a hope that he did comprehend me2 he said he understood my words very well1 but did not know their purport4 ,in fact he had not heard a single word about me or my request4 ,he stated with some indignation that1 so far from its being a subject on which the ,commission could not assemble1 it was one which it was their especial duty to take into consideration4 ,our conference ended with the arrangement that ,i was to write him an official letter stating the case1 which he was to forward to the ,intendant of the province of ,faucigny resident at ,bonneville4 ,all this was done4 ,sidenote3 ,,the ,,intendant ,,memorialised4 #aheh4 ,i subsequently memorialised the ,intendant himself2 and ,balmat visited him to secure his permission to accompany me4 ,i have to record1 that from first to last the ,intendant gave me his sympathy and support4 ,he could not alter laws1 but he deprecated a judaical interpretation of them4 ,his final letter to myself was as follows3-- ,sidenote3 ,,the ,,intendant',s ,,response4 #aheh4 ,intendance ,royale de la ,province de ,faucigny1 ,bonneville1 #aa ,septembre1 #aheh4 ,monsieur1-- ,j'apprends avec une veritable peine les difficultes que vous rencontrez de la part de ,m4 le ,guide ,chef pour l'effectuation de votre perilleuse entreprise scientifique1 mais je dois vous dire aussi avec regret que ces difficultes resident dans un reglement fait en vue de la securite des voyageurs1 quel que puisse etre le but de leurs excursions4 ,desireux neanmoins de vous etre utile1 notamment en la circonstance1 j'invite aujourd'hui meme ,m4 le ,guide ,chef a avoir egard a votre projet1 a faire en sa faveur une exception au reglement ci-devant eu1 tant qu'il n'y aura aucun danger pour votre surete et celle des personnes qui vous accompagneront1 et enfin de se preter dans les limites de ses moyens et attributions pour l'heureux succes de l'expedition1 dont les consequences et resultats n'interessent pas seulement la science1 mais encore la vallee de ,chamounix en particulier4 ,agreez1 ,monsieur1 l'assurance de ma consideration tres-distinguee4 ,pour l',intendant en conge1 ,le ,secretaire1 ,,deleglise4 ,while waiting for this permission ,i employed myself in various ways4 ,on the #bnd of ,september ,i ascended the ,brevent1 from which ,mont ,blanc is seen to great advantage4 ,from ,chamouni its vast slopes are so foreshortened that one gets a very imperfect idea of the extent to be traversed to reach the summit4 ,what1 however1 struck me most on the ,brevent was the changed relation of the ,aiguille du ,dru and the ,aiguille ,verte4 ,from ,montanvert the former appears a most imposing mass1 while the peak of the latter appears rather dwarfed behind it2 but from the ,brevent the ,aiguille du ,dru is a mere pinnacle stuck in the breast of the grander pyramid of the ,aiguille ,verte4 ,sidenote3 ,,the ,,seracs ,,revisited4 #aheh4 ,on the #dth ,i rose early1 and1 strapping on my telescope1 ascended to the ,montanvert1 where ,i engaged a youth to accompany me up the glacier4 ,the heavens were clear and beautiful3--blue over the ,aiguille du ,dru1 blue over the ,jorasse and ,mont ,mallet1 deep blue over the pinnacles of ,charmoz1 and the same splendid tint stretched grandly over the ,col du ,geant and its ,aiguille4 ,no trace of condensation appeared till towards eleven o'clock1 when a little black balloon of cloud swung itself over the ,aiguilles ,rouges4 ,at one o'clock there were two large masses and a little one between them2 while higher up a white veil1 almost too thin to be visible1 spread over a part of the heavens4 ,at the zenith1 however1 and south1 north1 and west1 the blue seemed to deepen as the day advanced4 ,i visited the ice-wall at the ,tacul1 which seemed lower than it was last year2 the cascade of le ,geant appeared also far less imposing4 ,only in the early part of summer do we see the ice in its true grandeur3 its edges and surfaces are then sharp and clear1 but afterwards its nobler masses shrink under the influence of sun and air4 ,the seracs now appeared wasted and dirty1 and not the sharp angular ice-castles which rose so grandly when ,i first saw them4 ,thirteen men had crossed the ,col du ,geant on the day previous1 and left an ample trace behind them4 ,this ,i followed nearly to the summit of the fall4 ,the condition of the glacier was totally different from that of the opposite side on the previous year4 ,the ice was riven1 burrowed1 and honeycombed1 but the track amid all was easy3 a vigorous ,english maiden might have ascended the fall without much difficulty4 ,my object now was to examine the structure of the fall2 but the ice was not in a good condition for such an examination3 it was too much broken4 ,still a definite structure was in many places to be traced1 and some of them apparently showed structure and bedding at a high angle to each other1 but ,i could not be certain of it4 ,i paused at every commanding point of view and examined the ice through my opera-glass2 but the result was inconclusive4 ,i observed that the terraces which compose the fall do not front the middle of the glacier1 but turn their foreheads rather towards its eastern side1 and the consequence is that the protuberances lower down1 which are the remains of these terraces1 are highest at the same side4 ,standing at the base of the ,aiguille ,noire1 and looking downwards where the ,glacier des ,periades pushes itself against the ,geant1 a series of fine crumples is formed on the former1 cut across by crevasses1 on the walls of which a forward and backward dipping of the blue veins is exhibited4 ,huge crumples are also formed by the ,glacier du ,geant1 which are well seen from a point nearly opposite the lowest lateral moraine of the ,glacier des ,periades4 ,in some cases the upper portions of the crumples had scaled off so as to form arches of ice--a consequence doubtless of the pressure4 ,sidenote3 ,,thermometer ,,at ,,the ,,jardin4 #aheh4 ,the beauty of some ,alpine skies is treacherous2 in fact the deepest blue often indicates an atmosphere charged almost to saturation with aqueous vapour4 ,this was the case on the present occasion4 ,soon after reaching ,chamouni in the evening1 rain commenced and continued with scarcely any intermission until the afternoon of the #hth4 ,i had given up all hopes of being able to ascend ,mont ,blanc2 and hence resolved to place the thermometers in some more accessible position4 ,on the #ith accordingly1 accompanied by ,mr4 ,wills1 ,balmat1 and some other friends1 ,i ascended to the summit of the ,jardin1 where we placed two thermometers3 one in the ice1 at a depth of three feet below the surface2 another on a ledge of the highest rock4,b ,the boiling point of water at this place was #aid4f deg4 ,fahr4 ,deep snow was upon the ,talefre1 and the surrounding precipices were also heavily laden4 ,avalanches thundered incessantly from the ,aiguille ,verte and the other mountains4 ,scarcely five minutes on an average intervened between every two successive peals2 and after the direct shock of each avalanche had died away the air of the basin continued to be shaken by the echoes reflected from its bounding walls4 ,sidenote3 ,,evening ,,red4 #aheh4 ,the day was far spent before we had completed our work4 ,all through the weather had been fine1 and towards evening augmented to magnificence4 ,as we descended the glacier from the ,couvercle the sun was just disappearing1 and the western heaven glowed with crimson1 which crept gradually up the sky until finally it reached the zenith itself4 ,such intensity of colouring is exceedingly rare in the ,alps2 and this fact1 together with the known variations in the intensity of the firmamental blue1 justify the conclusion that the colouring must1 in a great measure1 be due to some variable constituent of the atmosphere4 ,if the air were competent to produce these magnificent effects they would be the rule instead of the exception4 ,sidenote3 ,,finished ,,work4 #aheh4 ,no sooner had the thermometers been thus disposed of than the weather appeared to undergo a permanent change4 ,on the #ajth it was perfectly fine--not the slightest mist upon ,mont ,blanc2 on the #aath this was also the case4 ,balmat still had the old thermometer to which ,i have already referred2 it might not do to show the minimum temperature of the air1 but it might show the temperature at a certain depth below the surface4 ,i find in my own case that the finishing of work has a great moral value3 work completed is a safe fulcrum for the performance of other work2 and even though in the course of our labours experience should show us a better means of accomplishing a given end1 it is often far preferable to reach the end1 even by defective means1 than to swerve from our course4 ,the habits which this conviction had superinduced no doubt influenced me when ,i decided on placing ,balmat's thermometer on the summit of ,mont ,blanc4 ,,footnotes3 ,a ,i find with pleasure that my friend ,mr4 ,john ,ball is now exerting himself in this direction4 ,b ,the minimum temperature of the subsequent winter1 as shown by this thermometer1 was -#f deg4 ,fahr41 or #ch deg4 below the freezing point4 ,the instrument placed in the ice was broken4 ,,second ,,ascent ,,of ,,mont ,,blanc1 #aheh4 7#be47 ,sidenote3 ,,shadows ,,of ,,the ,,aiguilles4 #aheh4 ,on the #abth of ,september1 at #e-a_/b ,a4,m4 the sunbeams had already fallen upon the mountain2 but though the sky above him1 and over the entire range of the ,aiguilles1 was without a cloud1 the atmosphere presented an appearance of turbidity resembling that produced by the dust and thin smoke mechanically suspended in a ,london atmosphere on a dry summer's day4 ,at #bj minutes past #g we quitted ,chamouni1 bearing with us the good wishes of a portion of its inhabitants4 ,sidenote3 ,,interference-,,spectra4 #aheh4 ,a lady accompanied us on horseback to the point where the path to the ,grands ,mulets deviates from that to the ,plan des ,aiguilles2 here she turned to the left1 and we proceeded slowly upwards1 through woods of pine1 hung with fantastic lichens3 escaping from the gloom of these1 we emerged upon slopes of bosky underwood1 green hazel1 and green larch1 with the red berries of the mountain-ash shining brightly between them4 ,through the air above us1 like gnomons of a vast sundial1 the ,aiguilles cast their fanlike shadows1 which moved round as the day advanced4 ,slopes of rhododendrons with withered flowers next succeeded1 but the colouring of the bilberry-leaves was scarcely less exquisite than the freshest bloom of the ,alpine rose4 ,for a long time we were in the cool shadow of the mountain1 catching1 at intervals1 through the twigs in front of us1 glimpses of the sun surrounded by coloured spectra4 ,on one occasion a brow rose in front of me2 behind it was a lustrous space of heaven1 adjacent to the sun1 which1 however1 was hidden behind the brow2 against this space the twigs and weeds upon the summit of the brow shone as if they were self-luminous1 while some bits of thistle-down floating in the air appeared1 where they crossed this portion of the heavens1 like fragments of the sun himself4 ,once the orb appeared behind a rounded mass of snow which lay near the summit of the ,aiguille du ,midi4 ,looked at with the naked eyes1 it seemed to possess a billowy motion1 the light darting from it in dazzling curves1--a subjective effect produced by the abnormal action of the intense light upon the eye4 ,as the sun's disk came more into view1 its rays however still grazing the summit of the mountain1 interference-spectra darted from it on all sides1 and surrounded it with a glory of richly-coloured bars4 ,mingling however with the grandeur of nature1 we had the anger and obstinacy of man4 ,with a view to subsequent legal proceedings1 the ,guide ,chef sent a spy after us1 who1 having satisfied himself of our delinquency1 took his unpleasant presence from the splendid scene4 ,strange to say1 though the luminous appearance of bodies projected against the sky adjacent to the rising sun is a most striking and beautiful phenomenon1 it is hardly ever seen by either guides or travellers2 probably because they avoid looking towards a sky the brightness of which is painful to the eyes4 ,in #ahei ,auguste ,balmat had never seen the effect2 and the only written description of it which we possess is one furnished by ,professor ,necker1 in a letter to ,sir ,david ,brewster1 which is so interesting that ,i do not hesitate to reproduce it here3-- ,sidenote3 ,,professor ,,necker',s ,,letter4 #aheh4 ,i now come to the point1 writes ,m4 ,necker1 which you particularly wished me to describe to you2 ,i mean the luminous appearance of trees1 shrubs1 and birds1 when seen from the foot of a mountain a little before sunrise4 ,the wish ,i had to see again the phenomenon before attempting to describe it made me detain this letter a few days1 till ,i had a fine day to go to see it at the ,mont ,saleve2 so yesterday ,i went there1 and studied the fact1 and in elucidation of it ,i made a little drawing1 of which ,i give you here a copy3 it will1 with the explanation and the annexed diagram 7,fig4 #i71 impart to you1 ,i hope1 a correct idea of the phenomenon4 ,you must conceive the observer placed at the foot of a hill interposed between him and the place where the sun is rising1 and thus entirely in the shade2 the upper margin of the mountain is covered with woods or detached trees and shrubs1 which are projected as dark objects on a very bright and clear sky1 except at the very place where the sun is just going to rise1 for there all the trees and shrubs bordering the margin are entirely1--branches1 leaves1 stem and all1--of a pure and brilliant white1 appearing extremely bright and luminous1 although projected on a most brilliant and luminous sky1 as that part of it which surrounds the sun always is4 ,all the minutest details1 leaves1 twigs1 c41 are most delicately preserved1 and you would fancy you saw these trees and forests made of the purest silver1 with all the skill of the most expert workman4 ,the swallows and other birds flying in those particular spots appear like sparks of the most brilliant white4 ,unfortunately1 all these details1 which add so much to the beauty of this splendid phenomenon1 cannot be represented in such small sketches4 ,illustration3 ,fig4 #i4 ,luminous ,trees projected against the sky at sunrise4 ,neither the hour of the day nor the angle which the object makes with the observer appears to have any effect2 for on some occasions ,i have seen the phenomenon take place at a very early hour in the morning4 ,yesterday it was #aj ,a4,m41 when ,i saw it as represented in ,fig4 #aj4 ,i saw it again on the same day at #e ,p4,m41 at a different place of the same mountain1 for which the sun was just setting4 ,at one time the angle of elevation of the lighted white shrubs above the horizon of the spectator was about #bj deg41 while at another place it was only #ae deg4 ,but the extent of the field of illumination is variable1 according to the distance at which the spectator is placed from it4 ,when the object behind which the sun is just going to rise1 or has just been setting1 is very near1 no such effect takes place4 ,in the case represented in ,fig4 #i the distance was about #aid metres1 or #fcf ,english feet1 from the spectator in a direct line1 the height above his level being #fj metres1 or #aig ,english feet1 and the horizontal line drawn from him to the horizontal projection of these points on the plane of his horizon being #afj metres1 or #ebe ,english feet1 as will be seen in the following diagram1 ,fig4 #aj4 ,sidenote3 ,,silver ,,trees ,,at ,,sunrise4 #aheh4 ,illustration3 ,fig4 #aj4 ,luminous ,trees projected against the sky at sunrise4 ,sidenote3 ,,birds ,,as ,,sparks ,,or ,,stars4 #aheh4 ,in this case only small shrubs and the lower half of the stem of a tree are illuminated white1 and the horizontal extent of this effect is also comparatively small2 while at other places when ,i was near the edge behind which the sun was going to rise no such effect took place4 ,but on the contrary1 when ,i have witnessed the phenomenon at a greater distance and at a greater height1 as ,i have seen it other times on the same and on other mountains of the ,alps1 large tracts of forests and immense spruce-firs were illuminated white throughout their whole length1 as ,i have attempted to represent in ,fig4 #aa1 and the corresponding diagram1 ,fig4 #ab4 ,nothing can be finer than these silver-looking spruce-forests4 ,at the same time1 though at a distance of more than a thousand metres1 a vast number of large swallows or swifts 7,cypselus alpinus71 which inhabit these high rocks1 were seen as small brilliant stars or sparks moving rapidly in the air4 ,from these facts it appears to me obvious that the extent of the illuminated spots varies in a direct ratio of their distance2 but at the same time that there must be a constant angular space1 corresponding probably to the zone1 a few minutes of a degree wide1 around the sun's disk1 which is a limit to the occurrence of the appearance4 ,this would explain how the real extent which it occupies on the earth's surface varies with the relative distance of the spot from the eye of the observer1 and accounts also for the phenomenon being never seen in the low country1 where ,i have often looked for it in vain4 ,now that you are acquainted with the circumstances of the fact1 ,i have no doubt you will easily observe it in some part or other of your ,scotch hills2 it may be some long heather or furze will play the part of our ,alpine forests1 and ,i would advise you to try and place a bee-hive in the required position1 and it would perfectly represent our swallows1 sparks1 and stars4 ,illustration3 ,fig4 #aa4 ,luminous ,trees projected against the sky at sunrise4 ,illustration3 ,fig4 #ab4 ,luminous ,trees projected against the sky at sunrise4 ,sidenote3 ,,the ,,ladder ,,condemned4 #aheh4 ,our porters1 with one exception1 reached the ,pierre a l',echelle as soon as ourselves2 and here having refreshed themselves1 and the due exchange of loads having been made1 we advanced upon the glacier1 which we crossed1 until we came nearly opposite to the base of the ,grands ,mulets4 ,the existence of one wide crevasse1 which was deemed impassable1 had this year introduced the practice of assailing the rocks at their base1 and climbing them to the cabin1 an operation which ,balmat wished to avoid4 ,at ,chamouni1 therefore1 he had made inquiries regarding the width of the chasm1 and acting on his advice ,i had had a ladder constructed in two pieces1 which1 united together by iron attachments1 was supposed to be of sufficient length to span the fissure4 ,on reaching the latter1 the pieces were united1 and the ladder thrown across1 but the bridge was so frail and shaky at the place of junction1 and the chasm so deep1 that ,balmat pronounced the passage impracticable4 ,sidenote3 ,,crossing ,,crevasses4 #aheh4 ,the porters were all grouped beside the crevasse when this announcement was made1 and1 like hounds in search of the scent1 the group instantly broke up1 seeking in all directions for a means of passage4 ,the talk was incessant and animating2 attention was now called in one direction1 anon in another1 the men meanwhile throwing themselves into the most picturesque groups and attitudes4 ,all eyes at length were directed upon a fissure which was spanned at one point by an arch of snow1 certainly under two feet deep at the crown4 ,a stout rope was tied round the waist of one of our porters1 and he was sent forward to test the bridge4 ,he approached it cautiously1 treading down the snow to give it compactness1 and thus make his footing sure as he advanced2 bringing regelation into play1 he gave the mass the necessary continuity1 and crossed in safety4 ,the rope was subsequently stretched over the pont1 and each of us causing his right hand to slide along it1 followed without accident4 ,soon afterwards1 however1 we met with a second and very formidable crevasse1 to cross which we had but half of our ladder1 which was applied as follows3--,the side of the fissure on which we stood was lower than the opposite one2 over the edge of the latter projected a cornice of snow1 and a ledge of the same material jutted from the wall of the crevasse1 a little below us4 ,the ladder was placed from ledge to cornice1 both of its ends being supported by snow4 ,i could hardly believe that so frail a bearing could possibly support a man's weight2 but a porter was tied as before1 and sent up the ladder1 while we followed protected by the rope4 ,we were afterwards tied together1 and thus advanced in an orderly line to the ,grands ,mulets4 ,sidenote3 ,,gorgeous ,,sunset4 #aheh4 ,the cabin was wet and disagreeable1 but the sunbeams fell upon the brown rocks outside1 and thither ,mr4 ,wills and myself repaired to watch the changes of the atmosphere4 ,i took possession of the flat summit of a prism of rock1 where1 lying upon my back1 ,i watched the clouds forming1 and melting1 and massing themselves together1 and tearing themselves like wool asunder in the air above4 ,it was nature's language addressed to the intellect2 these clouds were visible symbols which enabled us to understand what was going on in the invisible air4 ,here unseen currents met1 possessing different temperatures1 mixing their contents both of humidity and motion1 producing a mean temperature unable to hold their moisture in a state of vapour4 ,the water-particles1 obeying their mutual attractions1 closed up1 and a visible cloud suddenly shook itself out1 where a moment before we had the pure blue of heaven4 ,some of the clouds were wafted by the air towards atmospheric regions already saturated with moisture1 and along their frontal borders new cloudlets ever piled themselves1 while the hinder portions1 invaded by a drier or a warmer air1 were dissipated2 thus the cloud advanced1 with gain in front and loss behind1 its permanence depending on the balance between them4 ,the day waned1 and the sunbeams began to assume the colouring due to their passage through the horizontal air4 ,the glorious light1 ever deepening in colour1 was poured bounteously over crags1 and snows1 and clouds1 and suffused with gold and crimson the atmosphere itself4 ,i had never seen anything grander than the sunset on that day4 ,clouds with their central portions densely black1 denying all passage to the beams which smote them1 floated westward1 while the fiery fringes which bordered them were rendered doubly vivid by contrast with the adjacent gloom4 ,the smaller and more attenuated clouds were intensely illuminated throughout4 ,across other inky masses were drawn zigzag bars of radiance which resembled streaks of lightning4 ,the firmament between the clouds faded from a blood-red through orange and daffodil into an exquisite green1 which spread like a sea of glory through which those magnificent argosies slowly sailed4 ,some of the clouds were drawn in straight chords across the arch of heaven1 these being doubtless the sections of layers of cloud whose horizontal dimensions were hidden from us4 ,the cumuli around and near the sun himself could not be gazed upon1 until1 as the day declined1 they gradually lost their effulgence and became tolerable to the eyes4 ,all was calm--but there was a wildness in the sky like that of anger1 which boded evil passions on the part of the atmosphere4 ,the sun at length sank behind the hills1 but for some time afterwards carmine clouds swung themselves on high1 and cast their ruddy hues upon the mountain snows4 ,duskier and colder waxed the west1 colder and sharper the breeze of evening upon the ,grands ,mulets1 and as twilight deepened towards night1 and the stars commenced to twinkle through the chilled air1 we retired from the scene4 ,sidenote3 ,,storm ,,on ,,the ,,grands ,,mulets4 #aheh4 ,the anticipated storm at length gave notice of its coming4 ,the sea-waves1 as observed by ,aristotle1 sometimes reach the shore before the wind which produces them is felt2 and here the tempest sent out its precursors1 which broke in detached shocks upon the cabin before the real storm arrived4 ,billows of air1 in ever quicker succession1 rolled over us with a long surging sound1 rising and falling as crest succeeded trough and trough succeeded crest4 ,and as the pulses of a vibrating body1 when their succession is quick enough1 blend to a continuous note1 so these fitful gusts linked themselves finally to a storm which made its own wild music among the crags4 ,grandly it swelled1 carrying the imagination out of doors1 to the clouds and darkness1 to the loosened avalanches and whirling snow upon the mountain heads4 ,moored to the rock on two sides1 the cabin stood firm1 and its manifest security allowed the mind the undisturbed enjoyment of the atmospheric war4 ,we were powerfully shaken1 but had no fear of being uprooted2 and a certain grandeur of the heart rose responsive to the grandeur of the storm4 ,mounting higher and higher1 it at length reached its maximum strength1 from which it lowered fitfully1 until at length1 with a melancholy wail1 it bade our rock farewell4 ,a little before half-past one we issued from the cabin4 ,the night being without a moon1 we carried three lanterns4 ,the heavens were crowded with stars1 among which1 however1 angry masses of cloud here and there still wandered4 ,the storm1 too1 had left a rear-guard behind it2 and strong gusts rolled down upon us at intervals1 at one time1 indeed1 so violent as to cause ,balmat to express doubts of our being able to reach the summit4 ,with a thick handkerchief bound around my hat and ears ,i enjoyed the onset of the wind4 ,once1 turning my head to the left1 ,i saw what appeared to me to be a huge mass of stratus cloud1 at a great distance1 with the stars shining over it4 ,in another instant a precipice of neve loomed upon us2 we were close to its base1 and along its front the annual layers were separated from each other by broad dark bands4 ,through the gloom it appeared like a cloud1 the lines of bedding giving to it the stratus character4 ,sidenote3 ,a ,,comet ,,discovered4 #aheh4 ,immediately before lying down on the previous evening ,i had opened the little window of the cabin to admit some air4 ,in the sky in front of me shone a curious nodule of misty light with a pale train attached to it4 ,in #ahec1 on the side of the ,brocken1 ,i had observed1 without previous notice1 a comet discovered a few days previously by a former fellow student1 and here was another discovery of the same kind4 ,i inspected the stranger with my telescope1 and assured myself that it was a comet4 ,mr4 ,wills chanced to be outside at the time1 and made the same observation independently4 ,as we now advanced up the mountain its ominous light gleamed behind us1 while high up in heaven to our left the planet ,jupiter burned like a lamp of intense brightness4 ,the ,petit ,plateau forms a kind of reservoir for the avalanches of the ,dome du ,gouter1 and this year the accumulation of frozen debris upon it was enormous4 ,we could see nothing but the ice-blocks on which the light of the lanterns immediately fell2 we only knew that they had been discharged from the seracs1 and that similar masses now rose threatening to our right1 and might at any moment leap down upon us4 ,balmat commanded silence1 and urged us to move across the plateau with all possible celerity4 ,the warning of our guide1 the wild and rakish appearance of the sky1 the spent projectiles at our feet1 and the comet with its horrid hair behind1 formed a combination eminently calculated to excite the imagination4 ,sidenote3 ,,dawn ,,on ,,the ,,grand ,,plateau4 #aheh4 ,and now the sky began to brighten towards dawn1 with that deep and calm beauty which suggests the thought of adoration to the human mind4 ,helped by the contemplation of the brightening east1 which seemed to lend lightness to our muscles1 we cheerily breasted the steep slope up to the ,grand ,plateau4 ,the snow here was deep1 and each of our porters took the lead in turn4 ,we paused upon the ,grand ,plateau and had breakfast2 digging1 while we halted1 our feet deeply into the snow4 ,thence up to the corridor1 by a totally different route from that pursued by ,mr4 ,hirst and myself the year previously2 the slope was steep1 but it had not a precipice for its boundary4 ,deep steps were necessary for a time1 but when we reached the summit our ascent became more gentle4 ,the eastern sky continued to brighten1 and by its illumination the ,grand ,plateau and its bounding heights were lovely beyond conception4 ,the snow was of the purest white1 and the glacier1 as it pushed itself on all sides into the basin1 was riven by fissures filled with a coerulean light1 which deepened to inky gloom as the vision descended into them4 ,the edges were overhung with fretted cornices1 from which depended long clear icicles1 tapering from their abutments like spears of crystal4 ,the distant fissures1 across which the vision ranged obliquely without descending into them1 emitted that magical firmamental shimmer which1 contrasted with the pure white of the snow1 was inexpressibly lovely4 ,near to us also grand castles of ice reared themselves1 some erect1 some overturned1 with clear cut sides1 striped by the courses of the annual snows1 while high above the seracs of the plateau rose their still grander brothers of the ,dome du ,gouter4 ,there was a nobility in this glacier scene which ,i think ,i have never seen surpassed2--a strength of nature1 and yet a tenderness1 which at once raised and purified the soul4 ,the gush of the direct sunlight could add nothing to this heavenly beauty2 indeed ,i thought its yellow beams a profanation as they crept down from the humps of the ,dromedary1 and invaded more and more the solemn purity of the realm below4 ,sidenote3 ,,balmat ,,in ,,danger4 #aheh4 ,our way lay for a time amid fine fissures with blue walls1 until at length we reached the edge of one which elicited other sentiments than those of admiration4 ,it must be crossed4 ,at the opposite side was a high and steep bank of ice which prolonged itself downwards1 and ended in a dependent eave of snow which quite overhung the chasm1 and reached to within about a yard of our edge of the crevasse4 ,balmat came forward with his axe1 and tried to get a footing on the eave3 he beat it gently1 but the axe went through the snow1 forming an aperture through which the darkness of the chasm was rendered visible4 ,our guide was quite free1 without rope or any other means of security2 he beat down the snow so as to form a kind of stirrup1 and upon this he stepped4 ,the stirrup gave way1 it was right over the centre of the chasm1 but with wonderful tact and coolness he contrived to get sufficient purchase from the yielding mass to toss himself back to the side of the chasm4 ,the rope was now brought forward and tied round the waist of one of the porters2 another step was cautiously made in the eave of snow1 the man was helped across1 and lessened his own weight by means of his hatchet4 ,he gradually got footing on the face of the steep1 which he mounted by escaliers2 and on reaching a sufficient height he cut two large steps in which his feet might rest securely4 ,here he laid his breast against the sloping wall1 and another person was sent forward1 who drew himself up by the rope which was attached to the leader4 ,thus we all passed1 each of us in turn bearing the strain of his successor upon the rope2 it was our last difficulty1 and we afterwards slowly plodded through the snow of the corridor towards the base of the ,mur de la ,cote4 ,sidenote3 ,,storm ,,on ,,mont ,,blanc4 #aheh4 ,sidenote3 ,,thermometer ,,buried4 #aheh4 ,climbing zigzag1 we soon reached the summit of the ,mur1 and immediately afterwards found ourselves in the midst of cold drifting clouds1 which obscured everything4 ,they dissolved for a moment and revealed to us the sunny valley of ,chamouni2 but they soon swept down again and completely enveloped us4 ,upon the ,calotte1 or last slope1 ,i felt no trace of the exhaustion which ,i had experienced last year1 but enjoyed free lungs and a quiet heart4 ,the clouds now whirled wildly round us1 and the fine snow1 which was caught by the wind and spit bitterly against us1 cut off all visible communication between us and the lower world4 ,as we approached the summit the air thickened more and more1 and the cold1 resulting from the withdrawal of the sunbeams1 became intense4 ,we reached the top1 however1 in good condition1 and found the new snow piled up into a sharp arete1 and the summit of a form quite different from that of the ,dos d'un ,ane1 which it had presented the previous year4 ,leaving ,balmat to make a hole for the thermometer1 ,i collected a number of batons1 drove them into the snow1 and1 drawing my plaid round them1 formed a kind of extempore tent to shelter my boiling-water apparatus4 ,the covering was tightly held1 but the snow was as fine and dry as dust1 and penetrated everywhere3 my lamp could not be secured from it1 and half a box of matches was consumed in the effort to ignite it4 ,at length it did flame up1 and carried on a sputtering combustion4 ,the cold of the snow-filled boiler condensing the vapour from the lamp gradually produced a drop1 which1 when heavy enough to detach itself from the vessel1 fell upon the flame and put it out4 ,it required much patience and the expenditure of many matches to relight it4 ,meanwhile the absence of muscular action caused the cold to affect our men severely4 ,my beard and whiskers were a mass of clotted ice4 ,the batons were coated with ice1 and even the stem of my thermometer1 the bulb of which was in hot water1 was covered by a frozen enamel4 ,the clouds whirled1 and the little snow granules hit spitefully against the skin wherever it was exposed4 ,the temperature of the air was #bj deg4 ,fahr4 below the freezing point4 ,i was too intent upon my work to heed the cold much1 but ,i was numbed2 one of my fingers had lost sensation1 and my right heel was in pain3 still ,i had no thought of forsaking my observation until ,mr4 ,wills came to me and said that we must return speedily1 for ,balmat's hands were gelees4 ,i did not comprehend the full significance of the word2 but1 looking at the porters1 they presented such an aspect of suffering that ,i feared to detain them longer4 ,they looked like worn old men1 their hair and clothing white with snow1 and their faces blue1 withered1 and anxious-looking4 ,the hole being ready1 ,i asked ,balmat for the magnet to arrange the index of the thermometer3 his hands seemed powerless4 ,i struck my tent1 deposited the instrument1 and1 as ,i watched the covering of it up1 some of the party1 among whom were ,mr4 ,wills and ,balmat1 commenced the descent4,a ,sidenote3 ,,balmat ,,frostbitten4 #aheh4 ,i followed them speedily4 ,midway down the ,calotte ,i saw ,balmat1 who was about a hundred yards in advance of me1 suddenly pause and thrust his hands into the snow1 and commence rubbing them vigorously4 ,the suddenness of the act surprised me1 but ,i had no idea at the time of its real significance3 ,i soon came up to him2 he seemed frightened1 and continued to beat and rub his hands1 plunging them1 at quick intervals1 into the snow4 ,still ,i thought the thing would speedily pass away1 for ,i had too much faith in the man's experience to suppose that he would permit himself to be seriously injured4 ,but it did not pass as ,i hoped it would1 and the terrible possibility of his losing his hands presented itself to me4 ,he at length became exhausted by his own efforts1 staggered like a drunken man1 and fell upon the snow4 ,mr4 ,wills and myself took each a hand1 and continued the process of beating and rubbing4 ,i feared that we should injure him by our blows1 but he continued to exclaim1 ,n'ayez pas peur1 frappez toujours1 frappez fortement6 ,we did so1 until ,mr4 ,wills became exhausted1 and a porter had to take his place4 ,meanwhile ,balmat pinched and bit his fingers at intervals1 to test their condition2 but there was no sensation4 ,he was evidently hopeless himself2 and1 seeing him thus1 produced an effect upon me that ,i had not experienced since my boyhood--my heart swelled1 and ,i could have wept like a child4 ,the idea that ,i should be in some measure the cause of his losing his hands was horrible to me2 schemes for his support rushed through my mind with the usual swiftness of such speculations1 but no scheme could restore to him his lost hands4 ,at length returning sensation in one hand announced itself by excruciating pain4 ,je souffre6 he exclaimed at intervals--words which1 from a man of his iron endurance1 had a more than ordinary significance4 ,but pain was better than death1 and1 under the circumstances1 a sign of improvement4 ,we resumed our descent1 while he continued to rub his hands with snow and brandy1 thrusting them at every few paces into the mass through which we marched4 ,at ,chamouni he had skilful medical advice1 by adhering to which he escaped with the loss of six of his nails--his hands were saved4 ,i cannot close this recital without expressing my admiration of the dauntless bearing of our porters1 and of the cheerful and efficient manner in which they did their duty throughout the whole expedition4 ,their names are ,edouard ,bellin1 ,joseph ,favret1 ,michel ,payot1 ,joseph ,folliguet1 and ,alexandre ,balmat4 ,,footnotes3 ,a ,in ,august1 #ahei1 ,i found the temperature of water1 boiling in an open vessel at the summit of ,mont ,blanc1 to be #ahd4ie deg4 ,fahr4 ,on that occasion also1 though a laborious search was made for the thermometer1 it could not be found4 7#bf47 ,sidenote3 ,,proces-,,verbal4 #aheh4 ,the hostility of the chief guide to the expedition was not diminished by the letter of the ,intendant2 and he at once entered a proces-verbal against ,balmat and his companions on their return to ,chamouni4 ,i felt that the power thus vested in an unlettered man to arrest the progress of scientific observations was so anomalous1 that the enlightened and liberal ,government of ,sardinia would never tolerate such a state of things if properly represented to it4 ,the ,british ,association met at ,leeds that year1 and to it1 as a guardian of science1 my thoughts turned4 ,i accordingly laid the case before the ,association1 and obtained its support3 a resolution was unanimously passed that application be made to the ,sardinian authorities for increased facilities for making scientific observations in the ,alps4 ,considering the arduous work which ,balmat had performed in former years in connexion with the glaciers1 and especially his zeal in determining1 under the direction of ,professor ,forbes1 their winter motion--for which1 as in the case above recorded1 he refused all personal remuneration--,i thought such services worthy of some recognition on the part of the ,royal ,society4 ,i suggested this to the ,council1 and was met by the same cordial spirit of co-operation which ,i had previously experienced at ,leeds4 ,a sum of five-and-twenty guineas was at once voted for the purchase of a suitable testimonial2 and a committee1 consisting of ,sir ,roderick ,murchison1 ,professor ,forbes1 and myself1 was appointed to carry the thing out4 ,balmat was consulted1 and he chose a photographic apparatus1 which1 with a suitable inscription1 was duly presented to him4 ,sidenote3 ,,british ,,association4 #aheh4 ,thus fortified1 ,i drew up an account of what had occurred at ,chamouni during my last visit1 accompanied by a brief statement of the changes which seemed desirable4 ,this was placed in the hands of the ,president of the ,british ,association1 to whose prompt and powerful co-operation in this matter every ,alpine explorer who aspires to higher ground than ordinary is deeply indebted4 ,the following letter assured me that the facility applied for by the ,british ,association would be granted by the ,sardinian ,government1 and that future men of science would find in the ,alps a less embarrassed field of operations than had fallen to my lot in the summer of #aheh4 ,sidenote3 ,,the ,,president',s ,,letter4 #aheh4 #ab1 ,hertford-street1 ,mayfair1 ,w41 ,february #ahth1 #ahei4 ,my dear ,sir1-- ,having1 as ,i informed you in my last note1 communicated with the ,sardinian ,minister ,plenipotentiary the day after receiving your statement relative to the guides at ,chamouni1 ,i have been favoured by replies from the ,minister1 of the #dth and #agth ,february4 ,in the first the ,marquis d',azeglio assures me that he will bring the subject before the competent authorities at ,turin1 accompanying the transmission 'd'une recommandation toute speciale4' ,in the second letter the ,marquis informs me that 'the preparation of new regulations for the guides at ,chamouni had for some time occupied the attention of the ,minister of the ,interior1 and that these regulations will be in rigorous operation1 in all probability1 at the commencement of the approaching summer4' ,the ,marquis adds that1 'as the regulations will be based upon a principle of much greater liberty1 he has every reason to believe that they will satisfy all the desires of travellers in the interests of science4' ,with much pleasure at the opportunity of having been in any degree able to bring about the fulfilment of your wishes on the subject1 ,i remain1 my dear ,sir1 ,faithfully yours1 ,,richard ,,owen4 ,pres4 ,brit4 ,association4 ,prof4 ,tyndall1 ,f4,r4,s4 ,it ought to be stated that1 previous to my arrival at ,chamouni in #aheh1 an extremely cogent memorial drawn up by ,mr4 ,john ,ball had been presented to the ,marquis d',azeglio by a deputation from the ,alpine ,club4 ,it was probably this memorial which first directed the attention of the ,sardinian ,minister of the ,interior to the subject4 ,,winter ,,expedition ,,to ,,the ,,mer ,,de ,,glace1 #ahei4 7#bg47 ,having ten days at my disposal last ,christmas1 ,i was anxious to employ them in making myself acquainted with the winter aspects and phenomena of the ,mer de ,glace4 ,on ,wednesday1 the #bast of ,december1 ,i accordingly took my place to ,paris1 but on arriving at ,folkestone found the sea so tempestuous that no boat would venture out4 ,sidenote3 ,,first ,,defeat1 ,,and ,,fresh ,,attempt4 #ahei4 ,the loss of a single day was more than ,i could afford1 and this failure really involved the loss of two4 ,seeing1 therefore1 the prospect of any practical success so small1 ,i returned to ,london1 purposing to give the expedition up4 ,on the following day1 however1 the weather lightened1 and ,i started again1 reaching ,paris on ,friday morning4 ,on that day it was not possible to proceed beyond ,macon1 where1 accordingly1 ,i spent the night1 and on the following day reached ,geneva4 ,much snow had fallen2 at ,paris it still cumbered the streets1 and round about ,macon it lay thick1 as if a more than usually heavy cloud had discharged itself on that portion of the country4 ,between ,macon and ,roussillon it was lighter1 but from the latter station onwards the quantity upon the ground gradually increased4 ,sidenote3 ,,geneva ,,to ,,chamouni4 #ahei4 ,on ,christmas morning1 at #h o'clock1 ,i left ,geneva by the diligence for ,sallenches4 ,the dawn was dull1 but the sky cleared as the day advanced1 and finally a dome of cloudless blue stretched overhead4 ,the mountains were grand2 their sunward portions of dazzling whiteness1 while the shaded sides1 in contrast with the blue sky behind them1 presented a ruddy1 subjective tint4 ,the brightness of the day reached its maximum towards one o'clock1 after which a milkiness slowly stole over the heavens1 and increased in density until finally a drowsy turbidity filled the entire air4 ,the distant peaks gradually blended with the white atmosphere above them and lost their definition4 ,the black pine forests on the slopes of the mountains stood out in strong contrast to the snow2 and1 when looked at through the spaces enclosed by the tree branches at either side of the road1 they appeared of a decided indigo-blue4 ,it was only when thus detached by a vista in front that the blue colour was well seen1 the air itself between the eye and the distant pines being the seat of the colour4 ,goethe would have regarded it as an excellent illustration of his ',farbenlehre4' ,we reached ,sallenches a little after #d ,p4,m41 where ,i endeavoured to obtain a sledge to continue my journey4 ,a fit one was not to be found1 and a carriage was therefore the only resort4 ,we started at five2 it was very dark1 but the feeble reflex of the snow on each side of the road was preferred by the postilion to the light of lamps4 ,unlike the enviable ostrich1 ,i cannot shut my eyes to danger when it is near3 and as the carriage swayed towards the precipitous road side1 ,i could not fold myself up1 as it was intended ,i should1 but1 quitting the interior and divesting my limbs of every encumbrance1 ,i took my seat beside the driver1 and kept myself in readiness for the spring1 which in some cases appeared imminent4 ,my companion however was young1 strong1 and keen-eyed2 and though we often had occasion for the exercise of the quality last mentioned1 we reached ,servoz without accident4 ,sidenote3 ,,desolation4 #ahei4 ,sidenote3 ,a ,,horse ,,in ,,the ,,snow4 #ahei4 ,here we baited1 and our progress afterwards was slow and difficult4 ,the snow on the road was deep and hummocky1 and the strain upon the horses very great4 ,having crossed the ,arve at the ,pont-,pelissier1 we both alighted1 and ,i went on in advance4 ,the air was warm1 and not a whisper disturbed its perfect repose4 ,there was no moon1 and the heavy clouds1 which now quite overspread the heavens1 cut off even the feeble light of the stars4 ,the sound of the ,arve1 as it rushed through the deep valley to my left1 came up to me through crags and trees with a sad murmur4 ,sometimes on passing an obstacle1 the sound was entirely cut off1 and the consequent silence was solemn in the extreme4 ,it was a churchyard stillness1 and the tall black pines1 which at intervals cast their superadded gloom upon the road1 seemed like the hearse-plumes of a dead world4 ,i reached a wooden hut1 where a lame man offers batons1 minerals1 and eau de vie1 to travellers in summer4 ,it was forsaken1 and half buried in the snow4 ,i leaned against the door1 and enjoyed for a time the sternness of the surrounding scene4 ,my conveyance was far behind1 and the intermittent tinkle of the horses' bells1 which augmented instead of diminishing the sense of solitude1 informed me of the progress and the pauses of the vehicle4 ,at the summit of the road ,i halted until my companion reached me2 we then both remounted1 and proceeded slowly towards ,les ,ouches4 ,we passed some houses1 the aspect of which was even more dismal than that of ,nature2 their roofs were loaded with snow1 and white buttresses were reared against the walls4 ,there was no sound1 no light1 no voice of joy to indicate that it was the pleasant ,christmas time4 ,we once met the pioneer of a party of four drunken peasants3 he came right against us1 and the coachman had to pull up4 ,planting his feet in the snow and propping himself against the leader's shoulder1 the bacchanal exhorted the postilion to drive on2 the latter took him at his word1 and overturned him in the snow4 ,after this we encountered no living thing4 ,the horses seemed seized by a kind of torpor1 and leaned listlessly against each other2 vainly the postilion endeavoured to rouse them by word and whip2 they sometimes essayed to trot down the slopes1 but immediately subsided to their former monotonous crawl4 ,as we ascended the valley1 the stillness of the air was broken at intervals by wild storm-gusts1 sent down against us from ,mont ,blanc himself4 ,these chilled me1 so ,i quitted the carriage1 and walked on4 ,not far from ,chamouni1 the road1 for some distance1 had been exposed to the full action of the wind1 and the snow had practically erased it4 ,its left wall was completely covered1 while a few detached stones1 rising here and there above the surface1 were the only indications of the presence and direction of the right-hand wall4 ,i could not see the state of the surface1 but ,i learned by other means that the snow had been heaped in oblique ridges across my path4 ,i staggered over four or five of these in succession1 sinking knee-deep1 and finally found myself immersed to the waist4 ,this made me pause2 ,i thought ,i must have lost the road1 and vainly endeavoured to check myself by the positions of surrounding objects4 ,i turned back and met the carriage3 it had stuck in one of the ridges2 one horse was down1 his hind legs buried to the haunches1 his left fore leg plunged to the shoulder in snow1 and the right one thrown forward upon the surface4 ,c'est bien la route8 demanded my companion4 ,i went back exploring1 and assured myself that we were over the road2 but ,i recommended him to release the horses and leave the carriage to its fate4 ,he1 however1 succeeding in extricating the leader1 and while ,i went on in advance seeking out the firmer portions of the road1 he followed1 holding his horses by their heads2 and half an hour's struggle of this kind brought us to ,chamouni4 ,sidenote3 ,,chamouni ,,on ,,christmas ,,night4 #ahei4 ,it also was a little city of the dead4 ,there was no living thing in the streets1 and neither sound nor light in the houses4 ,the fountain made a melancholy gurgle1 one or two loosened window-shutters creaked harshly in the wind1 and banged against the objects which limited their oscillations4 ,the ,hotel de l',union1 so bright and gay in summer1 was nailed up and forsaken2 and the cross in front of it1 stretching its snow-laden arms into the dim air1 was the type of desolation4 ,we rang the bell at the ,hotel ,royal1 but the bay of a watch-dog resounding through the house was long our only reply4 ,the bell appeared powerless to wake the sleepers1 and its sound mingled dismally with that of the wind howling through the deserted passages4 ,the noise of my boot-heel1 exerted long on the front door1 was at length effective2 it was unbarred1 and the physical heat of a good stove soon added itself to the warmth of the welcome with which my hostess greeted me4 ,december #bfth4--,the snow fell heavily1 at frequent intervals1 throughout the entire day4 ,dense clouds draped all the mountains1 and there was not the least prospect of my being able to see across the ,mer de ,glace4 ,i walked out alone in the dim light1 and afterwards traversed the streets before going to bed4 ,they were quite forsaken4 ,cold and sullen the ,arve rolled under its wooden bridge1 while the snow fell at intervals with heavy shock from the roofs of the houses1 the partial echoes from the surfaces of the granules combining to render the sound loud and hollow4 ,thus were the concerns of this little hamlet changed and fashioned by the obliquity of the earth's axis1 the chain of dependence which runs throughout creation1 linking the roll of a planet alike with the interests of marmots and of men4 ,sidenote3 ,,ascent ,,of ,,the ,,mountain4 #ahei4 ,sidenote3 ,,snow ,,on ,,the ,,pines4 #ahei4 ,tuesday1 #bgth ,december4--,i rose at six o'clock1 having arranged with my men to start at seven1 if the weather at all permitted4 ,edouard ,simond1 my old assistant of #aheg1 and ,joseph ,tairraz were the guides of the party2 the porters were ,edouard ,balmat1 ,joseph ,simond 7fils d',auguste71 ,francois ,ravanal1 and another4 ,they came at the time appointed2 it was snowing heavily1 and we agreed to wait till eight o'clock and then decide4 ,they returned at eight1 and finding them disposed to try the ascent to the ,montanvert1 it was not my place to baulk them4 ,through the valley the work was easy1 as the snow had been partially beaten down1 but we soon passed the habitable limits1 and had to break ground for ourselves4 ,three of my men had tried to reach the ,montanvert by la ,filia on the previous ,thursday1 but their experience of the route had been such as to deter them from trying it again4 ,we now chose the ordinary route1 breasting the slope until we reached the cluster of chalets1 under the projecting eave of one of which the men halted and applied pattens to their feet4 ,these consisted of planks about sixteen inches long and ten wide1 which were firmly strapped to the feet4 ,my first impression was that they were worse than useless1 for though they sank less deeply than the unarmed feet1 on being raised they carried with them a larger amount of snow1 which1 with the leverage of the leg1 appeared to necessitate an enormous waste of force4 ,i stated this emphatically1 but the men adhered to their pattens1 and before ,i reached the ,montanvert ,i had reason to commend their practice as preferable to my theory4 ,i was however guided by the latter1 and wore no pattens4 ,the general depth of the snow along the track was over three feet2 the footmarks of the men were usually rigid enough to bear my weight1 but in many cases ,i went through the crust which their pressure had produced1 and sank suddenly in the mass4 ,the snow became softer as we ascended1 and my immersions more frequent1 but the work was pure enjoyment1 and the scene one of extreme beauty4 ,the previous night's snow had descended through a perfectly still atmosphere1 and had loaded all the branches of the pines2 the long arms of the trees drooped under the weight1 and presented at their extremities the appearance of enormous talons turned downwards4 ,some of the smaller and thicker trees were almost entirely covered1 and assumed grotesque and beautiful forms2 the upper part of one in particular resembled a huge white parrot with folded wings and drooping head1 the slumber of the bird harmonizing with the torpor of surrounding nature4 ,i have given a sketch of it in ,fig4 #ac4 ,illustration3 ,fig4 #ac4 ,snow on the ,pines4 ,sidenote3 ,,sound ,,of ,,breaking ,,snow4 #ahei4 ,previous to reaching the half-way spring1 where the peasant girls offer strawberries to travellers in summer1 we crossed two large couloirs filled with the debris of avalanches which had fallen the night before4 ,between these was a ridge forty or fifty yards wide on which the snow was very deep1 the slope of the mountain also adding a component to the fair thickness of the snow4 ,my shoulder grazed the top of the embankment to my right as ,i crossed the ridge1 and once or twice ,i found myself waist deep in a vertical shaft from which it required a considerable effort to escape4 ,suddenly we heard a deep sound resembling the dull report of a distant gun1 and at the same moment the snow above us broke across1 forming a fissure parallel to our line of march4 ,the layer of snow had been in a state of strain1 which our crossing brought to a crisis3 it gave way1 but having thus relieved itself it did not descend4 ,several times during the ascent the same phenomenon occurred4 ,once1 while engaged upon a very steep slope1 one of the men cried out to the leader1 ,arretez6 ,immediately in front of the latter the snow had given way1 forming a zigzag fissure across the slope4 ,we all paused1 expecting to see an avalanche descend4 ,tairraz was in front2 he struck the snow with his baton to loosen it1 but seeing it indisposed to descend he advanced cautiously across it1 and was followed by the others4 ,i brought up the rear4 ,the steepness of the mountain side at this place1 and the absence of any object to which one might cling1 would have rendered a descent with the snow in the last degree perilous1 and we all felt more at ease when a safe footing was secured at the further side of the incline4 ,at the spring1 which showed a little water1 the men paused to have a morsel of bread4 ,the wind had changed1 the air was clearing1 and our hopes brightening4 ,as we ascended the atmosphere went through some extraordinary mutations4 ,clouds at first gathered round the ,aiguille and ,dome du ,gouter1 casting the lower slopes of the mountain into intense gloom4 ,after a little time all this cleared away1 and the beams of the sun striking detached pieces of the slopes and summits produced an extraordinary effect4 ,the ,aiguille and ,dome were most singularly illumined1 and to the extreme left rose the white conical hump of the ,dromedary1 from which a long streamer of snow-dust was carried southward by the wind4 ,the ,aiguille du ,dru1 which had been completely mantled during the earlier part of the day1 now threw off its cloak of vapour and rose in most solemn majesty before us2 half of its granite cone was warmly illuminated1 and half in shadow4 ,the wind was high in the upper regions1 and1 catching the dry snow which rested on the asperities and ledges of the ,aiguille1 shook it out like a vast banner in the air4 ,the changes of the atmosphere1 and the grandeur which they by turns revealed and concealed1 deprived the ascent of all weariness4 ,we were usually flanked right and left by pines1 but once between the fountain and the ,montanvert we had to cross a wide unsheltered portion of the mountain which was quite covered with the snow of recent avalanches4 ,this was lumpy and far more coherent than the undisturbed snow4 ,we took advantage of this1 and climbed zigzag over the avalanches for three-quarters of an hour1 thus reaching the opposite pines at a point considerably higher than the path4 ,this1 though not the least dangerous1 was the least fatiguing part of the ascent4 ,sidenote3 ,,colour ,,of ,,snow4 #ahei4 ,i frequently examined the colour of the snow3 though fresh1 its blue tint was by no means so pronounced as ,i have seen it on other occasions2 still it was beautiful4 ,the colour is1 no doubt1 due to the optical reverberations which occur within a fissure or cavity formed in the snow4 ,the light is sent from side to side1 each time plunging a little way into the mass2 and being ejected from it by reflection1 it thus undergoes a sifting process1 and finally reaches the eye as blue light4 ,the presence of any object which cuts off this cross-fire of the light destroys the colour4 ,i made conical apertures in the snow1 in some cases three feet deep1 a foot wide at the mouth1 and tapering down to the width of my baton4 ,when the latter was placed along the axis of such a cone1 the blue light which had previously filled the cavity disappeared2 on the withdrawal of the baton it was followed by the light1 and thus by moving the staff up and down its motions were followed by the alternate appearance and extinction of the light4 ,i have said that the holes made in the snow seemed filled with a blue light1 and it certainly appeared as if the air contained in the cavities had itself been coloured1 and thereby rendered visible1 the vision plunging into it as into a blue medium4 ,another fact is perhaps worth notice3 snow rarely lies so smooth as not to present little asperities at its surface2 little ridges or hillocks1 with little hollows between them4 ,such small hollows resemble1 in some degree1 the cavities which ,i made in the snow1 and from them1 in the present instance1 a delicate light was sent to the eye1 faintly tinted with the pure blue of the snow-crystals4 ,in comparison with the spots thus illuminated1 the little protuberances were gray4 ,the portions most exposed to the light seemed least illuminated1 and their defect in this respect made them appear as if a light-brown dust had been strewn over them4 ,sidenote3 ,,the ,,montanvert ,,in ,,winter4 #ahei4 ,after five hours and a half of hard work we reached the ,montanvert4 ,i had often seen it with pleasure4 ,often1 having spent the day alone amid the seracs of the ,col du ,geant1 on turning the promontory of ,trelaporte on my way home1 the sight of the little mansion has gladdened me1 and given me vigour to scamper down the glacier1 knowing that pleasant faces and wholesome fare were awaiting me4 ,this day1 also1 the sight of it was most welcome1 despite its desolation4 ,the wind had swept round the auberge1 and carried away its snow-buttresses1 piling the mass thus displaced against the adjacent sheds1 to the roofs of which one might step from the surface of the snow4 ,the floor of the little chateau in which ,i lodged in #aheg was covered with snow1 and on it were the fresh footmarks of a little animal--a marmot might have made such marks1 had not the marmots been all asleep--what the creature was ,i do not know4 ,sidenote3 ,,crystal ,,curtain4 #ahei4 ,in the application of her own principles1 ,nature often transcends the human imagination2 her acts are bolder than our predictions4 ,it is thus with the motion of glaciers2 it was thus at the ,montanvert on the day now referred to4 ,the floors1 even where the windows appeared well closed1 were covered with a thin layer of fine snow2 and some of the mattresses in the bedrooms were coated to the depth of half an inch with this fine powder4 ,given a chink through which the finest dust can pass1 dry snow appears competent to make its way through the same fissure4 ,it had also been beaten against the windows1 and clung there like a ribbed drapery4 ,in one case an effect so singular was exhibited1 that ,i doubted my eyes when ,i first saw it4 ,in front of a large pane of glass1 and quite detached from it1 save at its upper edge1 was a festooned curtain formed entirely of minute ice-crystals4 ,it appeared to be as fine as muslin2 the ease of its curves and the depth of its folds being such as could not be excelled by the intentional arrangement of ordinary gauze4 ,the frost-figures on some of the window-panes were also of the most extraordinary character3 in some cases they extended over large spaces1 and presented the appearance which we often observe in ,london2 but on other panes they occurred in detached clusters1 or in single flowers1 these grouping themselves together to form miniature bouquets of inimitable beauty4 ,i placed my warm hand against a pane which was covered by the crystallization1 and melted the frostwork which clung to it4 ,i then withdrew my hand and looked at the film of liquid through a pocket-lens4 ,the glass cooled by contact with the air1 and after a time the film commenced to move at one of its edges2 atom closed with atom1 and the motion ran in living lines through the pellicle1 until finally the entire film presented the beauty and delicacy of an organism4 ,the connexion between such objects and what we are accustomed to call the feelings may not be manifest1 but it is nevertheless true that1 besides appealing to the pure intellect of man1 these exquisite productions can also gladden his heart and moisten his eyes4 ,sidenote3 ,,the ,,mer ,,de ,,glace ,,in ,,winter4 #ahei4 ,the glacier excited the admiration of us all3 not as in summer1 shrunk and sullied like a spent reptile1 steaming under the influence of the sun2 its frozen muscles were compact1 strength and beauty were associated in its aspect4 ,at some places it was pure and smooth2 at others frozen fins arose from it1 high1 steep1 and sharply crested4 ,down the opposite mountain side arrested streams set themselves erect in successive terraces1 the fronts of which were fluted pillars of ice4 ,there was no sound of water2 even the ,nant ,blanc1 which gushes from a spring1 and which some describe as permanent throughout the winter1 showed no trace of existence4 ,from the ,montanvert to ,trelaporte the ,mer de ,glace was all in shadow2 but the sunbeams pouring down the corridor of the ,geant ruled a beam of light across the glacier at its upper portion1 smote the base of the ,aiguille du ,moine1 and flooded the mountain with glory to its crest4 ,at the opposite side of the valley was the ,aiguille du ,dru1 with a banneret of snow streaming from its mighty cone4 ,the ,grande ,jorasse1 and the range of summits between it and the ,aiguille du ,geant1 were all in view1 and the ,charmoz raised its precipitous cliffs to the right1 and pierced with its splinter-like pinnacles the clear cold air4 ,as the night drew on1 the mountains seemed to close in upon us2 and on looking out before retiring to rest1 a scene so solemn had never before presented itself to my eyes or affected my imagination4 ,sidenote3 ,,the ,,first ,,night4 #ahei4 ,my men occupied the afternoon of the day of our arrival in making a preliminary essay upon the glacier while ,i prepared my instruments4 ,to the person whom ,i intended to fix my stations1 three others were attached by sound ropes of considerable length4 ,hidden crevasses we knew were to be encountered1 and we had made due preparation for them4 ,throughout the afternoon the weather remained fine1 and at night the stars shone out1 but still with a feeble lustre4 ,i could notice a turbidity gathering in the air over the range of the ,brevent1 which seemed disposed to extend itself towards us4 ,at night ,i placed a chair in the middle of the snow1 at some distance from the house1 and laid on it a registering thermometer4 ,a bountiful fire of pine logs was made in the salle a manger2 a mattress was placed with its foot towards the fire1 its middle line bisecting the right angle in which the fireplace stood2 this being found by experiment to be the position in which the draughts from the door and from the windows most effectually neutralized each other4 ,in this region of calms ,i lay down1 and covering myself with blankets and duvets1 listened to the crackling of the logs1 and watched their ruddy flicker upon the walls1 until ,i fell asleep4 ,the wind rose during the night1 and shook the windows3 one pane in particular seemed set in unison to the gusts1 and responded to them by a loud and melodious vibration4 ,i rose and wedged it round with sous and penny pieces1 and thus quenched its untimely music4 ,december #bhth4--,we were up before the dawn4 ,tairraz put my fire in order1 and ,i then rose4 ,the temperature of the room at a distance of eight feet from the fire was two degrees of ,centigrade below zero2 the lowest temperature outside was eleven degrees of ,centigrade below zero1--not at all an excessive cold4 ,the clouds indeed had1 during the night1 thrown vast diaphragms across the sky1 and thus prevented the escape of the earth's heat into space4 ,while my assistants were preparing breakfast ,i had time to inspect the glacier and its bounding heights4 ,on looking up the ,mer de ,glace1 the ,grande ,jorasse meets the view1 rising in steep outline from the wall of cliffs which terminates the ,glacier de ,lechaud4 ,behind this steep ascending ridge1 which is shown on the frontispiece1 and upon it1 a series of clouds had ranged themselves1 stretching lightly along the ridge at some places1 and at others collecting into ganglia4 ,a string of rosettes was thus formed which were connected together by gauzy filaments4 ,the portion of the heavens behind the ridge was near the domain of the rising sun1 and when he cleared the horizon his red light fell upon the clouds1 and ignited them to ruddy flames4 ,some of the lighter clouds doubled round the summit of the mountain1 and swathed its black crags with a vestment of transparent red4 ,the adjacent sky wore a strange and supernatural air2 indeed there was something in the whole scene which baffled analysis1 and the words of ,tennyson rose to my lips as ,i gazed upon it3-- ,sidenote3 ,a ,,rose ,,of ,,dawn4 #ahei4 ,god made ,himself an awful rose of dawn4 ,i have spoken several times of the cloud-flag which the wind wafted from the summit of the ,aiguille du ,dru4 ,on the present occasion this grand banner reached extraordinary dimensions4 ,it was brindled in some places as if whipped into curds by the wind2 but through these continuous streamers were drawn1 which were bent into sinuosities resembling a waving flag at a mast-head4 ,all this was now illuminated with the sun's red rays1 which also fringed with fire the exposed edges and pinnacles both of the ,aiguille du ,dru and the ,aiguille ,verte4 ,thus rising out of the shade of the valley the mountains burned like a pair of torches1 the flames of which were blown half a mile through the air4 ,soon afterwards the summits of the ,aiguilles ,rouges were illuminated1 and day declared itself openly among the mountains4 ,sidenote3 ,,the ,,stakes ,,fixed4 #ahei4 ,but these red clouds of the morning1 magnificent though they were1 suggested thoughts which tended to qualify the pleasure which they gave3 they did not indicate good weather4 ,sometimes1 indeed1 they had to fight with denser masses1 which often prevailed1 swathing the mountains in deep neutral tint1 but which1 again yielding1 left the glory of the sunrise augmented by contrast with their gloom4 ,between eight and nine ,a4,m4 we commenced the setting out of our first line1 one of whose termini was a point about a hundred yards higher up than the ,montanvert hotel2 a withered pine on the opposite mountain side marking the other terminus4 ,the stakes made use of were four feet long4 ,with the selfsame baton which ,i had employed upon the ,mer de ,glace in #aheg1 and which ,simond had preserved1 the worthy fellow now took up the line4 ,at some places the snow was very deep1 but its lower portions were sufficiently compact to allow of a stake being firmly fixed in it4 ,at those places where the wind had removed the snow or rendered it thin1 the ice was pierced with an auger and the stake driven into it4 ,the greatest caution was of course necessary on the part of the men2 they were in the midst of concealed crevasses1 and sounding was essential at every step4 ,by degrees they withdrew from me1 and approached the eastern boundary of the glacier1 where the ice was greatly dislocated1 and the labour of wading through the snow enormous4 ,long detours were sometimes necessary to reach a required point2 but they were all accomplished1 and we at length succeeded in fixing eleven stakes along this line1 the most distant of which was within about eighty yards of the opposite side of the glacier4 ,sidenote3 ,,storm ,,on ,,the ,,glacier4 #ahei4 ,the men returned1 and ,i consulted them as to the possibility of getting a line across at the ,ponts2 but this was judged to be impossible in the time4 ,we thought1 however1 that a second line might be staked out at some distance below the ,montanvert4 ,i took the theodolite down the mountain-slope1 wading at times breast-deep in snow1 and having selected a line1 the men tied themselves together as before1 and commenced the staking out4 ,the work was slowly but steadily and steadfastly done4 ,the air darkened2 angry clouds gathered around the mountains1 and at times the glacier was swept by wild squalls4 ,the men were sometimes hidden from me by the clouds of snow which enveloped them1 but between those intermittent gusts there were intervals of repose1 which enabled us to prosecute our work4 ,this line was more difficult than the first one2 the glacier was broken into sharp-edged chasms2 the ridges to be climbed were steep1 and the snow which filled the depressions profound4 ,the oblique arrangement of the crevasses also magnified the labour by increasing the circuits4 ,i saw the leader of the party often shoulder-deep in snow1 treading the soft mass as a swimmer walks in water1 and ,i felt a wish to be at his side to cheer him and to share his toil4 ,each man there1 however1 knew my willingness to do this if occasion required it1 and wrought contented4 ,at length the last stake being fixed1 the faces of the men were turned homeward4 ,the evening became wilder1 and the storm rose at times to a hurricane4 ,on the more level portions of the glacier the snow lay deep and unsheltered2 among its frozen waves and upon its more dislocated portions it had been partially engulfed1 and the residue was more or less in shelter4 ,over the former spaces dense clouds of snow rose1 whirling in the air and cutting off all view of the glacier4 ,the whole length of the ,mer de ,glace was thus divided into clear and cloudy segments1 and presented an aspect of wild and wonderful turmoil4 ,a large pine stood near me1 with its lowest branch spread out upon the surface of the snow2 on this branch ,i seated myself1 and1 sheltered by the trunk1 waited until ,i saw my men in safety4 ,the wind caught the branches of the trees1 shook down their loads of snow1 and tossed it wildly in the air4 ,every mountain gave a quota to the storm4 ,the scene was one of most impressive grandeur1 and the moan of the adjacent pines chimed in noble harmony with the picture which addressed the eyes4 ,at length we all found ourselves in safety within doors4 ,the windows shook violently4 ,the tempest was however intermittent throughout1 as if at each effort it had exhausted itself1 and required time to recover its strength4 ,as ,i heard its heralding roar in the gullies of the mountains1 and its subsequent onset against our habitation1 ,i thought wistfully of my stations1 not knowing whether they would be able to retain their positions in the face of such a blast4 ,that night however1 as if the storm had sung our lullaby1 we all slept profoundly1 having arranged to commence our measurements as early as light permitted on the following day4 ,sidenote3 ,,heavy ,,snow4 #ahei4 ,thursday1 #bith ,december4--,snow1 heavy snow3 it must have descended throughout the entire night2 the quantity freshly fallen is so great2 the atmosphere at seven o'clock is thick with the descending flakes4 ,at eight o'clock it cleared up a little1 and ,i proceeded to my station1 while the men advanced upon the glacier2 but ,i had scarcely fixed my theodolite when the storm recommenced4 ,i had a man to clear away the snow and otherwise assist me2 he procured an old door from the hotel1 and by rearing it upon its end sheltered the object-glass of the instrument4 ,added to the flakes descending from the clouds was the spitting snow-dust raised by the wind1 which for a time so blinded me that ,i was unable to see the glacier4 ,the measurement of the first stake was very tedious1 but practice afterwards enabled me to take advantage of the brief lulls and periods of partial clearness with which the storm was interfused4 ,sidenote3 ,a ,,man ,,in ,a ,,crevasse4 #ahei4 ,at nine o'clock my telescope happened to be directed upon the men as they struggled through the snow2 all evidence of the deep track which they had formed yesterday having been swept away4 ,i saw the leader sink and suddenly disappear4 ,he had stood over a concealed fissure1 the roof of which had given way and he had dropped in4 ,i observed a rapid movement on the part of the remaining three men3 they grouped themselves beside the fissure1 and in a moment the missing man was drawn from between its jaws4 ,his disappearance and reappearance were both extraordinary4 ,we had1 as ,i have stated1 provided for contingencies of this kind1 and the man's rescue was almost immediate4 ,sidenote3 ,,six-,,rayed ,,crystals4 #ahei4 ,my attendant brought two poles from the hotel which we thrust obliquely into the snow1 causing the free ends to cross each other2 over these a blanket was thrown1 behind which ,i sheltered myself from the storm as the men proceeded from stake to stake4 ,at #i4cj the storm was so thick that ,i was unable to see the men at the stake which they had reached at the time2 the flakes sped wildly in their oblique course across the field of the telescope4 ,some time afterwards the air became quite still1 and the snow underwent a wonderful change4 ,frozen flowers similar to those ,i had observed on ,monte ,rosa fell in myriads4 ,for a long time the flakes were wholly composed of these exquisite blossoms entangled together4 ,on the surface of my woollen dress they were soft as down2 the snow itself on which they fell seemed covered by a layer of down2 while my coat was completely spangled with six-rayed stars4 ,and thus prodigal ,nature rained down beauty1 and had done so here for ages unseen by man4 ,and yet some flatter themselves with the idea that this world was planned with strict reference to human use2 that the lilies of the field exist simply to appeal to the sense of the beautiful in man4 ,true1 this result is secured1 but it is one of a thousand all equally important in the eyes of ,nature4 ,whence those frozen blossoms8 ,why for aeons wasted8 ,the question reminds one of the poet's answer when asked whence was the ,rhodora3-- ,why wert thou there1 ,o rival of the rose8 ,i never thought to ask1 ,i never knew2 ,but in my simple ignorance suppose ,the selfsame power that brought me there brought you6,a ,i sketched some of the crystals1 but1 instead of reproducing these sketches1 which were rough and hasty1 ,i have annexed two of the forms drawn with so much skill and patience by ,mr4 ,glaisher4 ,illustration3 ,fig4 #ad4 ,snow ,crystals4 ,illustration3 ,fig4 #ae4 ,snow ,crystals4 ,we completed the measurement of the first line before eleven o'clock1 and ,i felt great satisfaction in the thought that ,i possessed something of which the weather could not deprive me4 ,as ,i closed my note-book and shifted the instrument to the second station1 ,i felt that my expedition was already a success4 ,at a quarter past eleven ,i had my theodolite again fixed1 and ranging the telescope along the line of pickets1 ,i saw them all standing4 ,crossing the ice wilderness1 and suggesting the operation of intelligence amid that scene of desolation1 their appearance was pleasant to me4 ,just before ,i commenced1 a solitary jay perched upon the summit of an adjacent pine and watched me4 ,the air was still at the time1 and the snow fell heavily4 ,the flowers moreover were magnificent1 varying from about the twentieth of an inch to two lines in diameter1 while1 falling through the quiet air1 their forms were perfect4 ,adjacent to my theodolite was a stump of pine1 from which ,i had the snow removed1 in order to have something to kick my toes against when they became cold2 and on the stump was placed a blanket to be used as a screen in case of need4 ,while ,i remained at the station a layer of snow an inch thick fell upon this blanket1 the whole layer being composed of these exquisite flowers4 ,the atmosphere also was filled with them4 ,from the clouds to the earth ,nature was busy marshalling her atoms1 and putting to shame by the beauty of her structures the comparative barbarities of ,art4 ,sidenote3 ,,sound ,,through ,,the ,,snow-,,storm4 #ahei4 ,my men at length reached the first station1 and the measurement commenced4 ,the storm drifted up the valley1 thickening all the air as it approached4 ,denser and denser the flakes fell2 but still1 with care and tact ,i was able to follow my party to a distance of #hjj yards4 ,i had not thought it possible to see so far through so dense a storm4 ,at this distance also my voice could be heard1 and my instructions understood2 for once1 as the man who took up the line stood behind his baton and prevented its projection against the white snow1 ,i called out to him to stand aside1 and he promptly did so4 ,throughout the entire measurement the snow never ceased falling1 and some of the illusions which it produced were extremely singular4 ,the distant boundary of the glacier appeared to rise to an extraordinary height1 and the men wading through the snow appeared as if climbing up a wall4 ,the labour along this line was still greater than on the former2 on the steeper slopes especially the toil was great2 for here the effort of the leader to lift his own body added itself to that of cutting his way through the snow4 ,his footing ,i could see often yielded1 and he slid back1 checking his recession1 however1 by still plunging forward2 thus1 though the limbs were incessantly exerted1 it was1 for a time1 a mere motion of vibration without any sensible translation4 ,at the last stake the men shouted1 ,nous avons finis6 and ,i distinctly heard them through the falling snow4 ,by this time ,i was quite covered with the crystals which clung to my wrapper4 ,they also formed a heap upon my theodolite1 rising over the spirit-levels and embracing the lower portion of the vertical arc4 ,the work was done2 ,i struck my theodolite and ascended to the hotel2 the greatest depth of snow through which ,i waded reaching1 when ,i stood erect1 to within three inches of my breast4 ,sidenote3 ,,swift ,,descent4 #ahei4 ,the men returned2 dinner was prepared and consumed2 the disorder which we had created made good2 the rooms were swept1 the mattresses replaced1 and the shutters fastened1 where this was possible4 ,we locked up the house1 and with light hearts and lithe limbs commenced the descent4 ,my aim now was to reach the source of the ,arveiron1 to examine the water and inspect the vault4 ,with this view we went straight down the mountain4 ,the inclinations were often extremely steep1 and down these we swept with an avalanche-velocity2 indeed usually accompanied by an avalanche of our own creation4 ,on one occasion ,balmat was for a moment overwhelmed by the descending mass3 the guides were startled1 but he emerged instantly4 ,tairraz followed him1 and ,i followed ,tairraz1 all of us rolling in the snow at the bottom of the slope as if it were so much flour4 ,my practice on the ,finsteraarhorn rendered me at home here4 ,one of the porters could by no means be induced to try this flying mode of descent4 ,simond carried my theodolite box1 tied upon a crotchet on his back2 and once1 while shooting down a slope1 he incautiously allowed a foot to get entangled2 his momentum rolled him over and over down the incline1 the theodolite emerging periodically from the snow during his successive revolutions4 ,a succession of glissades brought us with amazing celerity to the bottom of the mountain1 whence we picked our way amid the covered boulders and over the concealed arms of the stream to the source of the ,arveiron4 ,the quantity of water issuing from the vault was considerable1 and its character that of true glacier water4 ,it was turbid with suspended matter1 though not so turbid as in summer2 but the difference in force and quantity would1 ,i think1 be sufficient to account for the greater summer turbidity4 ,this character of the water could only be due to the grinding motion of the glacier upon its bed2 a motion which seems not to be suspended even in the depth of winter4 ,the temperature of the water was the tenth of a degree ,centigrade above zero2 that of the ice was half a degree below zero3 this was also the temperature of the air1 while that of the snow1 which in some places covered the ice-blocks1 was a degree and a quarter below zero4 ,sidenote3 ,,vault ,,of ,,the ,,arveiron4 #ahei4 ,the entrance to the vault was formed by an arch of ice which had detached itself from the general mass of the glacier behind3 between them was a space through which we could look to the sky above4 ,beyond this the cave narrowed1 and we found ourselves steeped in the blue light of the ice4 ,the roof of the inner arch was perforated at one place by a shaft about a yard wide1 which ran vertically to the surface of the glacier4 ,water had run down the sides of this shaft1 and1 being re-frozen below1 formed a composite pillar of icicles at least twenty feet high and a yard thick1 stretching quite from roof to floor4 ,they were all united to a common surface at one side1 but at the other they formed a series of flutings of exceeding beauty4 ,this group of columns was bent at its base as if it had yielded to the forward motion of the glacier1 or to the weight of the arch overhead4 ,passing over a number of large ice-blocks which partially filled the interior of the vault1 we reached its extremity1 and here found a sloping passage with a perfect arch of crystal overhead1 and leading by a steep gradient to the air above4 ,this singular gallery was about seventy feet long1 and was floored with snow4 ,we crept up it1 and from the summit descended by a glissade to the frontal portion of the cavern4 ,to me this crystal cave1 with the blue light glistening from its walls1 presented an aspect of magical beauty4 ,my delight1 however1 was tame compared with that of my companions4 ,sidenote3 ,,majestic ,,scene4 #ahei4 ,looking from the blue arch westwards1 the heavens were seen filled by crimson clouds1 with fiery outliers reaching up to the zenith4 ,on quitting the vault ,i turned to have a last look at those noble sentinels of the ,mer de ,glace1 the ,aiguille du ,dru1 and the ,aiguille ,verte4 ,the glacier below the mountains was in shadow1 and its frozen precipices of a deep cold blue4 ,from this1 as from a basis1 the mountain cones sprang steeply heavenward1 meeting half way down the fiery light of the sinking sun4 ,the right-hand slopes and edges of both pyramids burned in this light1 while detached protuberant masses also caught the blaze1 and mottled the mountains with effulgent spaces4 ,a range of minor peaks ran slanting downwards from the summit of the ,aiguille ,verte2 some of these were covered with snow1 and shone as if illuminated with the deep crimson of a strontian flame4 ,i was absolutely struck dumb by the extraordinary majesty of this scene1 and watched it silently till the red light faded from the highest summits4 ,thus ended my winter expedition to the ,mer de ,glace4 ,next morning1 starting at three o'clock1 ,i was driven by my two guides in an open sledge to ,sallenches4 ,the rain was pitiless and the road abominable4 ,the distance1 ,i believe1 is only six leagues1 but it took us five hours to accomplish it4 ,the leading mule was beyond the reach of ,simond's whip1 and proved a mere obstructive2 during part of the way it was unloosed1 tied to the sledge1 and dragged after it4 ,simond afterwards mounted the hindmost beast and brought his whip to bear upon the leader1 the jerking he endured for an hour and a half seemed almost sufficient to dislocate his bones4 ,we reached ,sallenches half an hour late1 but the diligence was behind its time by this exact interval4 ,we met it on the ,pont ,st4 ,martin1 and ,i transferred myself from the sledge to the interior4 ,this was the morning of the #cjth of ,december1 and on the evening of the #ast of ,january ,i was in ,london4 ,sidenote3 ,,my ,,assistants4 #ahei4 ,i cannot finish this recital without saying one word about my men4 ,their behaviour was admirable throughout4 ,the labour was enormous1 but it was manfully and cheerfully done4 ,i know ,simond well2 he is intelligent1 truthful1 and affectionate1 and there is no guide of my acquaintance for whom ,i have a stronger regard4 ,joseph ,tairraz is an extremely intelligent and able guide1 and on this trying occasion proved himself worthy of my highest praise and commendation4 ,their two companions upon the glacier1 ,edouard ,balmat 7le ,petit ,balmat7 and ,joseph ,simond 7fils d',auguste71 acquitted themselves admirably2 and it also gives me pleasure to bear testimony to the willing and efficient service of ,francois ,ravanal1 who attended upon me during the observations4 ,,footnotes3 ,a ,emerson4 ,,part ,,ii4 ,,chiefly ,,scientific4 ,aber im stillen ,gemach entwirft bedeutende ,zirkel ,sinnend der ,weise1 beschleicht forschend den schaffenden ,geist1 ,prueft der ,stoffe ,gewalt1 der ,magnete ,hassen und ,lieben1 ,folgt durch die ,luefte dem ,klang1 folgt durch den ,aether dem ,strahl1 ,sucht das vertraute ,gesetz in des ,zufalls grausenden ,wundern1 ,sucht den ruhenden ,pol in der ,erscheinungen ,flucht4 ,schiller4 ,,on ,,light ,,and ,,heat4 7#a47 ,sidenote3 ,,theories ,,of ,,light4 ,what is ,light8 ,the ancients supposed it to be something emitted by the eyes1 and for ages no notion was entertained that it required time to pass through space4 ,in the year #afgf ,roemer first proved that the light from ,jupiter's satellites required a certain time to cross the earth's orbit4 ,bradley afterwards found that1 owing to the velocity with which the earth flies through space1 the rays of the stars are slightly inclined1 just as rain-drops which descend vertically appear to meet us when we move swiftly through the shower4 ,in ,kew ,gardens there is a sun-dial commemorative of this discovery1 which is called the aberration of light4 ,knowing the velocity of the earth1 and the inclination of the stellar rays1 ,bradley was able to calculate the velocity of light2 and his result agrees closely with that of ,roemer4 ,celestial distances were here involved1 but a few years ago ,m4 ,fizeau1 by an extremely ingenious contrivance1 determined the time required by light to pass over a distance of about #ijjj yards2 and his experiment is quite in accordance with the results of his predecessors4 ,but what is it which thus moves8 ,some1 and among the number ,newton1 imagined light to consist of particles darted out from luminous bodies4 ,this is the so-called ,emission-,theory1 which was held by some of the greatest men3 ,laplace1 for example1 accepted it2 and ,m4 ,biot has developed it with a lucidity and power peculiar to himself4 ,it was first opposed by the astronomer ,huyghens1 and afterwards by ,euler1 both of whom supposed light to be a kind of undulatory motion2 but they were borne down by their great antagonists1 and the emission-theory held its ground until the commencement of the present century1 when ,thomas ,young1 ,professor of ,natural ,philosophy in the ,royal ,institution1 reversed the scientific creed by placing the ,theory of ,undulation on firm foundations4 ,he was followed by a young ,frenchman of extraordinary genius1 who1 by the force of his logic and the conclusiveness of his experiments1 left the ,wave-,theory without a competitor4 ,the name of this young ,frenchman was ,augustin ,fresnel4 ,since his time some of the ablest minds in ,europe have been applied to the investigation of this subject2 and thus a mastery1 almost miraculous1 has been attained over the grandest and most subtle of natural phenomena4 ,true knowledge is always fruitful1 and a clear conception regarding any one natural agent leads infallibly to better notions regarding others4 ,thus it is that our knowledge of light has corrected and expanded our knowledge of heat1 while the latter1 in its turn1 will assuredly lead us to clearer conceptions regarding the other forces of ,nature4 ,i think it will not be a useless labour if ,i here endeavour to state1 in a simple manner1 our present views of light and heat4 ,such knowledge is essential to the explanation of many of the phenomena referred to in the foregoing pages2 and even to the full comprehension of the origin of the glaciers themselves4 ,a few remarks on the nature of sound will form a fit introduction4 ,sidenote3 ,,nature ,,of ,,sound4 ,it is known that sound is conveyed to our organs of hearing by the air3 a bell struck in a vacuum emits no sound1 and even when the air is thin the sound is enfeebled4 ,hawksbee proved this by the air-pump2 ,de ,saussure fired a pistol at the top of ,mont ,blanc1--,i have repeated the experiment myself1 and found1 with him1 that the sound is feebler than at the sea level4 ,sound is not produced by anything projected through the air4 ,the explosion of a gun1 for example1 is sent forward by a motion of a totally different kind from that which animates the bullet projected from the gun3 the latter is a motion of translation2 the former1 one of vibration4 ,to use a rough comparison1 sound is projected through the air as a push is through a crowd2 it is the propagation of a wave or pulse1 each particle taking up the motion of its neighbour1 and delivering it on to the next4 ,these aerial waves enter the external ear1 meet a membrane1 the so-called tympanic membrane1 which is drawn across the passage at a certain place1 and break upon it as sea-waves do upon the shore4 ,the membrane is shaken1 its tremors are communicated to the auditory nerve1 and transmitted by it to the brain1 where they produce the impression to which we give the name of sound4 ,sidenote3 ,,cause ,,of ,,music4 ,in the tumult of a city1 pulses of different kinds strike irregularly upon the tympanum1 and we call the effect noise2 but when a succession of impulses reach the ear at regular intervals we feel the effect as music4 ,thus1 a vibrating string imparts a series of shocks to the air around it1 which are transmitted with perfect regularity to the ear1 and produce a musical note4 ,when we hear the song of a soaring lark we may be sure that the entire atmosphere between us and the bird is filled with pulses1 or undulations1 or waves1 as they are often called1 produced by the little songster's organ of voice4 ,this organ is a vibrating instrument1 resembling1 in principle1 the reed of a clarionet4 ,let us suppose that we hear the song of a lark1 elevated to a height of #ejj feet in the air4 ,before this is possible1 the bird must have agitated a sphere of air #ajjj feet in diameter2 that is to say1 it must have communicated to #ag1hhh tons of air a motion sufficiently intense to be appreciated by our organs of hearing4 ,sidenote3 ,,cause ,,of ,,pitch4 ,musical sounds differ in pitch3 some notes are high and shrill1 others low and deep4 ,boys are chosen as choristers to produce the shrill notes2 men are chosen to produce the bass notes4 ,now1 the sole difference here is1 that the boy's organ vibrates more rapidly than the man's--it sends a greater number of impulses per second to the ear4 ,in like manner1 a short string emits a higher note than a long one1 because it vibrates more quickly4 ,the greater the number of vibrations which any instrument performs in a given time1 the higher will be the pitch of the note produced4 ,the reason why the hum of a gnat is shriller than that of a beetle is that the wings of the small insect vibrate more quickly than those of the larger one4 ,we can1 with suitable arrangements1 make those sonorous vibrations visible to the eye2,a and we also possess instruments which enable us to tell1 with the utmost exactitude1 the number of vibrations due to any particular note4 ,by such instruments we learn that a gnat can execute many thousand flaps of its little wings in a second of time4 ,sidenote3 ,,nature ,,of ,,light4 ,in the study of nature the coarser phenomena1 which come under the cognizance of the senses1 often suggest to us the finer phenomena which come under the cognizance of the mind2 and thus the vibrations which produce sound1 and which1 as has been stated1 can be rendered visible to the eye by proper means1 first suggested that light might be due to a somewhat similar action4 ,this is now the universal belief4 ,a luminous body is supposed to have its atoms1 or molecules1 in a state of intense vibration4 ,the motions of the atoms are supposed to be communicated to a medium suited to their transmission1 as air is to the transmission of sound4 ,this medium is called the luminiferous ether1 and the little billows excited in it speed through it with amazing celerity1 enter the pupil of the eye1 pass through the humours1 and break upon the retina or optic nerve1 which is spread out at the back of the eye4 ,hence the tremors they produce are transmitted along the nerve to the brain1 where they announce themselves as light4 ,the swiftness with which the waves of light are propagated through the ether1 is however enormously greater than that with which the waves of sound pass through the air4 ,an aerial wave of sound travels at about the rate of #aajj feet in a second3 a wave of light leaves #aib1jjj miles behind it in the same time4 ,sidenote3 ,,cause ,,of ,,colour4 ,thus1 then1 in the case of sound1 we have the sonorous body1 the air1 and the auditory nerve1 concerned in the phenomenon2 in the case of light1 we have the luminous body1 the ether1 and the optic nerve4 ,the fundamental analogy of sound and light is thus before us1 and it is easily remembered4 ,but we must push the analogy further4 ,we know that the white light which comes to us from the sun is made up of an infinite number of coloured rays4 ,by refraction with a prism we can separate those rays from each other1 and arrange them in the series of colours which constitute the solar spectrum4 ,the rainbow is an imperfect or impure spectrum1 produced by the drops of falling rain1 but by prisms we can unravel the white light into pure red1 orange1 yellow1 green1 blue1 indigo1 and violet4 ,now1 this spectrum is to the eye what the gamut is to the ear2 each colour represents a note1 and the different colours represent notes of different pitch4 ,the vibrations which produce the impression of red are slower1 and the waves which they produce are longer1 than those to which we owe the sensation of violet2 while the vibrations which excite the other colours are intermediate between these two extremes4 ,this1 then1 is the second grand analogy between light and sound3 ,colour answers to ,pitch4 ,there is therefore truth in the figure when we say that the gentian of the ,alps sings a shriller note than the wild rhododendron1 and that the red glow of the mountains at sunset is of a lower pitch than the blue of the firmament at noon4 ,sidenote3 ,,length ,,of ,,ethereal ,,waves4 ,these are not fanciful analogies4 ,to the mind of the philosopher these waves of ether are almost as palpable and certain as the waves of the sea1 or the ripples on the surface of a lake4 ,the length of the waves1 both of sound and light1 and the number of shocks which they respectively impart to the ear and eye1 have been the subjects of the strictest measurement4 ,let us here go through a simple calculation4 ,it has been found that #ci1jjj waves of red light placed end to end would make up an inch4 ,how many inches are there in #aib1jjj miles8 ,my youngest reader can make the calculation for himself1 and find the answer to be #ab1afe1abj1jjj inches4 ,it is evident that1 if we multiply this number by #ci1jjj1 we shall obtain the number of waves of red light in #aib1jjj miles2 this number is #dgd1dci1fhj1jjj1jjj4 ,all these waves enter the eye in one second2 thus the expression ,i see red colour1 strictly means1 ,my eye is now in receipt of four hundred and seventy-four millions of millions of impulses per second4 ,to produce the impression of violet light a still greater number of impulses is necessary2 the wave-length of violet is the #a_/egejjth part of an inch1 and the number of shocks imparted in a second by waves of this length is1 in round numbers1 six hundred and ninety-nine millions of millions4 ,the other colours of the spectrum1 as already stated1 rise gradually in pitch from the red to the violet4 ,a very curious analogy between the eye and ear may here be noticed4 ,the range of seeing is different in different persons--some see a longer spectrum than others2 that is to say1 rays which are obscure to some are luminous to others4 ,dr4 ,wollaston pointed out a similar fact as regards hearing2 the range of which differs in different individuals4 ,savart has shown that a good ear can hear a musical note produced by #h shocks in a second2 it can also hear a note produced by #bd1jjj shocks in a second2 but there are ears in which the range is much more limited4 ,it is possible indeed to produce a sound which shall be painfully shrill to one person1 while it is quite unheard by another4 ,i once crossed a ,swiss mountain in company with a friend2 a donkey was in advance of us1 and the dull tramp of the animal was plainly heard by my companion2 but to me this sound was almost masked by the shrill chirruping of innumerable insects which thronged the adjacent grass2 my friend heard nothing of this1 it lay quite beyond his range of hearing4 ,a third and most important analogy between sound and light is now to be noted2 and it will be best understood by reference to something more tangible than either4 ,when a stone is thrown into calm water a series of rings spread themselves around the centre of disturbance4 ,if a second stone be thrown in at some distance from the first1 the rings emanating from both centres will cross each other1 and at those points where the ridge of one wave coincides with the ridge of another the water will be lifted to a greater height4 ,at those points1 on the contrary1 where the ridge of one wave crosses the furrow of another1 we have both obliterated1 and the water restored to its ordinary level4 ,where two ridges or two furrows unite1 we have a case of coincidence2 but where a ridge and a furrow unite we have what is called interference4 ,it is quite possible to send two systems of waves into the same channel1 and to hold back one system a little1 so that its ridges shall coincide with the furrows of the other system4 ,the interference would be here complete1 and the waves thus circumstanced would mutually destroy each other1 smooth water being the result4 ,in this way1 by the addition of motion to motion1 rest may be produced4 ,sidenote3 ,,light ,,added ,,to ,,light ,,makes ,,darkness4 ,in a precisely similar manner two systems of sonorous waves can be caused to interfere and mutually to destroy each other3 thus1 by adding sound to sound1 silence may be produced4 ,two beams of light also may be caused to interfere and effect their mutual extinction3 thus1 by adding light to light1 we can produce darkness4 ,here indeed we have a critical analogy between sound and light--the one1 in fact1 which compels the most profound thinkers of the present day to assume that light1 like sound1 is a case of undulatory motion4 ,we see here the vision of the intellect prolonged beyond the boundaries of sense into the region of what might be considered mere imagination4 ,but1 unlike other imaginations1 we can bring ours to the test of experiment2 indeed1 so great a mastery have we obtained over these waves1 which eye has not seen1 nor ear heard1 that we can with mathematical certainty cause them to coincide or to interfere1 to help each other or to destroy each other1 at pleasure4 ,it is perhaps possible to be a little more precise here4 ,let two stones--with a small distance between them--be dropped into water at the same moment2 a system of circular waves will be formed round each stone4 ,let the distance from one little crest to the next following one be called the length of the wave1 and now let us inquire what will take place at a point equally distant from the places where the two stones were dropped in4 ,fixing our attention upon the ridge of the first wave in each case1 it is manifest that1 as the water propagates both systems with the same velocity1 the two foremost ridges will reach the point in question at the same moment2 the ridge of one would therefore coincide with the ridge of the other1 and the water at this point would be lifted to a height greater than that of either of the previous ridges4 ,sidenote3 ,,coincidence ,,and ,,interference4 ,again1 supposing that by any means we had it in our power to retard one system of waves so as to cause the first ridge of the one to be exactly one wave length behind the first ridge of the other1 when they arrive at the point referred to4 ,it is plain that the first ridge of the retarded system now falls in with the second ridge of the unretarded system1 and we have another case of coincidence4 ,a little reflection will show the same to be true when one system is retarded any number of whole wave-lengths2 the first ridge of the retarded system will always1 at the point referred to1 coincide with a ridge of the unretarded system4 ,but now suppose the one system to be retarded only half a wave-length2 it is perfectly clear that1 in this case the first ridge of the retarded system would fall in with the first furrow of the unretarded system1 and instead of coincidence we should have interference4 ,one system1 in fact1 would tend to make a hollow at the point referred to1 the other would tend to make a hill1 and thus the two systems would oppose and neutralize each other1 so that neither the hollow nor the hill would be produced2 the water would maintain its ordinary level4 ,what is here said of a single half-wave-length of retardation1 is also true if the retardation amount to any odd number of half-wave-lengths4 ,in all such cases we should have the ridge of the one system falling in with the furrow of the other2 a mutual destruction of the waves of both systems being the consequence4 ,the same remarks apply when the point1 instead of being equally distant from both stones1 is an even or an odd number of semi-undulations farther from the one than from the other4 ,in the former case we should have coincidence1 and in the latter case interference1 at the point in question4 ,sidenote3 ,,liquid ,,waves4 ,to the eye of a person who understands these things1 nothing can be more interesting than the rippling of water under certain circumstances4 ,by the action of interference its surface is sometimes shivered into the most beautiful mosaic1 shifting and trembling as if with a kind of visible music4 ,when the tide advances over a sea-beach on a calm and sunny day1 and its tiny ripples enter1 at various points1 the clear shallow pools which the preceding tide had left behind1 the little wavelets run and climb and cross each other1 and thus form a lovely chasing1 which has its counterpart in the lines of light converged by the ripples upon the sand underneath4 ,when waves are skilfully generated in a vessel of mercury1 and a strong light reflected from the surface of the metal is received upon a screen1 the most beautiful effects may be observed4 ,the shape of the vessel determines1 in part1 the character of the figures produced2 in a circular dish of mercury1 for example1 a disturbance at the centre propagates itself in circular waves1 which after reflection again encircle the centre4 ,if the point of disturbance be a little removed from the centre1 the intersections of the direct and reflected waves produce the magnificent chasing shown in the annexed figure 7#af71 which ,i have borrowed from the excellent work on ,waves by the ,messrs4 ,weber4 ,the luminous figure reflected from such a surface is exceedingly beautiful4 ,when the mercury is lightly struck by a glass point1 in a direction concentric with the circumference of the vessel1 the lines of light run round the vessel in mazy coils1 interlacing and unravelling themselves in the most wonderful manner4 ,if the vessel be square1 a splendid mosaic is produced by the crossing of the direct and reflected waves4 ,description1 however1 can give but a feeble idea of these exquisite effects2-- ,thou canst not wave thy staff in the air1 ,or dip thy paddle in the lake1 ,but it carves the brow of beauty there1 ,and the ripples in rhymes the oar forsake4 ,sidenote3 ,,chasing ,,produced ,,by ,,waves4 ,illustration3 ,fig4 #af4 ,chasing produced by waves4 ,sidenote3 ,,effect ,,of ,,retardation4 ,now1 all that we have said regarding the retardation of the waves of water1 by a whole undulation and a semi-undulation1 is perfectly applicable to the case of light4 ,two luminous points may be placed near to each other so as to resemble the two stones dropped into the water2 and when the light of these is properly received upon a screen1 or directly upon the retina1 we find that at some places the action of the rays upon each other produces darkness1 and at others augmented light4 ,the former places are those where the rays emitted from one point are an odd number of semi-undulations in advance of the rays sent from the other2 the latter places are those where the difference of path described by the rays is either nothing1 or an even number of semi-undulations4 ,supposing a and b 7,fig4 #ag7 to be two such sources of light1 and ,s ,r a screen on which the light falls2 at a point l1 equally distant from a and b1 we have light2 at a point d1 where a d is half an undulation longer than b d1 we have darkness2 at l'1 where a l' is a whole wave-length1 or two semi-undulations1 longer than b l'1 we again have light2 and at a point d'1 where the difference is three semi-undulations1 we have darkness2 and thus we obtain a series of bright and dark spaces as we recede laterally from the central point l4 ,illustration3 ,fig4 #ag4 ,diagram explanatory of ,interference4 ,let a bit of tin foil be closely pasted upon a piece of glass1 and the edge of a penknife drawn across the foil so as to produce a slit4 ,looking through this slit at a small and distant light1 we find the light spread out in a direction at right angles to the slit1 and if the light looked at be monochromatic1 that is1 composed of a single colour1 we shall have a series of bright and dark bars corresponding to the points at which the rays from the different points of the slit alternately coincide and interfere upon the retina4 ,by properly drawing a knife across a sheet of letter-paper a suitable slit may also be obtained2 and those practised in such things can obtain the effect by looking through their fingers or their eyelashes4 ,illustration3 ,,interference ,,spectra1 ,,produced ,,by ,,diffraction4 ,fig4 #ah4 ,to face p4 #bce4 ,sidenote3 ,,chromatic ,,effects4 ,but if the light looked at be white1 the light of a candle for example1 or of a jet of gas1 instead of having a series of bright and dark bars1 we have the bars coloured4 ,and see how beautifully this harmonizes with what has been already said regarding the different lengths of the waves which produce different colours4 ,looking again at ,fig4 #ag we see that a certain obliquity is necessary to cause one ray to be a whole undulation in advance of the other at the point l'2 but it is perfectly manifest that the obliquity must depend upon the length of the undulation2 a long undulation would require a greater obliquity than a short one2 red light1 for example1 requires a greater obliquity than blue light2 so that if the point l' represents the place where the first bar of red light would be at its maximum strength1 the maximum for blue would lie a little to the left of l'2 the different colours are in this way separated from each other1 and exhibit themselves as distinct fringes when a distant source of white light is regarded through a narrow slit4 ,by varying the shape of the aperture we alter the form of the chromatic image4 ,a circular aperture1 for example1 placed in front of a telescope through which a point of white light is regarded1 is seen surrounded by a concentric system of coloured rings4 ,if we multiply our slits or apertures the phenomena augment in complexity and splendour4 ,to give some notion of this ,i have copied from the excellent work of ,m4 ,schwerd the annexed figure 7,fig4 #ah7 which represents the gorgeous effect observed when a distant point of light is looked at through two gratings with slits of different widths4,b ,a bird's feather represents a peculiar system of slits1 and the effect observed on properly looking through it is extremely interesting4 ,sidenote3 ,,colours ,,of ,,thin ,,films4 ,there are many ways by which the retardation necessary to the production of interference is effected4 ,the splendid colours of a soap-bubble are entirely due to interference2 the beam falling upon the transparent film is partially reflected at its outer surface1 but a portion of it enters the film and is reflected at its inner surface4 ,the latter portion having crossed the film and returned1 is retarded1 in comparison with the former1 and1 if the film be of suitable thickness1 these two beams will clash and extinguish each other1 while another thickness will cause the beams to coincide and illuminate the film with a light of greater intensity4 ,from what has been said it must be manifest that to make two red beams thus coincide a thicker film would be required than would be necessary for two blue or green beams2 thus1 when the thickness of the bubble is suitable for the development of red1 it is not suitable for the development of green1 blue1 c42 the consequence is that we have different colours at different parts of the bubble4 ,owing to its compactness and to its being shaded by a covering of debris from the direct heat of the sun1 the ice underneath the moraines of glaciers appears sometimes of a pitchy blackness4 ,while cutting such ice with my axe ,i have often been surprised and delighted by sudden flashes of coloured light which broke like fire from the mass4 ,these flashes were due to internal rupture1 by which fissures were produced as thin as the film of a soap-bubble2 the colours being due to the interference of the light reflected from the opposite sides of the fissures4 ,if spirit of turpentine1 or olive oil1 be thrown upon water1 it speedily spreads in a thin film over the surface1 and the most gorgeous chromatic phenomena may be thus produced4 ,oil of lemons is also peculiarly suited to this experiment4 ,if water be placed in a tea-tray1 and light of sufficient intensity be suffered to fall upon it1 this light will be reflected from the upper and under surfaces of the film of oil1 and the colours thus produced may be received upon a screen1 and seen at once by many hundred persons4 ,if the oil of cinnamon be used1 fine colours are also obtained1 and the breaking up of this film exhibits a most interesting case of molecular action4 ,by using a kind of varnish1 instead of oil1 ,mr4 ,delarue has imparted such tenacity to these films that they may be removed from the water on which they rest and preserved for any length of time4 ,by such films the colours of certain beetles1 and of the wings of certain insects1 may be accurately imitated2 and a rook's feather may be made to shine with magnificent iridescences4 ,the colours of tempered metals1 and the beautiful metallochrome of ,nobili are also due to a similar cause4 ,sidenote3 ,,diffraction4 ,these colours are called the colours of thin plates1 and are distinguished in treatises on optics from the coloured bars and fringes above referred to1 which are produced by diffraction1 or the bending of the waves round the edge of an object4 ,one result of this bending1 which is of interest to us1 was obtained by the celebrated ,thomas ,young4 ,permitting a beam of sunlight to enter a dark room through an aperture made with a fine needle1 and placing in the path of the beam a bit of card one-thirtieth of an inch wide1 he found the shadow of this card1 or rather the line on which its shadow might be supposed to fall1 always bright2 and he proved the effect to be due to the bending of the waves of ether round the two edges of the card1 and their coincidence at the other side4 ,it has1 indeed1 been shown by ,m4 ,poisson1 that the centre of the shadow of a small circular opaque disk which stands in the way of a beam diverging from a point is exactly as much illuminated as if the disk were absent4 ,the singular effects described by ,m4 ,necker in the letter quoted at page #agh at once suggest themselves here2 and we see how possible it is for the solar rays1 in grazing a distant tree1 so to bend round it as to produce upon the retina1 where shadow might be expected1 the impression of a tree of light4,c ,another effect of diffraction is especially interesting to us at present4 ,let the seed of lycopodium be scattered over a glass plate1 or even like a cloud in the air1 and let a distant point of light be regarded through it2 the luminous point will appear surrounded by a series of coloured rings1 and when the light is intense1 like the electric or the ,drummond light1 the effect is exceedingly fine4 ,sidenote3 ,,cloud ,,iridescence1 ,,etc41 ,,explained4 ,and now for the application of these experiments4 ,i have already mentioned a series of coloured rings observed around the sun by ,mr4 ,huxley and myself from the ,rhone glacier2 ,i have also referred to the cloud iridescences on the ,aletschhorn2 and to the colours observed during my second ascent of ,monte ,rosa1 the magnificence of which is neither to be rendered by pigments nor described in words4 ,all these splendid phenomena are1 ,i believe1 produced by diffraction1 the vesicles or spherules of water in the case of the cloud acting the part of the sporules in the case of the lycopodium4 ,the coloured fringe which surrounds the ,spirit of the ,brocken1 and the spectra which ,i have spoken of as surrounding the sun1 are also produced by diffraction4 ,by the interference of their rays in the earth's atmosphere the stars can momentarily quench themselves2 and probably to an intermittent action of this kind their twinkling1 and the swift chromatic changes already mentioned1 are due4 ,does not all this sound more like a fairy tale than the sober conclusions of science8 ,what effort of the imagination could transcend the realities here presented to us8 ,the ancients had their spheral melodies1 but have not we ours1 which only want a sense sufficiently refined to hear them8 ,immensity is filled with this music2 wherever a star sheds its light its notes are heard4 ,our sun1 for example1 thrills concentric waves through space1 and every luminous point that gems our skies is surrounded by a similar system4 ,i have spoken of the rising1 climbing and crossing of the tiny ripples of a calm tide upon a smooth strand2 but what are they to those intersecting ripples of the uncontinented deep by which ,infinity is engine-turned6 ,crossing solar and stellar distances1 they bring us the light of sun and stars2 thrilled back from our atmosphere1 they give us the blue radiance of the sky2 rounding liquid spherules1 they clash at the other side1 and the survivors of the tumult bear to our vision the wondrous cloud-dyes of ,monte ,rosa4 ,,footnotes3 ,a ,the vibrations of the air of a room in which a musical instrument is sounded may be made manifest by the way in which fine sand arranges itself upon a thin stretched membrane over which it is strewn2 and indeed ,savart has thus rendered visible the vibrations of the tympanum itself4 ,every trace of sand was swept from a paper drum held in the clock-tower of ,westminster when the ,great ,bell was sounded4 ,another way of showing the propagation of aerial pulses is to insert a small gas jet into a vertical glass tube about a foot in length1 in which the flame may be caused to burn tranquilly4 ,on pitching the voice to the note of an open tube a foot long1 the little flame quivers1 stretches itself1 and responds by producing a clear melodious note of the same pitch as that which excited it4 ,the flame will continue its song for hours without intermission4 ,b ,i am not aware whether in his own country1 or in any other1 a recognition at all commensurate with the value of the performance has followed ,schwerd's admirable essay entitled ',the ,phenomena of ,diffraction deduced from the ,theory of ,undulation4' ,c ,i think1 however1 that the strong irradiation from the glistening sides of the twigs and branches must also contribute to the result4 ,sidenote3 ,,radiant ,,heat4 7#b47 ,thus1 then1 we have been led from ,sound to ,light1 and light now in its turn will lead us to ,radiant ,heat2 for in the order in which they are here mentioned the conviction arose that they are all three different kinds of motion4 ,it has been said that the beams of the sun consist of rays of different colours1 but this is not a complete statement of the case4 ,the sun emits a multitude of rays which are perfectly non-luminous2 and the same is true1 in a still greater degree1 of our artificial sources of illumination4 ,measured by the quantity of heat which they produce1 #ij per cent4 of the rays emanating from a flame of oil are obscure2 while #ii out of every #ajj of those which emanate from an alcohol flame are of the same description4,a ,sidenote3 ,,obscure ,,rays4 ,in fact1 the visible solar spectrum simply embraces an interval of rays of which the eye is formed to take cognizance1 but it by no means marks the limits of solar action4 ,beyond the violet end of the spectrum we have obscure rays capable of producing chemical changes1 and beyond the red we have rays possessing a high heating power1 but incapable of exciting the impression of light4 ,this latter fact was first established by ,sir ,william ,herschel1 and it has been amply corroborated since4 ,the belief now universally prevalent is1 that the rays of heat differ from the rays of light simply as one colour differs from another4 ,as the waves which produce red are longer than those which produce yellow1 so the waves which produce this obscure heat are longer than those which produce red4 ,in fact1 it may be shown that the longest waves never reach the retina at all2 they are completely absorbed by the humours of the eye4 ,what is true of the sun's obscure rays is also true of calorific rays emanating from any obscure source1--from our own bodies1 for example1 or from the surface of a vessel containing boiling water4 ,we must1 in fact1 figure a warm body also as having its particles in a state of vibration4 ,when these motions are communicated from particle to particle of the body the heat is said to be conducted2 when1 on the contrary1 the particles transmit their vibrations through the surrounding ether1 the heat is said to be radiant4 ,this radiant heat1 though obscure1 exhibits a deportment exactly similar to light4 ,it may be refracted and reflected1 and collected in the focus of a mirror or of a suitable lens4 ,the principle of interference also applies to it1 so that by adding heat to heat we can produce cold4 ,the identity indeed is complete throughout1 and1 recurring to the analogy of sound1 we might define this radiant heat to be light of too low a pitch to be visible4 ,i have thus far spoken of obscure heat only2 but the selfsame ray may excite both light and heat4 ,the red rays of the spectrum possess a very high heating power4 ,it was once supposed that the heat of the spectrum was an essence totally distinct from its light2 but a profounder knowledge dispels this supposition1 and leads us to infer that the selfsame ray1 falling upon the nerves of feeling1 excites heat1 and falling upon the nerves of seeing1 excites light4 ,as the same electric current1 if sent round a magnetic needle1 along a wire1 and across a conducting liquid1 produces different physical effects1 so also the same agent acting upon different organs of the body affects our consciousness differently4 ,,footnotes3 ,a ,melloni4 7#c47 ,sidenote3 ,,heat ,a ,,kind ,,of ,,motion4 ,heat has been defined in the foregoing section as a motion of the molecules or atoms of a body2 but though the evidence in favour of this view is at present overwhelming1 ,i do not ask the reader to accept it as a certainty1 if he feels sceptically disposed4 ,in this case1 ,i would only ask him to accept it as a symbol4 ,regarded as a mere physical image1 a kind of paper-currency of the mind1 convertible1 in due time1 into the gold of truth1 the hypothesis will be found exceedingly useful4 ,all known bodies possess more or less of this molecular motion1 and all bodies are communicating it to the ether in which they are immersed4 ,ice possesses it4 ,ice before it melts attains a temperature of #cb deg4 ,fahr41 but the substance in winter often possesses a temperature far below #cb deg41 so that in rising to #cb deg4 it is warmed4 ,in experimenting with ice ,i have often had occasion to cool it to #ajj deg4 and more below the freezing point1 and to warm it afterwards up to #cb deg4 ,if then we stand before a wall of ice1 the wall radiates heat to us1 and we also radiate heat to it2 but the quantity which we radiate being greater than that which the ice radiates1 we lose more than we gain1 and are consequently chilled4 ,if1 on the contrary1 we stand before a warm stove1 a system of exchanges also takes place2 but here the quantity we receive is in excess of the quantity lost1 and we are warmed by the difference4 ,in like manner the earth radiates heat by day and by night into space1 and against the sun1 moon1 and stars4 ,by day1 however1 the quantity received is greater than the quantity lost1 and the earth is warmed2 by night the conditions are reversed2 the earth radiates more heat than is sent to her by the moon and stars1 and she is consequently cooled4 ,but here an important point is to be noted3--the earth receives the heat of the sun1 moon1 and stars1 in great part as luminous heat1 but she gives it out as obscure heat4 ,i do not now speak of the heat reflected by the earth into space1 as the light of the moon is to us2 but of the heat which1 after it has been absorbed by the earth1 and has contributed to warm it1 is radiated into space1 as if the earth itself were its independent source4 ,thus we may properly say that the heat radiated from the earth is different in quality from that which the earth has received from the sun4 ,sidenote3 ,,qualities ,,of ,,heat4 ,in one particular especially does this difference of quality show itself2 besides being non-luminous1 the heat radiated from the earth is more easily intercepted and absorbed by almost all transparent substances4 ,a vast portion of the sun's rays1 for example1 can pass instantaneously through a thick sheet of water2 gunpowder could easily be fired by the heat of the sun's rays converged by passing through a thick water lens2 the drops upon leaves in greenhouses often act as lenses1 and cause the sun to burn the leaves upon which they rest4 ,but with regard to the rays of heat emanating from an obscure source1 they are all absorbed by a layer of water less than the #bjth of an inch in thickness3 water is opaque to such rays1 and cuts them off almost as effectually as a metallic screen4 ,the same is true of other liquids1 and also of many transparent solids4 ,sidenote3 ,,the ,,atmosphere ,,like ,a ,,ratchet4 ,assuming the same to be true of gaseous bodies1 that they also intercept the obscure rays much more readily than the luminous ones1 it would follow that while the sun's rays penetrate our atmosphere with freedom1 the change which they undergo in warming the earth deprives them in a measure of this penetrating power4 ,they can reach the earth1 but they cannot get back2 thus the atmosphere acts the part of a ratchet-wheel in mechanics2 it allows of motion in one direction1 but prevents it in the other4 ,de ,saussure1 ,fourier1 ,m4 ,pouillet1 and ,mr4 ,hopkins have developed this speculation1 and drawn from it consequences of the utmost importance2 but it nevertheless rested upon a basis of conjecture4 ,indeed some of the eminent men above-named deemed its truth beyond the possibility of experimental verification4 ,melloni showed that for a distance of #ah or #bj feet the absorption of obscure rays by the atmosphere was absolutely inappreciable4 ,hence1 the total absorption being so small as to elude even ,melloni's delicate tests1 it was reasonable to infer that differences of absorption1 if such existed at all1 must be far beyond the reach of the finest means which we could apply to detect them4 ,sidenote3 ,,differences ,,of ,,absorption ,,by ,,gases4 ,this exclusion of one of the three states of material aggregation from the region of experiment was1 however1 by no means satisfactory2 for our right to infer1 from the deportment of a solid or a liquid towards radiant heat1 the deportment of a gas1 is by no means evident4 ,in both liquids and solids we have the molecules closely packed1 and more or less chained by the force of cohesion2 in gases1 on the contrary1 they are perfectly free1 and widely separated4 ,how do we know that the interception of radiant heat by liquids and solids may not be due to an arrangement and comparative rigidity of their parts1 which gases do not at all share8 ,the assumption which took no note of such a possibility seemed very insecure1 and called for verification4 ,my interest in this question was augmented by the fact1 that the assumption referred to lies1 as will be seen1 at the root of the glacier question4 ,i therefore endeavoured to fill the gap1 and to do for gases and vapours what had been already so ably done for liquids and solids by ,melloni4 ,i tried the methods heretofore pursued1 and found them unavailing2 oxygen1 hydrogen1 nitrogen1 and atmospheric air1 examined by such methods1 showed no action upon radiant heat4 ,nature was dumb1 but the question occurred1 ,had she been addressed in the proper language8 ,if the experimentalist is convinced of this1 he will rest content even with a negative2 but the absence of this conviction is always a source of discomfort1 and a stimulus to try again4 ,the principle of the method finally applied is all that can here be referred to2 and it1 ,i hope1 will be quite intelligible4 ,two beams of heat1 from two distinct sources1 were allowed to fall upon the same instrument1,a and to contend there for mastery4 ,when both beams were perfectly equal1 they completely neutralized each other's action2 but when one of them was in any sensible degree stronger than the other1 the predominance of the former was shown by the instrument4 ,it was so arranged that one of the conflicting beams passed through a tube which could be exhausted of air1 or filled with any gas2 thus varying at pleasure the medium through which it passed4 ,the question then was1 supposing the two beams to be equal when the tube was filled with air1 will the exhausting of the tube disturb the equality8 ,the answer was affirmative2 the instrument at once showed that a greater quantity of heat passed through the vacuum than through the air4 ,the experiment was so arranged that the effect thus produced was very large as measured by the indications of the instrument4 ,but the action of the simple gases1 oxygen1 hydrogen1 and nitrogen1 was incomparably less than that produced by some of the compound gases1 while these latter again differed widely from each other4 ,vapours exhibited differences of equal magnitude4 ,the experiments indeed proved that gaseous bodies varied among themselves1 as to their power of transmitting radiant heat1 just as much as liquids and solids4 ,it was in the highest degree interesting to observe how a gas or vapour of perfect transparency1 as regards light1 acted like an opaque screen upon the heat4 ,to the eye1 the gas within the tube might be as invisible as the air itself1 while to the radiant heat it behaved like a cloud which it was almost impossible to penetrate4 ,sidenote3 ,,selected ,,heat4 ,applying the same method1 ,i have found that from the sun1 from the electric light1 or from the lime-light1 a large amount of heat can be selected1 which is unaffected not only by air1 but by the most energetic gases that experiment has revealed to me2 while this same heat1 when it has its quality changed by being rendered obscure1 is powerfully intercepted4 ,thus the bold and beautiful speculation above referred to has been made an experimental fact2 the radiant heat of the sun does certainly pass through the atmosphere to the earth with greater facility than the radiant heat of the earth can escape into space4 ,sidenote3 ,,possible ,,heat ,,of ,,neptune4 ,it is probable that1 were the earth unfurnished with this atmospheric swathing1 its conditions of temperature would be such as to render it uninhabitable by man2 and it is also probable that a suitable atmosphere enveloping the most distant planet might render it1 as regards temperature1 perfectly habitable4 ,if the planet ,neptune1 for example1 be surrounded by an atmosphere which permits the solar and stellar rays to pass towards the planet1 but cuts off the escape of the warmth which they excite1 it is easy to see that such an accumulation of heat may at length take place as to render the planet a comfortable habitation for beings constituted like ourselves4,b ,but let us not wander too far from our own concerns4 ,where radiant heat is allowed to fall upon an absorbing substance1 a certain thickness of the latter is always necessary for the absorption4 ,supposing we place a thin film of glass before a source of heat1 a certain percentage of the heat will pass through the glass1 and the remainder will be absorbed4 ,let the transmitted portion fall upon a second film similar to the first1 a smaller percentage than before will be absorbed4 ,a third plate would absorb still less1 a fourth still less2 and1 after having passed through a sufficient number of layers1 the heat would be so sifted that all the rays capable of being absorbed by glass would be abstracted from it4 ,suppose all these films to be placed together so as to form a single thick plate of glass1 it is evident that the plate must act upon the heat which falls upon it1 in such a manner that the major portion is absorbed near the surface at which the heat enters4 ,this has been completely verified by experiment4 ,sidenote3 ,,cold ,,of ,,upper ,,atmosphere4 ,applying this to the heat radiated from the earth1 it is manifest that the greatest quantity of this heat will be absorbed by the lowest atmospheric strata4 ,and here we find ourselves brought1 by considerations apparently remote1 face to face with the fact upon which the existence of all glaciers depends1 namely1 the comparative coldness of the upper regions of the atmosphere4 ,the sun's rays can pass in a great measure through these regions without heating them2 and the earth's rays1 which they might absorb1 hardly reach them at all1 but are intercepted by the lower portions of the atmosphere4,c ,another cause of the greater coldness of the higher atmosphere is the expansion of the denser air of the lower strata when it ascends4 ,the dense air makes room for itself by pushing back the lighter and less elastic air which surrounds it3 it does work1 and1 to perform this work1 a certain amount of heat must be consumed4 ,it is the consumption of this heat--its absolute annihilation as heat--that chills the expanded air1 and to this action a share of the coldness of the higher atmosphere must undoubtedly be ascribed4 ,a third cause of the difference of temperature is the large amount of heat communicated1 by way of contact1 to the air of the earth's surface2 and a fourth and final cause is the loss endured by the highest strata through radiation into space4 ,,footnotes3 ,a ,the opposite faces of a thermo-electric pile4 ,b ,see a most interesting paper on this subject by ,mr4 ,hopkins in the ,cambridge ',transactions1' ,may1 #ahef4 ,c ,see ,m4 ,pouillet's important ,memoir on ,solar ,radiation4 ,taylor's ,scientific ,memoirs1 vol4 iv4 p4 #dd4 ,,origin ,,of ,,glaciers4 7#d47 ,sidenote3 ,,the ,,snow-,,line4 ,having thus accounted for the greater cold of the higher atmospheric regions1 its consequences are next to be considered4 ,one of these is1 that clouds formed in the lower portions of the atmosphere1 in warm and temperate latitudes1 usually discharge themselves upon the earth as rain2 while those formed in the higher regions discharge themselves upon the mountains as snow4 ,the snow of the higher atmosphere is often melted to rain in passing through the warmer lower strata3 nothing indeed is more common than to pass1 in descending a mountain1 from snow to rain2 and ,i have already referred to a case of this kind4 ,the appearance of the grassy and pine-clad alps1 as seen from the valleys after a wet night1 is often strikingly beautiful2 the level at which the snow turned to rain being distinctly marked upon the slopes4 ,above this level the mountains are white1 while below it they are green4 ,the eye follows this snow-line with ease along the mountains1 and when a sufficient extent of country is commanded its regularity is surprising4 ,the term snow-line1 however1 which has been here applied to a local and temporary phenomenon1 is commonly understood to mean something else4 ,in the case just referred to it marked the place where the supply of solid matter from the upper atmospheric regions1 during a single fall1 was exactly equal to its consumption2 but the term is usually understood to mean the line along which the quantity of snow which falls annually is melted1 and no more4 ,below this line each year's snow is completely cleared away by the summer heat2 above it a residual layer abides1 which gradually augments in thickness from the snow-line upwards4 ,sidenote3 ,,mountains ,,unloaded ,,by ,,glaciers4 ,here then we have a fresh layer laid on every year2 and it is evident that1 if this process continued without interruption1 every mountain which rises above the snow-line must augment annually in height2 the waters of the sea thus piled1 in a solid form1 upon the summits of the hills1 would raise the latter to an indefinite elevation4 ,but1 as might be expected1 the snow upon steep mountain-sides frequently slips and rolls down in avalanches into warmer regions1 where it is reduced to water4 ,a comparatively small quantity of the snow is1 however1 thus got rid of1 and the great agent which ,nature employs to relieve her overladen mountains is the glaciers4 ,let us here avoid an error which may readily arise out of the foregoing reflections4 ,the principal region of clouds and rain and snow extends only to a limited distance upwards in the atmosphere2 the highest regions contain very little moisture1 and were our mountains sufficiently lofty to penetrate those regions1 the quantity of snow falling upon their summits would be too trifling to resist the direct action of the solar rays4 ,these would annually clear the summits to a certain level1 and hence1 were our mountains high enough1 we should have a superior1 as well as an inferior1 snow-line2 the region of perpetual snow would form a belt1 below which1 in summer1 snowless valleys and plains would extend1 and above which snowless summits would rise4 7#e47 ,sidenote3 ,,white ,,and ,,blue ,,ice4 ,at its origin then a glacier is snow--at its lower extremity it is ice4 ,the blue blocks that arch the source of the ,arveiron were once powdery snow upon the slopes of the ,col du ,geant4 ,could our vision penetrate into the body of the glacier1 we should find that the change from white to blue essentially consists in the gradual expulsion of the air which was originally entangled in the meshes of the fallen snow4 ,whiteness always results from the intimate and irregular mixture of air and a transparent solid2 a crushed diamond would resemble snow2 if we pound the most transparent rock-salt into powder we have a substance as white as the whitest culinary salt2 and the colourless glass vessel which holds the salt would also1 if pounded1 give a powder as white as the salt itself4 ,it is a law of light that in passing from one substance to another possessing a different power of refraction1 a portion of it is always reflected4 ,hence when light falls upon a transparent solid mixed with air1 at each passage of the light from the air to the solid and from the solid to the air a portion of it is reflected2 and1 in the case of a powder1 this reflection occurs so frequently that the passage of the light is practically cut off4 ,thus1 from the mixture of two perfectly transparent substances1 we obtain an opaque one2 from the intimate mixture of air and water we obtain foam2 clouds owe their opacity to the same principle2 and the condensed steam of a locomotive casts a shadow upon the fields adjacent to the line1 because the sunlight is wasted in echoes at the innumerable limiting surfaces of water and air4 ,sidenote3 ,,air-,,bubbles ,,in ,,ice4 ,the snow which falls upon high mountain-eminences has often a temperature far below the freezing point of water4 ,such snow is dry1 and if it always continued so the formation of a glacier from it would be impossible4 ,the first action of the summer's sun is to raise the temperature of the superficial snow to #cb deg41 and afterwards to melt it4 ,the water thus formed percolates through the colder mass underneath1 and this ,i take to be the first active agency in expelling the air entangled in the snow4 ,but as the liquid trickles over the surfaces of granules colder than itself it is partially deposited in a solid form on these surfaces1 thus augmenting the size of the granules1 and cementing them together4 ,when the mass thus formed is examined1 the air within it is found as round bubbles4 ,now it is manifest that the air caught in the irregular interstices of the snow can have no tendency to assume this form so long as the snow remains solid2 but the process to which ,i have referred--the saturation of the lower portions of the snow by the water produced by the melting of the superficial portions--enables the air to form itself into globules1 and to give the ice of the neve its peculiar character4 ,thus we see that1 though the sun cannot get directly at the deeper portions of the snow1 by liquefying the upper layer he charges it with heat1 and makes it his messenger to the cold subjacent mass4 ,the frost of the succeeding winter may1 ,i think1 or may not1 according to circumstances1 penetrate through this layer1 and solidify the water which it still retains in its interstices4 ,if the winter set in with clear frosty weather1 the penetration will probably take place2 but if heavy snow occur at the commencement of winter1 thus throwing a protective covering over the neve1 freezing to any great depth may be prevented4 ,mr4 ,huxley's idea seems to be quite within the range of possibility1 that water-cells may be transmitted from the origin of the glacier to its end1 retaining their contents always liquid4 ,sidenote3 ,,snow ,,pressed ,,to ,,ice4 ,it was formerly supposed1 and is perhaps still supposed by many1 that the snow of the mountains is converted into the ice of the glacier by the process of saturation and freezing just indicated4 ,but the frozen layer would not yet resemble glacier ice2 it is only at the deeper portions of the neve that we find an approximation to the true ice of the glacier4 ,this brings us to the second great agent in the process of glacification1 namely1 pressure4 ,the ice of the neve at #cb deg4 may be squeezed or crushed with extreme facility2 and if the force be applied slowly and with caution1 the yielding of the mass may be made to resemble the yielding of a plastic body4 ,in the depths of the neve1 where each portion of the ice is surrounded by a resistant mass1 rude crushing is of course out of the question4 ,the layers underneath yield with extreme slowness to the pressure of the mass above them2 they are squeezed1 but not rudely fractured2 and even should rude fracture occur1 the ice1 as shall subsequently be shown1 possesses the power of restoring its own continuity4 ,thus1 then1 the lower portions of the neve are removed by pressure more and more from the condition of snow1 the air-bubbles which give to the neve-ice its whiteness are more and more expelled1 and this process1 continued throughout the entire glacier1 finally brings the ice to that state of magnificent transparency which we find at the termination of the glacier of ,rosenlaui and elsewhere4 ,this is all capable of experimental proof4 ,the ,messrs4 ,schlagintweit compressed the snow of the neve to compact ice2 and ,i have myself frequently obtained slabs of ice from snow in ,london4 ,,colour ,,of ,,water ,,and ,,ice4 7#f47 ,the sun is continually sending forth waves of different lengths1 all of which travel with the same velocity through the ether4 ,when these waves enter a prism of glass they are retarded1 but in different degrees4 ,the shorter waves suffer the greatest retardation1 and in consequence of this are most deflected from their straight course4 ,it is this property which enables us to separate one from the other in the solar spectrum1 and this separation proves that the waves are by no means inextricably entangled with each other1 but that they travel independently through space4 ,in consequence of this independence1 the same body may intercept one system of waves while it allows another to pass3 on this quality1 indeed1 depend all the phenomena of colour4 ,a red glass1 for example1 is red because it is so constituted that it destroys the shorter waves which produce the other colours1 and transmits only the waves which produce red4 ,i may remark1 however1 that scarcely any glass is of a pure colour2 along with the predominant waves1 some of the other waves are permitted to pass4 ,the colours of flowers are also very impure2 in fact1 to get pure colours we must resort to a delicate prismatic analysis of white light4 ,sidenote3 ,,long ,,waves ,,most ,,absorbed4 ,it has already been stated that a layer of water less than the twentieth of an inch in thickness suffices to stop and destroy all waves of radiant heat emanating from an obscure source4 ,the longer waves of the obscure heat cannot get through water1 and ,i find that all transparent compounds which contain hydrogen are peculiarly hostile to the longer undulations4 ,it is1 ,i think1 the presence of this element in the humours of the eye which prevents the extra red rays of the solar spectrum from reaching the retina4 ,it is interesting to observe that while bisulphide of carbon1 chloride of phosphorus1 and other liquids which contain no hydrogen1 permit a large portion of the rays emanating from an iron or copper ball1 at a heat below redness1 to pass through them with facility1 the same thickness of substances equally transparent1 but which contain hydrogen1 such as ether1 alcohol1 water1 or the vitreous humour of the eye of an ox1 completely intercepts these obscure rays4 ,the same is true of solid bodies2 a very slight thickness of those which contain hydrogen offers an impassable barrier to all rays emanating from a non-luminous source4,a ,but the heat thus intercepted is by no means lost2 its radiant form merely is destroyed4 ,its waves are shivered upon the particles of the body1 but they impart warmth to it1 while the heat which retains its radiant form contributes in no way to the warmth of the body through which it passes4 ,sidenote3 ,,final ,,colour ,,of ,,ice ,,and ,,water ,,blue4 ,water then absorbs all the extra red rays of the sun1 and if the layer be thick enough it invades the red rays themselves4 ,thus the greater the distance the solar beams travel through pure water the more are they deprived of those components which lie at the red end of the spectrum4 ,the consequence is1 that the light finally transmitted by the water1 and which gives to it its colour1 is blue4 ,sidenote3 ,,experiment4 ,i find the following mode of examining the colour of water both satisfactory and convenient3--,a tin tube1 fifteen feet long and three inches in diameter1 has its two ends stopped securely by pieces of colourless plate glass4 ,it is placed in a horizontal position1 and pure water is poured into it through a small lateral pipe1 until the liquid reaches half way up the glasses at the ends2 the tube then holds a semi-cylinder of water and a semi-cylinder of air4 ,a white plate1 or a sheet of white paper1 well illuminated1 is then placed at a little distance from one end of the tube1 and is looked at through the tube4 ,two semicircular spaces are then seen1 one by the light which has passed through the air1 the other by the light which has passed through the water2 and their proximity furnishes a means of comparison1 which is absolutely necessary in experiments of this kind4 ,it is always found that1 while the former semicircle remains white1 the latter one is vividly coloured4,b ,when the beam from an electric lamp is sent through this tube1 and a convex lens is placed at a suitable distance from its most distant end1 a magnified image of the coloured and uncoloured semicircles may be projected upon a screen4 ,tested thus1 ,i have sometimes found1 after rain1 the ordinary pipe-water of the ,royal ,institution quite opaque2 while1 under other circumstances1 ,i have found the water of a clear green4 ,the pump-water of the ,institution thus examined exhibits a rich sherry colour1 while distilled water is blue-green4 ,the blueness of the ,grotto of ,capri is due to the fact that the light which enters it has previously traversed a great depth of clear water4 ,according to ,bunsen's account1 the laugs1 or cisterns of hot water1 in ,iceland must be extremely beautiful4 ,the water contains silica in solution1 which1 as the walls of the cistern arose1 was deposited upon them in fantastic incrustations4 ,these1 though white1 when looked at through the water appear of a lovely blue1 which deepens in tint as the vision plunges deeper into the liquid4 ,sidenote3 ,,ice ,,opaque ,,to ,,radiant ,,heat4 ,ice is a crystal formed from this blue liquid1 the colour of which it retains4 ,ice is the most opaque of transparent solids to radiant heat1 as water is the most opaque of liquids4 ,according to ,melloni1 a plate of ice one twenty-fifth of an inch thick1 which permits the rays of light to pass without sensible absorption1 cuts off #id per cent4 of the rays of heat issuing from a powerful oil lamp1 #ii-a_/b per cent4 of the rays issuing from incandescent platinum1 and the whole of the rays issuing from an obscure source4 ,the above numbers indicate how large a portion of the rays emitted by our artificial sources of light is obscure4 ,when the rays of light pass through a sufficient thickness of ice the longer waves are1 as in the case of water1 more and more absorbed1 and the final colour of the substance is therefore blue4 ,but when the ice is filled with minute air-bubbles1 though we should loosely call it white1 it may exhibit1 even in small pieces1 a delicate blue tint4 ,this1 ,i think1 is due to the frequent interior reflection which takes place at the surfaces of the air-cells2 so that the light which reaches the eye from the interior may1 in consequence of its having been reflected hither and thither1 really have passed through a considerable thickness of ice4 ,the same remark1 as we have already seen1 applies to the delicate colour of newly fallen snow4 ,,footnotes3 ,a ,what is here stated regarding hydrogen is true of all the liquids and solids which have hitherto been examined1--but whether any exceptions occur1 future experience must determine4 ,it is only when in combination that it exhibits this impermeability to the obscure rays4 ,b ,in my own experiments ,i have never yet been able to obtain a pure blue1 the nearest approach to it being a blue-green4 ,,colours ,,of ,,the ,,sky4 7#g47 ,sidenote3 ,,newton',s ,,hypothesis4 ,in treating of the ,colours of ,thin ,plates we found that a certain thickness was necessary to produce blue1 while a greater thickness was necessary for red4 ,with that wonderful power of generalization which belonged to him1 ,newton thus applies this apparently remote fact to the blue of the sky3--,the blue of the first order1 though very faint and little1 may possibly be the colour of some substances1 and particularly the azure colour of the skies seems to be of this order4 ,for all vapours1 when they begin to condense and coalesce into small parcels1 become first of that bigness whereby such an azure is reflected1 before they can constitute clouds of other colours4 ,and so1 this being the first colour which vapours begin to reflect1 it ought to be the colour of the finest and most transparent skies1 in which vapours are not arrived at that grossness requisite to reflect other colours1 as we find it is by experience4 ,m4 ,clausius has written a most interesting paper1 which he endeavours to show that the minute particles of water which are supposed by ,newton to reflect the light1 cannot be little globes entirely composed of water1 but bladders or hollow spheres2 the vapour must be in what is generally termed the vesicular state4 ,he was followed by ,m4 ,bruecke1 whose experiments prove that the suspended particles may be so small that the reasoning of ,m4 ,clausius may not apply to them4 ,but why need we assume the existence of such particles at all8--why not assume that the colour of the air is blue1 and renders the light of the sun blue1 after the fashion of a blue glass or a solution of the sulphate of copper8 ,i have already referred to the great variation which the colour of the firmament undergoes in the ,alps1 and have remarked that this seems to indicate that the blue depends upon some variable constituent of the atmosphere4 ,further1 we find that the blue light of the sky is reflected light2 and there must be something in the atmosphere capable of producing this reflection2 but this thing1 whatever it is1 produces another effect which the blue glass or liquid is unable to produce4 ,these transmit blue light1 whereas1 when the solar beams have traversed a great length of air1 as in the morning or the evening1 they are yellow1 or orange1 or even blood-red1 according to the state of the atmosphere3--the transmitted light and the reflected light of the atmosphere are then totally different in colour4 ,sidenote3 ,,goethe',s ,,hypothesis4 ,goethe1 in his celebrated ',farbenlehre1' gives a theory of the colour of the sky1 and has illustrated it by a series of striking facts4 ,he assumed two principles in the universe--,light and ,darkness--and an intermediate stage of ,turbidity4 ,when the darkness is seen through a turbid medium on which the light falls1 the medium appears blue2 when the light itself is viewed through such a medium1 it is yellow1 or orange1 or ruby-red4 ,this he applies to the atmosphere1 which sends us blue light1 or red1 according as the darkness of infinite space1 or the bright surface of the sun1 is regarded through it4 ,as a theory of colours ,goethe's work is of no value1 but the facts which he has brought forward in illustration of the action of turbid media are in the highest degree interesting4 ,he refers to the blueness of distant mountains1 of smoke1 of the lower part of the flame of a candle 7which if looked at with a white surface behind it completely disappears71 of soapy water1 and of the precipitates of various resins in water4 ,one of his anecdotes in connexion with this subject is extremely curious and instructive4 ,the portrait of a very dignified theologian having suffered from dirt1 it was given to a painter to be cleaned4 ,the clergyman was drawn in a dress of black velvet1 over which the painter1 in the first place1 passed his sponge4 ,to his astonishment the black velvet changed to the colour of blue plush1 and completely altered the aspect of its wearer4 ,goethe was informed of the fact2 the experiment was repeated in his presence1 and he at once solved it by reference to his theory4 ,the varnish of the picture when mixed with the water formed a turbid medium1 and the black coat seen through it appeared blue2 when the water evaporated the coat resumed its original aspect4 ,sidenote3 ,,suspended ,,particles4 ,with regard to the real explanation of these effects1 it may be shown1 that1 if a beam of white light be sent through a liquid which contains extremely minute particles in a state of suspension1 the short waves are more copiously reflected by such particles than the long ones2 blue1 for example1 is more copiously reflected than red4 ,this may be shown by various fine precipitates1 but the best is that of ,bruecke4 ,we know that mastic and various resins are soluble in alcohol1 and are precipitated when the solution is poured into water3 ,eau de ,cologne1 for example1 produces a white precipitate when poured into water4 ,if however this precipitate be sufficiently diluted1 it gives the liquid a bluish colour by reflected light4 ,even when the precipitate is very thick and gross1 and floats upon the liquid like a kind of curd1 its under portions often exhibit a fine blue4 ,to obtain particles of a proper size1 ,bruecke recommends #a gramme of colourless mastic to be dissolved in #hg grammes of alcohol1 and dropped into a beaker of water1 which is kept in a state of agitation4 ,in this way a blue resembling that of the firmament may be produced4 ,it is best seen when a black cloth is placed behind the glass2 but in certain positions this blue liquid appears yellow2 and these are the positions when the transmitted light reaches the eye4 ,it is evident that this change of colour must necessarily exist2 for the blue being partially withdrawn by more copious reflection1 the transmitted light must partake more or less of the character of the complementary colour2 though it does not follow that they should be exactly complementary to each other4 ,sidenote3 ,,the ,,sun ,,through ,,london ,,smoke4 ,when a long tube is filled with clear water1 the colour of the liquid1 as before stated1 shows itself by transmitted light4 ,the effect is very interesting when a solution of mastic is permitted to drop into such a tube1 and the fine precipitate to diffuse itself in the water4 ,the blue-green of the liquid is first neutralized1 and a yellow colour shows itself2 on adding more of the solution the colour passes from yellow to orange1 and from orange to blood-red4 ,with a cell an inch and a half in width1 containing water1 into which the solution of mastic is suffered to drop1 the same effect may be obtained4 ,if the light of an electric lamp be caused to form a clear sunlike disk upon a white screen1 the gradual change of this light by augmented precipitation into deep glowing red1 resembling the colour of the sun when seen through fine ,london smoke1 is exceedingly striking4 ,indeed the smoke acts1 in some measure1 the part of our finely-suspended matter4 ,sidenote3 ,,morning ,,and ,,evening ,,red4 ,by such means it is possible to imitate the phenomena of the firmament2 we can produce its pure blue1 and cause it to vary as in nature4 ,the milkiness which steals over the heavens1 and enables us to distinguish one cloudless day from another1 can be produced with the greatest ease4 ,the yellow1 orange1 and red light of the morning and evening can also be obtained3 indeed the effects are so strikingly alike as to suggest a common origin--that the colours of the sky are due to minute particles diffused through the atmosphere4 ,these particles are doubtless the condensed vapour of water1 and its variation in quality and amount enables us to understand the variability of the firmamental blue1 and of the morning and the evening red4 ,professor ,forbes1 moreover1 has made the interesting observation that the steam of a locomotive1 at a certain stage of its condensation1 is blue or red according as it is viewed by reflected or transmitted light4 ,these considerations enable us to account for a number of facts of common occurrence4 ,thin milk1 when poured upon a black surface1 appears bluish4 ,the milk is colourless2 that is1 its blueness is not due to absorption1 but to a separation of the light by the particles suspended in the liquid4 ,the juices of various plants owe their blueness to the same cause2 but perhaps the most curious illustration is that presented by a blue eye4 ,here we have no true colouring matter1 no proper absorption2 but we look through a muddy medium at the black choroid coat within the eye1 and the medium appears blue4,a ,sidenote3 ,,colour ,,of ,,swiss ,,lakes4 ,is it not probable that this action of finely-divided matter may have some influence on the colour of some of the ,swiss lakes--as that of ,geneva for example8 ,this lake is simply an expansion of the river ,rhone1 which rushes from the end of the ,rhone glacier1 as the ,arveiron does from the end of the ,mer de ,glace4 ,numerous other streams join the ,rhone right and left during its downward course2 and these feeders1 being almost wholly derived from glaciers1 join the ,rhone charged with the finer matter which these in their motion have ground from the rocks over which they have passed4 ,but the glaciers must grind the mass beneath them to particles of all sizes1 and ,i cannot help thinking that the finest of them must remain suspended in the lake throughout its entire length4 ,faraday has shown that a precipitate of gold may require months to sink to the bottom of a bottle not more than five inches high1 and in all probability it would require ages of calm subsidence to bring all the particles which the ,lake of ,geneva contains to its bottom4 ,it seems certainly worthy of examination whether such particles suspended in the water contribute to the production of that magnificent blue which has excited the admiration of all who have seen it under favourable circumstances4 ,,footnotes3 ,a ,helmholtz1 ',das ,sehen des ,menschen4' ,,the ,,moraines4 7#h47 ,the surface of the glacier does not long retain the shining whiteness of the snow from which it is derived4 ,it is flanked by mountains which are washed by rain1 dislocated by frost1 riven by lightning1 traversed by avalanches1 and swept by storms4 ,the lighter debris is scattered by the winds far and wide over the glacier1 sullying the purity of its surface4 ,loose shingle rattles at intervals down the sides of the mountains1 and falls upon the ice where it touches the rocks4 ,large rocks are continually let loose1 which come jumping from ledge to ledge1 the cohesion of some being proof against the shocks which they experience2 while others1 when they hit the rocks1 burst like bomb-shells1 and shower their fragments upon the ice4 ,sidenote3 ,,lateral ,,moraines4 ,thus the glacier is incessantly loaded along its borders with the ruins of the mountains which limit it2 and it is evident that the quantity of rock and rubbish thus cast upon the glacier depends upon the character of the adjacent mountains4 ,where the summits are bare and friable1 we may expect copious showers2 where they are resistant1 and particularly where they are protected by a covering of ice and snow1 the quantity will be small4 ,as the glacier moves downward1 it carries with it the load deposited upon it4 ,long ridges of debris thus flank the glacier1 and these ridges are called lateral moraines4 ,where two tributary glaciers join to form a trunk-glacier1 their adjacent lateral moraines are laid side by side at the place of confluence1 thus constituting a ridge which runs along the middle of the trunk-glacier1 and which is called a medial moraine4 ,the rocks and debris carried down by the glacier are finally deposited at its lower extremity1 forming there a terminal moraine4 ,sidenote3 ,,medial ,,and ,,terminal ,,moraines4 ,it need hardly be stated that the number of medial moraines is only limited by the number of branch glaciers4 ,if a glacier have but two branches1 it will have only one medial moraine2 if it have three branches1 it will have two medial moraines2 if n branches1 it will have n-#a medial moraines4 ,the number of medial moraines1 in short1 is always one less than the number of branches4 ,a glance at the annexed figure will reveal the manner in which the lateral moraines of the ,mer de ,glace unite to form medial ones4 7,see ,fig4 #ai47 ,illustration3 ,,moraines ,,of ,,the ,,mer ,,de ,,glace4 ,fig4 #ai4 ,to face p4 #bfd4 ,when a glacier diminishes in size it leaves its lateral moraines stranded on the flanks of the valleys4 ,successive shrinkings may thus occur1 and have occurred at intervals of centuries2 and a succession of old lateral moraines1 such as many glacier-valleys exhibit1 is the consequence4 ,the ,mer de ,glace1 for example1 has its old lateral moraines1 which run parallel with its present ones4 ,the glacier may also diminish in length at distant intervals2 the result being a succession of more or less concentric terminal moraines4 ,in front of the ,rhone-glacier we have six or seven such moraines1 and the ,mer de ,glace also possesses a series of them4 ,let us now consider the effect produced by a block of stone upon the surface of a glacier4 ,the ice around it receives the direct rays of the sun1 and is acted on by the warm air2 it is therefore constantly melting4 ,the stone also receives the solar beams1 is warmed1 and transmits its heat1 by conduction1 to the ice beneath it4 ,if the heat thus transmitted to the ice through the stone be less than an equal space of the surrounding ice receives1 it is manifest that the ice around the stone will waste more quickly than that beneath it1 and the consequence is1 that1 as the surface sinks1 it leaves behind it a pillar of ice1 on which the block is elevated4 ,if the stone be wide and flat1 it may rise to a considerable height1 and in this position it constitutes what is called a glacier-table4 7,see ,fig4 #f47 ,sidenote3 ,,glacier ,,tables ,,accounted ,,for4 ,almost all glaciers present examples of such tables2 but no glacier with which ,i am acquainted exhibits them in greater number and perfection than the ,unteraar glacier1 near the ,grimsel4 ,vast masses of granite are thus poised aloft on icy pedestals2 but a limit is placed to their exaltation by the following circumstance4 ,the sun plays obliquely upon the table all day2 its southern extremity receives more heat than its northern1 and the consequence is1 that it dips towards the south4 ,strictly speaking1 the plane of the dip rotates a little during the day1 being a little inclined towards the east in the morning1 north and south a little after noon1 and inclined towards the west in the evening2 so that1 theoretically speaking1 the block is a sun-dial1 showing by its position the hour of the day4 ,this rotation is1 however1 too small to be sensible1 and hence the dip of the stones upon a glacier sufficiently exposed to the sunlight1 enables us at any time to draw the meridian line along its surface4 ,the inclination finally becomes so great that the block slips off its pedestal1 and begins to form another1 while the one which it originally occupied speedily disappears1 under the influence of sun and air4 ,fig4 #bj represents a typical section of a glacier-table1 the sun's rays being supposed to fall in the direction of the shading lines4 ,sidenote3 ,,type ,,table4 ,illustration3 ,fig4 #bj4 ,typical section of a glacier ,table4 ,stones of a certain size are always lifted in the way described4 ,a considerable portion of the heat which a large block receives is wasted by radiation1 and by communication to the air1 so that the quantity which reaches the ice beneath is trifling4 ,such a mass is1 of course1 a protector of the ice beneath it4 ,but if the stone be small1 and dark in colour1 it absorbs the heat with avidity1 communicates it quickly to the ice with which it is in contact1 and consequently sinks in the ice4 ,this is also the case with bits of dirt and the finer fragments of debris2 they sink in the glacier4 ,sometimes1 however1 a pretty thick layer of sand is washed over the ice from the moraines1 or from the mountain-sides2 and such sand-layers give birth to ice-cones1 which grow to peculiarly grand dimensions on the ,lower ,aar glacier4 ,i say grow1 but the truth1 of course1 is1 that the surrounding ice wastes1 while the portion underneath the sand is so protected that it remains as an eminence behind4 ,at first sight1 these sand-covered cones appear huge heaps of dirt1 but on examination they are found to be cones of ice1 and that the dirt constitutes merely a superficial covering4 ,turn we now to the moraines4 ,protecting1 as they do1 the ice from waste1 they rise1 as might be expected1 in vast ridges above the general surface of the glacier4 ,in some cases the surrounding mass has been so wasted as to leave the spines of ice which support the moraines forty or fifty feet above the general level of the glacier4 ,i should think the moraines of the ,mer de ,glace about the ,tacul rise to this height4 ,but lower down1 in the neighbourhood of the ,echelets1 these high ridges disappear1 and nought remains to mark the huge moraine but a strip of dirt1 and perhaps a slight longitudinal protuberance on the surface of the glacier4 ,how have the blocks vanished that once loaded the moraines near the ,tacul8 ,they have been swallowed in the crevasses which intersect the moraines lower down2 and if we could examine the ice at the ,echelets we should find the engulfed rocks in the body of the glacier4 ,sidenote3 ,,moraines ,,engulfed ,,and ,,disgorged4 ,cases occur1 wherein moraines1 after having been engulfed1 and hidden for a time1 are again entirely disgorged by the glacier4 ,two moraines run along the basin of the ,talefre1 one from the ,jardin1 the other from an adjacent promontory1 proceeding parallel to each other towards the summit of the great ice-fall4 ,here the ice is riven1 and profound chasms are formed1 in which the blocks and shingle of the moraines disappear4 ,throughout the entire ice-fall the only trace of the moraines is a broad dirt-streak1 which the eye may follow along the centre of the fall1 with perhaps here and there a stone which has managed to rise from its frozen sepulchre4 ,but the ice wastes1 and at the base of the fall large masses of stone begin to reappear2 these become more numerous as we descend2 the smaller debris also appears1 and finally1 at some distance below the fall1 the moraine is completely restored1 and begins to exercise its protecting influence2 it rises upon its ridge of ice1 and dominates as before over the surface of the glacier4 ,sidenote3 ,,transparency ,,of ,,ice ,,under ,,the ,,moraines4 ,the ice under the moraines and sand-cones is of a different appearance from that of the surrounding glacier1 and the principles we have laid down enable us to explain the difference4 ,the sun's rays1 striking upon the unprotected surface of the glacier1 enter the ice to a considerable depth2 and the consequence is1 that the ice near the surface of the glacier is always disintegrated1 being cut up with minute fissures and cavities1 filled with water and air1 which1 for reasons already assigned1 cause the glacier1 when it is clean1 to appear white and opaque4 ,the ice under the moraines1 on the contrary1 is usually dark and transparent2 ,i have sometimes seen it as black as pitch1 the blackness being a proof of its great transparency1 which prevents the reflection of light from its interior4 ,the ice under the moraines cannot be assailed in its depths by the solar heat1 because this heat becomes obscure before it reaches the ice1 and as such it lacks the power of penetrating the substance4 ,it is also communicated in great part by way of contact instead of by radiation4 ,a thin film at the surface of the moraine-ice engages all the heat that acts upon it1 its deeper portions remaining intact and transparent4 ,,glacier ,,motion4 ,,preliminary4 7#i47 ,sidenote3 ,,neve ,,and ,,glacier4 ,though a glacier is really composed of two portions1 one above and the other below the snow-line1 the term glacier is usually restricted to the latter1 while the ,french term neve is applied to the former4 ,it is manifest that the snow which falls upon the glacier proper can contribute nothing to its growth or permanence2 for every summer is not only competent to abolish the accumulations of the foregoing winter1 but to do a great deal more4 ,during each summer indeed a considerable quantity of the ice below the snow-line is reduced to water2 so that1 if the waste were not in some way supplied1 it is manifest that in a few years the lower portion of the glacier must entirely disappear4 ,the end of the ,mer de ,glace1 for example1 could never year after year thrust itself into the valley of ,chamouni1 were there not some agency by which its manifest waste is made good4 ,this agency is the motion of the glacier4 ,to those unacquainted with the fact of their motion1 but who have stood upon these vast accumulations of ice1 and noticed their apparent fixity and rigidity1 the assertion that a glacier moves must appear in the highest degree startling and incredible4 ,they would naturally share the doubts of a certain professor of ,tuebingen1 who1 after a visit to the glaciers of ,switzerland1 went home and wrote a book flatly denying the possibility of their motion4 ,but reflection comes to the aid of sense1 and qualifies first impressions4 ,we ask ourselves how is the permanence of the glacier secured8 ,how are the moraines to be accounted for8 ,whence come the blocks which we often find at the terminus of a glacier1 and which we know belong to distant mountains8 ,the necessity of motion to produce these results becomes more and more apparent1 until at length we resort to actual experiment4 ,we take two fixed points at opposite sides of the glacier1 so that a block of stone which rests upon the ice may be in the straight line which unites the points2 and we soon find that the block quits the line1 and is borne downwards by the glacier4 ,we may well realize the interest of the man who first engaged in this experiment1 and the pleasure which he felt on finding that the block moved2 for even now1 after hundreds of observations on the motion of glaciers have been made1 the actual observance of this motion for the first time is always accompanied by a thrill of delight4 ,such pleasure the direct perception of natural truth always imparts4 ,like ,antaeus we touch our mother1 and are refreshed by the contact4 ,sidenote3 ,,hugi',s ,,measurements4 ,the fact of glacier-motion has been known for an indefinite time to the inhabitants of the mountains2 but the first who made quantitative observations of the motion was ,hugi4 ,he found that from #ahbg to #ahcj his cabin upon the glacier of the ,aar had moved #ajj metres1 or about #aaj yards1 downwards2 in #ahcf it had moved #gad metres2 and in #ahda ,m4 ,agassiz found it at a distance of #a1dbh metres from its first position4 ,this is equivalent in round numbers to an average velocity of #ajj metres a year4 ,in #ahdj ,m4 ,agassiz fixed the position of the rock known as the ,hotel des ,neufchatelois2 and on the #eth of ,september1 #ahda1 he found that it had moved #bac feet downward4 ,between this date and ,september1 #ahdb1 the rock moved #bgc feet1 thus accomplishing a distance of #dhf feet in two years4 ,but much uncertainty prevailed regarding the motion of the boulders1 for they sometimes rolled upon the glacier1 and hence it was resolved to use stakes of wood driven into the ice4 ,in the month of ,july1 #ahda1 ,m4 ,escher de la ,linth fixed a system of stakes1 every two of which were separated from each other by a distance of #ajj metres1 across the great ,aletsch glacier4 ,a considerable number of other stakes were fixed along the glacier1 the longitudinal separation being also #ajj metres4 ,on the #hth of ,july the stakes stood at a depth of about three feet in the ice4 ,on the #afth of ,august he returned to the glacier4 ,almost all the stakes had fallen1 and no trace1 even of the holes in which they had been sunk1 remained4 ,m4 ,agassiz was equally unsuccessful on the glacier of the ,aar4 ,it must therefore be borne in mind1 that1 previous to the introduction of the facile modes of measurement which we now employ1 severe labour and frequent disappointment had taught observers the true conditions of success4 ,after his defeat upon the ,aletsch1 ,m4 ,escher joined ,,mm4 ,agassiz and ,desor on the ,aar glacier1 where1 between the #cast of ,august and the #eth of ,september1 they fixed in concert the positions of a series of blocks upon the ice1 with the view of measuring their displacements the following year4 ,sidenote3 ,,agassiz',s ,,measurements4 ,another observation of great importance was also commenced in #ahda4 ,warned by previous failures1 ,m4 ,agassiz had iron boring-rods carried up the glacier1 with which he pierced the ice at six places to a depth of ten feet1 and at each place drove a wooden pile into the ice4 ,these six stations were in the same straight line across the glacier2 three of them standing upon the ,finsteraar and three on the ,lauteraar tributary4 ,about this time also ,m4 ,agassiz conceived the idea of having the displacements measured the year following with precise instruments1 and also of having constructed1 by a professional engineer1 a map of the entire glacier1 on which all its visible accidents should be drawn according to scale4 ,this excellent work was afterwards executed by ,m4 ,wild1 now ,professor of ,geodesy and ,topography in the ,polytechnic ,school of ,zuerich1 and it is published as a separate atlas in connexion with ,m4 ,agassiz's ',systeme ,glaciaire4' ,sidenote3 ,,prof4 ,j4 ,d4 ,,forbes ,,invited4 ,m4 ,agassiz is a naturalist1 and he appears to have devoted but little attention to the study of physics4 ,at all events1 the physical portions of his writings appear to me to be very often defective4 ,it was probably his own consciousness of this deficiency that led him to invoke the advice of ,arago and others previous to setting out upon his excursions4 ,it was also his desire to see a philosopher so justly celebrated occupy himself with the subject1 which induced him to invite ,prof4 ,j4 ,d4 ,forbes of ,edinburgh to be his guest upon the ,aar glacier in #ahda4 ,on the #hth of ,august they met at the ,grimsel ,hospice1 and for three weeks afterwards they were engaged together daily upon the ice1 sharing at night the shelter of the same rude roof4 ,it is in reference to this visit that ,prof4 ,forbes writes thus at page #ch of the ',travels in the ,alps'3--,far from being ready to admit1 as my sanguine companions wished me to do in #ahda1 that the theory of glaciers was complete1 and the cause of their motion certain1 after patiently hearing all they had to say and reserving my opinion1 ,i drew the conclusion that no theory which ,i had then heard of could account for the few facts admitted on all hands4 ,in #ahdb ,prof4 ,forbes repaired1 as early as the state of the snow permitted1 to the ,mer de ,glace2 he worked there1 in the first instance1 for a week1 and afterwards crossed over to ,courmayeur to witness a solar eclipse4 ,the result of his week's observations was immediately communicated to ,prof4 ,jameson1 then editor of the ',edinburgh ,new ,philosophical ,journal4' ,sidenote3 ,,centre ,,moves ,,quickest4 ,in that letter he announces the fact1 but gives no details of the measurement1 that the central part of the glacier moves faster than the edges in a very considerable proportion2 quite contrary to the opinion generally entertained4 ,he also announced at the same time the continuous hourly advance of the glacier4 ,this letter bears the date1 ,courmayeur1 ,piedmont1 #dth ,july1 but it was not published until the month of ,october following4 ,meanwhile ,m4 ,agassiz1 in company with ,m4 ,wild1 returned to complete his experiment upon the glacier of the ,aar4 ,on the #bjth of ,july1 #ahdb1 the displacements of the six piles which he had planted the year before were determined by means of a theodolite4 ,of the three upon the ,finsteraar affluent1 that nearest the side had moved #afj feet1 the next #bbe feet1 while that nearest to the centre had moved #bfi feet4 ,of those on the ,lauteraar1 that nearest the side had moved #abe feet1 the next #baj feet1 and that nearest the centre #bdf feet4 ,these observations were perfectly conclusive as to the quicker motion of the centre3 they embrace a year's motion2 and the magnitude of the displacements1 causing errors of inches1 which might seriously affect small displacements1 to vanish1 justifies us in ranking this experiment with the most satisfactory of the kind that have ever been made4 ,the results were communicated to ,arago in a letter dated from the glacier of the ,aar1 on the #ast of ,august1 #ahdb2 they were laid before the ,academy of ,sciences on the #bith of ,august1 #ahdb1 and are published in the ',comptes ,rendus' of the same date4 ,the facts1 then1 so far as ,i have been able to collect them1 are as follows3--,m4 ,agassiz commenced his experiment about ten months before ,professor ,forbes1 and the results of his measurements1 with quantities stated1 were communicated to the ,french ,academy about two months prior to the publication of the letter of ,professor ,forbes in the ',edinburgh ,philosophical ,journal4' ,but the latter communication1 announcing in general terms the fact of the speedier central motion1 was dated from ,courmayeur twenty-seven days before the date of ,m4 ,agassiz's letter from the glacier of the ,aar4 ,sidenote3 ,,state ,,of ,,the ,,question4 ,the speedier motion of the central portion of a glacier has been justly regarded as one of cardinal importance1 and no other observation has been the subject of such frequent reference2 but the general impression in ,england is that ,m4 ,agassiz had neither part nor lot in the establishment of the above fact2 and in no ,english work with which ,i am acquainted can ,i find any reference to the above measurements4 ,relying indeed upon such sources for my information1 ,i remained ignorant of the existence of the paper in the ',comptes ,rendus' until my attention was directed to it by ,professor ,wheatstone4 ,in the next following chapters ,i shall have to state the results of some of my own measurements1 and shall afterwards devote a little time to the consideration of the cause of glacier-motion4 ,in treating a question on which so much has been written1 it is of course impossible1 as it would be undesirable1 to avoid subjecting both my own views and those of others to a critical examination4 ,but in so doing ,i hope that no expression shall escape me inconsistent with the courtesy which ought to be habitual among philosophers or with the frank recognition of the just claims of my predecessors4 ,,motion ,,of ,,the ,,mer ,,de ,,glace4 7#aj47 ,sidenote3 ,,my ,,first ,,observation4 ,on ,tuesday1 the #adth of ,july1 #aheg1 ,i made my first observation on the motion of the ,mer de ,glace4 ,accompanied by ,mr4 ,hirst ,i selected on the steep slope of the ,glacier des ,bois a straight pinnacle of ice1 the front edge of which was perfectly vertical4 ,in coincidence with this edge ,i fixed the vertical fibre of the theodolite1 and permitted the instrument to stand for three hours4 ,on looking through it at the end of this interval1 the cross hairs were found projected against the white side of the pyramid2 the whole mass having moved several inches downwards4 ,the instrument here mentioned1 which had long been in use among engineers and surveyors1 was first applied to measure glacier-motion in #ahdb2 by ,prof4 ,forbes on the ,mer de ,glace1 and by ,m4 ,agassiz on the glacier of the ,aar4 ,the portion of the theodolite made use of is easily understood4 ,the instrument is furnished with a telescope capable of turning up and down upon a pivot1 without the slightest deviation right or left2 and also capable of turning right or left without the slightest deviation up or down4 ,within the telescope two pieces of spider's thread1 so fine as to be scarcely visible to the naked eye1 are drawn across the tube and across each other4 ,when we look through the telescope we see these fibres1 their point of intersection being exactly in the centre of the tube2 and the instrument is furnished with screws by means of which this point can be fixed upon any desired object with the utmost precision4 ,sidenote3 ,,mode ,,of ,,measurement4 ,in setting a straight row of stakes across the glacier1 our mode of proceeding was in all cases this3--,the theodolite was placed on the mountain-side flanking the glacier1 quite clear of the ice2 and having determined the direction of a line perpendicular to the axis of the glacier1 a well-defined object was sought at the opposite side of the valley as close as possible to this direction2 the object being1 in some cases1 the sharp edge of a cliff2 in others1 a projecting corner of rock2 and1 in others1 a well-defined mark on the face of the rock4 ,this object and those around it were carefully sketched1 so that on returning to the place it could be instantly recognized4 ,on commencing a line the point of intersection of the two spiders' threads within the telescope was first fixed accurately upon the point thus chosen1 and an assistant carrying a straight baton was sent upon the ice4 ,by rough signalling he first stood near the place where the first stake was to be driven in2 and the object end of the telescope was then lowered until he came within the field of view4 ,he held his staff upright upon the ice1 and1 in obedience to signals1 moved upwards or downwards until the point of intersection of the spiders-threads exactly hit the bottom of the baton2 a concerted signal was then made1 the ice was pierced with an auger to a depth of about sixteen inches1 and a stake about two feet long was firmly driven into it4 ,the assistant then advanced for some distance across the glacier2 the end of the telescope was now gently raised until he and his upright staff again appeared in the field of view4 ,he then moved as before until the bottom of his staff was struck by the point of intersection1 and here a second stake was fixed in the ice4 ,in this way the process was continued until the line of stakes was completed4 ,before quitting the station1 a plummet was suspended from a hook directly underneath the centre of the theodolite1 and the place where the point touched the ground was distinctly marked4 ,to measure the motion of the line of stakes1 we returned to the place a day or two afterwards1 and by means of the plummet were able to make the theodolite occupy the exact position which it occupied when the line was set out4 ,the telescope being directed upon the point at the opposite side of the valley1 and gradually lowered1 it was found that no single stake along the line preserved its first position3 they had all shifted downwards4 ,the assistant was sent to the first stake2 the point which it had first occupied was again determined1 and its present distance from that point accurately measured4 ,the same thing was done in the case of each stake1 and thus the displacement of the whole row of stakes was ascertained4,a ,the time at which the stake was fixed1 and at which its displacement was measured1 being carefully noted1 a simple calculation determined the daily motion of the stake4 ,sidenote3 ,,the ,,first ,,line4 ,thus1 on the #agth of ,july1 #aheg1 we set out our first line across the ,mer de ,glace1 at some distance below the ,montanvert2 on the day following we measured the progress of the stakes4 ,the observed displacements are set down in the following table3-- ,first ,line4--,daily ,motion4 ,no4 of stake4 ,inches4 ,west #a moved #ab-a_/d #b #af-c_/d #c #bb-a_/b #d 444 #e #bd-a_/b #f moved 444 #g #bf-a_/d #h 444 #i #bh-c_/d #aj #ce-a_/b ,east4 ,sidenote3 ,,the ,,centre-,,point ,,not ,,the ,,quickest4 ,the theodolite in this case stood on the ,montanvert side of the valley1 and the stakes are numbered from this side4 ,we see that the motion gradually augments from the #ast stake onward--the #ast stake being held back by the friction of the ice against the flanking mountain-side4 ,the stakes #d1 #f1 and #h have no motion attached to them1 as an accident rendered the measurement of their displacements uncertain4 ,but one remarkable fact is exhibited by this line2 the #gth stake stood upon the middle of the glacier1 and we see that its motion is by no means the quickest2 it is exceeded in this respect by the stakes #i and #aj4 ,the portion of the glacier on which the #ajth stake stood was very much cut up by crevasses1 and1 while the assistant was boring it with his auger1 the ice beneath him was observed1 through the telescope1 to slide suddenly forward for about #d inches4 ,the other stakes retained their positions1 so that the movement was purely local4 ,deducting the #d inches thus irregularly obtained1 we should have a daily motion of #ca-a_/b inches for stake ,no4 #aj4 ,the place was watched for some time1 but the slipping was not repeated2 and a second measurement on the succeeding day made the motion of the #ajth stake #cb inches1 whilst that of the centre of the glacier was only #bg4 ,here1 then1 was a fact which needed explanation2 but1 before attempting this1 ,i resolved1 by repeated measurements in the same locality1 to place the existence of the fact beyond doubt4 ,we therefore ascended to a point upon the old and now motionless moraine1 a little above the ,montanvert ,hotel2 and choosing1 as before1 a well-defined object at the opposite side of the valley1 we set between it and the theodolite a row of twenty stakes across the glacier4 ,their motions1 measured on a subsequent day1 and reduced to their daily rate1 gave the results set down in the following table3-- ,second ,line4--,daily ,motion4 ,no4 of stake4 ,inches4 ,west #a moved #g-a_/b #b #aj-c_/d #c #ab-a_/d #d #ad-a_/b #e #af #f #af-c_/d #g #ag-a_/b #h #ai #i #ai-a_/b #aj #ba #aa moved #ba #ab #bb-a_/b #ac #ba #ad #bb-a_/b #ae #bj-a_/b #af #ba-c_/d #ag #bb-a_/d #ah #be-a_/d #ai 444 #bj #be-c_/d ,east4 ,sidenote3 ,,corroborative ,,measurements4 ,as regards the retardation of the side1 we observe here the same fact as that revealed by our first line--the motion gradually augments from the first stake to the last4 ,the stake ,no4 #bj stood upon the dirty portion of the ice1 which was derived from the ,talefre tributary of the ,mer de ,glace1 and far beyond the middle of the glacier4 ,these measurements1 therefore1 corroborate that made lower down1 as regards the non-coincidence of the point of swiftest motion with the centre of the glacier4 ,but it will be observed that the measurements do not show any retardation of the ice at the eastern extremity of the line of stakes--the motion goes on augmenting from the first stake to the last4 ,the reason of this is1 that in neither of the cases recorded were we able to get the line quite across the glacier2 the crevasses and broken ice-ridges1 which intercepted the vision1 compelled us to halt before we came sufficiently close to the eastern side to make its retardation sensible4 ,but on the #bjth of ,july my friend ,hirst sought out an elevated station on the ,chapeau1 or eastern side of the valley1 whence he could command a view from side to side over all the humps and inequalities of the ice1 the fixed point at the opposite side1 upon which the telescope was directed1 being the corner of a window of the ,montanvert ,hotel4 ,along this line were placed twelve stakes1 the daily motions of which were found to be as follows3-- ,third ,line4--,daily ,motion4 ,no4 of stake4 ,inches4 ,east #a moved #ai-a_/b #b #bb-c_/d #c #bh-c_/d #d #cj-a_/d #e #cc-c_/d #f #bh-a_/d #g moved #bd-a_/b #h #be #i #be #aj #ah #aa 444 #ab #h-a_/b ,west4 ,the numbering of the stakes along this line commenced from the ,chapeau-side of the glacier1 and the retardation of that side is now manifest enough2 the motion gradually augmenting from #ai-a_/b to #cc-a_/b inches4 ,but1 comparing the velocity of the two extreme stakes1 we find that the retardation of stake #ab is much greater than that of stake #a4 ,stake #e1 moreover1 which moved with the maximum velocity1 was not upon the centre of the glacier1 but much nearer to the eastern than to the western side4 ,sidenote3 ,a ,,new ,,peculiarity ,,of ,,glacier ,,motion4 ,it was thus placed beyond doubt that the point of maximum motion of the ,mer de ,glace1 at the place referred to1 is not the centre of the glacier4 ,but1 to make assurance doubly sure1 ,i examined the comparative motion along three other lines1 and found in all the same undeviating result4 ,this result is not only unexpected1 but is quite at variance with the opinions hitherto held regarding the motion of the ,mer de ,glace4 ,the reader knows that the trunk-stream is composed of three great tributaries from the ,geant1 the ,lechaud1 and the ,talefre4 ,the ,glacier du ,geant fills more than half of the trunk-valley1 and the junction between it and its neighbours is plainly marked by the dirt upon the surface of the latter4 ,in fact four medial moraines are crowded together on the eastern side of the glacier1 and before reaching the ,montanvert they have strewn their debris quite over the adjacent ice4 ,a distinct limit is thus formed between the clean ,glacier du ,geant and the other dirty tributaries of the trunk-stream4 ,now the eastern side of the ,mer de ,glace is observed on the whole to be much more fiercely torn than the western side1 and this excessive crevassing has been referred to the swifter motion of the ,glacier du ,geant4 ,it has been thought that1 like a powerful river1 this glacier drags its more sluggish neighbours after it1 and thus tears them in the manner observed4 ,but the measurement of the foregoing three lines shows that this cannot be the true cause of the crevassing4 ,in each case the stakes which moved quickest lay upon the dirty portion of the trunk-stream1 far to the east of the line of junction of the ,glacier du ,geant1 which in fact moved slowest of all4 ,sidenote3 ,,law ,,of ,,motion ,,sought4 ,the general view of the glacier1 and of the shape of the valley which it filled1 suggested to me that the analogy with a river might perhaps make itself good beyond the limits hitherto contemplated4 ,the valley was not straight1 but sinuous4 ,at the ,montanvert the convex side of the glacier was turned eastward2 at some distance higher up1 near the passages called ,les ,ponts1 it was turned westward2 and higher up again it was turned once more1 for a long stretch1 eastward4 ,thus between ,trelaporte and the ,ponts we had what is called a point of contrary flexure1 and between the ,ponts and the ,montanvert a second point of the same kind4 ,sidenote3 ,,conjecture ,,regarding ,,change ,,of ,,flexure4 ,supposing a river1 instead of the glacier1 to sweep through this valley2 its point of maximum motion would not always remain central1 but would deviate towards that side of the valley to which the river turned its convex boundary4 ,indeed the positions of towns along the banks of a navigable river are mainly determined by this circumstance4 ,they are1 in most cases1 situate on the convex sides of the bends1 where the rush of the water prevents silting up4 ,can it be then that the ice exhibits a similar deportment8 that the same principle which regulates the distribution of people along the banks of the ,thames is also acting with silent energy amid the glaciers of the ,alps8 ,if this be the case1 the position of the point of maximum motion ought1 of course1 to shift with the bending of the glacier4 ,opposite the ,ponts1 for example1 the point ought to be on the ,glacier du ,geant1 and westward of the centre of the trunk-stream2 while1 higher up1 we ought to have another change to the eastern side1 in accordance with the change of flexure4 ,on the #beth of ,july a line was set out across the glacier1 one of its fixed termini being a mark upon the first of the three ,ponts4 ,the motion of this line1 measured on a subsequent day1 and reduced to its daily rate1 was found to be as follows3-- ,fourth ,line4--,daily ,motion4 ,no4 of stake4 ,inches4 ,east #a moved #f-a_/b #b #h #c #ab-a_/b #d #ae-a_/d #e #ae-a_/b #f #ah-c_/d #g #ah-a_/d #h #ah-c_/d #i #ai-a_/b #aj moved #ba #aa #bj-a_/b #ab #bc-a_/d #ac #bc-a_/d #ad #ba #ae #bb-a_/d #af #ag-a_/d #ag #ae ,west4 ,this line1 like the third1 was set out and numbered from the eastern side of the glacier1 the theodolite occupying a position on the heights of the ,echelets4 ,a moment's inspection of the table reveals a fact different from that observed on the third line2 there the most easterly stake moved with more than twice the velocity of the most westerly one2 here1 on the contrary1 the most westerly stake moves with more than twice the velocity of the most easterly one4 ,to enable me to compare the motion of the eastern and western halves of the glacier with greater strictness1 my able and laborious companion undertook the task of measuring with a surveyor's chain the line just referred to2 noting the pickets which had been fixed along the line1 and the other remarkable objects which it intersected4 ,the difficulty of thus directing a chain over crevasses and ridges can hardly be appreciated except by those who have tried it4 ,nevertheless1 the task was accomplished1 and the width of the ,mer de ,glace1 at this portion of its course1 was found to be #hfc yards1 or almost exactly half a mile4 ,referring to the last table1 it will be seen that the two stakes numbered #ab and #ac moved with a common velocity of #bc-a_/d inches per day1 and that their motion is swifter than that of any of the others4 ,the point of swiftest motion may be taken midway between them1 and this point was found by measurement to lie #bcc yards west of the dirt which marked the junction of the ,glacier du ,geant with its fellow tributaries3 whereas1 in the former cases1 it lay a considerable distance east of this limit4 ,its distance from the eastern side of the glacier was #fja yards1 and from the western side #bfb yards1 being #agj yards west of the centre of the glacier4 ,sidenote3 ,,conjecture ,,tested4 ,but the measurements enabled me to take the stakes in pairs1 and to compare the velocity of a number of them which stood at certain distances from the eastern side of the valley1 with an equal number which stood at the same distances from the western side4 ,by thus arranging the points two by two1 ,i was able to compare the motion of the entire body of the ice at the one side of the central line with that of the ice at the other side4 ,stake #ag stood about as far from the western side of the glacier as stake #c did from its eastern side2 #af occupied the same relation to #d2 #ae1 to #e2 #ac1 to #g2 and #ab1 to #i4 ,calling each pair of points which thus stand at equal distances from the opposite sides corresponding points1 the following little table exhibits their comparative motions3-- ,numbers and ,velocities of ,corresponding ,points on the ,fourth ,line4 ,no4 ,vel4 ,no4 ,vel4 ,no4 ,vel4 ,no4 ,vel4 ,no4 ,vel4 ,west #ag #ae #af #ag-a_/d #ae #bb-a_/d #ac #bc-a_/d #ab #bc-a_/d ,east #c #ab-a_/b #d #ae-a_/d #e #ae-a_/b #g #ah-a_/d #i #ai-a_/b ,sidenote3 ,,western ,,half ,,moves ,,quickest4 ,the table explains itself4 ,we see that while stake #ag1 which stands west of the centre1 moves #ae inches1 stake #c1 which stands an equal distance east of the centre1 moves only #ab-a_/b inches4 ,comparing every pair of the other points1 we find the same to hold good2 the western stake moves in each case faster than the corresponding eastern one4 ,hence1 the entire western half of the ,mer de ,glace1 at the place crossed by our fourth line1 moves more quickly than the eastern half of the glacier4 ,we next proceeded farther up1 and tested the contrary curvature of the glacier1 opposite to ,trelaporte4 ,the station chosen for this purpose was on a grassy platform of the promontory1 whence1 on the #bhth of ,july1 a row of stakes was fixed at right angles to the axis of the glacier4 ,their motions1 measured on the #cast1 gave the following results3-- ,fifth ,line4,b--,daily ,motion4 ,no4 of stake4 ,inches4 ,west #a moved #aa-a_/d #b #ac-a_/b #c #ab-c_/d #d #ae #e #ae-a_/d #f #af #g #ag-a_/d #h #ai-a_/d #i moved #ai-c_/d #aj #ai #aa #ai-a_/b #ab #ag-a_/b #ac #af #ad #ad-c_/d #ae #aj ,east4 ,this line was set out and numbered from the ,trelaporte side of the valley1 and was also measured by ,mr4 ,hirst1 over boulders1 ice-ridges1 chasms1 and moraines4 ,the entire width of the glacier here was found to be #hic yards1 or somewhat wider than it is at the ,ponts4 ,it will also be observed that its motion is somewhat slower4 ,an inspection of the notes of this line showed me that stakes #c and #ad1 #d and #ab1 #g and #aj1 were corresponding points2 the first of each pair standing as far from the western side1 as the second stood from the eastern4 ,in the following table these points and their velocities are arranged exactly as in the case of the fourth line4 ,numbers and ,velocities of the ,corresponding ,points on the ,fifth ,line4 ,no4 ,vel4 ,no4 ,vel4 ,no4 ,vel4 ,west #c #ab-c_/d #d #ae #g #ag-a_/d ,east #ad #ad-c_/d #ab #ag-a_/b #aj #ai ,sidenote3 ,,eastern ,,half ,,moves ,,quickest4 ,in each case we find that the stake on the eastern side moves more quickly than the corresponding one upon the western side3 so that where the fifth line crosses the glacier the eastern half of the ,mer de ,glace moves more quickly than the western half4 ,this is the reverse of the result obtained at our fourth line1 but it agrees with that obtained on our first three lines1 where the curvature of the valley is similar4 ,the analogy between a river and a glacier moving through a sinuous valley is therefore complete4 ,supposing the points of maximum motion to be determined for a great number of lines across the glacier1 the line uniting all these points is what mathematicians would call the locus of the point of maximum motion4 ,at ,trelaporte this line would lie east of the centre2 at the ,ponts it would lie west of the centre2 hence1 in passing from ,trelaporte to the ,ponts1 it must cross the axis of the glacier4 ,again1 at the ,montanvert1 it would lie east of the centre1 and between the ,ponts and the ,montanvert the axis of the glacier would be crossed a second time4 ,supposing the dotted line in ,fig4 #ba to represent the middle line of the glacier1 then the defined line would represent the locus of the point of maximum motion4 ,it is a curve more deeply sinuous than the valley itself1 and it crosses the axis of the glacier at each point of contrary flexure4 ,sidenote3 ,,locus ,,of ,,point ,,of ,,swiftest ,,motion4 ,illustration3 ,fig4 #ba4 ,locus of the ,point of ,maximum ,motion4 ,to complete our knowledge of the motion of the ,mer de ,glace1 we afterwards determined the velocity of its two accessible tributaries--the ,glacier du ,geant1 and the ,glacier de ,lechaud4 ,on the #bith of ,july1 a line of stakes was set out across the former1 a little above the ,tacul1 and their motion was subsequently found to be as follows3 ,sixth ,line4--,daily ,motion4 ,no4 of stake4 ,inches4 #a moved #aa #b #aj #c #ab #d #ac #e #ab #f moved #ab-c_/d #g #aj-a_/b #h #aj #i #i #aj #e ,the width of the glacier at this place we found to be #aacd yards1 and its maximum velocity1 as shown by the foregoing table1 #ac inches a day4 ,on the #ast of ,august a line was set out across the ,glacier de ,lechaud1 above its junction with the ,talefre3 it commenced beneath the block of stone known as the ,pierre de ,beranger4 ,the displacements of the stakes1 measured on the #crd of ,august1 gave the following results3-- ,seventh ,line4--,daily ,motion4 ,no4 of stake4 ,inches4 #a moved #d-a_/b #b #h-a_/d #c #i-a_/b #d #i #e #h-a_/b #f moved #g-a_/b #g #f-a_/d #h #h-a_/b #i #g #aj #e-a_/b ,the width of the ,glacier de ,lechaud at this place was found to be #hbe yards2 its maximum motion1 as shown by the table1 being #i-a_/b inches a day4 ,this is the slowest rate which we observed upon either the ,mer de ,glace or its tributaries4 ,the width of the ,talefre-branch1 as it descends the cascade1 or1 in other words1 before it is influenced by the pressure of the ,lechaud1 was found approximately to be #fch yards4 ,sidenote3 ,,squeezing ,,at ,,trelaporte4 ,the widths of the tributaries were determined for the purpose of ascertaining the amount of lateral compression endured by the ice in its passage through the neck of the valley at ,trelaporte4 ,adding all together we have-- ,geant #aacd yards4 ,lechaud #hbe ,talefre #fch ,total #beig yards4 ,these three branches1 as shown by the actual measurement of our #eth line1 are forced at ,trelaporte through a channel #hic yards wide2 the width of the trunk stream is a little better than one-third of that of its tributaries1 and it passes through this gorge at a velocity of nearly #bj inches a day4 ,sidenote3 ,,the ,,lechaud ,a ,,driblet4 ,limiting our view to one of the tributaries only1 the result is still more impressive4 ,previous to its junction with the ,talefre1 the ,glacier de ,lechaud stretches before the observer as a broad river of ice1 measuring #hbe yards across3 at ,trelaporte it is squeezed1 in a frozen vice1 between the ,talefre on one side and the ,geant on the other1 to a driblet1 measuring #he yards in width1 or about one-tenth of its former transverse dimension4 ,it will of course be understood that it is the form and not the volume of the glacier that is affected to this enormous extent by the pressure4 ,supposing no waste took place1 the ,glacier de ,lechaud would force precisely the same amount of ice through the narrows at ,trelaporte1 in one day1 as it sends past the ,pierre de ,beranger4 ,at the latter place its velocity is about half of what it is at the former1 but its width is more than nine times as great4 ,hence1 if no waste took place1 its depth1 at ,trelaporte1 would be at least #d-a_/b times its depth opposite the ,pierre de ,beranger4 ,superficial and subglacial melting greatly modify this result4 ,still ,i think it extremely probable that observations directed to this end would prove the comparative shallowness of the upper portions of the ,glacier de ,lechaud4 ,,footnotes3 ,a ,great care is necessary on the part of the man who measures the displacements4 ,the staff ought to be placed along the original line1 and the assistant ought to walk along it until the foot of a perpendicular from the stake is attained4 ,when several days' motion is to be measured1 this precaution is absolutely necessary2 the eye being liable to be grossly deceived in guessing the direction of a perpendicular4 ,b ,the details of the measurement of the fourth and fifth lines are published in the ',philosophical ,transactions1' vol4 cxlix41 p4 #bfa4 ,,ice-,,wall ,,at ,,the ,,tacul4 ,,velocities ,,of ,,top ,,and ,,bottom4 7#aa47 ,as regards the motion of the surface of a glacier1 two laws are to be borne in mind3 #ast1 that regarding the quicker movement of the centre2 #bnd1 that regarding the locus of the point of maximum motion4 ,our next care must be to compare the motion of the surface of a glacier with the motion of those parts which lie near its bed4 ,rendu first surmised that the bottom of the glacier was retarded by friction1 and both ,professor ,forbes,a and ,m4 ,martins,b have confirmed the conjecture4 ,theirs are the only observations which we possess upon the subject2 and ,i was particularly desirous to instruct myself upon this important head by measurements of my own4 ,sidenote3 ,,first ,,attempt ,,at ,,measurement4 ,during the summer of #aheg the eastern side of the ,glacier du ,geant1 near the ,tacul1 exposed a nearly vertical precipice of ice1 measuring #adj feet from top to bottom4 ,i requested ,mr4 ,hirst to fix two stakes in the same vertical plane1 one at the top of the precipice and one near the bottom4 ,this he did upon the #crd of ,august1 and on the #eth ,i accompanied him to measure the progress of the stakes4 ,on the summit of the precipice1 and running along it1 was the lateral moraine of the glacier4 ,the day was warm and the ice liquefying rapidly1 so that the boulders and debris1 deprived incessantly of their support1 came in frequent leaps and rushes down the precipice4 ,into this peril my guide was about to enter1 to measure the displacement of the lower stake1 while ,i was to watch1 and call out the direction in which he was to run when a stone gave way4 ,but ,i soon found that the initial motion was no sure index of the final motion4 ,by striking the precipice1 the stones were often deflected1 and carried wide of their original direction4 ,i therefore stopped the man1 and sent him to the summit of the precipice to remove all the more dangerous blocks4 ,this accomplished1 he descended1 and while ,i stood beside him1 executed the required measurement4 ,from the #crd to the #eth of ,august the upper stake had moved twelve inches1 and the lower one six4 ,unfortunately some uncertainty attached itself to this result1 due to the difficulty of fixing the lower stake4 ,the guide's attention had been divided between his work and his safety1 and he had to retreat more than a dozen times from the falling boulders and debris4 ,i1 on the other hand1 was unwilling to accept an observation of such importance with a shade of doubt attached to it4 ,hence arose the desire to measure the motion myself4 ,on the #aath of ,august ,i therefore reascended to the ,tacul1 and fixed a stake at the top of the precipice1 and another at the bottom4 ,while sitting on the old moraine looking at the two pickets1 the importance of determining the motion of a point midway between the top and bottom forcibly occurred to me1 but1 on mentioning it to my guide1 he promptly pronounced any attempt of the kind absurd4 ,sidenote3 ,,stakes ,,fixed ,,at ,,top1 ,,bottom1 ,,and ,,centre4 ,on scanning the place carefully1 however1 the value of the observation appeared to me to outweigh the amount of danger4 ,i therefore took my axe1 placed a stake and an auger against my breast1 buttoned my coat upon them1 and cut an oblique staircase up the wall of ice1 until ,i reached a height of forty feet from the bottom4 ,here the position of the stake being determined by ,mr4 ,hirst1 who was at the theodolite1 ,i pierced the ice with the auger1 drove in the stake1 and descended without injury4 ,during the whole operation however my guide growled audibly4 ,on the following morning we commenced the ascent of ,mont ,blanc1 a narrative of which is given in ,part ,i4 ,we calculated on an absence of three days1 and estimated that the stakes which had just been fixed would be ready for measurement on our return2 but we did not reach ,chamouni until the afternoon of ,friday1 the #adth4 ,heavy clouds settled1 during our descent1 upon the summits behind us1 and a thunder-peal from the ,aiguilles soon heralded a fall of rain1 which continued without intermission till the afternoon of the #afth1 when the atmosphere cleared1 and showed the mountains clothed to their girdles with snow4 ,the ,montanvert was thickly covered1 and on our way to it we met the servants in charge of the cattle1 which had been driven below the snow-line to obtain food4 ,sidenote3 ,,through ,,gloom ,,to ,,the ,,tacul4 ,on ,monday morning1 the #agth1 a dense fog filled the valley of the ,mer de ,glace4 ,i watched it anxiously4 ,the stakes which we had set at the ,tacul had been often in my thoughts1 and ,i wished to make some effort to save the labour and peril incurred in setting them from being lost4 ,i therefore set out1 in one of the clear intervals1 accompanied by my friend and ,simond1 determined to measure the motion of the stakes1 if possible1 or to fix them more firmly1 if they still stood4 ,as we passed1 however1 from l',angle to the glacier1 the fog became so dense and blinding that we halted4 ,at my request ,mr4 ,hirst returned to the ,montanvert2 and ,simond1 leaving the theodolite in the shelter of a rock1 accompanied me through the obscurity to the ,tacul4 ,we found the topmost stake still stuck by its point in the ice2 but the two others had disappeared1 and we afterwards discovered their fragments in a snow-buttress1 which reared itself against the base of the precipice4 ,they had been hit by the falling stones1 and crushed to pieces4 ,having thus learned the worst1 we descended to the ,montanvert amid drenching rain4 ,sidenote3 ,,descent ,,of ,,boulders4 ,on the morning of the #ahth there was no cloud to be seen anywhere1 and the sunlight glistened brightly on the surface of the ice4 ,we ascended to the ,tacul4 ,the spontaneous falling of the stones appeared more frequent this morning than ,i had ever seen it4 ,the sun shone with unmitigated power upon the ice1 producing copious liquefaction4 ,the rustle of falling debris was incessant1 and at frequent intervals the boulders leaped down the precipice1 and rattled with startling energy amid the rocks at its base4 ,i sent ,simond to the top to remove the looser stones2 he soon appeared1 and urged the moraine-shingle in showers down the precipice1 upon a bevelled slope of which some blocks long continued to rest4 ,they were out of the reach of the guide's baton1 and he sought to dislodge them by sending other stones down upon them4 ,some of them soon gave way1 drawing a train of smaller shingle after them2 others required to be hit many times before they yielded1 and others refused to be dislodged at all4 ,i then cut my way up the precipice in the manner already described1 fixed the stake1 and descended as speedily as possible4 ,we afterwards fixed the bottom stake1 and on the #bjth the displacements of all three were measured4,c ,the spaces passed over by the respective stakes in #bd hours were found to be as follows3-- ,inches4 ,top stake #f4jj ,middle stake #d4ej ,bottom stake #b4ef ,sidenote3 ,,motion ,,of ,,stakes4 ,the height of the precipice was #adj4h feet1 but it sloped off at its upper portion4 ,the height of the middle stake above the ground was #ce feet1 and of the bottom one #d feet4 ,it is therefore proved by these measurements that the bottom of the ice-wall at the ,tacul moves with less than half the velocity of the top2 while the displacement of the intermediate stake shows how the velocity gradually increases from the bottom upwards4 ,,footnotes3 ,a ',edinb4 ,phil4 ,journ41' ,oct4 #ahdf1 p4 #dag4 ,b ,agassiz1 ',systeme ,glaciaire1' p4 #ebb4 ,c ,on this latter occasion my guide volunteered to cut the steps for me up to the pickets2 and ,i permitted him to do so4 ,in fact1 he was at least as anxious as myself to see the measurement carried out4 ,,winter ,,motion ,,of ,,the ,,mer ,,de ,,glace4 7#ab47 ,the winter measurements were executed in the manner already described1 on the #bhth and #bith of ,december1 #ahei4 ,the theodolite was placed on the mountain's side flanking the glacier1 and a well-defined object was chosen at the opposite side of the valley1 so that a straight line between this object and the theodolite was approximately perpendicular to the axis of the glacier4 ,fixing the telescope in the first instance with its cross hairs upon the object1 its end was lowered until it struck the point upon the glacier at which a stake was to be fixed4 ,thanks to the intelligence of my assistants1 after the fixing of the first stake they speedily took up the line at all other points1 requiring very little correction to make their positions perfectly accurate4 ,on the day following that on which the stakes were driven in1 the theodolite was placed in the same position1 and the distances to which the stakes had moved from their original positions were accurately determined4 ,as already stated1 the first line crossed the glacier about #hj yards above the ,montanvert ,hotel4 ,sidenote3 ,,half ,,of ,,summer ,,motion4 ,line ,no4 ,i4--,winter ,motion in ,twenty-four ,hours4 ,no4 of stake4 ,inches4 ,west #a #g-a_/d #b #aa #c #ac-a_/b #d #ac #e #ac-c_/d #f #ad-a_/d #g #ae-c_/d #h #ae-c_/d #i #ab-a_/d #aj #ab #aa #f-a_/b ,east4 ,sidenote3 ,,the ,,same ,,law ,,in ,,summer ,,and ,,winter4 ,the maximum here is fifteen and three-quarters inches2 the maximum summer motion of the same portion of the glacier is about thirty inches4 ,these measurements also show that in winter1 as well as in summer1 the side of the glacier opposite to the ,montanvert moves quicker than that adjacent to it4 ,the stake which moved with the maximum velocity was beyond the moraine of ,la ,noire4 ,the second line crossed the glacier about #acj yards below the ,montanvert4 ,line ,no4 ,,ii4--,winter ,motion in ,twenty-four ,hours4 ,no4 of stake4 ,inches4 #a #g-c_/d #b #i-a_/b #c #ac-c_/d #d #af #e #af #f #ae-c_/d #g #ag-a_/b #h #af-a_/b #i #ad-a_/b #aj #ad ,the maximum here is an inch and three-quarters greater than that of line ,no4 #a4 ,the summer maximum at this portion of the glacier also exceeds that of the part intersected by line ,no4 #a4 ,the surface of the glacier between the two lines is in a state of tension which relieves itself by a system of transverse fissures1 and thus permits of the quicker advance of the forward portion4 ,my desire1 in making these measurements1 was1 in the first place1 to raise the winter observations of the motion to the same degree of accuracy as that already possessed by the summer ones4 ,auguste ,balmat had already made a series of winter observations on the ,mer de ,glace2 but they were made in the way employed before the introduction of the theodolite by ,agassiz and ,forbes1 and shared the unavoidable roughness of such a mode of measurement4 ,they moreover gave us no information as to the motion of the different parts of the glacier along the same transverse line1 and this1 for reasons which will appear subsequently1 was the point of chief interest to me4 ,,cause ,,of ,,glacier-,,motion4 ,,de ,,saussure',s ,,theory4 7#ac47 ,perhaps the first attempt at forming a glacier-theory is that of ,scheuchzer in #agje4 ,he supposed the motion to be caused by the conversion of water into ice within the glacier2 the known and almost irresistible expansion which takes place on freezing1 furnishing the force which pushed the glacier downward4 ,this idea was illustrated and developed with so much skill by ,m4 de ,charpentier1 that his name has been associated with it2 and it is commonly known as the ,theory of ,charpentier1 or the ,dilatation-,theory4 ,m4 ,agassiz supported this theory for a time1 but his own thermometric experiments show us that the body of the glacier is at a temperature of #cb deg4 ,fahr42 that consequently there is no interior magazine of cold to freeze the water with which the glacier is supposed to be incessantly saturated4 ,so that these experiments alone1 if no other grounds existed1 would prove the insufficiency of the theory of dilatation4 ,i may however add1 that the arguments most frequently urged against this theory deal with an assumption1 which ,i do not think its author ever intended to make4 ,sidenote3 ,,the ,,glacier ,,slides4 ,another early surmise was that of ,altmann and ,gruener 7#agfj71 both of whom conjectured that the glacier slid along its bed4 ,this theory received distinct expression from ,de ,saussure in #agii2 and has since been associated with the name of that great alpine traveller1 being usually called the ',theory of ,saussure1' and sometimes the ',sliding ,theory4' ,it is briefly stated in these words3-- ,almost every glacier reposes upon an inclined bed1 and those of any considerable size have beneath them1 even in winter1 currents of water which flow between the ice and the bed which supports it4 ,it may therefore be understood that these frozen masses1 drawn down the slope on which they repose1 disengaged by the water from all adhesion to the bottom1 sometimes even raised by this water1 must glide by little and little1 and descend1 following the inclinations of the valleys1 or of the slopes which they cover4 ,it is this slow but continual sliding of the ice on its inclined base which carries it into the lower valleys4,a ,sidenote3 ,,strained ,,interpretation4 ,de ,saussure devoted but little time to the subject of glacier-motion2 and the absence of completeness in the statement of his views1 arising no doubt from this cause1 has given subsequent writers occasion to affix what ,i cannot help thinking a strained interpretation to the sliding theory4 ,it is alleged that he regarded a glacier as a perfectly rigid body2 that he considered it to be a mass of ice of small depth1 and considerable but uniform breadth1 sliding down a uniform valley1 or pouring from a narrow valley into a wider one4,b ,the introduction of the smallest flexibility or plasticity is moreover emphatically denied to him4,c ,it is by no means probable that the great author of the ',voyages' would have subscribed to this rigid annotation4 ,his theory1 be it remembered1 is to some extent true3 the glacier moves over its bed in the manner supposed1 and the rocks of ,britain bear to this day the traces of these mighty sliders4 ,de ,saussure probably contented himself with a general statement of what he believed to be the substantial cause of the motion4 ,he visited the ,jardin1 and saw the tributaries of the ,mer de ,glace turning round corners1 welding themselves together1 and afterwards moving through a sinuous trunk-valley2 and it is scarcely credible that in the presence of such facts he would have denied all flexibility to the glacier4 ,the statement that he regarded a glacier to be a mass of ice of uniform width1 is moreover plainly inconsistent with the following description of the glacier of ,mont ,dolent3 ,its most elevated plateau is a great circus1 surrounded by high cliffs of granite1 of pyramidal forms2 thence the glacier descends through a gorge1 in which it is narrowed2 but after having passed the gorge1 it enlarges again1 spreading out like a fan4 ,thus it has on the whole the form of a sheaf tied in the middle and dilated at its two extremities4,d ,sidenote3 ,,glacier ,,of ,,mont ,,dolent4 ,curiously enough this very glacier1 and these very words1 are selected by ,m4 ,rendu as illustrative of the plasticity of glaciers4 ,nothing1 he says1 shows better the extent to which a glacier moulds itself to its locality than the form of the glacier of ,mont ,dolent in the ,valley of ,ferret2 and he adds1 in connexion with the same passage1 these remarkable words3--,there is a multitude of facts which would seem to necessitate the belief that the substance of glaciers enjoys a kind of ductility which permits it to mould itself to the locality which it occupies1 to grow thin1 to swell1 and to narrow itself like a soft paste4,e ,,footnotes3 ,a ',voyages1' ,sec4 #ece4 ,b ,james ,d4 ,forbes1 ',occasional ,papers on the ,theory of ,glaciers1' #ahei1 p4 #ajj4 ,c ,i adhere to the definition as excluding the introduction of the smallest flexibility or plasticity4 ',occ4 ,pap41' p4 #if4 ,d ',voyages1' tome ii4 p4 #bij4 ,e ,in connexion with this brief sketch of the ',sliding ,theory1' it ought to be stated1 that ,mr4 ,hopkins has proved experimentally1 that ice may descend an incline at a sensibly uniform rate1 and that the velocity is augmented by increasing the weight4 ,in this remarkable experiment the motion was due to the slow disintegration of the lower surface of the ice4 ,see ',phil4 ,mag41' #ahde1 vol4 #bf4 ,,rendu',s ,,theory4 7#ad47 ,sidenote3 ,,rendu',s ,,character4 ,m4 ,rendu1 ,bishop of ,annecy1 to whose writings ,i have just referred1 died last autumn4,a ,he was a man of great repute in his diocese1 and we owe to him one of the most remarkable essays upon glaciers that have ever appeared4 ,his knowledge was extensive1 his reasoning close and accurate1 and his faculty of observation extraordinary4 ,with these were associated that intuitive power1 that presentiment concerning things as yet untouched by experiment1 which belong only to the higher class of minds4 ,throughout his essay a constant effort after quantitative accuracy reveals itself4 ,he collects observations1 makes experiments1 and tries to obtain numerical results2 always taking care1 however1 so to state his premises and qualify his conclusions that nobody shall be led to ascribe to his numbers a greater accuracy than they merit4 ,it is impossible to read his work1 and not feel that he was a man of essentially truthful mind1 and that science missed an ornament when he was appropriated by the ,church4 ,the essay above referred to is printed in the tenth volume of the ,memoirs of the ,royal ,academy of ,sciences of ,savoy1 published in #ahda1 and is entitled1 ',theorie des ,glaciers de la ,savoie1 par ,m4 le ,chanoine ,rendu1 ,chevalier du ,merite ,civil et ,secretaire perpetuel4' ,the paper had been written for nearly two years1 and might have remained unprinted1 had not another publication on the same subject called it forth4 ,i will place a few of the leading points of this remarkable production before the reader2 commencing with a generalization which is highly suggestive of the character of the author's mind4 ,sidenote3 ,,theorie ,,des ,,glaciers ,,de ,,la ,,savoie4 ,he reflects on the accumulation of the mountain-snows1 each year adding fifty-eight inches of ice to a glacier4 ,this would make ,mont ,blanc four hundred feet higher in a century1 and four thousand feet higher in a thousand years4 ,it is evident1 he says1 that nothing like this occurs in nature4 ,the escape of the ice then leads him to make some general remarks on what he calls the law of circulation4 ,the conserving will of the ,creator has employed for the permanence of ,his work the great law of circulation1 which1 strictly examined1 is found to reproduce itself in all parts of nature4 ,the waters circulate from the ocean to the air1 from the air to the earth1 and from the earth to the ocean4444 ,the elements of organic substances circulate1 passing from the solid to the liquid or aeriform condition1 and thence again to the state of solidity or of organisation4 ,that universal agent which we designate by the names of fire1 light1 electricity1 and magnetism1 has probably also a circulation as wide as the universe4 ,the italics here are ,rendu's own4 ,this was published in #ahda1 but written1 we are informed1 nearly two years before4 ,in #ahdb ,mr4 ,grove wrote thus3--,light1 heat1 magnetism1 motion1 and chemical affinity1 are all convertible material affections4 ,more recently ,helmholtz1 speaking of the circuit formed by heat1 light1 electricity1 magnetism1 and chemical affinity1 writes thus3--,starting from each of these different manifestations of natural forces1 we can set every other in action4 ,i quote these passages because they refer to the same agents as those named by ,m4 ,rendu1 and to which he ascribes circulation4 ,can it be doubted that this ,savoyard priest had a premonition of the ,conservation of ,force8 ,i do not want to lay more stress than it deserves upon a conjecture of this kind2 but its harmony with an essay remarkable for its originality gives it a significance which1 if isolated1 it might not possess4 ,sidenote3 ,,glaciers ,,rightly ,,divided4 ,with regard to the glaciers1 ,rendu commences by dividing them into two kinds1 or rather the selfsame glacier into two parts1 one of which he calls the glacier reservoir1 the other the glacier d'ecoulement1--two terms highly suggestive of the physical relationship of the neve and the glacier proper4 ,he feeds the reservoirs from three sources1 the principal one of which is the snow1 to which he adds the rain1 and the vapours which are condensed upon the heights without passing into the state of either rain or snow4 ,the conversion of the snow into ice he supposes to be effected by four different causes1 the most efficacious of which is pressure4,b ,it is needless to remark that this quite agrees with the views now generally entertained4 ,in page #fj of the volume referred to there is a passage which shows that the veined structure of the glacier had not escaped him1 though it would seem that he ascribed it to stratification4 ,when1 he writes1 we perceive the profile of a glacier on the walls of a crevasse1 we see different layers distinct in colour1 but more particularly in density2 some seem to have the hardness1 as they have the greenish colour1 of glass2 others preserve the whiteness and porosity of the snow4 ,there is also a very close resemblance between his views of the influence of time and cohesion and those of ,prof4 ,forbes4 ,we may conclude1 he writes1 that time1 favouring the action of affinity1 and the pressure of the layers one upon the other1 causes the little crystals of which snow is composed to approach each other1 bring them into contact1 and convert them into ice4,c ,regelation also appears to have attracted his notice4,d ,when we fill an ice-house1 he writes1 we break the ice into very small fragments2 afterwards we wet it with water #h or #aj degrees above zero 7,cent47 in temperature2 but1 notwithstanding this1 the whole is converted into a compact mass of ice4 ,he moreover maintains1 in almost the same language as ,prof4 ,forbes1,e the opinion1 that ice has always an inner temperature lower than zero 7,cent474 ,he believed this to be a property inherent to ice4 ,never1 he says1 can a calorific ray pass the first surface of ice to raise the temperature of the interior4,f ,sidenote3 ,,observations ,,and ,,hypotheses4 ,he notices the direction of the glacier as influencing the wasting of its ridges by the sun's heat2 ascribing to it the effect to which ,i have referred in explaining the wave-like forms upon the surface of the ,mer de ,glace4 ,his explanation of the ,moulins1 too1 though insufficient1 assigns a true cause1 and is an excellent specimen of physical reasoning4 ,with regard to the diminution of the glaciers reservoirs1 or1 in other words1 to the manner in which the ice disappears1 notwithstanding the continual additions made to it1 we have the following remarkable passage3--,in seeking the cause of the diminution of glaciers1 it has occurred to my mind that the ice1 notwithstanding its hardness and its rigidity1 can only support a given pressure without breaking or being squeezed out4 ,according to this supposition1 whenever the pressure exceeds that force1 there will be rupture of the ice1 and a flow in consequence4 ,let us take1 at the summit of ,mont ,blanc1 a column of ice reposing on a horizontal base4 ,the ice which forms the first layer of that column is compressed by the weight of all the layers above it2 but if the solidity of the said first layer can only support a weight equal to #ajj1 when the weight exceeds this amount there will be rupture and spreading out of the ice of the base4 ,now1 something very similar occurs in the immense crust of ice which covers the summits of ,mont ,blanc4 ,this crust appears to augment at the upper surface and to diminish by the sides4 ,to assure oneself that the movement is due to the force of pressure1 it would be necessary to make a series of experiments upon the solidity of ice1 such as have not yet been attempted4,g ,i may remark that such experiments substantially verify ,m4 ,rendu's notion4 ,but it is his observations and reasoning upon the glaciers d'ecoulement that chiefly interest us4 ,the passages in his writings where he insists upon the power of the glaciers to mould themselves to their localities1 and compares them to a soft paste1 to lava at once ductile and liquid1 are well known from the frequent and flattering references of ,professor ,forbes2 but there are others of much greater importance1 which have hitherto remained unknown in this country4 ,regarding the motion of the ,mer de ,glace1 ,rendu writes as follows3-- ,sidenote3 ,,measurement ,,of ,,motion4 ,sidenote3 ,,the ,,sides ,,of ,,the ,,glacier ,,retarded4 ,i sought to appreciate the quantity of its motion2 but ,i could only collect rather vague data4 ,i questioned my guides regarding the position of an enormous rock at the edge of the glacier1 but still upon the ice1 and consequently partaking of its motion4 ,the guides showed me the place where it stood the preceding year1 and where it had stood two1 three1 four1 and five years previously2 they showed me the place where it would be found in a year1 in two years1 c42 so certain are they of the regularity of the motion4 ,their reports1 however1 did not always agree precisely with each other1 and their indications of time and distance lack the precision without which we proceed obscurely in the physical sciences4 ,in reducing these different indications to a mean1 ,i found the total advance of the glacier to be about #dj feet a year4 ,during my last journey ,i obtained more certain data1 which ,i have stated in the preceding chapter4 ,the enormous difference between the two results arises from the fact that the latter observations were made at the centre of the glacier1 ,,which ,,moves ,,more ,,rapidly1 while the former were made at the side1 where the ice ,,is ,,retained ,,by ,,the ,,friction ,,against ,,its ,,rocky ,,walls4,h ,an opinion1 founded on a grave misapprehension which ,rendu enables us to correct1 is now prevalent in this country1 not only among the general public1 but also among those of the first rank in science4 ,the nature of the mistake will be immediately apparent4 ,at page #abh of the ',travels in the ,alps' its distinguished author gives a sketch of the state of our knowledge of glacier-motion previous to the commencement of his inquiries4 ,he cites ,ebel1 ,hugi1 ,agassiz1 ,bakewell1 ,de la ,beche1 ,shirwell1 ,rendu1 and places them in open contradiction to each other4 ,rendu1 he says1 gives the motion of the ,mer de ,glace to be #bdb feet per annum2 #ddb feet per annum2 a foot a day2 #djj feet per annum1 and #dj feet per annum1 or one-tenth of the last6 444 and he adds1 ,i was not therefore wrong in supposing that the actual progress of a glacier was yet a new problem when ,i commenced my observations on the ,mer de ,glace in #ahdb4;,i ,in the ',north ,british ,review' for ,august1 #ahei1 a writer equally celebrated for the brilliancy of his discoveries and the vigour of his pen1 collected the data furnished by the above paragraph into a table1 which he introduced to his readers in the following words3--,it is to ,professor ,forbes alone that we owe the first and most correct researches respecting the motion of glaciers2 and in proof of this1 we have only to give the following list of observations which had been previously made4 ,observers4 ,name of glacier4 ,annual rate of motion4 ,ebel ,chamouni #ad feet ,ebel ,grindelwald #be ,hugi ,aar #bdj ,agassiz ,aar #bjj ,bakewell ,mer de ,glace #edj ,de la ,beche ,mer de ,glace #fjj ,shirwell ,mer de ,glace #cjj ,m4 ,rendu ,mer de ,glace #cfe ,saussure's ,ladder ,mer de ,glace #cge 444 ,such was the state of our knowledge when ,professor ,forbes undertook the investigation of the subject4 ,i am persuaded that the writer of this article will be the first to applaud any attempt to remove an error which1 advanced on his great authority1 must necessarily be widely disseminated4 ,the numbers in the above table certainly differ widely1 and it is perhaps natural to conclude that such discordant results can be of no value2 but the fact really is that every one of them may be perfectly correct4 ,this fact1 though overlooked by ,professor ,forbes1 was clearly seen by ,rendu1 who pointed out with perfect distinctness the sources from which the discrepancies were derived4 ,sidenote3 ,,discrepancies ,,explained4 ,it is easy1 he says1 to comprehend that it is impossible to obtain a general measure1--that there ought to be one for each particular glacier4 ,the nature of the slope1 the number of changes to which it is subjected1 the depth of the ice1 the width of the couloir1 the form of its sides1 and a thousand other circumstances1 must produce variations in the velocity of the glacier1 and these circumstances cannot be everywhere absolutely the same4 ,much more1 it is not easy to obtain this velocity for a single glacier1 and for this reason4 ,in those portions where the inclination is steep1 the layer of ice is thin1 and its velocity is great2 in those where the slope is almost nothing1 the glacier swells and accumulates2 the mass in motion being double1 triple1 c41 the motion is only the half1 the third1 c4 ,sidenote3 ,,liquid ,,motion ,,ascribed ,,to ,,glacier4 ,but this is not all1 adds ,m4 ,rendu3 ,between the ,mer de ,glace and a river1 there is a resemblance so complete that it is impossible to find in the latter a circumstance which does not exist in the former4 ,in currents of water the motion is not uniform1 neither throughout their width nor throughout their depth2 the friction of the bottom1 that of the sides1 the action of obstacles1 cause the motion to vary1 and only towards the middle of the surface is this entire4444,j ,in #ahde ,professor ,forbes appears to have come to the same conclusion as ,m4 ,rendu2 for after it had been proved that the centre of the ,aar glacier moved quicker than the side in the ratio of fourteen to one1 he accepted the result in these words3--,the movement of the centre of the glacier is to that of a point five metres from the edge as ,,fourteen to ,,one3 such is the effect of plasticity6,k ,indeed1 if the differences exhibited in the table were a proof of error1 the observations of ,professor ,forbes himself would fare very ill4 ,the measurements of glacier-motion made with his own hands vary from less than #db feet a year to #hdh feet a year1 the minimum being less than one-twentieth of the maximum2 and if we include the observations made by ,balmat1 the fidelity of which has been certified by ,professor ,forbes1 the minimum is only one-thirty-seventh of the maximum4 ,sidenote3 ,,north ,,british ,,review4 ,there is another point connected with ,rendu's theory which needs clearing up3--,the idea1 writes the eminent reviewer1 that a glacier is a semifluid body is no doubt startling1 especially to those who have seen the apparently rigid ice of which it is composed4 ,m4 ,rendu himself shrank from the idea1 and did not scruple to say that 'the rigidity of a mass of ice was in direct opposition to it2' and we think that ,professor ,forbes himself must have stood aghast when his fancy first associated the notion of imperfect fluidity with the solid or even the fissured ice of the glacier1 and when he saw in his mind's eye the glaciers of the ,alps flowing like a river along their rugged bed4 ,a truth like this was above the comprehension and beyond the sympathy of the age2 and it required a moral power of no common intensity to submit it to the ordeal of a shallow philosophy1 and the sneers of a presumptuous criticism4 ,these are strong words2 but the fact is that1 so far from shrinking from the idea1 ,rendu affirmed1 with a clearness and an emphasis which have not been exceeded since1 that all the phenomena of a river were reproduced upon the ,mer de ,glace2 its deeps1 its shallows1 its widenings1 its narrowings1 its rapids1 its places of slow motion1 and the quicker flow of its centre than of its sides4 ,he did not shrink from accepting a difference between the central and lateral motion amounting to a ratio of ten to one--a ratio so large that ,professor ,forbes at one time regarded the acceptance of it as a simple absurdity4 ,in this he was perhaps justified2 for his own first observations1 which1 however valuable1 were hasty and incomplete1 gave him a maximum ratio of about one and a half to one1 while the ratio in some cases was nearly one of equality4 ,the observations of ,agassiz however show that the ratio1 instead of being ten to one1 may be infinity to one2 for the lateral ice may be so held back by a local obstacle that in the course of a year it shall make no sensible advance at all4 ,sidenote3 ,,the ,,ice ,,and ,,the ,,glacier4 ,from one thing only did ,m4 ,rendu shrink2 and it is the thing regarding which we are still disunited4 ,he shrank from stating the physical quality of the ice in virtue of which a glacier moved like a river4 ,he demands experiments upon snow and ice to elucidate this subject4 ,the very observations which ,professor ,forbes regards as proofs are those of which we require the physical explanation4 ,it is not the viscous flow1 if you please to call it such1 of the glacier as a whole that here concerns us2 but it is the quality of the ice in virtue of which this kind of motion is accomplished4 ,professor ,forbes sees this difference clearly enough3 he speaks of fissured ice being flexible in hand specimens2 he compares the glacier to a mixture of ice and sand2 and finally1 in a more matured paper1 falls back for an explanation upon the observations of ,agassiz regarding the capillaries of the glacier4,l ,,footnotes3 ,a ,expressions such as last summer1 last autumn1 recently1 will be taken throughout in the sense which they had in the early half of #ahfj1 when this book was first published4--,l4 ,c4 ,t4 ,b ',memoir1' p4 #gg4 ,c ,p4 #ge4 ,d ,p4 #ga4 ,e ',philosophical ,magazine1' #ahei4 ,f ',memoir1' p4 #fi4 ,g ,page #hj4 ,h ,page #ie4 ,i ,at page #ch of the ',travels' the following passage also occurs3--,i believe that ,i may safely affirm that not one observation of the rate of motion of a glacier1 either on the average or at any particular season of the year1 existed when ,i commenced my experiments in #ahdb4 ,j ',theorie1' p4 #if4 ,k ',occ4 ,pap41' p4 #gd4 ,l ,in all that has been written upon glaciers in this country the above passages from the writings of ,rendu are unquoted2 and many who mingled very warmly in the discussions of the subject were1 until quite recently1 ignorant of their existence4 ,i was long in this condition myself1 for ,i never supposed that passages which bear so directly upon a point so much discussed1 and of such cardinal import1 could have been overlooked2 or that the task of calling attention to them should devolve upon myself nearly twenty years after their publication4 ,now that they are discovered1 ,i conceive no difference of opinion can exist as to the propriety of placing them in their true position4 7#ae47 ,the measurements of ,agassiz and ,forbes completely verify the anticipations of ,rendu2 but no writer with whom ,i am acquainted has added anything essential to the ,bishop's statements as to the identity of glacier and liquid motion4 ,he laid down the conditions of the problem with perfect clearness1 and1 as regards the distribution of merit1 the point to be decided is the relative importance of his idea1 and of the measurements which were subsequently made4 ,sidenote3 ,,observations ,,of ,,forbes4 ,the observations on which ,professor ,forbes based the analogy between a glacier and a river are the following3--,in #ahdb he fixed four marks upon the ,mer de ,glace a little below the ,montanvert1 the first of which was #ajj yards distant from the side of the glacier1 while the last was at the centre or a little beyond it4 ,the relative velocity of these four points was found to be #a4jjj #a4ccb #a4cef #a4cfg4 ,the first observations were made upon two of these points1 two others being subsequently added4 ,professor ,forbes also determined the velocity of two points on the ,glacier du ,geant1 and found the ratio of motion1 in the first instance1 to be as #ad to #cb4 ,subsequent measurements1 however1 showed the ratio to be as #ad to #ah1 the larger motion belonging to the station nearest to the centre of the glacier4 ,these are the only measurements which ,i can find in his large work that establish the swifter motion of the centre of the glacier2 and in these cases the velocity of the centre is compared with that of one side only4 ,in no instance that ,i am aware of1 either in #ahdb or subsequent years1 did ,professor ,forbes extend his measurements quite across a glacier2 and as regards completeness in this respect1 no observations hitherto made can at all compare with those executed at the instance of ,agassiz upon the glacier of the ,aar4 ,in #ahdd ,professor ,forbes made a series of interesting experiments on a portion of the ,mer de ,glace near l',angle4 ,he divided a length of #ij feet into #de equal spaces1 and fixed pins at the end of each4 ,his theodolite was placed upon the ice1 and in seventeen days he found that the ice #ij feet nearer the centre than the theodolite had moved #bf inches past the latter4 ,these measurements were undertaken for a special object1 and completely answered the end for which they were intended4 ,in #ahdf ,professor ,forbes made another important observation4 ,fixing three stakes at the heights of #h1 #ed1 and #adc feet above the bed of the glacier1 he found that in five days they moved respectively #b4hg1 #d4ah1 and #d4ff feet4 ,the stake nearest the bed moved most slowly1 thus showing that the ice is retarded by friction4 ,this result was subsequently verified by the measurements of ,m4 ,martins1 and by my own4 ,if we add to the above an observation made during a short visit to the ,aletsch glacier in #ahdd1 which showed its lateral retardation1 ,i believe we have before us the whole of the measurements executed by ,professor ,forbes1 which show the analogy between the motion of a glacier and that of a viscous body4 ,sidenote3 ,,measurements ,,of ,,agassiz4 ,illustrative of the same point1 we have the elaborate and extensive series of measurements executed by ,m4 ,wild under the direction of ,m4 ,agassiz upon the glacier of the ,aar in #ahdb1 #ahdc1 #ahdd1 and #ahde1 which exhibit on a grand scale1 and in the most conclusive manner1 the character of the motion of this glacier2 and also show1 on close examination1 an analogy with fluid motion which neither ,m4 ,agassiz nor ,professor ,forbes suspected4 ,the former philosopher publishes a section in his ',systeme ,glaciaire1' entitled ',migrations of the ,centre2' in which he shows that the middle of the glacier is not always the point of swiftest motion4 ,the detection of this fact demonstrates the attention devoted by ,m4 ,agassiz to the discussion of his observations1 but he gives no clue to the cause of the variation4 ,on inspecting the shape of the valley through which the ,aar glacier moves1 ,i find that these migrations follow the law established in #aheg upon the ,mer de ,glace1 and enunciated at page #bhf4 ,to sum up this part of the question3--,the idea of semi-fluid motion belongs entirely to ,rendu2 the proof of the quicker central flow belongs in part to ,rendu1 but almost wholly to ,agassiz and ,forbes2 the proof of the retardation of the bed belongs to ,forbes alone2 while the discovery of the locus of the point of maximum motion belongs1 ,i suppose1 to me4 ,,forbes',s ,,theory4 7#af47 ,the formal statement of this theory is given in the following words3--,a glacier is an imperfect fluid1 or viscous body1 which is urged down slopes of a certain inclination by the mutual pressure of its parts4 ,the consistency of the glacier is illustrated by reference to treacle1 honey1 and tar1 and the theory thus enunciated and exemplified is called the ',viscous ,theory4' ,it has been the subject of much discussion1 and great differences of opinion are still entertained regarding it4 ,able and sincere men take opposite sides2 and the extraordinary number of ,reviews which have appeared upon the subject during the last two years show the interest which the intellectual public of ,england take in the question4 ,the chief differences of opinion turn upon the inquiry as to what ,professor ,forbes really meant when he propounded the viscous theory2 some affirm one thing1 some another1 and1 singularly enough1 these differences continue1 though the author of the theory has at various times published expositions of his views4 ,sidenote3 ,,facts ,,and ,,principles4 ,the differences referred to arise from the circumstances that a sufficient distinction has not been observed between facts and principles1 and that the viscous theory has assumed various forms since its first promulgation4 ,it has been stated to me that the theory of ,professor ,forbes is the congeries of facts which he has discovered4 ,but it is quite evident that no recognition1 however ample1 of these facts would be altogether satisfactory to ,professor ,forbes himself4 ,he claims recognition of his theory1,a and no writer with whom ,i am acquainted makes such frequent use of the term4 ,what then can the viscous theory mean apart from the facts8 ,i interpret it as furnishing the principle from which the facts follow as physical consequences--that the glacier moves as a river because the ice is viscous4 ,in this sense only can ,professor ,forbes's views be called a theory2 in any other1 his experiments are mere illustrations of the facts of glacier motion1 which do not carry us a hair's breadth towards their physical cause4 ,sidenote3 ,,viscous ,,theory2--,,what ,,is ,,it8 ,what then is the meaning of viscosity or viscidity8 ,i have heard it defined by men of high culture as gluey tenacity2 and such tenacity they once supposed a glacier to possess4 ,if we dip a spoon into treacle1 honey1 or tar1 we can draw the substance out into filaments1 and the same may be done with melted caoutchouc or lava4 ,all these substances are viscous1 and all of them have been chosen to illustrate the physical property in virtue of which a glacier moves4 ,viscosity then consists in the power of being drawn out when subjected to a force of tension1 the substance1 after stretching1 being in a state of molecular equilibrium1 or1 in other words1 devoid of that elasticity which would restore it to its original form4 ,this certainly was the idea attached to ,professor ,forbes's words by some of his most strenuous supporters1 and also by eminent men who have never taken part in any controversy on the subject4 ,mr4 ,darwin1 for example1 speaks of felspathic rocks being stretched while flowing slowly onwards in a pasty condition1 in precisely the same manner as ,professor ,forbes believes that the ice of moving glaciers is stretched and fissured2 and ,professor ,forbes himself quotes these words of ,mr4 ,darwin as illustrative of his theory4,b ,the question now before us is1--,does a glacier exhibit that power of yielding to a force of tension which would entitle its ice to be regarded as a viscous substance8 ,sidenote3 ,,theory ,,tested4 ,with a view to the solution of this question ,mr4 ,hirst took for me the inclinations of the ,mer de ,glace and all its tributaries in #aheg2 the effect of a change of inclination being always noted4 ,i will select from those measurements a few which bear more specially upon the subject now under consideration1 commencing with the ,glacier des ,bois1 down which the ice moves in that state of wild dislocation already described4 ,the inclination of the glacier above this cascade is #e deg4 #aj'1 and that of the cascade itself is #bb deg4 #bj'1 the change of inclination being therefore #ag deg4 #aj'4 ,illustration3 ,fig4 #bb4 ,inclinations of ice cascasde of the ,glacier des ,bois4 ,in ,fig4 #bb ,i have protracted the inclination of the cascade and of the glacier above it2 the line ,a ,b representing the former and ,b ,c the latter4 ,now a stream of molten lava1 of treacle1 or tar1 would1 in virtue of its viscosity1 be able to flow over the brow at ,b without breaking across2 but this is not the case with the glacier2 it is so smashed and riven in crossing this brow1 that1 to use the words of ,professor ,forbes himself1 it pours into the valley beneath in a cascade of icy fragments4 ,sidenote3 ,,inclinations ,,of ,,the ,,mer ,,de ,,glace4 ,but this reasoning will appear much stronger when we revert to other slopes upon the ,mer de ,glace4 ,for example1 its inclination above l',angle is #d deg41 and it afterwards descends a slope of #i deg4 #be'1 the change of inclination being #e deg4 #be'4 ,if we protract these inclinations to scale1 we have the line ,a ,b1 ,fig4 #bc1 representing the steeper slope1 and ,b ,c that of the glacier above it4 ,one would surely think that a viscous body could cross the brow ,b without transverse fracture1 but this the glacier cannot do1 and ,professor ,forbes himself pronounces this portion of the ,mer de ,glace impassable4 ,indeed it was the profound crevasses here formed which placed me in a difficulty already referred to4 ,higher up again1 the glacier is broken on passing from a slope of #c deg4 #aj' to one of #e deg4 ,such observations show how differently constituted a glacier is from a stream of lava in a pasty condition1 or of treacle1 honey1 tar1 or melted caoutchouc1 to all which it has been compared4 ,in the next section ,i shall endeavour to explain the origin of the crevasses1 and shall afterwards make a few additional remarks on the alleged viscosity of ice4 ,illustration3 ,fig4 #bc4 ,inclinations of ,mer de ,glace above l',angle4 ,,footnotes3 ,a ,mr4 ,hopkins1 writes ,professor ,forbes1 has done me the honour1 in the memoirs before alluded to1 to mention with approbation my observations and experiments on the subject of glaciers4 ,he has been more sparing either in praise or criticism of the theory which ,i have founded upon them4 ,had ,mr4 ,hopkins1 c4--,eighth ,letter2 ',occ4 ,papers1' p4 #ff4 ,b ',occ4 ,papers1' p4 #ib4 ,,the ,,crevasses4 7#ag47 ,sidenote3 ,,crevasses ,,caused ,,by ,,the ,,motion4 ,having made ourselves acquainted with the motion of the glacier1 we are prepared to examine those rents1 fissures1 chasms1 or1 as they are most usually called1 ,crevasses1 by which all glaciers are more or less intersected4 ,they result from the motion of the glacier1 and the laws of their formation are deduced immediately from those of the motion4 ,the crevasses are sometimes very deep and numerous1 and apparently without law or order in their distribution4 ,they cut the ice into long ridges1 and break these ridges transversely into prisms2 these prisms gradually waste away1 assuming1 according to the accidents of their melting1 the most fantastic forms4 ,i have seen them like the mutilated statuary of an ancient temple1 like the crescent moon1 like huge birds with outstretched wings1 like the claws of lobsters1 and like antlered deer4 ,such fantastic sculpture is often to be found on the ice cascades1 where the riven glacier has piled vast blocks on vaster pedestals1 and presented them to the wasting action of sun and air4 ,in ,fig4 #bd ,i have given a sketch of a mass of ice of this character1 which stood in #ahei on the dislocated slope of the ,glacier des ,bois4 ,sidenote3 ,,fantastic ,,ice-,,masses4 ,illustration3 ,fig4 #bd4 ,fantastic ,mass of ice4 ,it is usual for visitors to the ,montanvert to descend to the glacier1 and to be led by their guides to the edges of the crevasses1 where1 being firmly held1 they look down into them2 but those who have only made their acquaintance in this way know but little of their magnitude and beauty in the more disturbed portions of glaciers4 ,as might be expected1 they have been the graves of many a mountaineer2 and the skeletons found upon the glacier prove that even the chamois itself1 with its elastic muscles and admirable sureness of foot1 is not always safe among the crevasses4 ,they are grandest in the higher ice-regions1 where the snow hangs like a coping over their edges1 and the water trickling from these into the gloom forms splendid icicles4 ,the ,goerner ,glacier1 as we ascend it towards the old ,weissthor1 presents many fine examples of such crevasses2 the ice being often torn in a most curious and irregular manner4 ,you enter a porch1 pillared by icicles1 and look into a cavern in the very body of the glacier1 encumbered with vast frozen bosses which are fringed all round by dependent icicles4 ,at the peril of your life from slipping1 or from the yielding of the stalactites1 you may enter these caverns1 and find yourself steeped in the blue illumination of the place4 ,their beauty is beyond description2 but you cannot deliver yourself up1 heart and soul1 to its enjoyment4 ,there is a strangeness about the place which repels you1 and not without anxiety do you look from your ledge into the darkness below1 through which the sound of subglacial water sometimes rises like the tolling of distant bells4 ,you feel that1 however the cold splendours of the place might suit a purely spiritual essence1 they are not congenial to flesh and blood1 and you gladly escape from its magnificence to the sunshine of the world above4 ,sidenote3 ,,birth ,,of ,a ,,crevasse4 ,from their numbers it might be inferred that the formation of crevasses is a thing of frequent occurrence and easy to observe2 but in reality it is very rarely observed4 ,simond was a man of considerable experience upon the ice1 but the first crevasse he ever saw formed was during the setting out of one of our lines1 when a narrow rent opened beneath his feet1 and propagated itself through the ice with loud cracking for a distance of #ej or #fj yards4 ,crevasses always commence in this way as mere narrow cracks1 which open very slowly afterwards4 ,i will here describe the only case of crevasse-forming which has come under my direct observation4 ,on the #cast of ,july1 #aheg1 ,mr4 ,hirst and myself1 having completed our day's work1 were standing together upon the ,glacier du ,geant1 when a loud dull sound1 like that produced by a heavy blow1 seemed to issue from the body of the ice underneath the spot on which we stood4 ,this was succeeded by a series of sharp reports1 which were heard sometimes above us1 sometimes below us1 sometimes apparently close under our feet1 the intervals between the louder reports being filled by a low singing noise4 ,we turned hither and thither as the direction of the sounds varied2 for the glacier was evidently breaking beneath our feet1 though we could discern no trace of rupture4 ,for an hour the sounds continued without our being able to discover their source2 this at length revealed itself by a rush of air-bubbles from one of the little pools upon the surface of the glacier1 which was intersected by the newly-formed crevasse4 ,we then traced it for some distance up and down1 but hardly at any place was it sufficiently wide to permit the blade of my penknife to enter it4 ,m4 ,agassiz has given an animated description of the terror of his guides upon a similar occasion1 and there was an element of awe in our own feelings as we heard the evening stillness of the glacier thus disturbed4 ,sidenote3 ,,mechanical ,,origin4 ,with regard to the mechanical origin of the crevasses the most vague and untenable notions had been entertained until ,mr4 ,hopkins published his extremely valuable papers4 ,to him1 indeed1 we are almost wholly indebted for our present knowledge of the subject1 my own experiments upon this portion of the glacier-question being for the most part illustrations of the truth of his reasoning4 ,to understand the fissures in their more complex aspects it is necessary that we should commence with their elements4 ,i shall deal with the question in my own way1 adhering1 however1 to the mechanical principles upon which ,mr4 ,hopkins has based his exposition4 ,illustration3 ,fig4 #be4 ,diagram explanatory of the mechanical origin of ,crevasses4 ,let ,a ,b1 ,c ,d1 be the bounding sides of a glacier moving in the direction of the arrow2 let m1 n be two points upon the ice1 one1 m1 close to the retarding side of the valley1 and the other1 n1 at some distance from it4 ,after a certain time1 the point m will have moved downwards to m'1 but in consequence of the swifter movement of the parts at a distance from the sides1 n will have moved in the same time to n'4 ,thus the line m n1 instead of being at right angles to the glacier1 takes up the oblique position m' n'2 but to reach from m' to n' the line m n would have to stretch itself considerably2 every other line that we can draw upon the ice parallel to m' n' is in a similar state of tension2 or1 in other words1 the sides of the glacier are acted upon by an oblique pull towards the centre4 ,now1 ,mr4 ,hopkins has shown that the direction in which this oblique pull is strongest encloses an angle of #de deg4 with the side of the glacier4 ,sidenote3 ,,line ,,of ,,greatest ,,strain4 ,illustration3 ,fig4 #bf4 ,diagram showing the line of ,greatest ,strain4 ,what is the consequence of this8 ,let ,a ,b1 ,c ,d1 ,fig4 #bf1 represent1 as before1 the sides of the glacier1 moving in the direction of the arrow2 let the shading lines enclose an angle of #de deg4 with the sides4 ,along these lines the marginal ice suffers the greatest strain1 and1 consequently across these lines and at right angles to them1 the ice tends to break and to form marginal crevasses4 ,the lines1 o p1 o p1 mark the direction of these crevasses2 they are at right angles to the line of greatest strain1 and hence also enclose an angle of #de deg4 with the side of the valley1 being obliquely pointed upwards4 ,sidenote3 ,,marginal ,,and ,,transverse ,,crevasses4 ,this latter result is noteworthy2 it follows from the mechanical data that the swifter motion of the centre tends to produce marginal crevasses which are inclined from the side of the glacier towards its source1 and not towards its lower extremity4 ,but when we look down upon a glacier thus crevassed1 the first impression is that the sides have been dragged down1 and have left the central portions behind them2 indeed1 it was this very appearance that led ,m4 de ,charpentier and ,m4 ,agassiz into the error of supposing that the sides of a glacier moved more quickly than its middle portions2 and it was also the delusive aspect of the crevasses which led ,professor ,forbes to infer the slower motion of the eastern side of the ,mer de ,glace4 ,the retardation of the ice is most evident near the sides2 in most cases1 the ice for a considerable distance right and left of the central line moves with a sensibly uniform velocity2 there is no dragging of the particles asunder by a difference of motion1 and1 consequently1 a compact centre is perfectly compatible with fissured sides4 ,nothing is more common than to see a glacier with its sides deeply cut1 and its central portions compact2 this1 indeed1 is always the case where the glacier moves down a bed of uniform inclination4 ,but supposing that the bed is not uniform--that the valley through which the glacier moves changes its inclination abruptly1 so as to compel the ice to pass over a brow2 the glacier is then circumstanced like a stick which we try to break by holding its two ends and pressing it against the knee4 ,the brow1 where the bed changes its inclination1 represents the knee in the case of the stick1 while the weight of the glacier itself is the force that tends to break it4 ,it breaks2 and fissures are formed across the glacier1 which are hence called transverse crevasses4 ,sidenote3 ,,grindelwald ,,glacier4 ,no glacier with which ,i am acquainted illustrates the mechanical laws just developed more clearly and fully than the ,lower glacier of ,grindelwald4 ,proceeding along the ordinary track beside the glacier1 at about an hour's distance from the village the traveller reaches a point whence a view of the glacier is obtained from the heights above it4 ,the marginal fissures are very cleanly cut1 and point nearly in the direction already indicated2 the glacier also changes its inclination several times along the distance within the observer's view4 ,on crossing each brow the glacier is broken across1 and a series of transverse crevasses is formed1 which follow each other down the slope4 ,at the bottom of the slope tension gives place to pressure1 the walls of the crevasses are squeezed together1 and the chasms closed up4 ,they remain closed along the comparatively level space which stretches between the base of one slope and the brow of the next2 but here the glacier is again transversely broken1 and continues so until the base of the second slope is reached1 where longitudinal pressure instead of longitudinal strain begins to act1 and the fissures are closed as before4 ,in ,fig4 #bg;,a ,i have given a sketchy section of a portion of the glacier1 illustrating the formation of the crevasses at the top of a slope1 and their subsequent obliteration at its base4 ,sidenote3 ,,compression ,,and ,,tension4 ,illustration3 ,fig4 #bg;,a1 ,b4 ,section and ,plan of a portion of the ,lower ,grindelwald ,glacier4 ,another effect is here beautifully shown1 namely1 the union of the transverse and marginal crevasses to form continuous fissures which stretch quite across the glacier4 ,fig4 #bg;,b will illustrate my meaning1 though very imperfectly2 it represents a plan of a portion of the ,lower ,grindelwald glacier1 with both marginal and transverse fissures drawn upon it4 ,i have placed it under the section so that each part of it may show in plan the portion of the glacier which is shown in section immediately above it4 ,it shows how the marginal crevasses remain after the compression of the centre has obliterated the transverse ones2 and how the latter join on to the former1 so as to form continuous fissures1 which sweep across the glacier in vast curves1 with their convexities turned upwards4 ,the illusion before referred to is here strengthened2 the crevasses turn1 so to say1 against the direction of motion1 instead of forming loops1 with their convexities pointing downwards1 and thus would impress a person unacquainted with the mechanical data with the idea that the glacier margins moved more quickly than the centre4 ,the figures are intended to convey the idea merely2 on the actual slopes of the glacier between twenty and thirty chasms may be counted3 also the word compression ought to have been limited to the level portions of the sketch4 ,sidenote3 ,,longitudinal ,,crevasses4 ,besides the two classes of fissures mentioned we often find others1 which are neither marginal nor transverse4 ,the terminal portions of many glaciers1 for example1 are in a state of compression2 the snout of the glacier abuts against the ground1 and having to bear the thrust of the mass behind it1 if it have room to expand laterally1 the ice will yield1 and longitudinal crevasses will be formed4 ,they are of very common occurrence1 but the finest example of the kind is perhaps exhibited by the glacier of the ,rhone4 ,after escaping from the steep gorge which holds the cascade1 this glacier encounters the bottom of a comparatively wide and level valley2 the resistance to its forward motion is augmented1 while its ability to expand laterally is increased2 it has to bear a longitudinal thrust1 and it splits at right angles to the pressure strain84 ,a series of fissures is thus formed1 the central ones of which are truly longitudinal2 but on each side of the central line the crevasses diverge1 and exhibit a fan-like arrangement4 ,this disposition of the fissures is beautifully seen from the summit of the ,mayenwand on the ,grimsel ,pass4 ,illustration3 ,fig4 #bh4 ,diagram illustrating the crevassing of ,convex ,sides of glacier4 ,here then we have the elements1 so to speak1 of glacier-crevassing1 and through their separate or combined action the most fantastic cutting up of a glacier may be effected4 ,and see how beautifully these simple principles enable us to account for the remarkable crevassing of the eastern side of the ,mer de ,glace4 ,let ,a ,b1 ,c ,d1 be the opposite sides of a portion of the glacier1 near the ,montanvert2 ,c ,d being east1 and ,a ,b west1 the glacier moving in the direction of the arrow2 let the points m n represent the extremities of our line of stakes1 and let us suppose an elastic string stretched across the glacier from one to the other4 ,we have proved that the point of maximum motion here lies much nearer to the side ,c ,d than to ,a ,b4 ,let o be this point1 and1 seizing the string at o1 let it be drawn in the direction of motion until it assumes the position1 m1 o'1 n4 ,it is quite evident that o' n is in a state greater tension than o' m1 and the ice at the eastern side of the ,mer de ,glace is in a precisely similar mechanical condition4 ,it suffers a greater strain than the ice at the opposite side of the valley1 and hence is more fissured and broken4 ,thus we see that the crevassing of the eastern side of the glacier is a simple consequence of the quicker motion of that side1 and does not1 as hitherto supposed1 demonstrate its slower motion4 ,the reason why the eastern side of the glacier1 as a whole1 is much more fissured than the western side is1 that there are two long segments which turn their convex curvature eastward1 and only one segment of the glacier which turns its convexity westward4 ,sidenote3 ,,crevassing ,,of ,,convex ,,side4 ,the lower portion of the ,rhone glacier sweeps round the side of the valley next the ,furca1 and turns throughout a convex curve to this side3 the crevasses here are wide and frequent1 while they are almost totally absent at the opposite side of the glacier4 ,the lower ,grindelwald glacier turns at one place a convex curve towards the ,eiger1 and is much more fissured at that side than at the opposite one2 indeed1 the fantastic ice-splinters1 columns1 and minarets1 which are so finely exhibited upon this glacier1 are mainly due to the deep crevassing of the convex side4 ,numerous other illustrations of the law might1 ,i doubt not1 be discovered1 and it would be a pleasant and useful occupation to one who takes an interest in the subject1 to determine1 by strict measurements upon other glaciers1 the locus of the point of maximum motion1 and to observe the associated mechanical effects4 ,sidenote3 ,,bergschrunds4 ,the appearance of crevasses is often determined by circumstances more local and limited than those above indicated2 a boss of rock1 a protuberance on the side of the flanking mountain1 anything1 in short1 which checks the motion of one part of the ice and permits an adjacent portion to be pushed away from it1 produces crevasses4 ,some valleys are terminated by a kind of mountain-circus with steep sides1 against which the snow rises to a considerable height4 ,as the mass is urged downwards1 the lower portion of the snow-slope is often torn away from its higher portion1 and a chasm is formed1 which usually extends round the head of the valley4 ,to such a crevasse the specific name ,bergschrund is applied in the ,bernese ,alps2 ,i have referred to one of them in the account of the ,passage of the ,strahleck4 7#ah47 ,the phenomena described and accounted for in the last chapter have a direct bearing upon the question of viscosity4 ,in virtue of the quicker central flow the lateral ice is subject to an oblique strain2 but1 instead of stretching1 it breaks1 and marginal crevasses are formed4 ,we also see that a slight curvature in the valley1 by throwing an additional strain upon one half of the glacier1 produces an augmented crevassing of that side4 ,but it is known that a substance confessedly viscous may be broken by a sudden shock or strain4 ,professor ,forbes justly observes that sealing-wax at moderate temperatures will mould itself 7with time7 to the most delicate inequalities of the surface on which it rests1 but may at the same time be shivered to atoms by the blow of a hammer4 ,hence1 in order to estimate the weight of the objection that a glacier breaks when subjected to strain1 we must know the conditions under which the force is applied4 ,the ,mer de ,glace has been shown 7p4 #bhg7 to move through the neck of the valley at ,trelaporte at the rate of twenty inches a day4 ,let the sides of this page represent the boundaries of the glacier at ,trelaporte1 and any one of its lines of print a transverse slice of ice4 ,supposing the line to move down the page as the slice of ice moves down the valley1 then the bending of the ice in twenty-four hours1 shown on such a scale1 would only be sufficient to push forward the centre in advance of the sides by a very small fraction of the width of the line of print4 ,to such an extremely gradual strain the ice is unable to accommodate itself without fracture4 ,sidenote3 ,,numerical ,,test ,,of ,,viscosity4 ,or1 referring to actual numbers3--the stake ,no4 #ae on our #eth line1 page #bhd1 stood on the lateral moraine of the ,mer de ,glace2 and between it and ,no4 #ad a distance of #aij feet intervened4 ,let ,a ,b1 ,fig4 #bi1 be the side of the glacier1 moving in the direction of the arrow1 and let a b c d be a square upon the glacier with a side of #aij feet4 ,the whole square moves with the ice1 but the side b d moves quickest2 the point a moving #aj inches1 while b moves #ad4ge inches in #bd hours2 the differential motion therefore amounts to an inch in five hours4 ,let a b' d' c be the shape of the figure after five hours' motion2 then the line a b would be extended to a b' and c d to c d'4 ,illustration3 ,fig4 #bi4 ,diagram illustrating test of viscosity4 ,the extension of these lines does not however express the maximum strain to which the ice is subjected4 ,mr4 ,hopkins has shown that this takes place along the line a d2 in five hours then this line1 if capable of stretching1 would be stretched to a d'4 ,from the data given every boy who has mastered the #dgth ,proposition of the ,first ,book of ,euclid can find the length both of a d and a d'2 the former is #cbbd4d inches1 and the latter is #cbbe4a1 the difference between them being seven-tenths of an inch4 ,this is the amount of yielding required from the ice in five hours1 but it cannot grant this2 the glacier breaks1 and numerous marginal crevasses are formed4 ,it must not be forgotten that the evidence here adduced merely shows what ice cannot do2 what it can do in the way of viscous yielding we do not know3 there exists as yet no single experiment on great masses or small to show that ice possesses in any sensible degree that power of being drawn out which seems to be the very essence of viscosity4 ,i have already stated that the crevasses1 on their first formation1 are exceedingly narrow rents1 which widen very slowly4 ,the new crevasse observed by our guide required several days to attain a width of three inches2 while that observed by ,mr4 ,hirst and myself did not widen a single inch in three days4 ,this1 ,i believe1 is the general character of the crevasses2 they form suddenly and open slowly4 ,both facts are at variance with the idea that ice is viscous2 for were this substance capable of stretching at the slow rate at which the fissures widen1 there would be no necessity for their formation4 ,sidenote3 ,,stretching ,,of ,,ice ,,not ,,proved4 ,it cannot be too clearly and emphatically stated that the proved fact of a glacier conforming to the law of semi-fluid motion is a thing totally different from the alleged fact of its being viscous4 ,nobody since its first enunciation disputed the former4 ,i had no doubt of it when ,i repaired to the glaciers in #ahef2 and none of the eminent men who have discussed this question with ,professor ,forbes have thrown any doubt upon his measurements4 ,it is the assertion that small pieces of ice are proved to be viscous,a by the experiments made upon glaciers1 and the consequent impression left upon the public mind--that ice possesses the gluey tenacity which the term viscous suggests--to which these observations are meant to apply4 ,,footnotes3 ,a ,the viscosity1 though it cannot be traced in the parts if very minute nevertheless exists there1 as unequivocally proved by experiments on the large scale4--,forbes in ',phil4 ,mag41' vol4 x41 p4 #cja4 ,,heat ,,and ,,work4 7#ai47 ,sidenote3 ,,connexion ,,of ,,natural ,,forces4 ,great scientific principles1 though usually announced by individuals1 are often merely the distinct expression of thoughts and convictions which had long been entertained by all advanced investigators4 ,thus the more profound philosophic thinkers had long suspected a certain equivalence and connexion between the various forces of nature2 experiment had shown the direct connexion and mutual convertibility of many of them1 and the spiritual insight1 which1 in the case of the true experimenter1 always surrounds and often precedes the work of his hands1 revealed more or less plainly that natural forces either had a common root1 or that they formed a circle1 whose links were so connected that by starting from any one of them we could go through the circuit1 and arrive at the point from which we set out4 ,for the last eighteen years this subject has occupied the attention of some of the ablest natural philosophers1 both in this country and on the ,continent4 ,the connexion1 however1 which has most occupied their minds is that between heat and work2 the absolute numerical equivalence of the two having1 ,i believe1 been first announced by a ,german physician named ,mayer1 and experimentally proved in this country by ,mr4 ,joule4 ,sidenote3 ,,mechanical ,,equivalent ,,of ,,heat4 ,a lead bullet may be made hot enough to burn the hand1 by striking it with a hammer1 or by rubbing it against a board2 a clever blacksmith can make a nail red-hot by hammering it2 ,count ,rumford boiled water by the heat developed in the boring of cannon1 and inferred from the experiment that heat was not what it was generally supposed to be1 an imponderable fluid1 but a kind of motion generated by the friction4 ,now ,mr4 ,joule's experiments enable us to state the exact amount of heat which a definite expenditure of mechanical force can originate4 ,i say originate1 not drag from any hiding-place in which it had concealed itself1 but actually bring into existence1 so that the total amount of heat in the universe is thereby augmented4 ,if a mass of iron fall from a tower #ggj feet in height1 we can state the precise amount of heat developed by its collision with the earth4 ,supposing all the heat thus generated to be concentrated in the iron itself1 its temperature would thereby be raised nearly #aj deg4 ,fahr4 ,gravity in this case has expended a certain amount of force in pulling the iron to the earth1 and this force is the mechanical equivalent of the heat generated4 ,furthermore1 if we had a machine so perfect as to enable us to apply all the heat thus produced to the raising of a weight1 we should be able1 by it1 to lift the mass of iron to the precise point from which it fell4 ,but the heat cannot lift the weight and still continue heat2 this is the peculiarity of the modern view of the matter4 ,the heat is consumed1 used up1 it is no longer heat2 but instead of it we have a certain amount of gravitating force stored up1 which is ready to act again1 and to regenerate the heat when the weight is let loose4 ,in fact1 when the falling weight is stopped by the earth1 the motion of its mass is converted into a motion of its molecules2 when the weight is lifted by heat1 molecular motion is converted into ordinary mechanical motion1 but for every portion of either of them brought into existence an equivalent portion of the other must be consumed4 ,what is true for masses is also true for atoms4 ,as the earth and the piece of iron mutually attract each other1 and produce heat by their collision1 so the carbon of a burning candle and the oxygen of the surrounding air mutually attract each other2 they rush together1 and on collision the arrested motion becomes heat4 ,in the former case we have the conversion of gravity into heat1 in the latter the conversion of chemical affinity into heat2 but in each case the process consists in the generation of motion by attraction1 and the subsequent change of that motion into motion of another kind4 ,mechanically considered1 the attraction of the atoms and its results is precisely the same as the attraction of the earth and weight and its results4 ,sidenote3 ,,heat ,,produced ,,if ,,the ,,earth ,,struck ,,the ,,sun4 ,but what is true for an atom is also true for a planet or a sun4 ,supposing our earth to be brought to rest in her orbit by a sudden shock1 we are able to state the exact amount of heat which would be thereby generated4 ,the consequence of the earth's being thus brought to rest would be that it would fall into the sun1 and the amount of heat which would be generated by this second collision is also calculable4 ,helmholtz has calculated that in the former case the heat generated would be equal to that produced by the combustion of fourteen earths of solid coal1 and in the latter case the amount would be #djj times greater4 ,sidenote3 ,,shifting ,,of ,,atoms4 ,whenever a weight is lifted by a steam-engine in opposition to the force of gravity an amount of heat is consumed equivalent to the work done2 and whenever the molecules of a body are shifted in opposition to their mutual attractions work is also performed1 and an equivalent amount of heat is consumed4 ,indeed the amount of work done in the shifting of the molecules of a body by heat1 when expressed in ordinary mechanical work1 is perfectly enormous4 ,the lifting of a heavy weight to the height of #ajjj feet may be as nothing compared with the shifting of the atoms of a body by an amount so small that our finest means of measurement hardly enable us to determine it4 ,different bodies give heat different degrees of trouble1 if ,i may use the term1 in shifting their atoms and putting them in new places4 ,iron gives more trouble than lead2 and water gives far more trouble than either4 ,the heat expended in this molecular work is lost as heat2 it does not show itself as temperature4 ,suppose the heat produced by the combustion of an ounce of candle to be concentrated in a pound of iron1 a certain portion of that heat would go to perform the molecular work to which ,i have referred1 and the remainder would be expended in raising the temperature of the body2 and if the same amount of heat were communicated to a pound of iron and to a pound of lead1 the balance in favour of temperature would be greater in the latter case than in the former1 because the heat would have less molecular work to do2 the lead would become more heated than the iron4 ,to raise a pound of iron a certain number of degrees in temperature would1 in fact1 require more than three times the absolute quantity of heat which would be required to raise a pound of lead the same number of degrees4 ,conversely1 if we place the pound of iron and the pound of lead1 heated to the same temperature1 into ice1 we shall find that the quantity of ice melted by the iron will be more than three times that melted by the lead4 ,in fact1 the greater amount of molecular work invested in the iron now comes into play1 the atoms again obey their own powerful forces1 and an amount of heat corresponding to the energy of these forces is generated4 ,this molecular work is that which has usually been called specific heat1 or capacity for heat4 ,according to the materialistic view of heat1 bodies are figured as sponges1 and heat as a kind of fluid absorbed by them1 different bodies possessing different powers of absorption4 ,according to the dynamic view1 as already explained1 heat is regarded as a motion1 and capacity for heat indicates the quantity of that motion consumed in internal changes4 ,the greatest of these changes occurs when a body passes from one state of aggregation to another1 from the solid to the liquid1 or from the liquid to the aeriform state2 and the quantity of heat required for such changes is often enormous4 ,to convert a pound of ice at #cb deg4 ,fahr4 into water at the same temperature would require an amount of heat competent1 if applied as mechanical force1 to lift the same pound of ice to a height of #aaj1jjj feet2 it would raise a ton of ice nearly #ej feet1 or it would lift between #di and #ej tons to a height of one foot above the earth's surface4 ,to convert a pound of water at #bab deg4 into a pound of steam at the same temperature would require an amount of heat which would perform nearly seven times the amount of mechanical work just mentioned4 ,sidenote3 ,,heat ,,consumed ,,in ,,molecular ,,work4 ,this heat is entirely expended in interior work1,a and does nothing towards augmenting the temperature2 the water is at the temperature of the ice which produced it1 both are #cb deg42 and the steam is at the temperature of the water which produced it1 both are #bab deg4 ,the whole of the heat is consumed in producing the change of aggregation2 ,i say consumed1 not hidden or latent in either the water or the steam1 but absolutely non-existent as heat4 ,the molecular forces1 however1 which the heat has sacrificed itself to overcome are able to reproduce it2 the water in freezing and the steam in condensing give out the exact amount of heat which they consumed when the change of aggregation was in the opposite direction4 ,at a temperature of several degrees below its freezing point ice is much harder than at #cb deg4 ,i have more than once cooled a sphere of the substance in a bath of solid carbonic acid and ether to a temperature of #ajj deg4 below the freezing point4 ,during the time of cooling the ice crackled audibly from its contraction1 and afterwards it quite resisted the edge of a knife2 while at #cb deg4 it may be cut or crushed with extreme facility4 ,the cold sphere was subjected to pressure2 it broke with the detonation of a vitreous body1 and was taken from the press a white opaque powder2 which1 on being subsequently raised to #cb deg4 and again compressed1 was converted into a pellucid slab of ice4 ,sidenote3 ,,ice ,,near ,,the ,,melting ,,point4 ,but before the temperature of #cb deg4 is quite attained1 ice gives evidence of a loosening of its crystalline texture4 ,indeed the unsoundness of ice at and near its melting point has been long known4 ,sir ,john ,leslie1 for example1 states that ice at #cb deg4 is friable2 and every skater knows how rotten ice becomes before it thaws4 ,m4 ,person has further shown that the latent heat of ice1 that is to say1 the quantity of heat necessary for its liquefaction1 is not quite expressed by the quantity consumed in reducing ice at #cb deg4 to the liquid state4 ,the heat begins to be rendered latent1 or in other words the change of aggregation commences1 a little before the substance reaches #cb deg41--a conclusion which is illustrated and confirmed by the deportment of melting ice under pressure4 ,sidenote3 ,,rotten ,,ice ,,and ,,softened ,,wax4 ,in reference to the above result ,professor ,forbes writes as follows3--,i have now to refer to a fact 444 established by a ,french experimenter1 ,m4 ,person1 who appears not to have had even remotely in his mind the theory of glaciers1 when he announced the following facts1 viz4--',that ice does not pass abruptly from the solid to the fluid state2 that it begins to soften at a temperature of #b deg4 ,centigrade below its thawing point2 that1 consequently1 between #bh deg4 #d' and #cb deg4 of ,fahr4 ice is actually passing through various degrees of plasticity within narrower limits1 but in the same manner that wax1 for example1 softens before it melts4' ,the softening here referred to is the friability1 of ,sir ,j4 ,leslie1 and what ,i have called a loosening of the texture4 ,let us suppose the ,serpentine covered by a sheet of pitch so smooth and hard as to enable a skater to glide over it2 and which is afterwards gradually warmed until it begins to bend under his weight1 and finally lets him through4 ,a comparison of this deportment with that of a sheet of ice under the same circumstances enables us to decide whether ice passes through various degrees of plasticity in the same manner as wax softens before it melts4 ,m4 ,person concerned himself solely with the heat absorbed1 and no doubt in both wax and ice that heat is expended in interior work4 ,in the one case1 however1 the body is so constituted that the absorbed heat is expended in rendering the substance viscous2 and the question simply is1 whether the heat absorbed by the ice gives its molecules a freedom of play which would entitle it also to be called viscous2 whether1 in short1 rotten ice and softened wax present the same physical qualities8 ,,footnotes3 ,a ,i borrow this term from ,professor ,clausius's excellent papers on the ,dynamical ,theory of ,heat4 7#bj47 ,there is one other point in connexion with the viscous theory which claims our attention4 ,the announcement of that theory startled scientific men1 and for two or three years after its first publication it formed the subject of keen discussion4 ,this finally subsided1 and afterwards ,professor ,forbes drew up an elaborate paper1 which was presented in three parts to the ,royal ,society in #ahde and #ahdf1 and subsequently published in the ',philosophical ,transactions4' ,in the concluding portion of ,part ,,iii4 ,professor ,forbes states and answers the question1 ,how far a glacier is to be regarded as a plastic mass8 in these words3--,were a glacier composed of a solid crystalline cake of ice1 fitted or moulded to the mountain bed which it occupies1 like a lake tranquilly frozen1 it would seem impossible to admit such a flexibility or yielding of parts as should permit any comparison to a fluid or semifluid body1 transmitting pressure horizontally1 and whose parts might change their mutual positions so that one part should be pushed out whilst another remained behind4 ,but we know1 in point of fact1 that a glacier is a body very differently constituted4 ,it is clearly proved by the experiments of ,agassiz and others that the glacier is not a mass of ice1 but of ice and water1 the latter percolating freely through the crevices of the former to all depths of the glacier2 and it is a matter of ocular demonstration that these crevices1 though very minute1 communicate freely with one another to great distances2 the water with which they are filled communicates force also to great distances1 and exercises a tremendous hydrostatic pressure to move onwards in the direction in which gravity urges it1 the vast porous mass of seemingly rigid ice in which it is as it were bound up4 ,sidenote3 ,,capillary ,,hypothesis4 ,now the water in the crevices1 continues ,professor ,forbes1 does not constitute the glacier1 but only the principal vehicle of the force which acts on it1 and the slow irresistible energy with which the icy mass moves onwards from hour to hour with a continuous march1 bespeaks of itself the presence of a fluid pressure4 ,but if the ice were not in some degree ductile or plastic1 this pressure could never produce any the least forward motion of the mass4 ,the pressure in the capillaries of the glacier can only tend to separate one particle from another1 and thus produce tensions and compressions within the body of the glacier itself1 which yields1 owing to its slightly ductile nature1 in the direction of least resistance1 retaining its continuity1 or recovering it by reattachment after its parts have suffered a bruise1 according to the violence of the action to which it has been exposed4 ,i will not pretend to say that ,i fully understand this passage1 but1 taking it and the former one together1 ,i think it is clear that the water which is supposed to gorge the capillaries of the glacier is assumed to be essential to its motion4 ,indeed1 an extreme degree of sensitiveness has been ascribed to the glacier as regards the changes of temperature by which the capillaries are affected4 ,in three succeeding days1 for example1 ,professor ,forbes found the diurnal summer motion of a point upon the ,mer de ,glace to increase from #ae4b to #ag4e inches a day2 a result which he says he is persuaded to be due to the increasing heat of the weather at the time4 ,if1 then1 the glacier capillaries can be gorged so quickly as this experiment would indicate1 it is fair to assume that they are emptied with corresponding speed when the supply is cut away4 ,sidenote3 ,,temperature ,,at ,,chamouni2 ,,winter #ahei4 ,the extraordinary coldness of the weather previous to the ,christmas of #ahei is in the recollection of everybody3 this lowness of temperature also extended to the ,mer de ,glace and its environs4 ,i had last summer left with ,auguste ,balmat and the ,abbe ,vueillet thermometers with which observations were made daily during the cold weather referred to4 ,i take the following from ,balmat's register4 ,minimum ,date4 temperature ,centigrade4 ,december #af -#ae deg4 #ag -#bj #ah -#af-a_/b #ai -#i #bj -#ac #ba -#bj-a_/b #bb -#d-a_/d ,december #bc -#d-a_/b deg4 #bd -#f-a_/b #be -#b #bf #b #bg -#c #bh -#aj-a_/b #bi -#f ,the temperature at the ,montanvert during the above period may be assumed as generally some degrees lower1 so that for a considerable period1 previous to my winter observations1 the portion of the ,mer de ,glace near the ,montanvert had been exposed to a very low temperature4 ,i reached the place after the weather had become warm1 but during my stay there the maximum temperature did not exceed -#d-a_/b deg4 ,c4 ,considering therefore the long drain to which the glacier had been subjected previous to the #bith of ,december1 it is not unreasonable to infer that the capillary supply assumed by ,professor ,forbes must by that time have been exhausted4 ,notwithstanding this1 the motion of the glacier at the ,montanvert amounted at the end of ,december to half its maximum summer motion4 ,sidenote3 ,,balmat',s ,,measurements4 ,the observations of ,balmat which have been published by ,professor ,forbes,a also militate1 as far as they go1 against the idea of proportionality between the capillary supply and the motion4 ,if the temperatures recorded apply to the ,mer de ,glace during the periods of observation1 it would follow that from the #aith of ,december #ahdf to the #abth of ,april #ahdg the temperature of the air was constantly under zero ,centigrade1 and hence1 during this time1 the gorging of the capillaries1 which is due to superficial melting1 must have ceased4 ,still1 throughout this entire period of depletion the motion of the glacier steadily increased from twenty-four inches to thirty-four and a half inches a day4 ,what has been here said of the ,montanvert1 and of the points lower down where ,balmat's measurements were made1 of course applies with greater force to the higher portions of the glacier1 which are withdrawn from the operation of superficial melting for a longer period1 and which1 nevertheless1 if ,i understand ,professor ,forbes aright1 have their motion least affected in winter4 ,he records1 for example1 an observation of ,mr4 ,bakewell's1 by which the ,glacier des ,bossons is shown to be stationary at its end1 while its upper portions are moving at the rate of a foot a day4 ,this surely indicates that1 at those places where the glacier is longest cut off from superficial supply1 the motion is least reduced1 which would be a most strange result if the motion depended1 as affirmed1 upon the gorging of the capillaries4 ,sidenote3 ,,bakewell',s ,,observations4 ,the perusal of the conclusion of ,professor ,forbes's last volume shows me that a thought similar to that expressed above occurred to ,mr4 ,bakewell also4 ,speaking of a shallow glacier which moved when the alleged temperature was so enormously below the freezing point that ,professor ,forbes regards the observation as open to question 7in which ,i agree with him71 ,mr4 ,bakewell asks1 ,is it possible that infiltrated water can have any action whatever under such circumstances8 ,the reply of ,professor ,forbes contains these words3--,i have nowhere affirmed the presence of liquid water to be a sine qua non to the plastic motion of glaciers4 ,this statement1 ,i confess1 took me by surprise1 which was not diminished by further reading4 ,speaking of the influence of temperature on the motion of the ,mer de ,glace1 ,professor ,forbes says1 the glacier took no real start until the frost had given way1 and the tumultuous course of the ,arveiron showed that its veins were again filled with the circulating medium to which the glacier1 like the organic frame1 owes its moving energy4,b ,and again3--,it is this fragility precisely which1 yielding to the hydrostatic pressure of the unfrozen water contained in the countless capillaries of the glacier1 produces the crushing action which shoves the ice over its neighbour particles4,c ,sidenote3 ,,huxley',s ,,observations4 ,after the perusal of the foregoing paragraphs the reader will probably be less interested in the question as to whether the assumed capillaries exist at all in the glacier4 ,according to ,mr4 ,huxley's observations1 they do not4,d ,during the summer of #aheg he carefully experimented with coloured liquids on the ,mer de ,glace and its tributaries1 and in no case was he able to discover these fissures in the sound unweathered ice4 ,i have myself seen the red liquid resting in an auger-hole1 where it had lain for an hour without diffusing itself in any sensible degree4 ,this cavity intersected both the white ice and the blue veins of the glacier2 and ,mr4 ,huxley1 in my presence1 cut away the ice until the walls of the cavity became extremely thin1 still no trace of liquid passed through them4 ,experiments were also made upon the higher portions of the ,mer de ,glace1 and also on the ,glacier du ,geant1 with the same result4 ,thus the very existence of these capillaries is rendered so questionable1 that no theory of glacier-motion which invokes their aid could be considered satisfactory4 ,,footnotes3 ,a ',occ4 ,pap41' p4 #bbd4 ,b ',phil4 ,trans41' #ahdf1 p4 #acg1 and ',occ4 ,pap41' p4 #ach4 ,c ',occ4 ,pap41' p4 #dg4 ,d ',phil4 ,mag41' #aheg1 vol4 xiv41 p4 #bda4 ,,thomson',s ,,theory4 7#ba47 ,in the ',transactions' of the ,royal ,society of ,edinburgh for #ahdi is published a very interesting paper by ,prof4 ,james ,thomson of ,queen's ,college1 ,belfast1 wherein he deduces1 as a consequence of a principle announced by the ,french philosopher ,carnot1 that water1 when subjected to pressure1 requires a greater cold to freeze it than when the pressure is removed4 ,he inferred that the lowering of the freezing point for every atmosphere of pressure amounted to 4#jjge of a degree ,centigrade4 ,this deduction was afterwards submitted to the test of experiment by his distinguished brother ,prof4 ,wm4 ,thomson1 and proved correct4 ,on the fact thus established is founded ,mr4 ,james ,thomson's theory of the ,plasticity of ,ice as manifested in ,glaciers4 ,sidenote3 ,,statement ,,of ,,theory4 ,the theory is this3--,certain portions of the glacier are supposed first to be subjected to pressure4 ,this pressure liquefies the ice1 the water thus produced being squeezed through the glacier in the direction in which it can most easily escape4 ,but cold has been evolved by the act of liquefaction1 and1 when the water has been relieved from the pressure1 it freezes in a new position4 ,the pressure being thus abolished at the place where it was first applied1 new portions of the ice are subjected to the force2 these in their turn liquefy1 the water is dispersed as before1 and re-frozen in some other place4 ,to the succession of processes here assumed ,mr4 ,thomson ascribes the changes of form observed in glaciers4 ,this theory was first communicated to the ,royal ,society through the author's brother1 ,prof4 ,william ,thomson1 and is printed in the ',proceedings' of the ,society for ,may1 #aheg4 ,it was afterwards communicated to the ,british ,association in ,dublin1 in whose ',reports' it is further published2 and again it was communicated to the ,belfast ,literary and ,philosophical ,society1 in whose ',proceedings' it also finds a place4 ,on the #bdth of ,november1 #ahei1 ,mr4 ,james ,thomson communicated to the ,royal ,society1 through his brother1 a second paper1 in which he again draws attention to his theory4 ,he offers it in substitution for my views as the best argument that he can adduce against them2 he also controverts the explanations of regelation propounded by ,prof4 ,james ,d4 ,forbes and ,prof4 ,faraday1 believing that his own theory explains all the facts so well as to leave room for no other4 ,sidenote3 ,,difficulties ,,of ,,theory4 ,but the passage in this paper which demands my chief attention is the following3--,prof4 ,tyndall 7writes ,mr4 ,thomson71 in papers and lectures subsequent to the publication of this theory1 appears to adopt it to some extent1 and to endeavour to make its principles co-operate with the views he had previously founded on ,mr4 ,faraday's fact of regelation4 ,i may say that ,mr4 ,thomson's main thought was familiar to me long before his first communication on the plasticity of ice appeared2 but it had little influence upon my convictions4 ,were the above passage correct1 ,i should deserve censure for neglecting to express my obligations far more explicitly than ,i have hitherto done2 but ,i confess that even now ,i do not understand the essential point of ,mr4 ,thomson's theory1--that is to say1 its application to the phenomena of glacier motion4 ,indeed1 it was the obscurity in my mind in connexion with this point1 and the hope that time might enable me to seize more clearly upon his meaning1 which prevented me from giving that prominence to the theory of ,mr4 ,thomson which1 for aught ,i know1 it may well deserve4 ,i will here briefly state one or two of my difficulties1 and shall feel very grateful to have them removed4 ,sidenote3 ,,improbable ,,deduction4 ,let us fix our attention on a vertical slice of ice transverse to the glacier1 and to which the pressure is applied perpendicular to its surfaces4 ,the ice liquefies1 and1 supposing the means of escape offered to the compressed water to be equal all round1 it is plain that there will be as great a tendency to squeeze the water upwards as downwards2 for the mere tendency to flow down by its own gravity becomes1 in comparison to the forces here acting on the water1 a vanishing quantity4 ,but the fact is1 that the ice above the slice is more permeable than that below it2 for1 as we descend a glacier1 the ice becomes more compact4 ,hence the greater part of the dispersed water will be refrozen on that side of the slice which is turned towards the origin of the glacier2 and the consequence is1 that1 according to ,mr4 ,thomson's principle1 the glacier ought to move up hill instead of down4 ,i would invite ,mr4 ,thomson to imagine himself and me together upon the ice1 desirous of examining this question in a philosophic spirit2 and that we have taken our places beside a stake driven into the ice1 and descending with the glacier4 ,we watch the ice surrounding the stake1 and find that every speck of dirt upon it retains its position2 there is no liquefaction of the ice that bears the dirt1 and consequently it rests on the glacier undisturbed4 ,after twelve hours we find the stake fifteen inches distant from its first position3 ,i would ask ,mr4 ,thomson how did it get there8 ,or let us fix our attention on those six stakes which ,m4 ,agassiz drove into the glacier of the ,aar in #ahda1 and found erect in #ahdb at some hundreds of feet from their first position3--how did they get there8 ,how1 in fine1 does the end of a glacier become its end8 ,has it been liquefied and re-frozen8 ,if not1 it must have been pushed down by the very forces which ,mr4 ,thomson invokes to produce his liquefaction4 ,both the liquefaction1 as far as it exists1 and the motion1 are products of the same cause4 ,in short1 this theory1 as it presents itself to my mind1 is so powerless to account for the simplest fact of glacier-motion1 that ,i feel disposed to continue to doubt my own competence to understand it rather than ascribe to ,mr4 ,thomson an hypothesis apparently so irrelevant to the facts which it professes to explain4 ,another difficulty is the following3--,mr4 ,thomson will have seen that ,i have recorded certain winter measurements made on the ,mer de ,glace1 and that these measurements show not only that the ice moves at that period of the year1 but that it exhibits those characteristics of motion from which its plasticity has been inferred2 the velocity of the central portions of the glacier being in round numbers double the velocity of those near the sides4 ,had there been any necessity for it1 this ratio might have been augmented by placing the side-stakes closer to the walls of the glacier4 ,considering the extreme coldness of the weather which preceded these measurements1 it is a moderate estimate to set down the temperature of the ice in which my stakes were fixed at #e deg4 ,cent4 below zero4 ,sidenote3 ,,requisite ,,pressure ,,calculated4 ,let us now endeavour to estimate the pressure existing at the portion of the glacier where these measurements were made4 ,the height of the ,montanvert above the sea-level is1 according to ,prof4 ,forbes1 #fcjj feet2 that of the ,col du ,geant1 which is the summit of the principal tributary of the ,mer de ,glace1 is #aa1adf feet3 deducting the former from the latter1 we find the height of the ,col du ,geant above the ,montanvert to be #dhdf feet4 ,now1 according to ,mr4 ,thomson's theory and his brother's experiments1 the melting point of ice is lowered 4#jjge deg4 ,centigrade for every atmosphere of pressure2 and one atmosphere being equivalent to the pressure of about thirty-three feet of water1 we shall not be over the truth if we take the height of an equivalent column of glacier-ice1 of a compactness the mean of those which it exhibits upon the ,col du ,geant and at the ,montanvert respectively1 at forty feet4 ,the compactness of glacier ice is1 of course1 affected by the air-bubbles contained within it4 ,sidenote3 ,,actual ,,pressure ,,insufficient4 ,if1 then1 the pressure of forty feet of ice lower the melting point 4#jjge deg4 ,centigrade1 it follows that the pressure of a column #dhdf feet high will lower it nine-tenths of a degree ,centigrade4 ,supposing1 then1 the unimpeded thrust of the whole glacier1 from the ,col du ,geant downwards1 to be exerted on the ice at the ,montanvert2 or1 in other words1 supposing the bed of the glacier to be absolutely smooth and every trace of friction abolished1 the utmost the pressure thus obtained could perform would be to lower the melting point of the ,montanvert ice by the quantity above mentioned4 ,taking into account the actual state of things1 the friction of the glacier against its sides and bed1 the opposition which the three tributaries encounter in the neck of the valley at ,trelaporte1 the resistance encountered in the sinuous valley through which it passes2 and finally1 bearing in mind the comparatively short length of the glacier1 which has to bear the thrust1 and oppose the latter by its own friction merely2--,i think it will appear evident that the ice at the ,montanvert cannot possibly have its melting point lowered by pressure more than a small fraction of a degree4 ,the ice in which my stakes were fixed being -#e deg4 ,centigrade1 according to ,mr4 ,thomson's calculation and his brother's experiments1 it would require #ffg atmospheres of pressure to liquefy it2 in other words1 it would require the unimpeded pressure of a column of glacier-ice #bf1fhj feet high4 ,did ,mont ,blanc rise to two and a half times its present height above the ,montanvert1 and were the latter place connected with the summit of the mountain by a continuous glacier with its bed absolutely smooth1 the pressure at the ,montanvert would be rather under that necessary to liquefy the ice on which my winter observations were made4 ,sidenote3 ,,measurements ,,apply ,,to ,,surface4 ,if it be urged that1 though the temperature near the surface may be several degrees below the freezing point1 the great body of the glacier does not share this temperature1 but is1 in all probability1 near to #cb deg41 my reply is simple4 ,i did not measure the motion of the ice in the body of the glacier2 nobody ever did2 my measurements refer to the ice at and near the surface1 and it is this ice which showed the plastic deportment which the measurements reveal4 ,such1 then1 are some of the considerations which prevent me from accepting the theory of ,mr4 ,thomson1 and ,i trust they will acquit me of all desire1 to make his theory co-operate with my views4 ,i am1 however1 far from considering his deduction the less important because of its failing to account for the phenomena of glacier motion4 ,,the ,,pressure-,,theory ,,of ,,glacier-,,motion4 7#bb47 ,sidenote3 ,,possible ,,moulding ,,of ,,ice4 ,broadly considered1 two classes of facts are presented to the glacier-observer2 the one suggestive of viscosity1 and the other of the reverse4 ,the former are seen where pressure comes into play1 the latter where tension is operative4 ,by pressure ice can be moulded to any shape1 while the same ice snaps sharply asunder if subjected to tension4 ,were the result worth the labour1 ice might be moulded into vases or statuettes1 bent into spiral bars1 and1 ,i doubt not1 by the proper application of pressure1 a rope of ice might be formed and coiled into a knot4 ,but not one of these experiments1 though they might be a thousandfold more striking than any ever made upon a glacier1 would in the least demonstrate that ice is really a viscous body4 ,illustration3 ,fig4 #cj4 ,moulds used in experiments with ice4 ,i have here stated what ,i believe to be feasible4 ,let me now refer to the experiments which have been actually made in illustration of this point4 ,two pieces of seasoned box-wood had corresponding cavities hollowed in them1 so that1 when one was placed upon the other1 a lenticular space was enclosed4 ,a and ,b1 ,fig4 #cj1 represent the pieces of box-wood with the cavities in plan3 ,c represents their section when they are placed upon each other4 ,sidenote3 ,,actual ,,moulding ,,of ,,ice4 ,a sphere of ice rather more than sufficient to fill the lenticular space was placed between the pieces of wood and subjected to the action of a small hydraulic press4 ,the ice was crushed1 but the crushed fragments soon reattached themselves1 and1 in a few seconds1 a lens of compact ice was taken from the mould4 ,illustration3 ,fig4 #ca4 ,moulds used in experiments with ice4 ,this lens was placed in a cylindrical cavity hollowed out in another piece of box-wood1 and represented at ,c1 ,fig4 #ca2 and a flat piece of the wood was placed over the lens as a cover1 as at ,d4 ,on subjecting the whole to pressure1 the lens broke1 as the sphere had done1 but the crushed mass soon re-established its continuity1 and in less than half a minute a compact cake of ice was taken from the mould4 ,illustration3 ,fig4 #cb4 ,moulds used in experiments with ice4 ,in the following experiment the ice was subjected to a still severer test3--,a hemispherical cavity was formed in one block of box-wood1 and upon a second block a hemispherical protuberance was turned1 smaller than the cavity1 so that1 when the latter was placed in the former1 a space of a quarter of an inch existed between the two4 ,fig4 #cb represents a section of the two pieces of box-wood2 the brass pins a1 b1 fixed in the slab ,g ,h1 and entering suitable apertures in the mould ,i ,k1 being intended to keep the two surfaces concentric4 ,a lump of ice being placed in the cavity1 the protuberance was brought down upon it1 and the mould subjected to hydraulic pressure3 after a short interval the ice was taken from the mould as a smooth compact cup1 its crushed particles having reunited1 and established their continuity4 ,sidenote3 ,,ice ,,moulded ,,to ,,cups ,,and ,,rings4 ,illustration3 ,fig4 #cc4 ,moulds used in experiments with ice4 ,to make these results more applicable to the bending of glacier-ice1 the following experiments were made3--,a block of box-wood1 ,m1 ,fig4 #cc1 #d inches long1 #c wide1 and #c deep1 had its upper surface slightly curved1 and a groove an inch wide1 and about an inch deep1 worked into it4 ,a corresponding plate was prepared1 having its under surface part of a convex cylinder1 of the same curvature as the concave surface of the former piece4 ,when the one slab was placed upon the other1 they presented the appearance represented in section at ,n4 ,a straight prism of ice #d inches long1 an inch wide1 and a little more than an inch in depth1 was placed in the groove2 the upper slab was placed upon it1 and the whole was subjected to the hydraulic press4 ,the prism broke1 but1 the quantity of ice being rather more than sufficient to fill the groove1 the pressure soon brought the fragments together and re-established the continuity of the ice4 ,after a few seconds it was taken from the mould a bent bar of ice4 ,this bar was afterwards passed through three other moulds of gradually augmenting curvature1 and was taken from the last of them a semi-ring of compact ice4 ,the ice1 in changing its form from that of one mould to that of another1 was in every instance broken and crushed by the pressure2 but suppose that instead of three moulds three thousand had been used2 or1 better still1 suppose the curvature of a single mould to change by extremely slow degrees2 the ice would then so gradually change its form that no rude rupture would be apparent4 ,practically the ice would behave as a plastic substance2 and indeed this plasticity has been contended for by ,m4 ,agassiz1 in opposition to the idea of viscosity4 ,as already stated1 the ice1 bruised1 and flattened1 and bent in the above experiments1 was incapable of being sensibly stretched2 it was plastic to pressure but not to tension4 ,a quantity of water was always squeezed out of the crushed ice in the above experiments1 and the bruised fragments were intermixed with this and with air4 ,minute quantities of both remained in the moulded ice1 and thus rendered it in some degree turbid4 ,its character1 however1 as to continuity may be inferred from the fact that the ice-cup1 moulded as described1 held water without the slightest visible leakage4 ,sidenote3 ,,softness ,,of ,,ice ,,defined4 ,sidenote3 ,,pressure ,,and ,,tension4 ,ice at #cb deg4 may1 as already stated1 be crushed with extreme facility1 and glacier-ice with still more readiness than lake-ice3 it may also be scraped with a knife with even greater facility than some kinds of chalk4 ,in comparison with ice at #ajj deg4 below the freezing point1 it might be popularly called soft4 ,but its softness is not that of paste1 or wax1 or treacle1 or lava1 or honey1 or tar4 ,it is the softness of calcareous spar in comparison with that of rock-crystal2 and although the latter is incomparably harder than the former1 ,i think it will be conceded that the term viscous would be equally inapplicable to both4 ,my object here is clearly to define terms1 and not permit physical error to lurk beneath them4 ,how far this ice1 with a softness thus defined1 when subjected to the gradual pressures exerted in a glacier1 is bruised and broken1 and how far the motion of its parts may approach to that of a truly viscous body under pressure1 ,i do not know4 ,the critical point here is that the ice changes its form1 and preserves its continuity1 during its motion1 in virtue of external force4 ,it remains continuous whilst it moves1 because its particles are kept in juxtaposition by pressure1 and when this external prop is removed1 and the ice1 subjected to tension1 has to depend solely upon the mobility of its own particles to preserve its continuity1 the analogy with a viscous body instantly breaks down4,a ,,footnotes3 ,a ,imagine1 writes ,professor ,forbes1 a long narrow trough or canal1 stopped at both ends and filled to a considerable depth with treacle1 honey1 tar1 or any such viscid fluid4 ,imagine one end of the trough to give way1 the bottom still remaining horizontal3 if the friction of the fluid against the bottom be greater than the friction against its own particles1 the upper strata will roll over the lower ones1 and protrude in a convex slope1 which will be propagated backwards towards the other or closed end of the trough4 ,had the matter been quite fluid the whole would have run out1 and spread itself on a level3 as it is1 it assumes precisely the conditions which we suppose to exist in a glacier4 ,this is perfectly definite1 and my equally definite opinion is that no glacier ever exhibited the mechanical effects implied by this experiment4 ,,regelation4 7#bc47 ,sidenote3 ,,faraday',s ,,first ,,experiment4 ,i was led to the foregoing results by reflecting on an experiment performed by ,mr4 ,faraday1 at a ,friday evening meeting of the ,royal ,institution1 on the #gth of ,june1 #ahej1 and described in the ',athenaeum' and ',literary ,gazette' for the same month4 ,mr4 ,faraday then showed that when two pieces of ice1 with moistened surfaces1 were placed in contact1 they became cemented together by the freezing of the film of water between them1 while1 when the ice was below #cb deg4 ,fahr41 and therefore dry1 no effect of the kind could be produced4 ,the freezing was also found to take place under water2 and indeed it occurs even when the water in which the ice is plunged is as hot as the hand can bear4 ,a generalisation from this interesting fact led me to conclude that a bruised mass of ice1 if closely confined1 must re-cement itself when its particles are brought into contact by pressure2 in fact1 the whole of the experiments above recorded immediately suggested themselves to my mind as natural deductions from the principle established by ,faraday4 ,a rough preliminary experiment assured me that the deductions would stand testing2 and the construction of the box-wood moulds was the consequence4 ,we could doubtless mould many solid substances to any extent by suitable pressure1 breaking the attachment of their particles1 and re-establishing a certain continuity by the mere force of cohesion4 ,with such substances1 to which we should never think of applying the term viscous1 we might also imitate the changes of form to which glaciers are subject3 but1 superadded to the mere cohesion which here comes into play1 we have1 in the case of ice1 the actual regelation of the severed surfaces1 and consequently a more perfect solid4 ,in the ,introduction to this book ,i have referred to the production of slaty cleavage by pressure2 and at a future page ,i hope to show that the lamination of the ice of glaciers is due to the same cause2 but1 as justly observed by ,mr4 ,john ,ball1 there is no tendency to cleave in the sound ice of glaciers2 in fact1 this tendency is obliterated by the perfect regelation of the severed surfaces4 ,sidenote3 ,,recent ,,experiments ,,of ,,faraday4 ,mr4 ,faraday has recently placed pieces of ice1 in water1 under the strain of forces tending to pull them apart4 ,when two such pieces touch at a single point they adhere and move together as a rigid piece2 but a little lateral force carefully applied breaks up this union with a crackling noise1 and a new adhesion occurs which holds the pieces together in opposition to the force which tends to divide them4 ,mr4 ,james ,thomson had referred regelation to the cold produced by the liquefaction of the pressed ice2 but in the above experiment all pressure is not only taken away1 but is replaced by tension4 ,mr4 ,thomson also conceives that1 when pieces of ice are simply placed together without intentional pressure1 the capillary attraction brings the pressure of the atmosphere into play2 but ,mr4 ,faraday finds that regelation takes place in vacuo4 ,a true viscidity on the part of ice ,mr4 ,faraday never has observed1 and he considers that his recent experiments support the view originally propounded by himself1 namely1 that a particle of water on a surface of ice becomes solid when placed between two surfaces1 because of the increased influence due to their joint action4 ,,crystallization ,,and ,,internal ,,liquefaction4 7#bd47 ,sidenote3 ,,how ,,crystals ,,are ,,nursed4 ,in the ,introduction to this book ,i have briefly referred to the force of crystallization4 ,to permit this force to exercise its full influence1 it must have free and unimpeded action2 a crystal1 for instance1 to be properly built1 ought to be suspended in the middle of the crystallizing solution1 so that the little architects can work all round it2 or if placed upon the bottom of a vessel1 it ought to be frequently turned1 so that all its facets may be successively subjected to the building process4 ,in this way crystals can be nursed to an enormous size4 ,but where other forces mingle with that of crystallization1 this harmony of action is destroyed2 the figures1 for example1 that we see upon a glass window1 on a frosty morning1 are due to an action compounded of the pure crystalline force and the cohesion of the liquid to the window-pane4 ,a more regular effect is obtained when the freezing particles are suspended in still air1 and here they build themselves into those wonderful figures which ,dr4 ,scoresby has observed in the ,polar ,regions1 ,mr4 ,glaisher at ,greenwich1 and ,i myself on the summit of ,monte ,rosa and elsewhere4 ,not only however in air1 but in water also1 figures of great beauty are sometimes formed4 ,harrison's excellent machine for the production of artificial ice is1 ,i suppose1 now well known2 the freezing being effected by carrying brine1 which had been cooled by the evaporation of ether1 round a series of flat tin vessels containing water4 ,the latter gradually freezes1 and1 on watching those vessels while the action was proceeding very slowly1 ,i have seen little six-rayed stars of thin ice forming1 and rising to the surface of the liquid4 ,i believe the fact was never before observed1 but it would be interesting to follow it up1 and to develop experimentally this most interesting case of crystallization4 ,sidenote3 ,,dissection ,,of ,,ice ,,by ,,sunbeam4 ,the surface of a freezing lake presents to the eye of the observer nothing which could lead him to suppose that a similar molecular architecture is going on there4 ,still the particles are undoubtedly related to each other in this way2 they are arranged together on this starry type4 ,and not only is this the case at the surface1 but the largest blocks of ice which reach us from ,norway and the ,wenham ,lake are wholly built up in this way4 ,we can reveal the internal constitution of these masses by a reverse process to that which formed them2 we can send an agent into the interior of a mass of ice which shall take down the atoms which the crystallizing forces had set up4 ,this agent is a solar beam2 with which it first occurred to me to make this simple experiment in the autumn of #aheg4 ,i placed a large converging lens in the sunbeams passing through a room1 and observed the place where the rays were brought to a focus behind the lens2 then shading the lens1 ,i placed a clear cube of ice so that the point of convergence of the rays might fall within it4 ,on removing the screen from the lens1 a cone of sunlight went through the cube1 and along the course of the cone the ice became studded with lustrous spots1 evidently formed by the beam1 as if minute reflectors had been suddenly established within the mass1 from which the light flashed when it met them4 ,on examining the cube afterwards ,i found that each of these spots was surrounded by a liquid flower of six petals2 such flowers were distributed in hundreds through the ice1 being usually clear and detached from each other1 but sometimes crowded together into liquid bouquets1 through which1 however1 the six-starred element could be plainly traced4 ,at first the edges of the leaves were unbroken curves1 but when the flowers expanded under a long-continued action1 the edges became serrated4 ,when the ice was held at a suitable angle to the solar beams1 these liquid blossoms1 with their central spots shining more intensely than burnished silver1 presented an exhibition of beauty not easily described4 ,i have given a sketch of their appearance in ,fig4 #cd4 ,sidenote3 ,,liquid ,,flowers ,,in ,,ice4 ,illustration3 ,fig4 #cd4 ,liquid ,flowers in lake ice4 ,i have here to direct attention to an extremely curious fact4 ,on sending the sunbeam through the transparent ice1 ,i often noticed that the appearance of the lustrous spots was accompanied by an audible clink1 as if the ice were ruptured inwardly4 ,but there is no ground for assuming such rupture1 and on the closest examination no flaw is exhibited by the ice4 ,what then can be the cause of the noise8 ,i believe the following considerations will answer the question3-- ,water always holds a quantity of air in solution1 the diffusion of which through the liquid1 as proved by ,m4 ,donny1 has an immense effect in weakening the cohesion of its particles2 recent experiments of my own show that this is also the case in an eminent degree with many volatile liquids4 ,m4 ,donny has proved that1 if water be thoroughly purged of its air1 a long glass tube filled with this liquid may be inverted1 while the tenacity with which the water clings to the tube1 and with which its particles cling to each other1 is so great that it will remain securely suspended1 though no external hindrance be offered to its descent4 ,owing to the same cause1 water deprived of its air will not boil at #bab deg4 ,fahr41 and may be raised to a temperature of nearly #cjj deg4 without boiling2 but when this occurs the particles break their cohesion suddenly1 and ebullition is converted into explosion4 ,now1 when ice is formed1 every trace of the air which the water contained is squeezed out of it2 the particles in crystallizing reject all extraneous matter1 so that in ice we have a substance quite free from the air1 which is never absent in the case of water2 it therefore follows that if we could preserve the water derived from the melting of ice from contact with the atmosphere1 we should have a liquid eminently calculated to show the effects described by ,m4 ,donny4 ,mr4 ,faraday has proved by actual experiment that this is the case4 ,sidenote3 ,,water ,,deprived ,,of ,,air ,,snaps ,,asunder4 ,let us apply these facts to the explanation of the clink heard in my experiments4 ,on sending a sunbeam through ice1 liquid cavities are suddenly formed at various points within the mass1 and these cavities are completely cut off from atmospheric contact4 ,but the water formed by the melting ice is less in volume than the ice which produces it2 the water of a cavity is not able to fill it1 hence a vacuous space must be formed in the cell4 ,i have no doubt that1 for a time1 the strong cohesion between the walls of the cell and the drop within it augments the volume of the latter a little1 so as to compel it to fill the cell2 but as the quantity of liquid becomes greater the shrinking force augments1 until finally the particles snap asunder like a broken spring4 ,at the same moment a lustrous spot appears1 which is a vacuum1 and simultaneously with the appearance of this vacuum the clink was always heard4 ,multitudes of such little explosions must be heard upon a glacier when the strong summer sun shines upon it1 the aggregate of which must1 ,i think1 contribute to produce the crepitation noticed by ,m4 ,agassiz1 and to which ,i have already referred4 ,sidenote3 ,,figures ,,in ,,ice2 ,,vacuous ,,spots4 ,in ,plate ,,vi4 of the ,atlas which accompanies the ',systeme ,glaciaire' of ,m4 ,agassiz1 ,i notice drawings of figures like those ,i have described1 which he has observed in glacier-ice1 and which were doubtless produced by direct solar radiation4 ,i have often myself observed figures of exquisite beauty formed in the ice on the surface of glacier-pools by the morning sun4 ,in some cases the spaces between the leaves of the liquid flowers melt partially away1 and leave the central spot surrounded by a crimped border2 sometimes these spaces wholly disappear1 and the entire space bounded by the lines drawn from point to point of the leaves becomes liquid1 thus forming perfect hexagons4 ,the crimped borders exhibit different degrees of serration1 from the full leaves themselves to a gentle undulating line1 which latter sometimes merges into a perfect circle4 ,in the ice of glaciers1 ,i have seen the internal liquefaction ramify itself like sprigs of myrtle2 in the same ice1 and particularly towards the extremities of the glacier1 disks innumerable are also formed1 consisting of flat round liquid spaces1 a bright spot being usually associated with each4 ,these spots have been hitherto mistaken for air-bubbles2 but both they and the lustrous disks at the centres of the flowers are vacuous4 ,i proved them to be so by plunging the ice containing them into hot water1 and watching what occurred when the walls of the cells were dissolved1 and a liquid connexion established between them and the atmosphere4 ,in all cases they totally collapsed1 and no trace of air rose to the surface of the warm water4 ,no matter in what direction a solar beam is sent through lake-ice1 the liquid flowers are all formed parallel to the surface of freezing4 ,the beam may be sent parallel1 perpendicular1 or oblique to this surface2 the flowers are always formed in the same planes4 ,every line perpendicular to the surface of a frozen lake is in fact an axis of symmetry1 round which the molecules so arrange themselves1 that1 when taken down by the delicate fingers of the sunbeam1 the six-leaved liquid flowers are the result4 ,in the ice of glaciers we have no definite planes of freezing4 ,it is first snow1 which has been disturbed by winds while falling1 and whirled and tossed about by the same agency after it has fallen1 being often melted1 saturated with its own water1 and refrozen3 it is cast in shattered fragments down cascades1 and reconsolidated by pressure at the bottom4 ,in ice so formed and subjected to such mutations1 definite planes of freezing are1 of course1 out of the question4 ,sidenote3 ,,constitution ,,of ,,glacier-,,ice4 ,the flat round disks and vacuous spots to which ,i have referred come here to our aid1 and furnish us with an entirely new means of analysing the internal constitution of a glacier4 ,when we examine a mass of glacier-ice which contains these disks1 we find them lying in all imaginable planes2 not confusedly1 however--closer examination shows us that the disks are arranged in groups1 the members of each group being parallel to a common plane1 but the parallelism ceases when different groups are compared4 ,the effect is exactly what would be observed1 supposing ordinary lake-ice to be broken up1 shaken together1 and the confused fragments regelated to a compact continuous mass4 ,in such a jumble the original planes of freezing would lie in various directions2 but no matter how compact or how transparent ice thus constituted might appear1 a solar beam would at once reveal its internal constitution by developing the flowers parallel to the planes of freezing of the respective fragments4 ,a sunbeam sent through glacier-ice always reveals the flowers in the planes of the disks1 so that the latter alone at once informs us of its crystalline constitution4 ,sidenote3 ,,vacuous ,,cells ,,mistaken ,,for ,,air-,,cells4 ,hitherto1 as ,i have said1 these disks have been mistaken for bubbles containing air1 and their flattening has been ascribed to the pressure to which they have been subjected4 ,m4 ,agassiz thus refers to them3--,the air-bubbles undergo no less curious modifications4 ,in the neighbourhood of the neve1 where they are most numerous1 those which one sees on the surface are all spherical or ovoid1 but by degrees they begin to be flattened1 and near the end of the glacier there are some that are so flat that they might be taken for fissures when seen in profile4 ,the drawing represents a piece of ice detached from the gallery of infiltration4 ,all the bubbles are greatly flattened4 ,but what is most extraordinary is1 that1 far from being uniform1 the flattening is different in each fragment2 so that the bubbles1 according to the face which they offer1 appear either very broad or very thin4 ,this description of glacier-ice is correct3 it agrees with the statements of all other observers4 ,but there are two assumptions in the description which must henceforth be given up2 first1 the bubbles seen like fissures in profile are not air-bubbles at all1 but vacuous spots1 which the very constitution of ice renders a necessary concomitant of its inward melting2 secondly1 the assumption that the bubbles have been flattened by pressure must be abandoned2 for they are found1 and may be developed at will1 in lake-ice on which no pressure has been exerted4 ,sidenote3 ,,cells ,,of ,,air ,,and ,,water4 ,but these remarks dispose only of a certain class of cells contained in glacier-ice4 ,besides the liquid disks and vacuous spots1 there are innumerable true bubbles entangled in the mass4 ,these have also been observed and described by ,m4 ,agassiz2 and ,mr4 ,huxley has also given us an accurate account of them4 ,m4 ,agassiz frequently found air and water associated in the same cell4 ,mr4 ,huxley found no exception to the rule3 in each case the bubble of air was enclosed in a cell which was also partially filled with water4 ,he supposes that the water may be that of the originally-melted snow which has been carried down from the neve unfrozen4 ,this hypothesis is worthy of a great deal more consideration than ,i have had time to give to it1 and ,i state it here in the hope that it will be duly examined4 ,my own experience of these associated air and water cells is derived almost exclusively from lake-ice1 in which ,i have often observed them in considerable numbers4 ,in examining whether the liquid contents had ever been frozen or not1 ,i was guided by the following considerations4 ,if the air be that originally entangled in the solid1 it will have the ordinary atmospheric density at least2 but if it be due to the melting of the walls of the cell1 then the water so formed being only eight-ninths of that of the ice which produced it1 the air of the bubble must be rarefied4 ,i suppose ,i have made a hundred different experiments upon these bubbles to determine whether the air was rarefied or not1 and in every case found it so4 ,ice containing the bubbles was immersed in warm water1 and always1 when the rigid envelope surrounding a bubble was melted away1 the air suddenly collapsed to a fraction of its original dimensions4 ,i think ,i may safely affirm that1 in some cases1 the collapse reduced the bubbles to the thousandth part of their original volume4 ,from these experiments ,i should undoubtedly infer1 that in lake-ice at least1 the liquid of the cells is produced by the melting of the ice surrounding the bubbles of air4 ,but ,i have not subjected the bubbles of glacier-ice to the same searching examination4 ,i have tried whether the insertion of a pin would produce the collapse of the bubbles1 but it did not appear to do so4 ,i also made a few experiments at ,rosenlaui1 with warm water1 but the result was not satisfactory4 ,that ice melts internally at the surfaces of the bubbles is1 ,i think1 rendered certain by my experiments1 but whether the water-cells of glacier-ice are entirely due to such melting1 subsequent observers will no doubt determine4 ,sidenote3 ,,liquid ,,liberty4 ,i have found these composite bubbles at all parts of glaciers2 in the ice of the moraines1 over which a protective covering had been thrown2 in the ice of sand-cones1 after the removal of the superincumbent debris2 also in ice taken from the roofs of caverns formed in the glacier1 and which the direct sunlight could hardly by any possibility attain4 ,that ice should liquefy at the surface of a cavity is1 ,i think1 in conformity with all we know concerning the physical nature of heat4 ,regarding it as a motion of the particles1 it is easy to see that this motion is less restrained at the surface of a cavity than in the solid itself1 where the oscillation of each atom is controlled by the particles which surround it2 hence liquid liberty1 if ,i may use the term1 is first attained at the surface4 ,indeed ,i have proved by experiment that ice may be melted internally by heat which has been conducted through its external portions without melting them4 ,these facts are the exact complements of those of regelation2 for here1 two moist surfaces of ice being brought into close contact1 their liquid liberty is destroyed and the surfaces freeze together4 ,,the ,,moulins4 7#be47 ,sidenote3 ,,moulin ,,of ,,grindelwald ,,glacier4 ,sidenote3 ,,depth ,,of ,,the ,,shaft4 ,the first time ,i had an opportunity of seeing these remarkable glacier-chimneys was in the summer of #ahef1 upon the lower glacier of ,grindelwald4 ,mr4 ,huxley was my companion at the time1 and on crossing the so-called ,eismeer we heard a sound resembling the rumble of distant thunder1 which proceeded from a perpendicular shaft formed in the ice1 and into which a resounding cataract discharged itself4 ,the tube in fact resembled a vast organ-pipe1 whose thunder-notes were awakened by the concussion of the falling water1 instead of by the gentle flow of a current of air4 ,beside the shaft our guide hewed steps1 on which we stood in succession1 and looked into the tremendous hole4 ,near the first shaft was a second and smaller one1 the significance of which ,i did not then understand2 it was not more than #bj feet deep1 but seemed filled with a liquid of exquisite blue1 the colour being really due to the magical shimmer from the walls of the moulin1 which was quite empty4 ,as far as we could see1 the large shaft was vertical1 but on dropping a stone into it a shock was soon heard1 and after a succession of bumps1 which occupied in all seven seconds1 we heard the stone no more4 ,the depth of the moulin could not be thus ascertained1 but we soon found a second and still larger one which gave us better data4 ,a stone dropped into this descended without interruption for four seconds1 when a concussion was heard2 and three seconds afterwards the final shock was audible3 there was thus but a single interruption in the descent4 ,supposing all the acquired velocity to have been destroyed by the shock1 by adding the space passed over by the stone in four and in three seconds respectively1 and making allowance for the time required by the sound to ascend from the bottom1 we find the depth of the shaft to be about #cde feet4 ,there is1 however1 no reason to suppose that this measures the depth of the glacier at the place referred to4 ,these shafts are to be found in almost all great glaciers2 they are very numerous in the ,unteraar ,glacier1 numbers of them however being empty4 ,on the ,mer de ,glace they are always to be found in the region of ,trelaporte1 one of the shafts there being1 par excellence1 called the ,grand ,moulin4 ,many of them also occur on the ,glacier de ,lechaud4 ,as truly observed by ,m4 ,agassiz1 these moulins occur only at those parts of the glacier which are not much rent by fissures1 for only at such portions can the little rills produced by superficial melting collect to form streams of any magnitude4 ,the valley of unbroken ice formed in the ,mer de ,glace near ,trelaporte is peculiarly favourable for the collection of such streams2 we see the little rills commencing1 and enlarging by the contributions of others1 the trunk-rill pouring its contents into a little stream which stretches out a hundred similar arms over the surface of the glacier4 ,several such streams join1 and finally a considerable brook1 which receives the superficial drainage of a large area1 cuts its way through the ice4 ,sidenote3 ,,moulins ,,explained4 ,but although this portion of the glacier is free from those long-continued and permanent strains which1 having once rent the ice1 tend subsequently to widen the rent and produce yawning crevasses1 it is not free from local strains sufficient to produce cracks which penetrate the glacier to a great depth4 ,imagine such a crack intersecting such a glacier-rivulet as we have described4 ,the water rushes down it1 and soon scoops a funnel large enough to engulf the entire stream4 ,the moulin is thus formed1 and1 as the ice moves downward1 the sides of the crack are squeezed together and regelated1 the seam which marks the line of junction being in most cases distinctly visible4 ,but as the motion continues1 other portions of the glacier come into the same state of strain as that which produced the first crack2 a second one is formed across the stream1 the old shaft is forsaken1 and a new one is hollowed out1 in which for a season the cataract plays the thunderer4 ,i have in some cases counted the forsaken shafts of six old moulins in advance of an active one4 ,not far from the ,grand ,moulin of the ,mer de ,glace in #aheg there was a second empty shaft1 which evidently communicated by a subglacial duct with that into which the torrent was precipitated4 ,out of the old orifice issued a strong cold blast1 the air being manifestly impelled through the duct by the falling water of the adjacent moulin4 ,these shafts are always found in the same locality2 the portion of the ,mer de ,glace to which ,i have referred is never without them4 ,some of the guides affirm that they are motionless2 and a statement of ,prof4 ,forbes has led to the belief that this was also his opinion4,a ,m4 ,agassiz1 however1 observed the motion of some of these shafts upon the glacier of the ,aar2 and when on the spot in #aheg1 ,i was anxious to decide the point by accurate measurements with the theodolite4 ,my friend ,mr4 ,hirst took charge of the instrument1 and on the #bhth of ,july ,i fixed a single stake beside the ,grand ,moulin1 in a straight line between a station at ,trelaporte and a well-defined mark on the rock at the opposite side of the valley4 ,on the #cast1 the displacement of the stake amounted to #ej inches1 and on the #ast of ,august it had moved #gd-a_/b inches--the moulin1 to all appearance1 occupying throughout the same position with regard to the stake4 ,to render this certain1 moreover we subsequently drove two additional stakes into the ice1 thus enclosing the mouth of the shaft in a triangle4 ,on the #hth of ,august the displacements were measured and gave the following results3-- ,total ,motion4 ,first 7old7 stake #aih inches4 ,second 7new7 do4 #abc ,third #abd ,sidenote3 ,,motion ,,of ,,the ,,moulins4 ,the old stake had been fixed for #aa days1 and its daily motion--which was also that of the moulin--averaged #ah inches a day4 ,hence the moulins share the general motion of the glacier1 and their apparent permanence is not1 as has been alleged1 a proof of the semi-fluidity of the glacier1 but is due to the breaking of the ice as it passes the place of local strain4 ,sidenote3 ,,depth ,,of ,,grand ,,moulin ,,sought4 ,wishing to obtain some estimate as to the depth of the ice1 ,mr4 ,hirst undertook the sounding of some of the moulins upon the ,glacier de ,lechaud1 making use of a tin vessel filled with lumps of lead and iron as a weight4 ,the cord gave way and he lost his plummet4 ,to measure the depth of the ,grand ,moulin1 we obtained fresh cord from ,chamouni1 to which we attached a four-pound weight4 ,into a cavity at the bottom of the weight we stuffed a quantity of butter1 to indicate the nature of the bottom against which the weight might strike4 ,the weight was dropped into the shaft1 and the cord paid out until its slackening informed us that the weight had come to rest2 by shaking the string1 however1 and walking round the edge of the shaft1 the weight was liberated1 and sank some distance further4 ,the cord partially slackened a second time1 but the strain still remaining was sufficient to render it doubtful whether it was the weight or the action of the falling water which produced it4 ,we accordingly paid out the cord to the end1 but1 on withdrawing it1 found that the greater part of it had been coiled and knotted up by the falling water4 ,we uncoiled1 and sounded again4 ,at a depth of #acb feet the weight reached a ledge or protuberance of ice1 and by shaking and lifting it1 it was caused to descend #ca feet more4 ,a depth of #afc feet was the utmost we could attain to4 ,we sounded the old moulin to a depth of #ij feet2 while a third little shaft1 beside the large one1 measured only #ah feet in depth4 ,we could see the water escape from it through a lateral canal at its bottom1 and doubtless the water of the ,grand ,moulin found a similar exit4 ,there was no trace of dirt upon the butter1 which might have indicated that we had reached the bed of the glacier4 ,,footnotes3 ,a ,every year1 and year after year1 the watercourses follow the same lines of direction--their streams are precipitated into the heart of the glacier by vertical funnels1 called 'moulins1' at the very same points4--,forbes's ,fourth ,letter upon ,glaciers3 ',occ4 ,pap41' p4 #bi4 ,illustration3 ,,dirt-,,bands ,,of ,,the ,,mer ,,de ,,glace1 ,,as ,,seen ,,from ,a ,,point ,,near ,,the ,,flegere4 ,fig4 #ce4 ,to face p4 #cfg4 ,,dirt-,,bands ,,of ,,the ,,mer ,,de ,,glace4 7#bf47 ,sidenote3 ,,dirt-,,bands ,,from ,,the ,,flegere4 ,these bands were first noticed by ,prof4 ,forbes on the #bdth of ,july1 #ahdb1 and were described by him in the following words3--,my eye was caught by a very peculiar appearance of the surface of the ice1 which ,i was certain that ,i now saw for the first time4 ,it consisted of nearly hyperbolic brownish bands on the glacier1 the curves pointing downwards1 and the two branches mingling indiscriminately with the moraines1 presenting an appearance of a succession of waves some hundred feet apart4,a ,from no single point of view hitherto attained can all the ,dirt-,bands of the ,mer de ,glace be seen at once4 ,to see those on the terminal portion of the glacier1 a station ought to be chosen on the opposite range of the ,brevent1 a few hundred yards beyond the ,croix de la ,flegere1 where we stand exactly in front of the glacier as it issues into the valley of ,chamouni4 ,the appearance of the bands upon the portion here seen is represented in ,fig4 #ce4 ,it will be seen that the bands are confined to one side of the glacier1 and either do not exist1 or are obliterated by the debris1 upon the other side4 ,the cause of the accumulation of dirt on the right side of the glacier is1 that no less than five moraines are crowded together at this side4 ,in the upper portions of the ,mer de ,glace these moraines are distinct from each other2 but in descending1 the successive engulfments and disgorgings of the blocks and dirt have broken up the moraines2 and at the place now before us the materials which composed them are strewn confusedly on the right side of the glacier4 ,the portion of the ice on which the dirt-bands appear is derived from the ,col du ,geant4 ,they do not quite extend to the end of the glacier1 being obliterated by the dislocation of the ice upon the frozen cascade of ,des ,bois4 ,sidenote3 ,,dirt-,,bands ,,from ,,les ,,charmoz4 ,let us now proceed across the valley of ,chamouni to the ,montanvert2 where1 climbing the adjacent heights to an elevation of six or eight hundred feet above the hotel1 we command a view of the ,mer de ,glace1 from ,trelaporte almost to the commencement of the ,glacier des ,bois4 ,it was from this position that ,professor ,forbes first observed the bands4 ,fifteen1 sixteen1 and seventeen years later ,i observed them from the same position4 ,the number of bands which ,professor ,forbes counted from this position was eighteen1 with which my observations agree4 ,the entire series of bands which ,i observed1 with the exception of one or two1 must have been the successors of those observed by ,professor ,forbes2 and my finding the same number after an interval of so many years proves that the bands must be due to some regularly recurrent cause4 ,fig4 #cf represents the bands as seen from the heights adjacent to the ,montanvert4 ,illustration3 ,,dirt-,,bands ,,of ,,the ,,mer ,,de ,,glace1 ,,as ,,seen ,,from ,,les ,,charmoz4 ,fig4 #cf4 ,to face p4 #cfh4 ,i would here direct attention to an analogy between a glacier and a river1 which may be observed from the heights above the ,montanvert1 but to which no reference1 as far as ,i know1 has hitherto been made4 ,when a river meets the buttress of a bridge1 the water rises against it1 and1 on sweeping round it1 forms an elevated ridge1 between which and the pier a depression occurs which varies in depth with the force of the current4 ,this effect is shown by the ,mer de ,glace on an exaggerated scale4 ,sweeping round ,trelaporte1 the ice pushes itself beyond the promontory in an elevated ridge1 from which it drops by a gradual slope to the adjacent wall of the valley1 thus forming a depression typified by that already alluded to4 ,a similar effect is observed at the opposite side of the glacier on turning round the ,echelets2 and both combine to form a kind of skew surface4 ,a careful inspection of the frontispiece will detect this peculiarity in the shape of the glacier4 ,sidenote3 ,,from ,,the ,,cleft-,,station4 ,from neither of the stations referred to do we obtain any clue to the origin of the dirt-bands4 ,a stiff but pleasant climb will place us in that singular cleft in the cliffy mountain-ridge which is seen to the right of the frontispiece2 and from it we easily attain the high platform of rock immediately to the left of it4 ,we stand here high above the promontory of ,trelaporte1 and occupy the finest station from which the ,mer de ,glace and its tributaries can be viewed4 ,from this station we trace the dirt-bands over most of the ice that we have already scanned1 and have the further advantage of being able to follow them to their very source4 ,this source is the grand ice-cascade which descends in a succession of precipices from the plateau of the ,col du ,geant into the valley which the ,glacier du ,geant fills4 ,we see from our present point of view that the bands are confined to the portion of the glacier which has descended the cascade4 ,fig4 #cg represents the bands as seen from the ,cleft-station above ,trelaporte4 ,illustration3 ,,dirt-,,bands ,,of ,,the ,,mer ,,de ,,glace1 ,,as ,,seen ,,from ,,the ,,cleft ,,station1 ,,trelaporte4 ,fig4 #cg4 ,to face p4 #cfi4 ,we are now however at such a height above the glacier and at such a distance from the base of the cascade1 that we can form but an imperfect notion of the true contour of the surface4 ,let us therefore descend1 and walk up the ,glacier du ,geant towards the cascade4 ,at first our road is level1 but we gradually find that at certain intervals we have to ascend slopes which follow each other in succession1 each being separated from its neighbour by a space of comparatively level ice4 ,the slopes increase in steepness as we ascend2 they are steepest1 moreover1 on the right-hand side of the glacier1 where it is bounded by that from the ,periades1 and at length we are unable to climb them without the aid of an axe4 ,soon afterwards the dislocation of the glacier becomes considerable2 we are lost in the clefts and depressions of the ice1 and are unable to obtain a view sufficiently commanding to subdue these local appearances and convey to us the general aspect4 ,we have at all events satisfied ourselves as to the existence1 on the upper portion of the glacier1 of a succession of undulations which sweep transversely across it4 ,the term wrinkles1 applied to them by ,prof4 ,forbes1 is highly suggestive of the appearance which they present4 ,sidenote3 ,,snow-,,bands ,,on ,,the ,,glacier ,,du ,,geant4 ,from the ,cleft-station bands of snow may also be seen partially crossing the glacier in correspondence with the undulations upon its surface4 ,if the quantity deposited the winter previous be large1 and the heat of summer not too great1 these bands extend quite across the glacier4 ,they were first observed by ,professor ,forbes in #ahdc4 ,in his ,fifth ,letter is given an illustrative diagram1 which1 though erroneous as regards the position of the veined structure1 is quite correct in limiting the snow-bands to the ,glacier du ,geant proper4 ,at the place where the three welded tributaries of the ,mer de ,glace squeeze themselves through the strait of ,trelaporte1 the bands undergo a considerable modification in shape4 ,near their origin they sweep across the ,glacier du ,geant in gentle curves1 with their convexities directed downwards2 but at ,trelaporte these curves1 the chords of which a short time previous measured a thousand yards in length1 have to squeeze themselves through a space of four hundred and ninety-five yards wide2 and as might be expected1 they are here suddenly sharpened4 ,the apex of each being thrust forward1 they take the form of sharp hyperbolas1 and preserve this character throughout the entire length of the ,mer de ,glace4 ,i would now conduct the reader to a point from which a good general view of the ice cascade of the ,geant is attainable4 ,from the old moraine near the lake of the ,tacul we observe the ice1 as it descends the fall1 to be broken into a succession of precipices4 ,it would appear as if the glacier had its back periodically broken at the summit of the fall1 and formed a series of vast chasms separated from each other by cliffy ridges of corresponding size4 ,these1 as they approach the bottom of the fall1 become more and more toned down by the action of sun and air1 and at some distance below the base of the cascade they are subdued so as to form the transverse undulations already described4 ,these undulations are more and more reduced as the glacier descends2 and long before the ,tacul is attained1 every sensible trace of them has disappeared4 ,the terraces of the ice-fall are referred to by ,professor ,forbes in his ,thirteenth ,letter1 where he thus describes them3--,the ice-falls succeed one another at regulated intervals1 which appear to correspond to the renewal of each summer's activity in those realms of almost perpetual frost1 when a swifter motion occasions a more rapid and wholesale projection of the mass over the steep1 thus forming curvilinear terraces like vast stairs1 which appear afterwards by consolidation to form the remarkable protuberant wrinkles on the surface of the ,glacier du ,geant4 ,sidenote3 ,,forbes',s ,,explanation4 ,with regard to the cause of the distribution of the dirt in bands1 ,professor ,forbes writes thus in his ,third ,letter3--,i at length assured myself that it was entirely owing to the structure of the ice1 which retains the dirt diffused by avalanches and the weather on those parts which are most porous1 whilst the compacter portion is washed clean by the rain1 so that those bands are nothing more than visible traces of the direction of the internal icy structure4 ,professor ,forbes's theory1 at that time1 was that the glacier is composed throughout of a series of alternate segments of hard and porous ice1 in the latter of which the dirt found a lodgment4 ,i do not know whether he now retains his first opinion2 but in his ,fifteenth ,letter he speaks of accounting for the less compact structure of the ice beneath the dirt-band4 ,it appears to me that in the above explanation cause has been mistaken for effect4 ,the ice on which the dirt-bands rest certainly appears to be of a spongier character than the cleaner intermediate ice2 but instead of this being the cause of the dirt-bands1 the latter1 ,i imagine1 by their more copious absorption of the sun's rays and the consequent greater disintegration of the ice1 are the cause of the apparent porosity4 ,i have not been able to detect any relative porosity in the internal icy structure1 nor am ,i able to find in the writings of ,professor ,forbes a description of the experiments whereby he satisfied himself that this assumed difference exists4 ,sidenote3 ,,transverse ,,undulations4 ,sidenote3 ,,influence ,,of ,,direction ,,of ,,glacier4 ,several days of the summer of #aheg were devoted by me to the examination of these bands4 ,i then found the bases and the frontal slopes of the undulations to which ,i have referred covered with a fine brown mud4 ,these slopes were also1 in some cases1 covered with snow which the great heat of the weather had not been able entirely to remove4 ,at places where the residue of snow was small its surface was exceedingly dirty--so dirty indeed that it appeared as if peat-mould had been strewn over it2 its edges particularly were of a black brown4 ,it was perfectly manifest that this snow formed a receptacle for the fine dirt transported by the innumerable little rills which trickled over the glacier4 ,the snow gradually wasted1 but it left its sediment behind1 and thus each of the snowy bands observed by ,professor ,forbes in #ahdc1 contributed to produce an appearance perfectly antithetical to its own4 ,i have said that the frontal slopes of the undulations were thus covered2 and it was on these1 and not in the depressions1 that the snow principally rested4 ,the reason of this is to be found in the bearing of the ,glacier du ,geant1 which1 looking downwards1 is about fourteen degrees east of the meridian4,b ,hence the frontal slopes of the undulations have a northern aspect1 and it is this circumstance which1 in my opinion1 causes the retention of the snow upon them4 ,irrespective of the snow1 the mere tendency of the dirt to accumulate at the bases of the undulations would also produce bands1 and indeed does so on many glaciers2 but the precision and beauty of the dirt-bands of the ,mer de ,glace are1 ,i think1 to be mainly referred to the interception by the snow of the fine dark mud before referred to on the northern slopes of its undulations4 ,sidenote3 ,,bands ,,do ,,not ,,cross ,,moraines4 ,were the statements of some writers upon this subject well founded1 or were the dirt-bands as drawn upon the map of ,professor ,forbes correctly shown1 this explanation could not stand a moment4 ,it has been urged that the dirt-bands cannot thus belong to a single tributary of the ,mer de ,glace2 for if they did1 they would be confined to that tributary upon the trunk-glacier2 whereas the fact is that they extend quite across the trunk1 and intersect the moraines which divide the ,glacier du ,geant from its fellow-tributaries4 ,from my first acquaintance with the ,mer de ,glace ,i had reason to believe that this statement was incorrect2 but last year ,i climbed a third time to the ,cleft-station for the purpose of once more inspecting the bands from this fine position4 ,i was accompanied by ,dr4 ,frankland and ,auguste ,balmat1 and ,i drew the attention of both particularly to this point4 ,neither of them could discern1 nor could ,i1 the slightest trace of a dirt-band crossing any one of the moraines4 ,upon the trunk-stream they were just as much confined to the ,glacier du ,geant as ever4 ,if the bands even existed east of the moraines1 they could not be seen1 the dirt on this part of the glacier being sufficient to mask them4 ,the following interesting fact may perhaps have contributed to the production of the error referred to4 ,opposite to ,trelaporte the eastern arms of the dirt-bands run so obliquely into the moraine of ,la ,noire that the latter appears to be a tangent to them4 ,but this moraine runs along the ,mer de ,glace1 not far from its centre1 and consequently the point of contact of each dirt-band with the moraine moves more quickly than the point of contact of the western arm of the same band with the side of the valley4 ,hence there is a tendency to straighten the bands2 and at some distance down the glacier the effect of this is seen in the bands abutting against the moraine of ,la ,noire at a larger angle than before4 ,the branches thus abutting have1 ,i believe1 been ideally prolonged across the moraines4 ,illustration3 ,fig4 #ch4 ,plan of ,dirt-bands taken from ,johnson's ',physical ,atlas4' ,on the map published by ,prof4 ,forbes in #ahdc the bands are shown crossing the medial moraines of the ,mer de ,glace2 and they are also thus drawn on the map in ,johnson's ',physical ,atlas' published in #ahdi4 ,the text is also in accordance with the map3--,opposite to the ,montanvert1 and beyond les ,echelets1 the curved loops 7dirt-bands7 extend across the entire glacier4 ,they are single1 and therefore cut the medial moraine1 though at a very slight angle4--',travels1' p4 #aff4 ,the italics here belong to ,prof4 ,forbes4 ,in order to help future observers to place this point beyond doubt1 ,i annex1 in ,fig4 #ch1 a portion of the map of the ,mer de ,glace taken from the ,atlas referred to4 ,if it be compared with ,fig4 #ce the difference between ,prof4 ,forbes and myself will be clearly seen4 ,the portion of the glacier represented in both diagrams may be viewed from the point near the ,flegere already referred to4 ,sidenote3 ,,annual ,,rings4 ,the explanation which ,i have given involves three considerations3--,the transverse breaking of the glacier on the cascade1 and the gradual accumulation of the dirt in the hollows between the ridges2 the subsequent toning down of the ridges to gentle protuberances which sweep across the glacier2 and the collection of the dirt upon the slopes and at the bases of these protuberances4 ,whether the periods of transverse fracture are annual or not--whether the wrinkles correspond to a yearly gush--and whether1 consequently1 the dirt-bands mark the growth of a glacier as the annual rings mark the growth of a tree1 ,i do not know4 ,it is a conjecture well worthy of consideration2 but it is only a conjecture1 which future observation may either ratify or refute4 ,,footnotes3 ,a ',travels1' page #afb4 ,b ,in the large map of ,professor ,forbes the bearing of the valley is nearly sixty degrees west of the meridian2 but this is caused by the true north being drawn on the wrong side of the magnetic north2 thus making the declination easterly instead of westerly4 ,in the map in ,johnson's ',physical ,atlas' this mistake is corrected4 ,,the ,,veined ,,structure ,,of ,,glaciers4 7#bg47 ,sidenote3 ,,general ,,appearance4 ,the general appearance of the veined structure may be thus briefly described3--,the ice of glaciers1 especially midway between their mountain-sources and their inferior extremities1 is of a whitish hue1 caused by the number of small air-bubbles which it contains1 and which1 no doubt1 constitute the residue of the air originally entrapped in the interstices of the snow from which it has been derived4 ,through the general whitish mass1 at some places1 innumerable parallel veins of clearer ice are drawn1 which usually present a beautiful blue colour1 and give the ice a laminated appearance4 ,the cause of the blueness is1 that the air-bubbles1 distributed so plentifully through the general mass1 do not exist in the veins1 or only in comparatively small numbers4 ,in different glaciers1 and in different parts of the same glacier1 these veins display various degrees of perfection4 ,on the clean unweathered walls of some crevasses1 and in the channels worn in the ice by glacier-streams1 they are most distinctly seen1 and are often exquisitely beautiful4 ,they are not to be regarded as a partial phenomenon1 or as affecting the constitution of glaciers to a small extent merely4 ,a large portion of the ice of some glaciers is thus affected4 ,the greater part1 for example1 of the ,mer de ,glace consists of this laminated ice2 and the whole of the ,glacier of the ,rhone1 from the base of the ice-cascade downwards1 is composed of ice of the same description4 ,sidenote3 ,,grooves ,,on ,,the ,,surface ,,of ,,glaciers4 ,those who have ascended ,snowdon1 or wandered among the hills of ,cumberland1 or even walked in the environs of ,leeds1 ,blackburn1 and other towns in ,yorkshire and ,lancashire1 where the stratified sandstone of the district is used for building purposes1 may have observed the weathered edges of the slate rocks or of the building-stone to be grooved and furrowed4 ,some laminae of such rocks withstand the action of the atmosphere better than others1 and the more resistant ones stand out in ridges after the softer parts between them have been eaten away4 ,an effect exactly similar is observed where the laminated ice of glaciers is exposed to the action of the sun and air4 ,little grooves and ridges are formed upon its surface1 the more resistant plates protruding after the softer material between them has been melted away4 ,one consequence of this furrowing is1 that the light dirt scattered by the winds over the surface of the glacier is gradually washed into the little grooves1 thus forming fine lines resembling those produced by the passage of a rake over a sanded walk4 ,these lines are a valuable index to some of the phenomena of motion4 ,from a position on the ice of the ,glacier du ,geant a little higher up than ,trelaporte a fine view of these superficial groovings is obtained2 but the dirt-lines are not always straight4 ,a slight power of independent motion is enjoyed by the separate parts into which a glacier is divided by its crevasses and dislocations1 and hence it is1 that1 at the place alluded to1 the dirt-lines are bent hither and thither1 though the ruptures of continuity are too small to affect materially the general direction of the structure4 ,on the glacier of the ,talefre ,i found these groovings useful as indicating the character of the forces to which the ice near the summit of the fall is subjected4 ,the ridges between the chasms are in many cases violently bent and twisted1 while the adjacent groovings enable us to see the normal position of the mass4 ,sidenote3 ,,guyot',s ,,observations4 ,the veined structure has been observed by different travellers2 but it was probably first referred to by ,sir ,david ,brewster1 who noticed the veins of the ,mer de ,glace on the #ajth of ,september1 #ahad4 ,it was also observed by ,general ,sabine1,a by ,rendu1 by ,agassiz1 and no doubt by many others2 but the first clear description of it was given by ,m4 ,guyot1 in a communication presented to the ,geological ,society of ,france in #ahch4 ,i quote the following passage from this paper3--,i saw under my feet the surface of the entire glacier covered with regular furrows 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 mass of the glacier here was composed of two sorts of ice1 one that of the furrows1 snowy and more easily melted2 the other that 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 furrows and ridges4 ,after having followed them for several hundreds of yards1 ,i reached a fissure 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 vision could reach ,i saw the mass of the glacier composed of layers of snowy ice1 each two of which were separated by one of the plates of which ,i have spoken1 the whole forming a regularly laminated mass1 which resembled certain calcareous slates4 ,sidenote3 ,,forbes',s ,,researches4 ,previous observers had mistaken the lamination for stratification2 but ,m4 ,guyot not only clearly saw that they were different1 but in the comparison which he makes he touches1 ,i believe1 on the true cause of the glacier-structure4 ,he did not hazard an explanation of the phenomenon1 and ,i believe his memoir remained unprinted4 ,in #ahda the structure was noticed by ,professor ,forbes during his visit to ,m4 ,agassiz on the lower ,aar ,glacier1 and described in a communication presented by him to the ,royal ,society of ,edinburgh4 ,he subsequently devoted much time to the subject1 and his great merit in connexion with it consists in the significance which he ascribed to the phenomenon when he first observed it1 and in the fact of his having proved it to be a constitutional feature of glaciers in general4 ,sidenote3 ,,forbes',s ,,theory4 ,the first explanation given of those veins by ,professor ,forbes was1 that they were small fissures formed in the ice by its motion2 that these were filled with the water of the melted ice in summer1 which froze in winter so as to form the blue veins4 ,this is the explanation given in his ',travels1' page #cgg2 and in a letter published in the ',edinburgh ,new ,philosophical ,journal1' ,october1 #ahdd1 it is re-affirmed in these words3--,with the abundance of blue bands before us in the direction in which the differential motion must take place 7in this case sensibly parallel to the sides of the glacier71 it is impossible to doubt that these infiltrated crevices 7for such they undoubtedly are7 have this origin4 ,this theory was examined by ,mr4 ,huxley and myself in our joint paper2 but it has been since alleged that ours was unnecessary labour1 ,prof4 ,forbes himself having in his ,thirteenth ,letter renounced the theory1 and substituted another in its place4 ,the latter theory differs1 so far as ,i can understand it1 from the former in this particular1 that the freezing of the water in the fissures is discarded1 their sides being now supposed to be united by the simple effects of time and cohesion4,b ,for a statement of the change which his opinions have undergone1 ,i would refer to the ,prefatory ,note which precedes the volume of ',occasional ,papers' recently published by ,prof4 ,forbes2 but it would have diminished my difficulty had the author given1 in connexion with his new volume1 a more distinct statement of his present views regarding the veined structure4 ,with many of his observations and remarks ,i should agree2 with many others ,i cannot say whether ,i agree or not2 and there are others still with which ,i do not think ,i should agree3 but in hardly any case am ,i certain of his precise views1 excepting1 indeed1 the cardinal one1 wherein he and others agree in ascribing to the structure a different origin from stratification4 ,thus circumstanced1 my proper course1 ,i think1 will be to state what ,i believe to be the cause of the structure1 and leave it to the reader to decide how far our views harmonize2 or to what extent either of them is a true interpretation of nature4 ,sidenote3 ,,usual ,,aspect ,,of ,,blue ,,veins4 ,most of the earlier observers considered the structure to be due to the stratification of the mountain-snows--a view which has received later development at the hands of ,mr4 ,john ,ball2 and the practical difficulty of distinguishing the undoubted effects of stratification from the phenomena presented by structure1 entitles this view to the fullest consideration4 ,the blue veins of glaciers are1 however1 not always1 nor even generally1 such as we should expect to result from stratification4 ,the latter would furnish us with distinct planes extending parallel to each other for considerable distances through the glacier2 but this1 though sometimes the case1 is by no means the general character of the structure4 ,we observe blue streaks1 from a few inches to several feet in length1 upon the walls of the same crevasse1 and varying from the fraction of an inch to several inches in thickness4 ,in some cases the streaks are definitely bounded1 giving rise to an appearance resembling the section of a lens1 and hence called the lenticular structure by ,mr4 ,huxley and myself2 but more usually they fade away in pale washy streaks through the general mass of the whitish ice4 ,in ,fig4 #ci ,i have given a representation of the structure as it is very commonly exhibited on the walls of crevasses4 ,its aspect is not that which we should expect from the consolidation of successive beds of mountain snow4 ,illustration3 ,fig4 #ci4 ,veined ,structure of the walls of crevasses4 ,further1 at the bases of ice-cascades the structural laminae are usually vertical3 below the cascade of the ,talefre1 of the ,noire1 of the ,strahleck branch of the ,lower ,grindelwald ,glacier1 of the ,rhone1 and other ice-falls1 this is the case2 and it seems extremely difficult to conceive that a mass horizontally stratified at the summit of the fall1 should1 in its descent1 contrive to turn its strata perfectly on end4 ,again1 we often find a very feebly-developed structure at the central portions of a glacier1 while the lateral portions are very decidedly laminated4 ,this is the case where the inclination of the glacier is nearly uniform throughout2 and where no medial moraines occur to complicate the phenomenon4 ,but if the veins mark the bedding1 there seems to be no sufficient reason for their appearance at the lateral portions of the glacier1 and their absence from the centre4 ,sidenote3 ,,illustrative ,,experiments4 ,this leads me to the point at which what ,i consider to be the true cause of the structure may be referred to4 ,the theoretic researches of ,mr4 ,hopkins have taught us a good deal regarding the pressures and tensions consequent upon glacier-motion4 ,aided by this knowledge1 and also by a mode of experiment first introduced by ,professor ,forbes1 ,i will now endeavour to explain the significance of the fact referred to in the last paragraph4 ,if a plastic substance1 such as mud1 flow down a sloping canal1 the lateral portions1 being held back by friction1 will be outstripped by the central ones4 ,when the flow is so regulated that the velocity of a point at the centre shall not vary throughout the entire length of the canal1 a coloured circle stamped upon the centre of the mud stream1 near its origin1 will move along with the mud1 and still retain its circular form2 for1 inasmuch as the velocity of all points along the centre is the same1 there can be no elongation of the circle longitudinally or transversely by either strain or pressure4 ,a similar absence of longitudinal pressure may exist in a glacier1 and1 where it exists throughout1 no central structure can1 in my opinion1 be developed4 ,but let a circle be stamped upon the mud-stream near its side1 then1 when the mud flows1 this circle will be distorted to an oval1 with its major axis oblique to the direction of motion2 the cause of this is that the portion of the circle farthest from the side of the canal moves more freely than that adjacent to the side4 ,the mechanical effect of the slower lateral motion is to squeeze the circle in one direction1 and draw it out in the perpendicular one4 ,sidenote3 ,,marginal ,,structure4 ,illustration3 ,fig4 #dj4 ,figure explanatory of the ,marginal ,structure4 ,a glance at ,fig4 #dj will render all that ,i have said intelligible4 ,the three circles are first stamped on the mud in the same transverse line2 but after they have moved downwards they will be in the same straight line no longer4 ,the central one will be the foremost2 while the lateral ones have their forms changed from circles to ovals4 ,in a glacier of the shape of this canal exactly similar effects are produced4 ,now the shorter axis m n of each oval is a line of squeezing or pressure2 the longer axis is a line of strain or tension2 and the associated glacier-phenomena are as follows3--,across the line m n1 or perpendicular to the pressure1 we have the veined structure developed1 while across the line of tension the glacier usually breaks and forms marginal crevasses4 ,mr4 ,hopkins has shown that the lines of greatest pressure and of greatest strain are at right angles to each other1 and that in valleys of a uniform width they enclose an angle of forty-five degrees with the side of the glacier4 ,to the structure thus formed ,i have applied the term marginal structure4 ,here1 then1 we see that there are mechanical agencies at work near the side of such a glacier which are absent from the centre1 and we have effects developed--,i believe by the pressure--in the lateral ice1 which are not produced in the central4 ,i have used the term uniform inclination in connexion with the marginal structure1 and my reason for doing so will now appear4 ,in many glaciers the structure1 instead of being confined to the margins1 sweeps quite across them4 ,this is the case1 for example1 on the ,glacier du ,geant1 the structure of which is prolonged into the ,mer de ,glace4 ,in passing the strait at ,trelaporte1 however1 the curves are squeezed and their apices bruised1 so that the structure is thrown into a state of confusion2 and thus upon the ,mer de ,glace we encounter difficulty in tracing it fairly from side to side4 ,now the key to this transverse structure ,i believe to be the following3 ,where the inclination of the glacier suddenly changes from a steep slope to a gentler1 as at the bases of the cascades1--the ice to a certain depth must be thrown into a state of violent longitudinal compression2 and along with this we have the resistance which the gentler slope throws athwart the ice descending from the steep one4 ,at such places a structure is developed transverse to the axis of the glacier1 and likewise transverse to the pressure4 ,the quicker flow of the centre causes this structure to bend more and more1 and after a time it sweeps in vast curves across the entire glacier4 ,sidenote3 ,,structure ,,of ,,grindelwald ,,glacier4 ,in illustration of this point ,i will refer1 in the first place1 to that tributary of the ,lower ,glacier of ,grindelwald which descends from the ,strahleck4 ,walking up this tributary we come at length to the base of an ice-fall4 ,let the observer here leave the ice1 and betake himself to either side of the flanking mountain4 ,on attaining a point which commands a view both of the fall and of the glacier below it1 an inspection of the glacier will1 ,i imagine1 solve to his satisfaction the case of structure now under consideration4 ,it is indeed a grand experiment which ,nature here submits to our inspection4 ,the glacier descending from its neve reaches the summit of the cascade1 and is broken transversely as it crosses the brow2 it afterwards descends the fall in a succession of cliffy ice-ridges with transverse hollows between them4 ,in these latter the broken ice and debris collect1 thus partially choking the fissures formed in the first instance4 ,carrying the eye downwards along the fall1 we see1 as we approach the base1 these sharp ridges toned down2 and a little below the base they dwindle into rounded protuberances which sweep in curves quite across the glacier4 ,at the base of the fall the structure begins to appear1 feebly at first1 but becoming gradually more pronounced1 until1 at a short distance below the base of the fall1 the eye can follow the fine superficial groovings from side to side2 while at the same time the ice underneath the surface has become laminated in the most beautiful manner4 ,it is difficult to convey by writing the force of the evidence which the actual observation of this natural experiment places before the mind4 ,the ice at the base of the fall1 retarded by the gentler inclination of the valley1 has to bear the thrust of the descending mass1 the sudden change of inclination producing powerful longitudinal compression4 ,the protuberances are squeezed more closely together1 the hollows between them appear to wrinkle up in submission to the pressure--in short1 the entire aspect of the glacier suggests the powerful operations of the latter force4 ,at the place where it is exerted the veined structure makes its appearance2 and being once formed1 it moves downwards1 and gives a character to other portions of the glacier which had no share in its formation4 ,sidenote3 ,,base ,,of ,,cascade ,a ,,structure-,,mill4 ,an illustration almost as good1 and equally accessible1 is furnished by the ,glacier of the ,rhone4 ,i have examined the grand cascade of this glacier from both sides2 and an ordinary mountaineer will find little difficulty in reaching a point from which the fall and the terminal portion of the glacier are both distinctly visible4 ,here also he will find the cliffy ridges separated from each other by transverse chasms1 becoming more and more subdued at the bottom of the fall1 and disappearing entirely lower down the glacier4 ,as in the case of the ,grindelwald ,glacier the squeezing of the protuberances and of the spaces between them1 is quite apparent1 and where this squeezing commences the transverse structure makes its appearance4 ,all the ice that forms the lower portion of this glacier has to pass through the structure-mill at the bottom of the fall1 and the consequence is that it is all laminated4 ,sidenote3 ,,structure ,,of ,,rhone ,,glacier4 ,illustration3 ,fig4 #da4 ,plan of part of ice-fall1 and of glacier below it 7,glacier of the ,rhone74 ,illustration3 ,fig4 #db4 ,section of part of ice-fall1 and of glacier below it 7,glacier of the ,rhone74 ,sidenote3 ,,transverse ,,structure4 ,this case of structural development will be better appreciated on reference to ,figs4 #da and #db1 the former of which is a plan1 and the latter a section1 of a part of the ice-fall and of the glacier below it2 a b e f is the gorge of the fall1 f b being the base4 ,the transverse cliffy ice-ridges are shown crossing the cascade1 being subdued at the base to protuberances which gradually disappear as they advance downwards4 ,the structure sweeps over the glacier in the direction of the fine curved lines2 and ,i have also endeavoured to show the direction of the radial crevasses1 which1 in the centre at least1 are at right angles to the veins4 ,to the manifestation of structure here considered ,i have1 for the sake of convenient reference1 applied the term transverse structure4 ,a third exhibition of the structure is now to be noticed4 ,we sometimes find it in the middle of a glacier and running parallel to its length4 ,on the centre of the ice-fall of the ,talefre1 for example1 we have a structure of this kind which preserves itself parallel to the axis of the fall from top to bottom4 ,but we discover its origin higher up4 ,the structure here has been produced at the extremity of the ,jardin1 where the divided ice meets1 and not only brings into partial parallelism the veins previously existing along the sides of the ,jardin1 but develops them still further by the mutual pressure of the portions of newly welded ice4 ,where two tributary glaciers unite1 this is perhaps without exception the case4 ,underneath the moraine formed by the junction of the ,talefre and ,lechaud the structure is finely developed1 and the veins run in the direction of the moraine4 ,the same is true of the ice under the moraine formed by the junction of the ,lechaud and ,geant4 ,these afterwards form the great medial moraines of the ,mer de ,glace1 and hence the structure of the trunk-stream underneath these moraines is parallel to the direction of the glacier4 ,this is also true of the system of moraines formed by the glaciers of ,monte ,rosa4 ,it is true in an especial manner of the lower glacier of the ,aar1 whose medial moraine perhaps attains grander proportions than any other in the ,alps1 and underneath which the structure is finely developed4 ,sidenote3 ,,longitudinal ,,structure4 ,illustration3 ,fig4 #dc4 ,figure explanatory of ,longitudinal ,structure4 ,the manner in which ,i have illustrated the production of this structure will be understood from ,fig4 #dc4 ,b ,b are two wooden boxes1 communicating by sluice-fronts with two branch canals1 which unite to a common trunk at ,g4 ,they are intended to represent respectively the trunk and tributaries of the ,unteraar ,glacier1 the part ,g being the ,abschwung1 where the ,lauteraar and ,finsteraar glaciers unite to form the ,unteraar4 ,the mud is first permitted to flow beneath the two sluices until it has covered the bottom of the trough for some distance1 when it is arrested4 ,the end of a glass tube is then dipped into a mixture of rouge and water1 and small circles are stamped upon the mud4 ,the two branches are thickly covered with these circles4 ,the sluices being again raised1 the mud in the branches moves downwards1 carrying with it the circles stamped upon it2 and the manner in which these circles are distorted enables us to infer the strains and pressures to which the mud is subjected during its descent4 ,the figure represents approximately what takes place4 ,the side-circles1 as might be expected1 are squeezed to oblique ovals1 but it is at the junction of the branches that the chief effect of pressure is produced4 ,here1 by the mutual thrust of the branches1 the circles are not only changed to elongated ellipses1 but even squeezed to straight lines4 ,in the case of the glacier this is the region at which the structure receives its main development4 ,to this manifestation of the veins ,i have applied the term longitudinal structure4 ,the three main sources of the blue veins are1 ,i think1 here noted2 but besides these there are many local causes which influence their production4 ,i have seen them well formed where a glacier is opposed by the sudden bend of a valley1 or by a local promontory which presents an obstacle sufficient to bring the requisite pressure into play4 ,in the glaciers of the ,tyrol and of the ,oberland ,i have seen examples of this kind2 but the three principal sources of the veins are1 ,i think1 those stated above4 ,sidenote3 ,,efforts ,,to ,,solve ,,question4 ,it was long before ,i cleared my mind of doubt regarding the origin of the lamination4 ,when on the ,mer de ,glace in #aheg ,i spared neither risk nor labour to instruct myself regarding it4 ,i explored the ,talefre basin1 its cascade1 and the ice beneath it4 ,several days were spent amid the ice humps and cliffs at the lower portion of the fall4 ,i suppose ,i traversed the ,glacier du ,geant twenty times1 and passed eight or ten days amid the confusion of its great cascade4 ,i visited those places where1 it had been affirmed1 the veins were produced4 ,i endeavoured to satisfy myself of the mutability which had been ascribed to them2 but a close examination reduced the value of each particular case so much that ,i quitted the glacier that year with nothing more than an opinion that the structure and the stratification were two different things4 ,i1 however1 drew up a statement of the facts observed1 with the view of presenting it to the ,royal ,society2 but ,i afterwards felt that in thus acting ,i should merely swell the literature of the subject without adding anything certain4 ,i therefore withheld the paper1 and resolved to devote another year to a search among the chief glaciers of the ,oberland1 of the ,canton ,valais1 and of ,savoy1 for proofs which should relieve my mind of all doubt upon the subject4 ,sidenote3 ,,expedition ,,for ,,this ,,purpose4 ,accordingly in #aheh ,i visited the glaciers of ,rosenlaui1 ,schwartzwald1 ,grindelwald1 the ,aar1 the ,rhone1 and the ,aletsch1 to the examination of which latter ,i devoted more than a week4 ,i afterwards went to ,zermatt1 and1 taking up my quarters at the ,riffelberg1 devoted eleven days to the examination of the great system of glaciers of ,monte ,rosa4 ,i explored the ,goerner ,glacier up almost to the ,cima de ,jazzi2 and believed that in it ,i could trace the structure from portions of the glacier where it vanished1 through various stages of perfection1 up to its full development4 ,i believe this still2 but yet it is nothing but a belief1 which the utmost labour that ,i could bestow did not raise to a certainty4 ,the ,western glacier of ,monte ,rosa1 the ,schwartze ,glacier1 the ,trifti ,glacier1 the glacier of the little ,mont ,cervin1 and of ,st4 ,theodule1 were all examined in connexion with the great trunk-stream of the ,goerner1 to which they weld themselves2 and though the more ,i pursued the subject the stronger my conviction became that pressure was the cause of the structure1 a crucial case was still wanting4 ,in the phenomena of slaty cleavage1 it is often1 if not usually1 found that the true cleavage cuts the planes of stratification--sometimes at a very high angle4 ,had this not been proved by the observations of ,sedgwick and others1 geologists would not have been able to conclude that cleavage and bedding were two different things1 and needed wholly different explanations4 ,my aim1 throughout the expedition of #aheh1 was to discover in the ice a parallel case to the above2 to find a clear and undoubted instance where the veins and the stratification were simultaneously exhibited1 cutting each other at an unmistakable angle4 ,on the #fth of ,august1 while engaged with ,professor ,ramsay upon the ,great ,aletsch ,glacier1 not far from its junction with the ,middle ,aletsch1 ,i observed what appeared to me to be the lines of bedding running nearly horizontal along the wall of a great crevasse1 while cutting them at a large angle was the true veined structure4 ,i drew my friend's attention to the fact1 and to him it appeared perfectly conclusive4 ,it is from a sketch made by him at the place that ,fig4 #dd has been taken4 ,sidenote3 ,,case ,,of ,,structure ,,on ,,the ,,aletsch4 ,illustration3 ,fig4 #dd4 ,structure and bedding on the ,great ,aletsch ,glacier4 ,this was the only case of the kind which ,i observed upon the ,aletsch ,glacier2 and as ,i afterwards spent day after day upon the ,monte ,rosa glaciers1 vainly seeking a similar instance1 the thought again haunted me that we might have been mistaken upon the ,aletsch4 ,in this state of mind ,i remained until the #ahth of ,august1 a day devoted to the examination of the ,furgge ,glacier1 which lies at the base of the ,mont ,cervin4 ,sidenote3 ,,structure ,,of ,,the ,,furgge ,,glacier4 ,crossing the valley of the ,goerner ,glacier1 and taking a plunge as ,i passed into the ,schwarze ,see1 ,i reached1 in good time1 the object of my day's excursion4 ,walking up the glacier1 ,i at length found myself opposed by a frozen cascade composed of four high terraces of ice4 ,the highest of these was chiefly composed of ice-cliffs and seracs1 many of which had fallen1 and now stood like rocking-stones upon the edge of the second terrace4 ,the glacier at the base of the cascade was strewn with broken ice1 and some blocks two hundred cubic feet in volume had been cast to a considerable distance down the glacier4 ,upon the faces of the terraces the stratification of the neve was most beautifully shown1 running in parallel and horizontal lines along the weathered surface4 ,the snow-field above the cascade is a frozen plain1 smooth almost as a sheltered lake4 ,the successive snow-falls deposit themselves with great regularity1 and at the summit of the cascade the sections of the neve are for the first time exposed4 ,hence their peculiar beauty and definition4 ,sidenote3 ,,ice ,,terrace ,,examined4 ,indeed the figure of a lake pouring itself over a rocky barrier which curves convexly upwards1 thus causing the water to fall down it1 not only longitudinally over the vertex of the curve1 but laterally over its two arms1 will convey a tolerably correct conception of the shape of the fall4 ,towards the centre the ice was powerfully squeezed laterally1 the beds were bent1 and their continuity often broken by faults4 ,on inspecting the ice from a distance with my opera glass1 ,i thought ,i saw structural groovings cutting the strata at almost a right angle4 ,had the question been an undisputed one1 ,i should perhaps have felt so sure of this as not to incur the danger of pushing the inquiry further2 but1 under the circumstances1 danger was a secondary point4 ,resigning1 therefore1 my glass to my guide1 who was to watch the tottering blocks overhead1 and give me warning should they move1 ,i advanced to the base of the fall1 removed with my hatchet the weathered surface of the ice1 and found underneath it the true veined structure1 cutting1 at nearly a right angle1 the planes of stratification4 ,the superficial groovings were not uniformly distributed over the fall1 but appeared most decided at those places where the ice appeared to have been most squeezed4 ,i examined three or four of these places1 and in each case found the true veins nearly vertical1 while the bedding was horizontal4 ,having perfectly satisfied myself of these facts1 ,i made a speedy retreat1 for the ice-blocks seemed most threatening1 and the sunny hour was that at which they fall most frequently4 ,i next tried the ascent of the glacier up a dislocated declivity to the right4 ,the ice was much riven1 but still practicable4 ,my way for a time lay amid fissures which exposed magnificent sections1 and every step ,i took added further demonstration to what ,i had observed below4 ,the strata were perfectly distinct1 the structure equally so1 and one crossed the other at an angle of seventy or eighty degrees4 ,mr4 ,sorby has adduced a case of the crumpling of a bed of sandstone through which the cleavage passes3 here on the glacier ,i had parallel cases2 the beds were bent and crumpled1 but the structure ran through the ice in sharp straight lines4 ,this perhaps was the most pleasant day ,i ever spent upon the glaciers3 my mind was relieved of a long brooding doubt1 and the intellectual freedom thus obtained added a subjective grandeur to the noble scene before me4 ,climbing the cliffs near the base of the ,matterhorn1 ,i walked along the rocky spine which extends to the ,hoernli1 and afterwards descended by the valley of ,zmutt to ,zermatt4 ,a year after my return to ,england a remark contained in ,professor ,mousson's interesting little work ',die ,gletscher der ,jetzzeit' caused me to refer to the atlas of ,m4 ,agassiz's ',systeme ,glaciaire1' from which ,i learned that this indefatigable observer had figured a case of stratification and structure cutting each other4 ,if1 however1 ,i had seen this figure beforehand1 it would not have changed my movements2 for the case1 as sketched1 would not have convinced me4 ,i have now no doubt that ,m4 ,agassiz has preceded me in this observation1 and hence my results are to be taken as mere confirmations of his4 ,sidenote3 ,,lamination ,,and ,,stratification4 ,fig4 #de represents a crumpled portion of the ice with the lines of lamination passing through the strata4 ,fig4 #df represents a case where a fault had occurred1 the veins at both sides of the line of dislocation being inclined towards each other4 ,illustration3 ,fig4 #de4 ,structure and ,stratification on the ,furgge glacier4 ,illustration3 ,fig4 #df4 ,structure and ,stratification on the ,furgge glacier4 ,figs4 #de and #df are from sketches made on the ,furgge ,glacier4--,l4 ,c4 ,t4 ,,footnotes3 ,a ,in reply to a question in connexion with this subject1 ,general ,sabine has favoured me with the following note3-- ,my dear ,tyndall1 ,it was in the summer of #ahda1 at the ,lower ,grindelwald ,glacier1 that ,i first saw1 and was greatly impressed and interested by examining and endeavouring to understand 7in which ,i did not succeed71 the veined structure of the ice4 ,i do not remember when ,i mentioned it to ,forbes1 but it must be before #ahdc1 because it is noticed in his book1 p4 #bi4 ,i had never observed it in the glaciers of ,spitzbergen or ,baffin's ,bay1 or in the icebergs of the shores and straits of ,davis or ,barrow4 ,i feel the more confident of this1 because1 when ,i first saw the veined structure in ,switzerland1 my ,arctic experience was more fresh in my recollection1 and ,i recollected nothing like it4 ,veins are indeed not uncommon in icebergs1 but they quite resemble veins in rocks1 and are formed by water filling fissures and freezing into blue ice1 finely contrasted with the white granular substance of the berg4 ,the ice of the ,grindelwald ,glacier 7where ,i examined the veined structure7 was broken up into very large masses1 which by pressure had been upturned1 so that a very poor judgment would be formed of the direction of the veins as they existed in the glacier before it had broken up4 ,sincerely yours1 ,,edward ,,sabine4 ,feb4 #bj1 #ahfj4 ,b ,in a letter to myself1 published in the #agth volume of the ',philosophical ,magazine1' ,professor ,forbes writes as follows3--,in #ahdf1 then1 ,i abandoned no part of the theory of the veined structure1 on which as you say so much labour had been expended1 except the admission1 always yielded with reluctance1 and got rid of with satisfaction1 that the congelation of water in the crevices of the glacier may extend in winter to a great depth4 ,,the ,,veined ,,structure ,,and ,,the ,,differential ,,motion4 7#bh47 ,sidenote3 ,,differential ,,motion ,,greatest ,,at ,,edges4 ,i have now to examine briefly the explanation of the structure which refers it to differential motion--to a sliding of the particles of ice past each other1 which leaves the traces of its existence in the blue veins4 ,the fact is emphatically dwelt upon by those who hold this view1 that the structure is best developed nearest to the sides of the glacier1 where the differential motion is greatest4 ,why the differential motion is at its maximum near to the sides is easily understood4 ,let ,a ,b1 ,c ,d1 ,fig4 #dg1 represent the two sides of a glacier1 moving in the direction of the arrow1 and let m a b c n be a straight line of stakes set out across the glacier to-day4 ,six months hence this line1 by the motion of the ice downwards1 will be bent to the form m a' b' c' n3 this curve will not be circular1 it will be flattened in the middle2 the points a and c1 at some distance on each side of the centre b1 move in fact with nearly the same velocity as the centre itself4 ,not so with the sides3--a' and c' have moved considerably in advance of m and n1 and hence we say that the difference of motion1 or the differential motion1 of the particles of ice near to the side is a maximum4 ,illustration3 ,fig4 #dg4 ,diagram illustrating ,differential ,motion4 ,during all this time the points m a' b' c' n have been moving straight down the glacier2 and hence it will be understood that the sliding of the parts past each other1 or1 in other words1 the differential motion1 is parallel to the sides of the glacier4 ,this1 indeed1 is the only differential motion that experiment has ever established2 and consequently1 when we find the best blue veins referred to the sides of the glacier because the differential motion is there greatest1 we naturally infer that the motion meant is parallel to the sides4 ,sidenote3 ,,structure ,,oblique ,,to ,,sides4 ,but the fact is1 that this motion would not at all account for the blue veins1 for they are not parallel to the sides1 but oblique to them4 ,this difficulty revealed itself after a time to those who first propounded the theory of differential motion1 and caused them to modify their explanation of the structure4 ,differential motion is still assumed to be the cause of the veins1 but now a motion is meant oblique to the sides1 and it is supposed to be obtained in the following way3--,through the quicker motion of the point c' the ice between it and n becomes distended2 that is to say1 the line c' n is in a state of strain--there is a drag1 it is said1 oblique to the sides of the glacier2 and it is therefore in this direction that the particles will be caused to slide past each other4 ,dr4 ,whewell1 who advocates this view1 thus expounds it4 ,he supposes the case of an alpine valley filled with india-rubber which has been warmed until it has partially melted1 or become viscous1 and then asks1 ,what will now be the condition of the mass8 ,the sides and bottom will still be held back by the friction2 the middle and upper part will slide forwards1 but not freely4 ,this want of freedom in the motion 7arising from the viscosity7 will produce a drag towards the middle of the valley1 where the motion is freest2 hence the direction in which the filaments slide past each other will be obliquely directed towards the middle4 ,the sliding will separate the mass according to such lines2 and though new attachments will take place1 the mass may be expected to retain the results of this separation in the traces of parallel fissures4,a ,nothing can be clearer than the image of the process thus placed before the mind's eye4 ,one fact of especial importance is to be borne in mind3 the sliding of filaments which is thus supposed to take place oblique to the glacier has never been proved2 it is wholly assumed4 ,a moraine1 it is admitted1 will run parallel to the side of a glacier1 or a block will move in the same direction from beginning to end1 without being sensibly drawn towards the centre1 but still it is supposed that the sliding of parts exists1 though of a character so small as to render it insensible to measurement4 ,sidenote3 ,,structure ,,crosses ,,lines ,,of ,,sliding4 ,my chief difficulty as regards this theory may be expressed in a very few words4 ,if the structure be produced by differential motion1 why is the large and real differential motion which experiments have established incompetent to produce it8 ,and how can the veins run1 as they are admitted to do1 across the lines of maximum sliding from their origin throughout the glacier to its end8 ,that a drag towards the centre of the glacier exists is undeniable1 but that in consequence of the drag there is a sliding of filaments in this direction1 is quite another thing4 ,i have in another place,b endeavoured to show experimentally that no such sliding takes place1 that the drag on any point towards the centre expresses only half the conditions of the problem2 being exactly neutralized by the thrust towards the sides4 ,it has been1 moreover1 shown by ,mr4 ,hopkins that the lines of maximum strain and of maximum sliding cannot coincide2 indeed1 if all the particles be urged by the same force1 no matter how strong the pull may be1 there will be no tendency of one to slide past the other4 ,,footnotes3 ,a ',philosophical ,magazine1' ,ser4 ,,iii41 vol4 xxvi4 ,b ',proceedings of the ,royal ,institution1' vol4 ii4 p4 #cbd4 ,,the ,,ripple-,,theory ,,of ,,the ,,veined ,,structure4 7#bi47 ,sidenote3 ,,theory ,,stated4 ,sidenote3 ,,theory ,,examined4 ,the assumption of oblique sliding1 and the production thereby of the marginal structure1 have1 however1 been fortified by considerations of an ingenious and very interesting kind4 ,how1 ,i have asked1 can the oblique structure persist across the lines of greatest differential motion throughout the length of the glacier8 ,but here ,i am met by another question which at first sight might seem equally unanswerable--,how do ripple-marks on the surface of a flowing river1 which are nothing else than lines of differential motion of a low order1 cross the river from the sides obliquely1 while the direction of greatest differential motion is parallel to the sides8 ,if ,i understand aright1 this is the main argument of ,professor ,forbes in favour of his theory of the oblique marginal structure4 ,it is first introduced in a note at page #cgh of his ',travels2' he alludes to it in a letter written the following year2 in his paper in the ',philosophical ,transactions' he develops the theory4 ,he there gives drawings of ripple-marks observed in smooth gutters after rain1 and which he finds to be inclined to the course of the stream1 exactly as the marginal structure is inclined to the side of the glacier4 ,the explanation also embraces the case of an obstacle placed in the centre of a river4 ,a case1 writes ,professor ,forbes1 parallel to the last mentioned1 where a fixed obstacle cleaves a descending stream1 and leaves its trace in a fan-shaped tail1 is well known in several glaciers1 as in that at ,ferpecle1 and the ,glacier de ,lys on the south side of ,monte ,rosa2 particularly the last1 where the veined structure follows the law just mentioned4 ,in his ,twelfth ,letter he also refers to the ripples as exactly corresponding to the position of the icy bands4 ,in his letter to ,dr4 ,whewell1 published in the ',occasional ,papers1' page #eh1 he writes as follows3--,the same is remarkably shown in the case of a stream of water1 for instance a mill-race4 ,although the movement of the water1 as shown by floating bodies1 is exceedingly nearly 7for small velocities sensibly7 parallel to the sides1 yet the variation of the speed from the side to the centre of the stream occasions a ripple1 or molecular discontinuity1 which inclines forwards from the sides to the centre of the stream at an angle with the axis depending on the ratio of the central and lateral velocity4 ,the veined structure of the ice corresponds to the ripple of the water1 a molecular discontinuity whose measure is not comparable to the actual velocity of the ice2 and therefore the general movement of the glacier1 as indicated by the moraines1 remains sensibly parallel to the sides4 ,this theory opens up to us a series of interesting and novel considerations which ,i think will repay the reader's attention4 ,if the ripples in the water and the veins in the ice be due to the same mechanical cause1 when we develop clearly the origin of the former we are led directly to the explanation of the latter4 ,i shall now endeavour to reduce the ripples to their mechanical elements4 ,the ,messrs4 ,weber have described in their ',wellenlehre' an effect of wave-motion which it is very easy to obtain4 ,when a boat moves through perfectly smooth water1 and the rower raises his oar out of the water1 drops trickle from its blade1 and each drop where it falls produces a system of concentric rings4 ,the circular waves as they widen become depressed1 and1 if the drops succeed each other with sufficient speed1 the rings cross each other at innumerable points4 ,the effect of this is to blot out more or less completely all the circles1 and to leave behind two straight divergent ripple-lines1 which are tangents to all the external rings2 being in fact formed by the intersections of the latter1 as a caustic in optics is formed by the intersection of luminous rays4 ,fig4 #dh1 which is virtually copied from ,m4 ,weber1 will render this description at once intelligible4 ,the boat is supposed to move in the direction of the arrow1 and as it does so the rings which it leaves behind widen1 and produce the divergence of the two straight resultant lines of ripple4 ,sidenote3 ,,ripples ,,deduced ,,from ,,rings4 ,illustration3 ,fig4 #dh4 ,diagram explanatory of the formation of ,ripples4 ,the more quickly the drops succeed each other1 the more frequent will be the intersections of the rings2 but as the speed of succession augments we approach the case of a continuous vein of liquid2 and if we suppose the continuity to be perfectly established1 the ripples will still be produced with a smooth space between them as before4 ,this experiment may indeed be made with a well-wetted oar1 which on its first emergence from the water sends into it a continuous liquid vein4 ,the same effect is produced when we substitute for the stream of liquid a solid rod--a common walking-stick for example4 ,a water-fowl swimming in calm water produces two divergent lines of ripples of a similar kind4 ,we have here supposed the water of the lake to be at rest1 and the liquid vein or the solid rod to move through it2 but precisely the same effect is produced if we suppose the rod at rest and the liquid in motion4 ,let a post1 for example1 be fixed in the middle of a flowing river2 diverging from that post right and left we shall have lines of ripples exactly as if the liquid were at rest and the post moved through it with the velocity of the river4 ,if the same post be placed close to the bank1 so that one of its edges only shall act upon the water1 diverging from that edge we shall have a single line of ripples which will cross the river obliquely towards its centre4 ,it is manifest that any other obstacle will produce the same effect as our hypothetical post4 ,in the words of ,professor ,forbes1 the slightest prominence of any kind in the wall of such a conduit1 a bit of wood or a tuft of grass1 is sufficient to produce a well-marked ripple-streak from the side towards the centre4 ,sidenote3 ,,measure ,,of ,,divergence ,,of ,,ripples4 ,the foregoing considerations show that the divergence of the two lines of ripples from the central post1 and of the single line in the case of the lateral post1 have their mechanical element1 if ,i may use the term1 in the experiment of the ,messrs4 ,weber4 ,in the case of a swimming duck the connexion between the diverging lines of ripples and the propagation of rings round a disturbed point is often very prettily shown4 ,when the creature swims with vigour the little foot with which it strikes the water often comes sufficiently near to the surface to produce an elevation1--sometimes indeed emerging from the water altogether4 ,round the point thus disturbed rings are immediately propagated1 and the widening of those rings is the exact measure of the divergence of the ripple lines4 ,the rings never cross the lines2--the lines never retreat from the rings4 ,sidenote3 ,,ripples ,,and ,,veins ,,due ,,to ,,different ,,causes4 ,if we compare the mechanical actions here traced out with those which take place upon a glacier1 ,i think it will be seen that the analogy between the ripples and the veined structure is entirely superficial4 ,how the structure ascribed to the ,glacier de ,lys is to be explained ,i do not know1 for ,i have never seen it2 but it seems impossible that it could be produced1 as ripples are1 by a fixed obstacle which cleaves a descending stream4 ,no one surely will affirm that glacier-ice so closely resembles a fluid as to be capable of transmitting undulations1 as water propagates rings round a disturbed point4 ,the difficulty of such a supposition would be augmented by taking into account the motion of the individual liquid particles which go to form a ripple2 for the ,messrs4 ,weber have shown that these move in closed curves1 describing orbits more or less circular4 ,can it be supposed that the particles of ice execute a motion of this kind8 ,if so1 their orbital motions may be easily calculated1 being deducible from the motion of the glacier compounded with the inclination of the veins4 ,if so important a result could be established1 all glacier theories would vanish in comparison with it4 ,sidenote3 ,,position ,,of ,,ripples ,,not ,,that ,,of ,,structure4 ,there is another interesting point involved in the passage above quoted4 ,professor ,forbes considers that the ripple is occasioned by the variation of speed from the side to the centre of the stream1 and that its inclination depends on the ratio of the central and lateral velocity4 ,if ,i am correct in the above analysis1 this cannot be the case4 ,the inclination of the ripple depends solely on the ratio of the river's translatory motion to the velocity of its wave-motion4 ,were the lateral and central velocities alike1 a momentary disturbance at the side would produce a straight ripple-mark1 whose inclination would be compounded of the two elements just mentioned4 ,if the motion of the water vary from side to centre1 the velocity of wave-propagation remaining constant1 the inclination of the ripple will also vary1 that is to say1 we shall have a curved ripple instead of a straight one4 ,this1 of course1 is the case which we find in ,nature1 but the curvature of such ripples is totally different from that of the veined structure4 ,owing to the quicker translatory movement1 the ripples1 as they approach the centre1 tend more to parallelism with the direction of the river2 and after having passed the centre1 and reached the slower water near the opposite side1 their inclination to the axis gradually augments4 ,thus the ripples from the two sides form a pair of symmetric curves1 which cross each other at the centre1 and possess the form a o b1 c o d1 shown in ,fig4 #di4 ,a similar pair of curves would be produced by the reflection of these4 ,knowing the variation of motion from side to centre1 any competent mathematician could find the equation of the ripple-curves2 but it would be out of place for me to attempt it here4 ,illustration3 ,fig4 #di4 ,diagram explanatory of the formation of ,ripples4 ,,the ,,veined ,,structure ,,and ,,pressure4 7#cj47 ,if a prism of glass be pressed by a sufficient weight1 the particles in the line of pressure will be squeezed more closely together1 while those at right angles to this line will be forced further apart4 ,the existence of this state of strain may be demonstrated by the action of such squeezed glass upon polarised light4 ,it gives rise to colours1 and it is even possible to infer from the tint the precise amount of pressure to which the glass is subjected4 ,m4 ,wertheim indeed has most ably applied these facts to the construction of a dynamometer1 or instrument for measuring pressures1 exceeding in accuracy any hitherto devised4 ,when the pressure applied becomes too great for the glass to sustain1 it flies to pieces4 ,but let us suppose the sides of the prism defended by an extremely strong jacket1 in which the prism rests like a closely-fitting plug1 and which yields only when a pressure more than sufficient to crush the glass is applied4 ,let the pressure be gradually augmented until this point is attained2 afterwards both the glass and its jacket will shorten and widen2 the jacket will yield laterally1 being pushed out with extreme slowness by the glass within4 ,sidenote3 ,,possible ,,experiment ,,with ,,glass ,,prism4 ,now ,i believe that it would be possible to make this experiment in such a manner that the glass should be flattened1 partly through rupture1 and partly through lateral molecular yielding2 the prism would change its form1 and yet present a firmly coherent mass when removed from its jacket4 ,i have never made the experiment2 nobody has1 as far as ,i know2 but experiments of this kind are often made by ,nature4 ,in the ,museum of the ,government ,school of ,mines1 for example1 we have a collection of quartz stones placed there by ,mr4 ,salter1 and which have been subjected to enormous pressure in the neighbourhood of a fault4 ,these rigid pebbles have1 in some cases1 been squeezed against each other so as to produce mutual flattening and indentation4 ,some of them have yielded along planes passing through them1 as if one half had slidden over the other2 but the reattachment is very strong4 ,some of the larger stones1 moreover1 which have endured pressure at a particular point1 are fissured radially around this point4 ,in short1 the whole collection is a most instructive example of the manner and extent to which one of the most rigid substances in ,nature can yield on the application of a sufficient force4 ,sidenote3 ,,possible ,,experiment ,,with ,,prism ,,of ,,ice4 ,let a prism of ice at #cb deg4 be placed in a similar jacket to that which we have supposed to envelop the glass prism4 ,the ice yields to the pressure with incomparably greater ease than the glass2 and if the force be slowly applied1 the lateral yielding will far more closely resemble that of a truly plastic body4 ,supposing such a piece of ice to be filled with numerous small air-bubbles1 the tendency of the pressure would be to flatten these bubbles1 and to squeeze them out of the ice4 ,were the substance perfectly homogeneous1 this flattening and expulsion would take place uniformly throughout its entire mass2 but ,i believe there is no such homogeneous substance in nature2--the ice will yield at different places1 leaving between them spaces which are comparatively unaffected by the pressure4 ,from the former spaces the air-bubbles will be more effectually expelled2 and ,i have no doubt that the result of such pressure acting upon ice so protected would be to produce a laminated structure somewhat similar to that which it produces in those bodies which exhibit slaty cleavage4 ,sidenote3 ,,lamination ,,produced ,,by ,,pressure4 ,sidenote3 ,,no ,,sliding ,,of ,,filaments4 ,i also think it certain that1 in this lateral displacement of the particles1 these must move past each other4 ,this is an idea which ,i have long entertained1 as the following passage taken from the paper published by ,mr4 ,huxley and myself will prove3--,three principal causes may operate in producing cleavage3 first1 the reducing of surfaces of weak cohesion to parallel planes2 second1 the flattening of minute cavities2 and third1 the weakening of cohesion by tangential action4 ,the third action is exemplified by the state of the rails near a station where a break is habitually applied to a locomotive4 ,in this case1 while the weight of the train presses vertically1 its motion tends to cause longitudinal sliding of the particles of the rail4 ,tangential action does not1 however1 necessarily imply a force of the latter kind4 ,when a solid cylinder an inch in height is squeezed to a vertical cake a quarter of an inch in height1 it is impossible1 physically speaking1 that the particles situated in the same vertical line shall move laterally with the same velocity2 but if they do not1 the cohesion between them will be weakened or ruptured4 ,the pressure1 however1 will produce new contact2 and if this have a cohesive value equal to that of the old contact1 no cleavage from this cause can arise4 ,the relative capacities of different substances for cleavage appear to depend in a great measure upon their different properties in this respect4 ,in butter1 for example1 the new attachments are equal1 or nearly so1 to the old1 and the cleavage is consequently indistinct2 in wax this does not appear to be the case1 and hence may arise in a great degree the perfection of its cleavage4 ,the further examination of this subject promises interesting results4 ,i would dwell upon this point the more distinctly as the advocates of differential motion may deem it to be in their favour2 but it appears to me that the mechanical conceptions implied in the above passage are totally different from theirs4 ,if they think otherwise1 then it seems to me that they should change the expressions which refer the differential motion to a drag towards the centre1 and the structure to the sliding of filaments past each other in consequence of this drag4 ,such filamentary sliding may take place in a truly viscous body1 but it does not take place in ice4 ,in one particular the ice resembles the butter referred to in the above quotation2 for its new attachments appear to be equal to the old1 and this1 ,i think1 is to be ascribed to its perfect regelation4 ,as justly pointed out by ,mr4 ,john ,ball1 the veined ice of a glacier1 if unweathered1 shows no tendency to cleave2 for though the expulsion of the air-bubbles has taken place1 the reattachment of the particles is so firm as to abolish all evidence of cleavage4 ,when the ice1 on the contrary1 is weathered1 the plates become detached1 and ,i have often been able to split such ice into thin tablets having an area of two or three square feet4 ,in his ,thirteenth ,letter ,professor ,forbes throws out a new and possibly a pregnant thought in connexion with the veins4 ,if ,i understand him aright--and ,i confess it is usually a matter of extreme difficulty with me to make sure of this--he there refers the veins1 not to the expulsion of the air from the ice1 but to its redistribution4 ,the pressure produces lines of tearing in which the air is distributed in the form of regular globules4 ,i do not know what might be made of this idea if it were developed1 but at present ,i do not see how the supposed action could produce the blue bands2 and ,i agree with ,professor ,wm4 ,thomson in regarding the explanation as improbable4,a ,,footnotes3 ,a ,for an extremely ingenious view of the origin of the veined structure1 ,i would refer to a paper by ,professor ,thomson1 in the ',proceedings of the ,royal ,society1' ,april1 #aheh4 ,,the ,,veined ,,structure ,,and ,,the ,,liquefaction ,,of ,,ice ,,by ,,pressure4 7#ca47 ,i have already noticed an important fact for which we are indebted to ,mr4 ,james ,thomson1 and have referred to the original communications on the subject4 ,i shall here place the physical circumstances connected with this fact before my reader in the manner which ,i deem most likely to interest him4 ,sidenote3 ,,influence ,,of ,,pressure ,,on ,,boiling ,,point4 ,when a liquid is heated1 the attraction of the molecules operates against the action of the heat1 which tends to tear them asunder4 ,at a certain point the force of heat triumphs1 the cohesion is overcome1 and the liquid boils4 ,but supposing we assist the attraction of the molecules by applying an external pressure1 the difficulty of tearing them asunder will be increased2 more heat will be required for this purpose2 and hence we say that the boiling point of the liquid has been elevated by the pressure4 ,sidenote3 ,,influence ,,of ,,pressure ,,on ,,fusing ,,point4 ,if molten sulphur be poured into a bullet-mould1 it will be found on cooling to contract1 so as to leave a large hollow space in the middle of each sphere4 ,cast musket-bullets are thus always found to possess a small cavity within them produced by the contraction of the lead4 ,conceive the bullet placed within its mould and the latter heated2 to produce fusion it is necessary that the sulphur or the lead should swell4 ,here1 as in the case of the heated water1 the tendency to expand is opposed by the attraction of the molecules2 with a certain amount of heat however this attraction is overcome and the solid melts4 ,but suppose we assist the molecular attraction by a suitable force applied externally1 a greater amount of heat than before will be necessary to tear them asunder2 and hence we say that the fusing point has been elevated by the pressure4 ,this fact has been experimentally established by ,messrs4 ,hopkins and ,fairbairn1 who applied to spermaceti and other substances pressures so great as to raise their points of fusion a considerable number of degrees4 ,let us now consider the case of the metal bismuth4 ,if the molten metal be poured into a bullet-mould it will expand on solidifying4 ,i have myself filled a strong cast-iron bottle with the metal1 and found its expansion on cooling sufficiently great to split the bottle from neck to bottom4 ,hence1 in order to fuse the bismuth the substance must contract2 and it is manifest that an external pressure which tends to squeeze the molecules more closely together here assists the heat instead of opposing it4 ,hence1 to fuse bismuth under great pressure1 a less amount of heat will be required than when the pressure is removed2 or1 in other words1 the fusing point of bismuth is lowered by the pressure4 ,now1 in passing from the solid to the liquid state1 ice1 like bismuth1 contracts1 and if the contraction be promoted by external pressure1 as shown by the ,messrs4 ,thomson1 a less amount of heat suffices to liquefy it4 ,sidenote3 ,,experiments4 ,these remarks will enable us to understand a singular effect first obtained by myself at the close of #ahef or in ,january #aheg1 noticed at the time in the ',proceedings of the ,royal ,society1' and afterwards fully described in a paper presented to the ,society in ,december of that year4 ,a cylinder of clear ice two inches high and an inch in diameter was placed between two slabs of box-wood1 and subjected to a gradual pressure4 ,i watched the ice in a direction perpendicular to its length1 and saw cloudy lines drawing themselves across it4 ,as the pressure continued1 these lines augmented in numbers1 until finally the prism presented the appearance of a crystal of gypsum whose planes of cleavage had been forced out of optical contact4 ,when looked at obliquely it was found that the lines were merely the sections of flat dim surfaces1 which lay like laminae one over the other throughout the length of the prism4 ,fig4 #ej represents the prism as it appeared when looked at in a direction perpendicular to its axis2 ,fig4 #ea shows the appearance when viewed obliquely4,a ,illustration3 ,fig4 #ej1 #ea4 ,appearance of a prism of ice partially liquefied by ,pressure4 ,at first sight it might appear as if air had intruded itself between the separated surfaces of the ice1 and to test this point ,i placed a cylinder two inches long and an inch wide upright in a copper vessel which was filled with ice-cold water4 ,the ice cylinder rose about half an inch above the surface of the water4 ,placing the copper vessel on a slab of wood1 and a second slab on the top of the cylinder of ice1 the latter was subjected to the gradual action of a small hydraulic press4 ,when the hazy surfaces were well developed in the portion of the ice above the water1 the cylinder was removed and examined3 the planes of rupture extended throughout the entire length of the cylinder1 just as if it had been squeezed in air4 ,i subsequently placed the ice in a stout vessel of glass1 and squeezed it1 as in the last experiment3 the surfaces of discontinuity were seen forming under the liquid quite as distinctly as in air4 ,to prove that the surfaces were due to compression and not to any tearing asunder of the mass by tension1 the following experiment was made3--,a cylindrical piece of ice1 one of whose ends1 however1 was not parallel to the other1 was placed between the slabs of wood1 and subjected to pressure4 ,fig4 #eb shows the disposition of the experiment4 ,the effect upon the ice cylinder was that shown in ,fig4 #ec1 the surfaces being developed along that side which had suffered the pressure4 ,on examining the surfaces by a pocket lens they resembled the effect produced upon a smooth cold surface by breathing on it4 ,illustration3 ,fig4 #eb1 #ec4 ,figures illustrative of compression and liquefaction of ice4 ,sidenote3 ,,liquid ,,layers ,,produced ,,by ,,pressure4 ,the surfaces were always dim2 and had the spaces been filled with air1 or were they simply vacuous1 the reflection of light from them would have been so copious as to render them much more brilliant than they were observed to be4 ,to examine them more particularly ,i placed a concave mirror so as to throw the diffused daylight from a window full upon the cylinder4 ,on applying the pressure dim spots were sometimes seen forming in the very middle of the ice1 and these as they expanded laterally appeared to be in a state of intense motion1 which followed closely the edge of each surface as it advanced through the solid ice4 ,once or twice ,i observed the hazy surfaces pioneered through the mass by dim offshoots1 apparently liquid1 and constituting a kind of decrystallisation4 ,from the closest examination to which ,i was able to subject them1 the surfaces appeared to me to be due to internal liquefaction2 indeed1 when the melting point of ice1 having already a temperature of #cb deg41 is lowered by pressure1 its excess of heat must instantly be applied to produce this effect4 ,sidenote3 ,,application ,,to ,,the ,,veined ,,structure4 ,i have already given a drawing 7p4 #chf7 showing the development of the veined structure at the base of the ice-cascade of the ,rhone2 and if we compare that diagram with ,fig4 #ec a striking similarity at once reveals itself4 ,the ice of the glacier must undoubtedly be liquefied to some extent by the tremendous pressure to which it is here subjected4 ,surfaces of discontinuity will in all probability be formed1 which facilitate the escape of the imprisoned air4 ,the small quantity of water produced will be partly imbibed by the adjacent porous ice1 and will be refrozen when relieved from the pressure4 ,this action1 associated with that ascribed to pressure in the last section1 appears to me to furnish a complete physical explanation of the laminated structure of glacier-ice4 ,,footnotes3 ,a ,this effect projected upon a screen is a most striking and instructive class experiment4 ,,white ,,ice-,,seams ,,in ,,the ,,glacier ,,du ,,geant4 7#cb47 ,sidenote3 ,,general ,,appearance ,,of ,,white ,,ice-,,seams4 ,on the #bhth of ,july1 #aheg1 while engaged upon the ,glacier du ,geant1 my attention was often attracted by protuberant ridges of what at first appeared to be pure white snow1 but which on examination ,i found to be compact ice filled with innumerable round air-cells2 and which1 in virtue of its greater power of resistance to wasting1 often rose to a height of three or four feet above the general level of the ice4 ,as ,i stood amongst these ridges1 they appeared detached and without order of arrangement1 but looked at from a distance they were seen to sweep across the proper ,glacier du ,geant in a direction concentric with its dirt-bands and its veined structure4 ,in some cases the seams were admirable indications of the relative displacement of two adjacent portions of the glacier1 which were divided from each other by a crevasse4 ,usually the sections of a seam exposed on the opposite sides of a fissure accurately faced each other1 and the direction of the seam on both sides was continuous2 but at other places they demonstrated the existence of lateral faults1 being shifted asunder laterally through spaces varying from a few inches to six or seven feet4 ,on the following day ,i was again upon the same glacier1 and noticed in many cases the white ice-seams exquisitely honeycombed4 ,the case was illustrative of the great difference between the absorptive power of the ice itself and of the objects which lie upon its surface4 ,deep cylindrical cells were produced by spots of black dirt which had been scattered upon the surface of the white ice1 and which sank to a depth of several inches into the mass4 ,i examined several sections of the veins1 and in general ,i found that their deeper portions blended gradually with the ice on either side of them4 ,but higher up the glacier ,i found that the veins penetrated only to a limited depth1 and did not therefore form an integrant portion of the glacier4 ,figs4 #ed and #ee show the sections of two of the seams which were exposed on the wall of a crevasse at some distance below the great ice-fall of the ,glacier du ,geant4 ,sidenote3 ,,sections ,,of ,,seams4 ,illustration3 ,fig4 #ed1 #ee4 ,sections of ,white ,ice-seams4 ,illustration3 ,fig4 #ef4 ,variations in the ,dip of the ,veined ,structure4 ,it was at the base of the ,talefre cascade that the explanation of these curious seams presented itself to me4 ,in one of my earliest visits to this portion of the glacier ,i was struck by a singular disposition of the blue veins on the vertical wall of a crevasse4 ,fig4 #ef will illustrate what ,i saw4 ,the veins1 within a short distance1 dipped backward and forward1 like the junctions of stones used to turn an arch4 ,in some cases ,i found this variation of the structure so great as to pass in a short distance from the vertical to the horizontal1 as shown in ,fig4 #eg4 ,sidenote3 ,,variations ,,in ,,dip ,,of ,,structure4 ,illustration3 ,fig4 #eg4 ,variations in the ,dip of the ,veined ,structure4 ,further examination taught me that the glacier here is crumpled in a most singular manner2 doubtless by the great pressure to which it is exposed4 ,the following illustration will convey a notion of its aspect3 ,let one hand be laid flat upon a table1 palm downwards1 and let the fingers be bent until the space between the first joint and the ends of the fingers is vertical2 one of the crumples to which ,i refer will then be represented4 ,the ice seems bent like the fingers1 and the crumples of the glacier are cut by crevasses1 which are accurately typified by the spaces between the fingers4 ,let the second hand now be placed upon the first1 as the latter is upon the table1 so that the tops of the bent fingers of the second hand shall rest upon the roots of the first3 two crumples would thus be formed2 a series of such protuberances1 with steep fronts1 follow each other from the base of the ,talefre cascade for some distance downwards4 ,on ,saturday the #ast of ,august ,i ascended these rounded terraces in succession1 and observed among them an extremely remarkable disposition of the structure4 ,fig4 #eh is a section of a series of three of the crumples1 on which the shading lines represent the direction of the blue veins4 ,at the base of each protuberance ,i found a seam of white ice wedged firmly into the glacier1 and each of the seams marked a place of dislocation of the veins4 ,the white seams thinned off gradually1 and finally vanished where the violent crumpling of the ice disappeared4 ,in ,fig4 #ei ,i have sketched the wall of a crevasse1 which represents what may be regarded as the incipient crumpling4 ,the undulating line shows the contour of the surface1 and the shading lines the veins4 ,it will be observed that the direction of the veins yields in conformity with the undulation of the surface2 and an augmentation of the effect would evidently result in the crumples shown in ,fig4 #eh4 ,the appearance of the white seams at those places where a dislocation occurred was1 as far as ,i could observe1 invariable2 but in a few instances the seams were observed upon the platforms of the terraces1 and also upon their slopes4 ,the width of a seam was very irregular1 varying from a few inches at some places to three or four feet at others4 ,sidenote3 ,,crumples ,,of ,,the ,,talefre4 ,illustration3 ,fig4 #eh4 ,section of three glacier ,crumples4 ,illustration3 ,fig4 #ei4 ,wall of a crevasse1 with incipient crumpling4 ,sidenote3 ,,moulds ,,of ,,white ,,ice-,,seams4 ,on the #crd of ,august ,i was again at the base of the ,talefre cascade1 and observed a fact the significance of which had previously escaped me4 ,the rills which ran down the ice-slopes collected at the base of each protuberance into a stream1 which1 at the time of my visit1 had hollowed out for itself a deep channel in the ice4 ,at some places the stream widened1 at others its banks of ice approached each other1 and rapids were produced2 in fact1 the channels of such streams appeared to be the exact moulds of the seams of white ice4 ,instructed thus far1 ,i ascended the ,glacier du ,geant on the #eth of ,august1 and then observed on the wrinkles of this glacier the same leaning backwards and forwards of the blue veins as ,i had previously observed upon the ,talefre4 ,i also noticed on this day that a seam of white ice would sometimes open out into two branches1 which1 after remaining for some distance separate1 would reunite and thus enclose a little glacier-island4 ,at other places lateral branches were thrown off from the principal seam1 thus suggesting the form of a glacier-rivulet which had been fed by tributary branches4 ,on the #gth of ,august ,i hunted the seams still farther up the glacier2 and found them at one place descending a steep ice-hill1 being crossed by other similar bands1 which however were far less white and compact4 ,i followed these new bands to their origin1 and found it to be a system of crevasses formed at the summit of the hill1 some of which were filled with snow4 ,lower down the crevasses closed1 and the snow thus jammed between their walls was converted into white ice4 ,these seams1 however1 never attained the compactness and prominence of the larger ones which had their origin far higher up4 ,i singled out one of the best of the latter1 and traced it through all the dislocation and confusion of the ice1 until ,i found it to terminate in a cavity filled with snow4 ,this was near the base of the seracs1 and the streams here were abundant4 ,comparing the shapes of some of them with that of the ice-bands lower down the glacier1 a striking resemblance was observed4 ,fig4 #fj is the plan of a deep-cut channel through which a stream flowed on the day to which ,i now refer4 ,fig4 #fa is the plan of a seam of white ice sketched on the same day1 low down upon the glacier4 ,instances of this kind might be multiplied2 and the result1 ,i think1 renders it certain that the white ice-seams referred to are due to the filling up of the channels of glacier-streams by snow during winter1 and the subsequent compression of the mass to ice during the descent of the glacier4 ,i have found such seams at the bases of all cascades that ,i have visited2 and in all cases they appear to be due to the same cause4 ,the depth to which they penetrate the glacier must be profound1 or the ablation of the ice must be less than what is generally supposed2 for the seams formed so high up on the ,glacier du ,geant may be traced low down upon the trunk-stream of the ,mer de ,glace4,a ,sidenote3 ,,streams ,,and ,,seams4 ,illustration3 ,fig4 #fj4 ,plan of a ,stream on the ,glacier du ,geant4 ,illustration3 ,fig4 #fa4 ,plan of a ,seam of ,white ,ice on the ,glacier du ,geant4 ,sidenote3 ,,scaling ,,off ,,by ,,pressure4 ,these observations on the white ice-seams enable us to add an important supplement to what has been stated regarding the origin of the dirt-bands of the ,mer de ,glace2 ,the protuberances at the base of the cascade are due not only to the toning down of the ridges produced by the transverse fracture of the glacier at the summit of the fall1 but they undergo modifications by the pressure locally exerted at its base4 ,the state of things represented in ,fig4 #eg is plainly due to the partial pushing of one crumple over that next in advance of it4 ,there seems to be a differential motion of the parts of the glacier in the same longitudinal line2 showing that upon the general motion of the glacier smaller local motions are superposed4 ,the occurrence of the seams upon the faces of the slopes seems also to prove that the pressure is competent1 in some cases1 to cause the bases of the protuberances to swell1 so that what was once the base of a crumple may subsequently form a portion of its slope4 ,another interesting fact is also observed where the pressure is violent3 the crumples scale off1 bows of ice being thus formed which usually span the crumples over their most violently compressed portions4 ,i have found this scaling off at the bases of all the cascades which ,i have visited1 and it is plainly due to the pressure exerted at such places upon the ice4 ,,footnotes3 ,a ,the more permanent seams may possibly be due to the filling of the profound crevasses of the cascade4 7#cc47 ,sidenote3 ,,compression ,,of ,,glacier ,,du ,,geant4 ,not only at the base of its great cascade1 but throughout the greater part of its length1 the ,glacier du ,geant is in a state of longitudinal compression4 ,the meaning of this term will be readily understood3 ,let two points1 for example1 be marked upon the axis of the glacier2 if these during its descent were drawn wider apart1 it would show that the glacier was in a state of longitudinal strain or tension2 if they remained at the same distance apart1 it would indicate that neither strain nor pressure was exerted2 whereas1 if the two points approached each other1 which could only be by the quicker motion of the hinder one1 the existence of longitudinal compression would be thereby demonstrated4 ,taking ,le ,petit ,balmat with me1 to carry my theodolite1 ,i ascended the ,glacier du ,geant until ,i came near the place where it is joined by the ,glacier des ,periades1 and whence ,i observed a patch of fresh green grass upon the otherwise rocky mountain-side4 ,to this point ,i climbed1 and made it the station for my instrument4 ,choosing a well-defined object at the opposite side of the glacier1 ,i set1 on the #ith of ,august1 in the line between this object and the theodolite1 three stakes1 one in the centre of the glacier1 and the other two at opposite sides of the centre and about #ajj yards from it4 ,this done1 ,i descended for a quarter of a mile1 when ,i again climbed the flanking rocks1 placing my theodolite in a couloir1 down which stones are frequently discharged from the end of a secondary glacier which hangs upon the heights above4 ,here1 as before1 ,i fixed three stakes1 chiselled a mark upon the granite1 so as to enable me to find the place1 and regained the ice without accident4 ,a day or two previously we had set out a third line at some distance lower down1 and ,i was thus furnished with a succession of points along the glacier1 the relative motions of which would decide whether it was pressed or stretched in the direction of its length4 ,on the #ajth of ,august ,mr4 ,huxley joined us2 and on the following day we all set out for the ,glacier du ,geant1 to measure the progress of the stakes which ,i had fixed there4 ,hirst remained upon the glacier to measure the displacements2 ,i shouldered the theodolite2 and ,huxley was my guide to the mountain-side1 sounding in advance of me the treacherous-looking snow over which we had to pass4 ,calling the central stake of the highest line ,no4 #a1 that of the middle line ,no4 #b1 and that of the line nearest the ,tacul ,no4 #c1 the following are the spaces moved over by these three points in twenty-four hours3 ,inches4 ,distances asunder4 ,no4 #a #bj4ee #ede yards4 ,no4 #b #ae4dc #dhg yards4 ,no4 #c #ab4ge ,here we have the fact which the aspect of the glacier suggested4 ,the first stake moves five inches a day more than the second1 and the second nearly three inches a day more than the third4 ,as surmised1 therefore1 the glacier is in a state of longitudinal compression1 whereby a portion of it #ajjj yards in length is shortened at the rate of eight inches a day4 ,sidenote3 ,,structure ,,in ,,white ,,ice-,,seams4 ,in accordance with this result1 the transverse undulations of the ,glacier du ,geant1 described in the chapter upon ,dirt-,bands1 shorten as they descend4 ,a series of three of them measured along the axis of the glacier on the #fth of ,august1 #aheg1 gave the following respective lengths3--#iee links1 #hee links1 #ggj links1 the shortest undulation being the farthest from the origin of the undulations4 ,this glacier then constitutes a vast ice-press1 and enables us to test the explanation which refers the veined structure of the ice to pressure4 ,the glacier itself is transversely laminated1 as already stated2 and in many cases a structure of extreme definition and beauty is developed in the compressed snow1 which constitutes the seams of white ice4 ,in #aheg ,i discovered a well-developed lenticular structure in some of these seams4 ,in #aheh ,i again examined them4 ,clearing away the superficial portions with my axe1 ,i found1 drawn through the body of the seams1 long lines of blue ice of exquisite definition2 in fact1 ,i had never seen the structure so delicately exhibited4 ,the seams1 moreover1 were developed in portions of the white ice which were near the centre of the glacier1 and where consequently filamentous sliding was entirely out of the question4 ,sidenote3 ,,partial ,,summary4 ,,partial ,,summary4 #a4 ,glaciers are derived from mountain snow1 which has been consolidated to ice by pressure4 #b4 ,that pressure is competent to convert snow into ice has been proved by experiment4 #c4 ,the power of yielding to pressure diminishes as the mass becomes more compact2 but it does not cease even when the substance has attained the compactness which would entitle it to be called ice4 #d4 ,when a sufficient depth of snow collects upon the earth's surface1 the lower portions are squeezed out by the pressure of the superincumbent mass4 ,if it rests upon a slope it will yield principally in the direction of the slope1 and move downwards4 #e4 ,in addition to this1 the whole mass slides bodily along its inclined bed1 and leaves the traces of its sliding on the rocks over which it passes1 grinding off their asperities1 and marking them with grooves and scratches in the direction of the motion4 #f4 ,in this way the deposit of consolidated and unconsolidated snow which covers the higher portions of lofty mountains moves slowly down into an adjacent valley1 through which it descends as a true glacier1 partly by sliding and partly by the yielding of the mass itself4 #g4 ,several valleys thus filled may unite in a single valley1 the tributary glaciers welding themselves together to form a trunk-glacier4 #h4 ,both the main valley and its tributaries are often sinuous1 and the tributaries must change their direction to form the trunk2 the width of the valley often varies4 ,the glacier is forced through narrow gorges1 widening after it has passed them2 the centre of the glacier moves more quickly than the sides1 and the surface more quickly than the bottom2 the point of swiftest motion follows the same law as that observed in the flow of rivers1 shifting from one side of the centre to the other as the flexure of the valley changes4 #i4 ,these various effects may be reproduced by experiments on small masses of ice4 ,the substance may moreover be moulded into vases and statuettes4 ,straight bars of it may be bent into rings1 or even coiled into knots4 #aj4 ,ice1 capable of being thus moulded1 is practically incapable of being stretched4 ,the condition essential to success is that the particles of the ice operated on shall be kept in close contact1 so that when old attachments have been severed new ones may be established4 #aa4 ,the nearer the ice is to its melting point in temperature1 the more easily are the above results obtained2 when ice is many degrees below its freezing point it is crushed by pressure to a white powder1 and is not capable of being moulded as above4 #ab4 ,two pieces of ice at #cb deg4 ,fahr41 with moist surfaces1 when placed in contact freeze together to a rigid mass2 this is called ,regelation4 #ac4 ,when the attachments of pressed ice are broken1 the continuity of the mass is restored by the regelation of the new contiguous surfaces4 ,regelation also enables two tributary glaciers to weld themselves to form a continuous trunk2 thus also the crevasses are mended1 and the dislocations of the glacier consequent on descending cascades are repaired4 ,this healing of ruptures extends to the smallest particles of the mass1 and it enables us to account for the continued compactness of the ice during the descent of the glacier4 #ad4 ,the quality of viscosity is practically absent in glacier-ice4 ,where pressure comes into play the phenomena are suggestive of viscosity1 but where tension comes into play the analogy with a viscous body breaks down4 ,when subjected to strain the glacier does not yield by stretching1 but by breaking2 this is the origin of the crevasses4 #ae4 ,the crevasses are produced by the mechanical strains to which the glacier is subjected4 ,they are divided into marginal1 transverse1 and longitudinal crevasses2 the first produced by the oblique strain consequent on the quicker motion of the centre2 the second by the passage of the glacier over the summit of an incline2 the third by pressure from behind and resistance in front1 which causes the mass to split at right angles to the pressure strain84 #af4 ,the moulins are formed by deep cracks intersecting glacier rivulets4 ,the water in descending such cracks scoops out for itself a shaft1 sometimes many feet wide1 and some hundreds of feet deep1 into which the cataract plunges with a sound like thunder4 ,the supply of water is periodically cut off from the moulins by fresh cracks1 in which new moulins are formed4 #ag4 ,the lateral moraines are formed from the debris which loads the glacier along its edges2 the medial moraines are formed on a trunk-glacier by the union of the lateral moraines of its tributaries2 the terminal moraines are formed from the debris carried by the glacier to its terminus1 and there deposited4 ,the number of medial moraines on a trunk glacier is always one less than the number of tributaries4 #ah4 ,when ordinary lake-ice is intersected by a strong sunbeam it liquefies so as to form flower-shaped figures within the mass2 each flower consists of six petals with a vacuous space at the centre2 the flowers are always formed parallel to the planes of freezing1 and depend on the crystallization of the substance4 #ai4 ,innumerable liquid disks1 with vacuous spots1 are also formed by the solar beams in glacier-ice4 ,these empty spaces have been hitherto mistaken for air-bubbles1 the flat form of the disks being erroneously regarded as the result of pressure4 #bj4 ,these disks are indicators of the intimate constitution of glacier-ice1 and they teach us that it is composed of an aggregate of parts with surfaces of crystallization in all possible planes4 #ba4 ,there are also innumerable small cells in glacier-ice holding air and water2 such cells also occur in lake-ice2 and here they are due to the melting of the ice in contact with the bubble of air4 ,experiments are needed on glacier-ice in reference to this point4 #bb4 ,at a free surface within or without1 ice melts with more ease than in the centre of a compact mass4 ,the motion which we call heat is less controlled at a free surface1 and it liberates the molecules from the solid condition sooner than when the atoms are surrounded on all sides by other atoms which impede the molecular motion4 ,regelation is the complementary effect to the above2 for here the superficial portions of a mass of ice are made virtually central by the contact of a second mass4 #bc4 ,the dirt-bands have their origin in the ice-cascades4 ,the glacier1 in passing the brow1 is transversely fractured2 ridges are formed with hollows between them2 these transverse hollows are the principal receptacles of the fine debris scattered over the glacier2 and after the ridges have been melted away1 the dirt remains in successive stripes upon the glacier4 #bd4 ,the ice of many glaciers is laminated1 and when weathered may be cloven into thin plates4 ,in the sound ice the lamination manifests itself in blue stripes drawn through the general whitish mass of the glacier2 these blue veins representing portions of ice from which the air-bubbles have been more completely expelled4 ,this is the veined structure of the ice4 ,it is divided into marginal1 transverse1 and longitudinal structure2 which may be regarded as complementary to marginal1 longitudinal1 and transverse crevasses4 ,the latter are produced by tension1 the former by pressure1 which acts in two different ways3 firstly1 the pressure acts upon the ice as it has acted upon rocks which exhibit the lamination technically called cleavage2 secondly1 it produces partial liquefaction of the ice4 ,the liquid spaces thus formed help the escape of the air from the glacier2 and the water produced1 being refrozen when the pressure is relieved1 helps to form the blue veins4 ,,appendix4 ,,comparative ,,view ,,of ,,the ,,cleavage ,,of ,,crystals ,,and ,,slate-,,rocks4 ,a ,,lecture ,,delivered ,,at ,,the ,,royal ,,institution1 ,,on ,,friday ,,evening ,,the #f,,th ,,of ,,june1 #ahef4;,a ,when the student of physical science has to investigate the character of any natural force1 his first care must be to purify it from the mixture of other forces1 and thus study its simple action4 ,if1 for example1 he wishes to know how a mass of water would shape itself1 supposing it to be at liberty to follow the bent of its own molecular forces1 he must see that these forces have free and undisturbed exercise4 ,we might perhaps refer him to the dew-drop for a solution of the question2 but here we have to do1 not only with the action of the molecules of the liquid upon each other1 but also with the action of gravity upon the mass1 which pulls the drop downwards and elongates it4 ,if he would examine the problem in its purity1 he must do as ,plateau has done1 withdraw the liquid mass from the action of gravity1 and he would then find the shape of the mass to be perfectly spherical4 ,natural processes come to us in a mixed manner1 and to the uninstructed mind are a mass of unintelligible confusion4 ,suppose half-a-dozen of the best musical performers to be placed in the same room1 each playing his own instrument to perfection3 though each individual instrument might be a well-spring of melody1 still the mixture of all would produce mere noise4 ,thus it is with the processes of nature4 ,in nature1 mechanical and molecular laws mingle1 and create apparent confusion4 ,their mixture constitutes what may be called the noise of natural laws1 and it is the vocation of the man of science to resolve this noise into its components1 and thus to detect the music in which the foundations of nature are laid4 ,the necessity of this detachment of one force from all other forces is nowhere more strikingly exhibited than in the phenomena of crystallization4 ,i have here a solution of sulphate of soda4 ,prolonging the mental vision beyond the boundaries of sense1 we see the atoms of that liquid1 like squadrons under the eye of an experienced general1 arranging themselves into battalions1 gathering round a central standard1 and forming themselves into solid masses1 which after a time assume the visible shape of the crystal which ,i here hold in my hand4 ,i may1 like an ignorant meddler wishing to hasten matters1 introduce confusion into this order4 ,i do so by plunging this glass rod into the vessel4 ,the consequent action is not the pure expression of the crystalline forces2 the atoms rush together with the confusion of an unorganized mob1 and not with the steady accuracy of a disciplined host4 ,here1 also1 in this mass of bismuth we have an example of this confused crystallization2 but in the crucible behind me a slower process is going on3 here there is an architect at work who makes no chips1 no din1 and who is now building the particles into crystals1 similar in shape and structure to those beautiful masses which we see upon the table4 ,by permitting alum to crystallize in this slow way1 we obtain these perfect octahedrons2 by allowing carbonate of lime to crystallize1 nature produces these beautiful rhomboids2 when silica crystallizes1 we have formed these hexagonal prisms capped at the ends by pyramids2 by allowing saltpetre to crystallize1 we have these prismatic masses2 and when carbon crystallizes1 we have the diamond4 ,if we wish to obtain a perfect crystal1 we must allow the molecular forces free play3 if the crystallizing mass be permitted to rest upon a surface it will be flattened1 and to prevent this a small crystal must be so suspended as to be surrounded on all sides by the liquid1 or1 if it rest upon the surface1 it must be turned daily so as to present all its faces in succession to the working builder4 ,in this way the scientific man nurses these children of his intellect1 watches over them with a care worthy of imitation1 keeps all influences away which might possibly invade the strict morality of crystalline laws1 and finally sees them developed into forms of symmetry and beauty which richly reward the care bestowed upon them4 ,in building up crystals1 these little atomic bricks often arrange themselves into layers which are perfectly parallel to each other1 and which can be separated by mechanical means2 this is called the cleavage of the crystal4 ,i have here a crystallized mass which has thus far escaped the abrading and disintegrating forces which1 sooner or later1 determine the fate of sugar-candy4 ,if ,i am skilful enough1 ,i shall discover that this crystal of sugar cleaves with peculiar facility in one direction4 ,here1 again1 ,i have a mass of rock-salt3 ,i lay my knife upon it1 and with a blow cleave it in this direction2 but ,i find on further examining this substance that it cleaves in more directions than one4 ,laying my knife at right angles to its former position1 the crystal cleaves again2 and1 finally placing the knife at right angles to the two former positions1 the mass cleaves again4 ,thus rock-salt cleaves in three directions1 and the resulting solid is this perfect cube1 which may be broken up into any number of smaller cubes4 ,here is a mass of ,iceland spar1 which also cleaves in three directions1 not at right angles1 but obliquely to each other1 the resulting solid being a rhomboid4 ,in each of these cases the mass cleaves with equal facility in all three directions4 ,for the sake of completeness1 ,i may say that many substances cleave with unequal facility in different directions1 and the heavy spar ,i hold in my hand presents an example of this kind of cleavage4 ,turn we now to the consideration of some other phenomena to which the term cleavage may be applied4 ,this piece of beech-wood cleaves with facility parallel to the fibre1 and if our experiments were fine enough we should discover that the cleavage is most perfect when the edge of the axe is laid across the rings which mark the growth of the tree4 ,the fibres of the wood lie side by side1 and a comparatively small force is sufficient to separate them4 ,if you look at this mass of hay severed from a rick1 you will see a sort of cleavage developed in it also2 the stalks lie in parallel planes1 and only a small force is required to separate them laterally4 ,but we cannot regard the cleavage of the tree as the same in character as the cleavage of the hayrick4 ,in the one case it is the atoms arranging themselves according to organic laws which produce a cleavable structure2 in the other case the easy separation in a certain direction is due to the mechanical arrangement of the coarse sensible masses of stalks of hay4 ,in like manner ,i find that this piece of sandstone cleaves parallel to the planes of bedding4 ,this rock was once a powder1 more or less coarse1 held in mechanical suspension by water4 ,the powder was composed of two distinct parts1 fine grains of sand and small plates of mica4 ,imagine a wide strand covered by a tide which holds such powder in suspension3,b how will it sink8 ,the rounded grains of sand will reach the bottom first1 the mica afterwards1 and when the tide recedes we have the little plates shining like spangles upon the surface of the sand4 ,each successive tide brings its charge of mixed powder1 deposits its duplex layer day after day1 and finally masses of immense thickness are thus piled up1 which1 by preserving the alternations of sand and mica1 tell the tale of their formation4 ,i do not wish you to accept this without proof4 ,take the sand and mica1 mix them together in water1 and allow them to subside1 they will arrange themselves in the manner ,i have indicated2 and by repeating the process you can actually build up a sandstone mass which shall be the exact counterpart of that presented by nature1 as ,i have done in this glass jar4 ,now this structure cleaves with readiness along the planes in which the particles of mica are strewn4 ,here is a mass of such a rock sent to me from ,halifax3 here are other masses from the quarries of ,over ,darwen in ,lancashire4 ,with a hammer and chisel you see ,i can cleave them into flags2 indeed these flags are made use of for roofing purposes in the districts from which the specimens have come1 and receive the name of slate-stone4 ,but you will discern1 without a word from me1 that this cleavage is not a crystalline cleavage any more than that of a hayrick is4 ,it is not an arrangement produced by molecular forces2 indeed it would be just as reasonable to suppose that in this jar of sand and mica the particles arranged themselves into layers by the forces of crystallization1 instead of by the simple force of gravity1 as to imagine that such a cleavage as this could be the product of crystallization4 ,this1 so far as ,i am aware of1 has never been imagined1 and it has been agreed among geologists not to call such splitting as this cleavage at all1 but to restrict the term to a class of phenomena which ,i shall now proceed to consider4 ,those who have visited the slate quarries of ,cumberland and ,north ,wales will have witnessed the phenomena to which ,i refer4 ,we have long drawn our supply of roofing-slates from such quarries2 schoolboys ciphered on these slates1 they were used for tombstones in churchyards1 and for billiard-tables in the metropolis2 but not until a comparatively late period did men begin to inquire how their wonderful structure was produced4 ,what is the agency which enables us to split ,honister ,crag1 or the cliffs of ,snowdon1 into laminae from crown to base8 ,this question is at the present moment one of the greatest difficulties of geologists1 and occupies their attention perhaps more than any other4 ,you may wonder at this4 ,looking into the quarry of ,penrhyn1 you may be disposed to explain the question as ,i heard it explained two years ago4 ,these planes of cleavage1 said a friend who stood beside me on the quarry's edge1 are the planes of stratification which have been lifted by some convulsion into an almost vertical position4 ,but this was a great mistake1 and indeed here lies the grand difficulty of the problem4 ,these planes of cleavage stand in most cases at a high angle to the bedding4 ,thanks to ,sir ,roderick ,murchison1 who has kindly permitted me the use of specimens from the ,museum of ,practical ,geology 7and here ,i may be permitted to express my acknowledgments to the distinguished staff of that noble establishment1 who1 instead of considering me an intruder1 have welcomed me as a brother71 ,i am able to place the proof of this before you4 ,here is a mass of slate in which the planes of bedding are distinctly marked2 here are the planes of cleavage1 and you see that one of them makes a large angle with the other4 ,the cleavage of slates is therefore not a question of stratification1 and the problem which we have now to consider is1 ,by what cause has this cleavage been produced8 ,in an able and elaborate essay on this subject in #ahce1 ,professor ,sedgwick proposed the theory that cleavage is produced by the action of crystalline or polar forces after the mass has been consolidated4 ,we may affirm1 he says1 that no retreat of the parts1 no contraction of dimensions in passing to a solid state can explain such phenomena4 ,they appear to me only resolvable on the supposition that crystalline or polar forces acted upon the whole mass simultaneously in one direction and with adequate force4 ,and again1 in another place3 ,crystalline forces have rearranged whole mountain-masses1 producing a beautiful crystalline cleavage1 passing alike through all the strata4,c ,the utterance of such a man struck deep1 as was natural1 into the minds of geologists1 and at the present day there are few who do not entertain this view either in whole or in part4,d ,the magnificence of the theory1 indeed1 has in some cases caused speculation to run riot1 and we have books published1 aye and largely sold1 on the action of polar forces and geologic magnetism1 which rather astonish those who know something about the subject4 ,according to the theory referred to1 miles and miles of the districts of ,north ,wales and ,cumberland1 comprising huge mountain-masses1 are neither more nor less than the parts of a gigantic crystal4 ,these masses of slate were originally fine mud2 this mud is composed of the broken and abraded particles of older rocks4 ,it contains silica1 alumina1 iron1 potash1 soda1 and mica1 mixed in sensible masses mechanically together4 ,in the course of ages the mass became consolidated1 and the theory before us assumes that afterwards a process of crystallization rearranged the particles and developed in the mass a single plane of crystalline cleavage4 ,with reference to this hypothesis1 ,i will only say that it is a bold stretch of analogies2 but still it has done good service3 it has drawn attention to the question2 right or wrong1 a theory thus thoughtfully uttered has its value2 it is a dynamic power which operates against intellectual stagnation2 and1 even by provoking opposition1 is eventually of service to the cause of truth4 ,it would1 however1 have been remarkable1 if1 among the ranks of geologists themselves1 men were not found to seek an explanation of the phenomena in question1 which involved a less hardy spring on the part of the speculative faculty than the view to which ,i have just referred4 ,the first step in an inquiry of this kind is to put oneself into contact with nature1 to seek facts4 ,this has been done1 and the labours of ,sharpe 7the late ,president of the ,geological ,society1 who1 to the loss of science and the sorrow of all who knew him1 has so suddenly been taken away from us71 ,sorby1 and others1 have furnished us with a body of evidence which reveals to us certain important physical phenomena1 associated with the appearance of slaty cleavage1 if they have not produced it4 ,the nature of this evidence we will now proceed to consider4 ,fossil shells are found in these slate-rocks4 ,i have here several specimens of such shells1 occupying various positions with regard to the cleavage planes4 ,they are squeezed1 distorted1 and crushed4 ,in some cases a flattening of the convex shell occurs1 in others the valves are pressed by a force which acted in the plane of their junction1 but in all cases the distortion is such as leads to the inference that the rock which contains these shells has been subjected to enormous pressure in a direction at right angles to the planes of cleavage2 the shells are all flattened and spread out upon these planes4 ,i hold in my hand a fossil trilobite of normal proportions4 ,here is a series of fossils of the same creature which have suffered distortion4 ,some have lain across1 some along1 and some oblique to the cleavage of the slate in which they are found2 in all cases the nature of the distortion is such as required for its production a compressing force acting at right angles to the planes of cleavage4 ,as the creatures lay in the mud in the manner indicated1 the jaws of a gigantic vice appear to have closed upon them and squeezed them into the shape you see4 ,as further evidence of the exertion of pressure1 let me introduce to your notice a case of contortion which has been adduced by ,mr4 ,sorby4 ,the bedding of the rock shown in this figure,e was once horizontal2 at ,a we have a deep layer of mud1 and at m n a layer of comparatively unyielding gritty material2 below that again1 at ,b1 we have another layer of the fine mud of which slates are formed4 ,this mass cleaves along the shading lines of the diagram2 but look at the shape of the intermediate bed3 it is contorted into a serpentine form1 and leads irresistibly to the conclusion that the mass has been pressed together at right angles to the planes of cleavage4 ,this action can be experimentally imitated1 and ,i have here a piece of clay in which this is done and the same result produced on a small scale4 ,the amount of compression1 indeed1 might be roughly estimated by supposing this contorted bed m n to be stretched out1 its length measured and compared with the distance c d2 we find in this way that the yielding of the mass has been considerable4 ,let me now direct your attention to another proof of pressure4 ,you see the varying colours which indicate the bedding on this mass of slate4 ,the dark portion1 as ,i have stated1 is gritty1 and composed of comparatively coarse particles1 which1 owing to their size1 shape1 and gravity1 sink first and constitute the bottom of each layer4 ,gradually from bottom to top the coarseness diminishes1 and near the upper surface of each layer we have a mass of comparatively fine clean mud4 ,sometimes this fine mud forms distinct layers in a mass of slate-rock1 and it is the mud thus consolidated from which are derived the ,german razor-stones1 so much prized for the sharpening of surgical instruments4 ,i have here an example of such a stone4 ,when a bed is thin1 the clean white mud is permitted to rest1 as in this case1 upon a slab of the coarser slate in contact with it3 when the bed is thick1 it is cut into slices which are cemented to pieces of ordinary slate1 and thus rendered stronger4 ,the mud thus deposited sometimes in layers is1 as might be expected1 often rolled up into nodular masses1 carried forward1 and deposited by the rivers from which the slate-mud has subsided4 ,here1 indeed1 are such nodules enclosed in sandstone4 ,everybody who has ciphered upon a school-slate must remember the whitish-green spots which sometimes dotted the surface of the slate2 he will remember how his slate-pencil usually slid over such spots as if they were greasy4 ,now these spots are composed of the finer mud1 and they could not1 on account of their fineness1 bite the pencil like the surrounding gritty portions of the slate4 ,here is a beautiful example of the spots3 you observe them on the cleavage surface in broad patches2 but if this mass has been compressed at right angles to the planes of cleavage1 ought we to expect the same marks when we look at the edge of the slab8 ,the nodules will be flattened by such pressure1 and we ought to see evidence of this flattening when we turn the slate edgeways4 ,here it is4 ,the section of a nodule is a sharp ellipse with its major axis parallel to the cleavage4 ,there are other examples of the same nature on the table2 ,i have made excursions to the quarries of ,wales and ,cumberland1 and to many of the slate-yards of ,london1 but the same fact invariably appears1 and thus we elevate a common experience of our boyhood into evidence of the highest significance as regards one of the most important problems of geology4 ,in examining the magnetism of these slates1 ,i was led to infer that these spots would contain a less amount of iron than the surrounding dark slate4 ,the analysis was made for me by ,mr4 ,hambly in the laboratory of ,dr4 ,percy at the ,school of ,mines4 ,the result which is stated in this ,table justifies the conclusion to which ,i have referred4 ,analysis of ,slate4 ,purple ,slate4 ,two ,analyses4 #a4 ,percentage of iron #e4he #b4 #f4ac ,mean #e4ii ,greenish ,slate4 #a4 ,percentage of iron #c4bd #b4 #c4ab ,mean #c4ah ,the quantity of iron in the dark slate immediately adjacent to the greenish spot is1 according to these analyses1 nearly double of the quantity contained in the spot itself4 ,this is about the proportion which the magnetic experiments suggested4 ,let me now remind you that the facts which ,i have brought before you are typical facts--each is the representative of a class4 ,we have seen shells crushed1 the unhappy trilobites squeezed1 beds contorted1 nodules of greenish marl flattened2 and all these sources of independent testimony point to one and the same conclusion1 namely1 that slate-rocks have been subjected to enormous pressure in a direction at right angles to the planes of cleavage4,f ,in reference to ,mr4 ,sorby's contorted bed1 ,i have said that by supposing it to be stretched out and its length measured1 it would give us an idea of the amount of yielding of the mass above and below the bed4 ,such a measurement1 however1 would not quite give the amount of yielding2 and here ,i would beg your attention to a point1 the significance of which has1 so far as ,i am aware of1 hitherto escaped attention4 ,i hold in my hand a specimen of slate1 with its bedding marked upon it2 the lower portions of each bed are composed of a comparatively coarse gritty material1 something like what you may suppose this contorted bed to be composed of4 ,well1 ,i find that the cleavage takes a bend in crossing these gritty portions1 and that the tendency of these portions is to cleave more at right angles to the bedding4 ,look to this diagram3 when the forces commenced to act1 this intermediate bed1 which though comparatively unyielding is not entirely so1 suffered longitudinal pressure2 as it bent1 the pressure became gradually more lateral1 and the direction of its cleavage is exactly such as you would infer from a force of this kind--it is neither quite across the bed1 nor yet in the same direction as the cleavage of the slate above and below it1 but intermediate between the two4 ,supposing the cleavage to be at right angles to the pressure1 this is the direction which it ought to take across these more unyielding strata4 ,thus we have established the concurrence of the phenomena of cleavage and pressure--that they accompany each other2 but the question still remains1 ,is this pressure of itself sufficient to account for the cleavage8 ,a single geologist1 as far as ,i am aware1 answers boldly in the affirmative4 ,this geologist is ,sorby1 who has attacked the question in the true spirit of a physical investigator4 ,you remember the cleavage of the flags of ,halifax and ,over ,darwen1 which is caused by the interposition of plates of mica between the layers4 ,mr4 ,sorby examines the structure of slate-rock1 and finds plates of mica to be a constituent4 ,he asks himself1 what will be the effect of pressure upon a mass containing such plates confusedly mixed up in it8 ,it will be1 he argues--and he argues rightly--to place the plates with their flat surfaces more or less perpendicular to the direction in which the pressure is exerted4 ,he takes scales of the oxide of iron1 mixes them with a fine powder1 and1 on squeezing the mass1 finds that the tendency of the scales is to set themselves at right angles to the line of pressure4 ,now the planes in which these plates arrange themselves will1 he contends1 be those along which the mass cleaves4 ,i could show you1 by tests of a totally different character from those applied by ,mr4 ,sorby1 how true his conclusion is1 that the effect of pressure on elongated particles or plates will be such as he describes it4 ,nevertheless1 while knowing this fact1 and admiring the ability with which ,mr4 ,sorby has treated this question1 ,i cannot accept his explanation of slate-cleavage4 ,i believe that even if these plates of mica were wholly absent1 the cleavage of slate-rocks would be much the same as it is at present4 ,i will not dwell here upon minor facts1--,i will not urge that the perfection of the cleavage bears no relation to the quantity of mica present2 but ,i will come at once to a case which to my mind completely upsets the notion that such plates are a necessary element in the production of cleavage4 ,here is a mass of pure white wax3 there are no mica particles here2 there are no scales of iron1 or anything analogous mixed up with the mass4 ,here is the self-same substance submitted to pressure4 ,i would invite the attention of the eminent geologists whom ,i see before me to the structure of this mass4 ,no slate ever exhibited so clean a cleavage2 it splits into laminae of surpassing tenuity1 and proves at a single stroke that pressure is sufficient to produce cleavage1 and that this cleavage is independent of the intermixed plates of mica assumed in ,mr4 ,sorby's theory4 ,i have purposely mixed this wax with elongated particles1 and am unable to say at the present moment that the cleavage is sensibly affected by their presence1--if anything1 ,i should say they rather impair its fineness and clearness than promote it4 ,the finer the slate the more perfect will be the resemblance of its cleavage to that of the wax4 ,compare the surface of the wax with the surface of this slate from ,borrodale in ,cumberland4 ,you have precisely the same features in both3 you see flakes clinging to the surfaces of each1 which have been partially torn away by the cleavage of the mass3 ,i entertain the conviction that if any close observer compares these two effects1 he will be led to the conclusion that they are the product of a common cause4,g ,but you will ask1 how1 according to my view1 does pressure produce this remarkable result8 ,this may be stated in a very few words4 ,nature is everywhere imperfect6 ,the eye is not perfectly achromatic1 the colours of the rose and tulip are not pure colours1 and the freshest air of our hills has a bit of poison in it4 ,in like manner there is no such thing in nature as a body of perfectly homogeneous structure4 ,i break this clay which seems so intimately mixed1 and find that the fracture presents to my eyes innumerable surfaces along which it has given way1 and it has yielded along these surfaces because in them the cohesion of the mass is less than elsewhere4 ,i break this marble1 and even this wax1 and observe the same result3 look at the mud at the bottom of a dried pond2 look to some of the ungravelled walks in ,kensington ,gardens on drying after rain1--they are cracked and split1 and other circumstances being equal1 they crack and split where the cohesion of the mass is least4 ,take then a mass of partially consolidated mud4 ,assuredly such a mass is divided and subdivided by surfaces along which the cohesion is comparatively small4 ,penetrate the mass1 and you will see it composed of numberless irregular nodules bounded by surfaces of weak cohesion4 ,figure to your mind's eye such a mass subjected to pressure1--the mass yields and spreads out in the direction of least resistance2,h the little nodules become converted into laminae1 separated from each other by surfaces of weak cohesion1 and the infallible result will be that such a mass will cleave at right angles to the line in which the pressure is exerted4 ,further1 a mass of dried mud is full of cavities and fissures4 ,if you break dried pipe-clay you see them in great numbers1 and there are multitudes of them so small that you cannot see them4 ,i have here a piece of glass in which a bubble was enclosed2 by the compression of the glass the bubble is flattened1 and the sides of the bubble approach each other so closely as to exhibit the colours of thin plates4 ,a similar flattening of the cavities must take place in squeezed mud1 and this must materially facilitate the cleavage of the mass in the direction already indicated4 ,although the time at my disposal has not permitted me to develop this thought as far as ,i could wish1 yet for the last twelve months the subject has presented itself to me almost daily under one aspect or another4 ,i have never eaten a biscuit during this period in which an intellectual joy has not been superadded to the more sensual pleasure1 for ,i have remarked in all such cases cleavage developed in the mass by the rolling-pin of the pastrycook or confectioner4 ,i have only to break these cakes1 and to look at the fracture1 to see the laminated structure of the mass2 nay1 ,i have the means of pushing the analogy further3 ,i have here some slate which was subjected to a high temperature during the conflagration of ,mr4 ,scott ,russell's premises4 ,i invite you to compare this structure with that of a biscuit2 air or vapour within the mass has caused it to swell1 and the mechanical structure it reveals is precisely that of a biscuit4 ,i have gone a little into the mysteries of baking while conducting my inquiries on this subject1 and have received much instruction from a lady-friend in the manufacture of puff-paste4 ,here is some paste baked in this house under my own superintendence4 ,the cleavage of our hills is accidental cleavage1 but this is cleavage with intention4 ,the volition of the pastrycook has entered into the formation of the mass1 and it has been his aim to preserve a series of surfaces of structural weakness1 along which the dough divides into layers4 ,puff-paste must not be handled too much1 for then the continuity of the surfaces is broken2 it ought to be rolled on a cold slab1 to prevent the butter from melting and diffusing itself through the mass1 thus rendering it more homogeneous and less liable to split4 ,this is the whole philosophy of puff-paste2 it is a grossly exaggerated case of slaty cleavage4 ,as time passed on1 cases multiplied1 illustrating the influence of pressure in producing lamination4 ,mr4 ,warren ,de la ,rue informs me that he once wished to obtain white-lead in a fine granular state1 and to accomplish this he first compressed the mass3 the mould was conical1 and permitted the mass to spread a little laterally under the pressure4 ,the lamination was as perfect as that of slate1 and quite defeated him in his effort to obtain a granular powder4 ,mr4 ,brodie1 as you are aware1 has recently discovered a new kind of graphite3 here is the substance in powder1 of exquisite fineness4 ,this powder has the peculiarity of clinging together in little confederacies2 it cannot be shaken asunder like lycopodium2 and when the mass is squeezed1 these groups of particles flatten1 and a perfect cleavage is produced4 ,mr4 ,brodie himself has been kind enough to furnish me with specimens for this evening's lecture4 ,i will cleave them before you3 you see they split up into plates which are perpendicular to the line in which the pressure was exerted4 ,this testimony is all the more valuable1 as the facts were obtained without any reference whatever to the question of cleavage4 ,i have here a mass of that singular substance ,boghead ,cannel4 ,this was once a mass of mud1 more or less resembling this one1 which ,i have obtained from a bog in ,lancashire4 ,i feel some hesitation in bringing this substance before you1 for1 as in other cases1 so in regard to ,boghead ,cannel1 science--not science1 let me not libel it1 but the quibbling1 litigious1 money-loving portion of human nature speaking through the mask of science--has so contrived to split hairs as to render the qualities of the substance somewhat mythical4 ,i shall therefore content myself with showing you how it cleaves1 and with expressing my conviction that pressure had a great share in the production of this cleavage4 ,the principle which ,i have enunciated is so simple as to be almost trivial2 nevertheless1 it embraces not only the cases ,i have mentioned1 but1 if time permitted1 ,i think ,i could show you that it takes a much wider range4 ,when iron is taken from the puddling furnace1 it is a more or less spongy mass3 it is at a welding heat1 and at this temperature is submitted to the process of rolling3 bright smooth bars such as this are the result of this rolling4 ,but ,i have said that the mass is more or less spongy or nodular1 and1 notwithstanding the high heat1 these nodules do not perfectly incorporate with their neighbours3 what then8 ,you would say that the process of rolling must draw the nodules into fibres--it does so2 and here is a mass acted upon by dilute sulphuric acid1 which exhibits in a striking manner this fibrous structure4 ,the experiment was made by my friend ,dr4 ,percy1 without any reference to the question of cleavage4 ,here are other cases of fibrous iron4 ,this fibrous structure is the result of mechanical treatment4 ,break a mass of ordinary iron and you have a granular fracture2 beat the mass1 you elongate these granules1 and finally render the mass fibrous4 ,here are pieces of rails along which the wheels of locomotives have slidden2 the granules have yielded and become plates2 they exfoliate or come off in leaves4 ,all these effects belong1 ,i believe1 to the great class of phenomena of which slaty cleavage forms the most prominent example4,i ,thus1 ladies and gentlemen1 we have reached the termination of our task4 ,i commenced by exhibiting to you some of the phenomena of crystallization4 ,i have placed before you the facts which are found to be associated with the cleavage of slate-rocks4 ,these facts1 as finely expressed by ,helmholtz1 are so many telescopes to our spiritual vision1 by which we can see backward through the night of antiquity1 and discern the forces which have been in operation upon the earth's surface ,ere the lion roared1 ,or the eagle soared4 ,from evidence of the most independent and trustworthy character1 we come to the conclusion that these slaty masses have been subjected to enormous pressure1 and by the sure method of experiment we have shown--and this is the only really new point which has been brought before you--how the pressure is sufficient to produce the cleavage4 ,expanding our field of view1 we find the self-same law1 whose footsteps we trace amid the crags of ,wales and ,cumberland1 stretching its ubiquitous fingers into the domain of the pastrycook and ironfounder2 nay1 a wheel cannot roll over the half-dried mud of our streets without revealing to us more or less of the features of this law4 ,i would say1 in conclusion1 that the spirit in which this problem has been attacked by geologists indicates the dawning of a new day for their science4 ,the great intellects who have laboured at geology1 and who have raised it to its present pitch of grandeur1 were compelled to deal with the subject in mass2 they had no time to look after details4 ,but the desire for more exact knowledge is increasing2 facts are flowing in1 which1 while they leave untouched the intrinsic wonders of geology1 are gradually supplanting by solid truths the uncertain speculations which beset the subject in its infancy4 ,geologists now aim to imitate1 as far as possible1 the conditions of nature1 and to produce her results2 they are approaching more and more to the domain of physics2 and ,i trust the day will soon come when we shall interlace our friendly arms across the common boundary of our sciences1 and pursue our respective tasks in a spirit of mutual helpfulness1 encouragement1 and good-will4 ,,footnotes3 ,a ,referred to in the ,introduction4 ,b ,i merely use this as an illustration2 the deposition may have really been due to sediment carried down by rivers4 ,but the action must have been periodic1 and the powder duplex4 ,c ',transactions of the ,geological ,society1' ,ser4 ii4 vol4 iii4 p4 #dgg4 ,d ,in a letter to ,sir ,charles ,lyell1 dated from the ,cape of ,good ,hope1 ,february #bj1 #ahcf1 ,sir ,john ,herschel writes as follows3--,if rocks have been so heated as to allow of a commencement of crystallization1 that is to say1 if they have been heated to a point at which the particles can begin to move amongst themselves1 or at least on their own axes1 some general law must then determine the position in which these particles will rest on cooling4 ,probably that position will have some relation to the direction in which the heat escapes4 ,now when all or a majority of particles of the same nature have a general tendency to one position1 that must of course determine a cleavage plane4 ,e ,omitted here4 ,f ,while to my mind the evidence in proof of pressure seems perfectly irresistible1 ,i by no means assert that the manner in which ,i stated it is incapable of modification4 ,all that ,i deem important is the fact that pressure has been exerted2 and provided this remain firm1 the fate of any minor portion of the evidence by which it is here established is of comparatively little moment4 ,g ,i have usually softened the wax by warming it1 kneaded it with the fingers1 and pressed it between thick plates of glass previously wetted4 ,at the ordinary summer-temperature the wax is soft1 and tears rather than cleaves2 on this account ,i cool my compressed specimens in a mixture of pounded ice and salt1 and when thus cooled they split beautifully4 ,h ,it is scarcely necessary to say that if the mass were squeezed equally in all directions no laminated structure could be produced2 it must have room to yield in a lateral direction4 ,i ,an eminent authority informs me that he believes these surfaces of weak cohesion to be due to the interposition of films of graphite1 and not to any tendency of the iron itself to become fibrous3 this of course does not in any way militate against the theory which ,i have ventured to propose4 ,all that the theory requires is surfaces of weak cohesion1 however produced1 and a change of shape of such surfaces consequent on pressure or rolling4 ,,index4 ,a,eggischhorn1 #ajj1 #aje4 ,agassiz on glacier motion1 #bgj1 #caj4 ,air-bubbles1 #cei1 #cgf4 ,aletsch ,glacier1 #aja4 -- --1 bedding and structure observed on1 #abj1 #cia4 ,aletschhorn1 cloud iridescences on1 #ajj1 #bch4 ,allalein ,glacier1 #afb4 ,alpine climbers1 suggestions to1 #afi4 ,alps1 winter temperature of1 #afh4 ,altmann's theory of glacier motion1 #bif4 ,ancient glaciers1 action of1 #ii1 #ada4 ,arveiron1 arch of1 #ch1 #bag4 ,atmosphere1 permeability of1 to radiant heat1 #aje1 #bdc-bdg4 ,atmospheric refraction1 #ce4 ,avalanche at ,saas1 #afd4 --1 sound of1 explained1 #ab1 #ad4 ,bakewell1 ,mr41 on motion of ,glacier des ,bossons1 #ccg4 ,balmat1 ,auguste1 #afi1 #ahh4 ,bedding1 lines of1 #cia4 ,bennen1 ,johann ,joseph1 #ajd1 #aah4 ,bergschrund1 #ih1 #cbe4 ,blower1 glacier1 #hg4 ,blue colour of ice1 #bef4 -- -- -- snow1 #bi1 #hc1 #acb1 #bjc4 -- -- -- water1 #cc1 #bec1 #bei-bfb4 ,blueness of sky1 #bb1 #agd1 #beg-bfa4 ,blue veins1 #cgf1 #cha4 ,boiling-point1 influence of pressure on1 #djh4 -- -- at different altitudes1 #aje1 #ajf1 #aac1 #abj1 #abi1 #age1 #aij4 ,bois1 ,glacier des1 #ci1 #bge1 #cfh4 ,brevent1 ascent of1 #agb4 ,brocken1 ,spirit of the1 #bb1 #bch4 ,bubbles1 in ice1 #dd1 #adg1 #cei1 #dbe4 -- in snow1 #ah1 #bea4 ,capillaries of glacier1 #cce-cci4 ,cave of ice1 #ace4 ,cavities in ice1 #afc1 #cef1 #dbd4 ,cells in ice1 #adg1 see ,bubbles4 ,chamouni1 #cg4 --1 difficulties at1 #agj1 #aib4 -- in winter1 #aih1 #ccf4 ,charmoz1 view from1 #de1 #fh1 #cfh4 ,charpentier's theory of glacier motion1 #bif4 ,chemical action1 rays producing1 #bdj4 ,chromatic effects1 #bce4 ,cleavage1 #djf4 -- and stratification distinct1 #b1 #cij1 #dca4 -- caused by pressure1 #f1 #dcf4 --1 contortions of1 #i1 #ei4 -- of crystals and slate rocks1 lecture on1 #dbg4 -- of glaciers1 #bf1 #cic1 #dbe-dbf4 -- -- ice1 #ceb1 #djg4 -- -- slate1 c41 #a1 #dcj4 ,cleft station1 the1 #dg1 #cfi4 ,clouds1 formation and dissipation of1 #bb1 #ig1 #acg1 #adf4 --1 iridescent1 #ajj1 #aje1 #adg1 #aed1 #bch4 -- on ,mont ,blanc1 #hb4 -- on ,monte ,rosa1 #abd4 --1 winter1 at ,montanvert1 #bjh4 ,colour answers to pitch1 #bbg4 ,colours of sky1 #beg4 --1 subjective1 #cg4 ,comet1 discovery of1 #ahf4 ,compass affected by rocks1 #adj4 ,crepitation of glaciers1 #dd1 #ceg4 ,crevasses1 #cae 7marginal1 #cah2 transverse1 #cbj2 longitudinal1 #cbb71 #dbd4 --1 first opening of1 #cag1 #cbg4 ,crumples in ice1 #agd1 #dae1 #dai4 ,crystallization of ice1 #cec4 ,crystals1 cleavage of1 #c1 #dbh4 -- of snow1 #acj1 #bje1 #bab4 ,deafness1 artificial1 #afg4 ,differential motion1 #cie4 -- --1 ,dr4 ,whewell on1 #cif4 ,diffraction1 explanation of1 #bcg4 ,dirt-bands1 #de1 #df1 #fh1 #ie1 #cfg1 #cgc4 -- --1 maps of1 #cfg1 #cfh1 #cfi4 -- --1 ,forbes on1 #cga4 -- --1 source of1 #cfi1 #dbe4 ,disks in ice1 planes of1 #afc1 #ceh1 #dbe4 ,dollfuss1 ,m41 hut of1 #ah1 #aab4 ,dome du ,gouter1 #fh1 #ge4 ,donny1 ,m41 on cohesion of liquids1 #cee4 ,echoes1 theory of1 #ae4 ,eismeer1 the1 #ac1 #cfb4 ,expedition of #ahef1 ,oberland and ,tyrol1 #i-cb4 -- -- #aheg1 ,montanvert and ,mer de ,glace1 #cc-ia4 -- -- #aheh1 ,oberland1 ,valais1 and ,monte ,rosa district1 #ib-aib4 -- -- #ahei1 winter1 ,chamouni1 and ,mer de ,glace1 #aie-bai4 ,faraday1 ,prof41 on ,regelation1 #cea4 ,faulberg1 cave of1 #ajg4 ,fee1 glacier of1 #afe4 ,fend1 #cb4 ,finsteraarhorn1 #ajd1 #aaj4 --1 summit of1 #aab4 ,flowers1 liquid1 in ice1 #adg1 #ced-ceh1 #dbd4 ,forbes1 ,prof41 comparison of glacier to river1 #cjf1 #cjh4 -- --1 on glacier motion1 #bgb1 #cjd1 #cjh4 -- --1 on magnetism of rocks1 #ade4 -- --1 on veined structure1 #cgi4 -- --1 viscous theory1 #caa1 #cbg1 #ccc1 #cce4 ,freezing1 planes of1 #afc1 #ceh1 #dbd4 ,frost-bites1 #aia4 ,frozen flowers1 #acj1 #bab4 ,furgge glacier1 structure crossing strata on1 #afj1 #cib-cid4 ,gases1 passage of heat through1 #bdc4 ,geant1 ,col du1 #ej1 #agc4 ,geant1 glacier du1 #ec-eg1 #bhj1 #cfi-cgc4 --1 measurements on1 #dai-dba4 --1 motion of1 #bha1 #bhf4 --1 white ice seams of1 #ef1 #dac4 ,gebatsch ,alp1 #bc4 --1 glacier of1 #bd1 #bf4 ,geneva1 ,lake of1 #cc1 #bei-bfb4 ,glaciers1 ancient1 action of1 #ii1 #afc4 -- blower1 #hg4 --1 capillaries of1 #cce-cci4 --1 crepitation of1 #dd1 #ceg4 -- d'ecoulement1 #cja4 -- de ,lechaud1 see ,lechaud4 -- des ,bois1 #ci1 #bge1 #cfh4 -- du ,geant1 see ,geant4 -- du ,talefre1 see ,talefre4 --1 groovings on1 #bj1 #ef1 #cgg4 --1 measurement of1 #bgf4 -- motion1 #eb1 #bfi-bie1 #dbb4 -- --1 earlier theories of1 #bif-cad4 -- --1 pressure theory of1 #cdf4 --1 origin of1 #bdh-beb4 -- reservoirs1 #cja4 --1 ridges on1 #db1 #ee4 --1 structure of1 #acf1 #adh1 see ,veined structure4 -- tables1 #dd1 #bfe4 --1 veins of1 #ed1 #cgf1 #cha4 --1 wrinkles on1 #cgj4 ,goethe's theory of colours1 #beh4 ,goerner glacier1 #abj1 #ach4 ,goerner grat1 #acg1 #ade4 ,goernerhorn glacier1 #adg1 #adi4 ,grand ,plateau1 #ahg4 ,grands ,mulets1 #gc1 #ahe4 ,graun1 #bi4 ,grimsel1 the1 #ah1 #ii4 ,grindelwald1 lower glacier of1 #ac1 #ib1 #cba1 #chd4 ,groovings on glaciers1 #bj1 #ef1 #cgg4 ,gruener's theory of glacier motion1 #bif4 ,guides of ,chamouni1 rules of1 #fj1 #agj1 #aib4 -- lost in crevasse1 #gf4 ,guyot1 ,m41 on veined structure1 #cgh4 ,hailstones1 conical1 #ca4 --1 spherical1 #fe4 ,handeck1 waterfall of1 #ag4 ,hasli1 valley of1 #ag1 #ii4 ,heat and light1 #bbc1 #bci1 #bda4 -- -- work1 #cbh4 --1 luminous1 #bda-bdg4 --1 mechanical equivalent of1 #cbi4 --1 obscure1 #bdj4 --1 passage through gases1 #bdc-bde4 --1 radiant1 #bci4 -- --1 permeability of atmosphere to1 #aje1 #bdc-bdg4 --1 radiated1 #bdb4 --1 specific1 #cca4 ,heisse ,platte1 the1 #ac4 ,hirst1 ,mr41 measurements on ,mer de ,glace1 #ch1 #df1 #bge1 #bhc1 #bhi1 #cac1 #dbj4 ,hochjoch1 #cb4 ,hoechste ,spitze of ,monte ,rosa1 #abh4 ,hopkins1 ,mr41 on crevasses1 #cah1 #chc4 ,hotel des ,neufchatelois1 #ai1 #aab1 #bgj4 ,hugi on glacier motion1 #bgj4 ,huxley1 ,mr41 on glacier capillaries1 #cch4 -- --1 on water-cells1 #bea1 #cei4 ,hydrogen1 effect on rays1 #bec4 ,ice1 blue colour of1 #bef4 -- cascades1 #id1 #chd1 #cia4 -- cave1 #ace4 -- cells1 #adg1 see ,bubbles4 -- cones1 #bff4 --1 cracking of1 #cag1 #cbf4 --1 crystallization of1 #cec4 --1 effects of pressure on1 #dje1 #dji4 --1 experiments on1 #cdf4 --1 friability of1 #ccc4 --1 liquefaction of1 #cec1 #djh4 --1 liquid flowers in1 #ced-ceh1 #dbd4 --1 ,thomson's theory of plasticity of1 #cdj4 --1 softening of1 #ccc4 --1 structure of1 #acf1 #adh4 --1 temperature of1 #bda1 #ccb4 --1 white1 seams of1 #ef1 #dac1 #dba4 ,illumination of trees1 c41 at sunrise and sunset1 #agh1 #bch4 ,interference rings1 #bbi4 -- spectra1 #gf1 #agh1 #bce1 #bch4 ,iridescent clouds1 #ajj1 #aje1 #adg1 #aed1 #bch4 ,jardin1 the1 #fa1 #agd4 ,joch1 the passage of a1 #bh4 ,joule1 ,m41 on heat and work1 #cbh4 ,jungfrau1 the1 #aa4 --1 evening near1 #ajf4 ,laminated structure1 #cgf1 #cgh1 #dbf4 ,lechaud1 glacier de1 #ec1 #chg4 -- -- --1 motion of1 #fj1 #bhf-bhh4 ,lenticular structure1 #cha4 ,light and heat1 #bbc1 #bci1 #bda4 --1 undulation theory of1 #bbd4 ,linth1 ,m4 ,escher de la1 #bga4 ,liquefaction of ice1 #cec1 #djh4 ,liquid flowers1 #adg1 #ced-ceh1 #dbd4 ,magnetic force1 #add4 ,magnetism of rocks1 #adj1 #adc1 #ade4 ,maerjelen ,see1 #aja1 #aai4 ,mastic1 ,bruecke's solution of1 #bei4 ,mattmark ,see1 #afb4 ,maximum motion1 locus of point of1 #bhe1 #cbc4 ,mayenwand1 summit of1 #bj1 #ajj1 #cbc4 ,mayer1 on connexion of heat with work1 #cbh4 ,measurement of glaciers1 #bgf4 ,mer de ,glace1 #db-fg1 #hf-ij1 #agc4 -- -- --1 dirt-bands of the1 #cfg 7seen from ,charmoz1 #de1 #cfh2 from ,cleft station1 #dg1 #cfi2 from the ,flegere1 #cfg74 -- -- --1 map of1 #ec1 #bfd4 -- -- --1 motion of1 #bge-bic4 -- -- --1 winter motion of1 #bid1 #cdc4 -- -- --1 winter visit to1 #aie1 #bjf-bah4 ,milk1 cause of blueness of1 #bfa4 ,mirage1 #cf4 ,montanvert1 #dj1 #hi1 #agc4 -- in winter1 #bjd4 ,mont ,blanc1 first ascent of1 #fh4 -- --1 second ascent of1 #agg4 -- --1 summit of1 #ha1 #ahi4 ,monte ,rosa1 first ascent of1 #abb4 -- --1 second ascent of1 #aea4 -- --1 summit of1 #abh1 #aef4 -- --1 western glacier of1 #ach1 #adg4 -- --1 zones of colour1 #aed1 #bch4 ,moraines1 #bfc4 -- of ,talefre1 #ed1 #fc1 #bfg1 #chg4 ,motion of glaciers1 #eb1 #bfi-bie1 #dbb4 ,moulins1 #cfb1 #dbd4 --1 depth of1 #cfe4 --1 motion of1 #cfd4 ,necker1 letter from1 #agh4 ,neufchatelois1 ,hotel des1 #ai1 #aab1 #bgj4 ,neve ice1 #bdi1 #bea4 ,oberland1 the1 visited1 #i-bb2 #ib-abj2 #cij4 ,oils1 effect of films of1 #bcf4 ,person1 ,m41 on softening of ice1 #ccc4 ,pistol fired on summit of ,mont ,blanc1 #hb1 #hc1 #bbd4 ,pitch of musical sounds1 #bbe4 ,planes of freezing1 #afc1 #ceh1 #dbd4 ,plasticity of ice1 ,thomson's theory of1 #cdj4 ,polar forces1 #d4 ,pressure and cleavage1 see ,cleavage4 -- and liquefaction of ice1 #cdj1 #djh4 -- -- veined structure1 #djd2 #adg-adi1 #chb-cid1 #dab1 #dbe-dbf4 --1 effects of1 on boiling point1 #djh4 -- -- -- -- ice1 #dje1 #dji4 -- theory of glacier motion1 #cdf4 ,radiant heat1 #aje1 #bci4 ,rays1 calorific1 #bdj4 --1 transmission of1 #bdb4 ,redness of sunset1 #age4 ,refraction on lake of ,geneva1 #ce4 ,regelation1 #cdg1 #cea4 ,reichenbach fall1 #ag4 ,rendu1 comparison of glacier to river1 #cjf4 --1 measurements of glaciers1 #cjd4 --1 notice of regelation1 #cja4 -- on conversion of snow into ice1 #cja4 -- on ductility1 #bih4 -- on law of circulation1 #cjj4 -- on motion of glaciers1 #cje4 -- on veined structure1 #cja4 -- theory of glaciers1 #bii4 ,rhone at lake of ,geneva1 #cd1 #bfa4 -- glacier1 #bj1 #ajj1 #cbc1 #chf4 -- --1 chromatic effects1 #ba1 #bch4 ,ridges on glaciers1 #db1 #ee4 ,riffelhorn1 the1 #acc1 #ada-ade4 ,rings1 interference1 #bbi4 -- round sun1 #ba1 #bch4 ,ripples deduced from rings1 #djj4 ,ripple theory1 ,forbes on1 #cih4 -- -- of veined structure1 #cih4 -- waves1 movement of1 #bcb4 ,river and glacier1 analogies between1 #bha-bhe1 #dbc2 #cfh4 ,rocks1 magnetism of1 #adj1 #adc1 #ade4 ,saas1 avalanche at1 #afd4 ,sabine1 ,gen41 on veined structure1 #cgh4 ,sand-cones1 #bff4 ,saussure's theory of glacier motion1 #eb1 #bif4 ,scheuchzer's theory of glacier motion1 #bif4 ,seams1 white1 in ice1 #ef1 #hh1 #dac1 #dba4 ,sedgwick1 ,prof41 on cleavage1 #b-e1 #cij1 #dca4 ,seracs1 #ea1 #ge4 ,serpentine1 boulders of1 #afa4 ,shadows1 coloured1 #ch4 ,sharpe1 on slaty cleavage1 #e1 #dcb4 ,silberhorn1 the1 #aa4 ,sky1 blueness of1 #bb1 #agd1 #age4 --1 colours of1 explained1 #beg4 ,slate1 cleavage of1 #a1 #dcj4 ,snow1 blue colour of1 #bi1 #acb1 #bjc4 -- crystals1 #acj1 #bje1 #bab4 --1 dry1 #bej4 -- line1 #bi1 #bdh4 --1 perpetual1 #bdh4 --1 sound of breaking1 #bjb4 -- storm1 sound through1 #bae4 --1 whiteness of1 explained1 #bej4 ,sorby1 ,mr41 on slaty cleavage1 #e1 #dce4 ,sound in a vacuum1 #bbd4 --1 intensity of1 #hc4 --1 rate of motion of1 #bbf4 ,spectra1 interference1 #gf1 #agh1 #bce1 #bch4 ,spectrum1 rays of1 #bdj4 ,stars1 twinkling of1 #gb1 #bch4 ,stelvio1 pass of1 #bi4 ,storm on ,grands ,mulets1 #ahe4 -- -- ,mer de ,glace1 #baj4 ,strahleck1 glacier of1 #id1 #chd4 --1 passage of1 #ic1 #ig4 ,strata of ice1 #acf4 ,stratification of neve1 #cib4 -- -- slate1 #a1 #dcj4 ,structure1 doubts regarding1 #dd1 #ib1 #chi4 -- of ice1 #acf1 #adh1 see ,veined structure4 ,subjective colours1 #cg4 ,summary of glacier theory1 #dbb4 ,sun1 rings round1 #ba1 #bch4 ,sunrise at ,chamouni1 #ci4 -- and sunset1 illumination of trees1 c41 at1 #agh1 #bch4 ,sunset1 gorgeous1 #ahd4 ,tables1 glacier1 #dd1 #bfe-bff4 ,tacul1 motion of ice-wall at1 #bhi4 ,talefre1 glacier of1 #dc1 #fa-fb1 #hg4 --1 moraines of1 #ed1 #fc1 #bfg1 #chg4 ,temperature1 winter1 of ,alps1 #afh4 ,theodolite1 use of1 #bge4 ,theory of cleavage1 #e4 ,thermometer at ,jardin1 #agd4 -- buried on ,mont ,blanc1 #aij4 -- on ,finsteraarhorn1 #aac4 ,thomson1 ,prof41 theory of plasticity1 #cdj4 -- -- -- -- regelation1 #ceb4 ,twinkling of stars1 #gb1 #bch4 ,tyrol1 the1 #bc4 ,undulation theory of light1 #bbd4 ,unteraar1 glacier of1 #ah1 #bfe1 #chh4 ,vacuum in ice-cavities1 #afc1 #cef4 ,veined structure1 #cgf 7marginal1 #chc2 transverse1 #chd2 longitudinal1 #chg71 #cie1 #djd1 #djh4 -- --1 experiments on1 #chb1 #chh4 -- -- caused by pressure1 #adg-adi1 #chb-chi1 #dab1 #dbe-dbf4 -- -- crossing strata1 #chi-cid4 -- --1 ,forbes on1 #cgi4 -- --1 ,gen4 ,sabine on1 #cgh4 -- --1 ,m4 ,guyot on1 #cgh4 -- --1 ripple theory of1 #cih4 ,viesch1 glacier of1 #aji1 #aah4 ,viscosity1 #cab1 #cbe1 #ccd1 #cej1 #dbc4 ,water absorbs red rays1 #bed4 --1 blue colour of1 #bed2 #cc1 #bei1 #bfa4 --1 rippling waves of1 #bcb4 ,waves1 frozen1 #dc1 #ee4 --1 interference of1 #bca4 -- motion1 ,weber on1 #bcb1 #cii4 -- of sound1 #bbe4 ,wengern ,alp1 #i4 ,wetterhorn1 echoes of1 #ae4 ,white ice1 seams of1 #ef1 #eg1 #hh1 #dac1 #dba4 ,whiteness of ice1 #bej1 #bfh1 #cgf4 ,winter motion of ,mer de ,glace1 #bid4 ,wrinkles on glacier1 #cgj4 ,young1 ,thomas1 theory of light1 #bbd4 ,spottiswoode ,co4 ,printers1 ,new-street ,square1 ,london4 ,,works by ,,john ,,tyndall4 ,,fragments of ,,science3 a ,series of ,detached ,essays1 ,addresses1 and ,reviews4 #b vols4 crown #hvo4 #afs4 ,,vol4 ,i4--,the ,constitution of ,nature--,radiation--,on ,radiant ,heat in ,relation to the ,colour and ,chemical ,constitution of ,bodies--,new ,chemical ,reactions produced by ,light--,on ,dust and ,disease--,voyage to ,algeria to observe the ,eclipse--,niagara--,the ,parallel ,roads of ,glen ,roy--,alpine ,sculpture--,recent ,experiments on ,fog-,signals--,on the ,study of ,physics--,on ,crystalline and ,slaty ,cleavage--,on ,paramagnetic and ,diamagnetic ,forces--,physical ,basis of ,solar ,chemistry--,elementary ,magnetism--,on ,force--,contributions to ,molecular ,physics--,life and ,letters of ,,faraday--,the ,copley ,medalist of #ahgj--,the ,copley ,medalist of #ahga--;,death by ,lightning--,science and the ,spirits4 ,,vol4 ,,ii4--,reflections on ,prayer and ,natural ,law--,miracles and ,special ,providences--,on ,prayer as a ,form of ,physical ,energy--,vitality--,matter and ,force--,scientific ,materialism--,an ,address to ,students--,scientific ,use of the ,imagination--,the ,belfast ,address--,apology for the ,belfast ,address--,the ,rev4 ,,james ,,martineau and the ,belfast ,address--,fermentation1 and its ,bearings on ,surgery and ,medicine--,spontaneous ,generation--,science and ,man--,professor ,,virchow and ,evolution--,the ,electric ,light4 ,,new ,,fragments4 ,crown #hvo4 #ajs4 #f;d4 ,,contents3 ,the ,sabbath--,goethe's ',farbenlehre'--,atoms1 ,molecules and ,ether ,waves--,count ,rumford--,louis ,pasteur1 his ,life and ,labours--,the ,rainbow and its ,congeners--,address delivered at the ,birkbeck ,institution on ,october #bb1 #ahhd--,thomas ,young--,life in the ,alps--,about ,common ,water--,personal ,recollections of ,thomas ,carlyle--,on ,unveiling the ,statue of ,thomas ,carlyle--,on the ,origin1 ,propagation1 and ,prevention of ,phthisis--,old ,alpine ,jottings--,a ,morning on ,alp ,lusgen4 ,,lectures on ,,sound4 ,with ,frontispiece of ,fog-,syren1 and #bjc other ,woodcuts and ,diagrams in the ,text4 ,crown #hvo4 #ajs4 #f;d4 ,,heat1 a ,,mode of ,,motion4 ,with #abe ,woodcuts and ,diagrams4 ,crown #hvo4 #abs4 ,,lectures on ,,light ,,delivered in the ,,united ,,states in #ahgb and #ahgc4 ,with ,portrait1 ,lithographic ,plate1 and #ei ,diagrams4 ,crown #hvo4 #es4 ,,essays on the ,,floating ,,matter of the ,,air in ,,relation to ,,putrefaction and ,,infection4 ,with #bd ,woodcuts4 ,crown #hvo4 #gs4 #f;d4 ,,researches on ,,diamagnetism and ,,magne-,,crystallic ,,action2 including the ,question of ,diamagnetic ,polarity4 ,crown #hvo4 #abs4 ,,notes of a ,,course of ,,nine ,,lectures on ,,light1 delivered at the ,royal ,institution of ,great ,britain1 #ahfi4 ,crown #hvo4 #as4 #f;d4 ,,notes of a ,,course of ,,seven ,,lectures on ,,electrical ,,phenomena and ,,theories1 delivered at the ,royal ,institution of ,great ,britain1 #ahgj4 ,crown #hvo4 #as4 #f;d4 ,,lessons in ,,electricity at the ,,royal ,,institution1 #ahge-ahgf4 ,with #eh ,woodcuts and ,diagrams4 ,crown #hvo4 #bs4 #f;d4 ,,faraday as a ,,discoverer4 ,crown #hvo4 #cs4 #f;d4 ,london3 ,,longmans1 ,,green1 ,,co4 ,transcriber's ,notes4 ,the titles from the ,list of ,illustrations were copied to the captions of the figures that otherwise had no caption1 for the convenience of the reader4 ,the sidenotes in the main body of the text were originally page headers4 ,they have been moved to a place more fitting for the flow1 typically to the head of the appropriate paragraph4 ,spelling variants where there was no obviously preferred choice were retained4 ,these include3 ,cleft-,station and ,cleft ,station1 plus variants2 ,cima di ,jazzi and ,cima de ,jazzi2 fanlike and fan-like2 firewood and fire-wood2 ,flegere and ,flegere2 foreshorten7ed7 and fore-shorten7ing72 generalisation and generalization2 judgment and judgement2 ,kumm and ,kumme1 which may be the same as ,kamm2 lime light and lime-light2 realize and realise7d72 recognise and recognize7d72 rearranged and re-arranged2 refrozen and re-frozen2 self-same and selfsame2 semifluid and semi-fluid2 sundial and sun-dial2 ,trift and ,trifti1 probably the same glacier2 weatherworn and weather-worn4 ,in the ,latin-#a encoded text version1 the oe-ligature was replaced by the two separate characters1 oe4 ,changed ,hockjoch to ,hochjoch on page xi3 passage of the ,hochjoch4 ,changed #ci to #bci on page xvii1 as the page number for chapter #b4 ,changed icefall to ice-fall on page xxvi3 part of ice-fall4 ,changed havresack to haversack on page #ga3 my waterproof haversack4 ,changed affluent to affluent on page #ih3 ,finsteraar affluent4 ,changed #ahd deg4#ib to #ahd4ib deg4 on page #abi4 ,changed gulleys to gullies on page #adc3 fissures and gullies4 ,changed ,,snowstorm to ,,snow-,,storm in the sidenote from page #bae3 ,,sound ,,through ,,the ,,snow-,,storm4 ,changed neutralise to neutralize on page #bca3 oppose and neutralize4 ,moved the semi-colon inside the double quotes on page #bhe1 around3 corresponding points4 ,changed ,,thompson',s to ,,thomson',s in the chapter heading on page #cdj3 ,,thomson',s ,,theory4 ,changed last to least in the footnote to page #bib3 at least as anxious4 ,changed ,i to ,it on page #cgg3 ,it was also4 ,die ,gletscher der ,jetzzeit on page #cic should probably be ,die ,gletscher der ,jetztzeit1 but was not changed4 ,inserted a comma in the index entry for ,aletsch ,glacier3 -- --1 bedding4 ,inserted a comma in the index entry for ,dirt-bands3 -- --1 maps of4 ,changed ,gouter to ,gouter in the index entry for ,dome du ,gouter4 ,changed ,hoch-joch to ,hochjoch in its index entry4 ,inserted second em-dash in the index entry for ,mont ,blanc3 -- --1 second ascent of4 ,inserted a comma in the index entry for ,rays3 --1 transmission of4 ,inserted a comma in the index entry for ,strahleck3 --1 passage of4