Ateightinthemorningarayofdaylightcametowakeusup.Thethousandshiningsurfacesoflavaonthewallsreceiveditonitspassage,andscattereditlikeashowerofsparks. Therewaslightenoughtodistinguishsurroundingobjects. "Well,Axel,whatdoyousaytoit?"criedmyuncle,rubbinghishands. "DidyoueverspendaquieternightinourlittlehouseatKönigsberg? Nonoiseofcartwheels,nocriesofbasketwomen,noboatmenshouting!" "Nodoubtitisveryquietatthebottomofthiswell,butthereissomethingalarminginthequietnessitself." "Nowcome!"myunclecried;"ifyouarefrightenedalready,whatwillyoubebyandby?Wehavenotgoneasingleinchyetintothebowelsoftheearth." "Imeanthatwehaveonlyreachedtheleveloftheisland.longverticaltube,whichterminatesatthemouthofthecrater,hasitslowerendonlyatthelevelofthesea." "Quitesure.Consultthebarometer." Infact,themercury,whichhadrisenintheinstrumentasfastaswedescended,hadstoppedattwenty–nineinches. "Yousee,"saidtheProfessor,"wehavenowonlythepressureofouratmosphere,andIshallbegladwhentheaneroidtakestheplaceofthebarometer." Andintruththisinstrumentwouldbecomeuselessassoonastheweightoftheatmosphereshouldexceedthepressureascertainedatthelevelofthesea. "But,"Isaid,"istherenotreasontofearthatthisever–increasingpressurewillbecomeatlastverypainfultobear?" "No;weshalldescendataslowrate,andourlungswillbecomeinuredtoadenseratmosphere. Aeronautsfindthewantofairastheyrisetohighelevations,butweshallperhapshavetoomuch:ofthetwo,thisiswhatIshouldprefer.Don'tletusloseamoment. Whereisthebundlewesentdownbeforeus?" Ithenrememberedthatwehadsearchedforitinvaintheeveningbefore.MyunclequestionedHans,who,afterhavingexaminedattentivelywiththeeyeofahuntsman,replied: Andsoitwas.Thebundlehadbeencaughtbyaprojectionahundredfeetaboveus.ImmediatelytheIcelanderclimbeduplikeacat,andinafewminutesthepackagewasinourpossession. "Now,"saidmyuncle,"letusbreakfast;butwemustlayinagoodstock,forwedon'tknowhowlongwemayhavetogoon." Thebiscuitandextractofmeatwerewasheddownwithadraughtofwatermingledwithalittlegin. Breakfastover,myuncledrewfromhispocketasmallnotebook,intendedforscientificobservations.Heconsultedhisinstruments,andrecorded: "Chronometer,8.17a.m.;barometer,297in.;thermometer,6°(43°F.).Direction,E.S.E." Thislastobservationappliedtothedarkgallery,andwasindicatedbythecompass. "Now,Axel,"criedtheProfessorwithenthusiasm,"nowwearereallygoingintotheinterioroftheearth.Atthisprecisemomentthejourneycommences." Sosaying,myuncletookinonehandRuhmkorff'sapparatus,whichwashangingfromhisneck;andwiththeotherheformedanelectriccommunicationwiththecoilinthelantern,andasufficientlybrightlightdispersedthedarknessofthepassage. Hanscarriedtheotherapparatus,whichwasalsoputintoaction. Thisingeniousapplicationofelectricitywouldenableustogoonforalongtimebycreatinganartificiallighteveninthemidstofthemostinflammablegases. "Now,march!"criedmyuncle. Eachshoulderedhispackage.Hansdrovebeforehimtheloadofcordsandclothes;and,myselfwalkinglast,weenteredthegallery. Atthemomentofbecomingengulfedinthisdarkgallery,Iraisedmyhead,andsawforthelasttimethroughthelengthofthatvasttubetheskyofIceland,whichIwasnevertobeholdagain. Thelava,inthelasteruptionof1229,hadforcedapassagethroughthistunnel. Itstilllinedthewallswithathickandglisteningcoat. Theelectriclightwashereintensifiedahundredfoldbyreflection. Theonlydifficultyinproceedinglayinnotslidingtoofastdownaninclineofaboutforty–fivedegrees;happilycertainasperitiesandafewblisteringshereandthereformedsteps,andwedescended,lettingourbaggageslipbeforeusfromtheendofalongrope. Butthatwhichformedstepsunderourfeetbecamestalactitesoverhead. Thelava,whichwasporousinmanyplaces,hadformedasurfacecoveredwithsmallroundedblisters;crystalsofopaquequartz,setwithlimpidtearsofglass,andhanginglikeclusteredchandeliersfromthevaultedroof,seemedasitweretokindleandformasuddenilluminationaswepassedonourway. Itseemedasifthegeniiofthedepthswerelightinguptheirpalacetoreceivetheirterrestrialguests. "Itismagnificent!"Icriedspontaneously."Myuncle,whatasight! Don'tyouadmirethoseblendinghuesoflava,passingfromreddishbrowntobrightyellowbyimperceptibleshades? Andthesecrystalsarejustlikeglobesoflight." "Ali,youthinkso,doyou,Axel,myboy?Well,youwillseegreatersplendoursthanthese,Ihope.Nowletusmarch:march!" Hehadbetterhavesaidslide,forwedidnothingbutdropdownthesteepinclines. ItwasthefacifsdescensusAverniofVirgil. Thecompass,whichIconsultedfrequently,gaveourdirectionassoutheastwithinflexiblesteadiness. Thislavastreamdeviatedneithertotherightnortotheleft. Yettherewasnosensibleincreaseoftemperature. ThisjustifiedDavy'stheory,andmorethanonceIconsultedthethermometerwithsurprise. Twohoursafterourdepartureitonlymarked10°(50°Fahr.),anincreaseofonly4°. Thisgavereasonforbelievingthatourdescentwasmorehorizontalthanvertical. Asfortheexactdepthreached,itwasveryeasytoascertainthat;theProfessormeasuredaccuratelytheanglesofdeviationandinclinationontheroad,buthekepttheresultstohimself. Abouteightintheeveninghesignalledtostop.Hanssatdownatonce. Thelampswerehunguponaprojectioninthelava;wewereinasortofcavernwheretherewasplentyofair.Certainpuffsofairreachedus. Whatatmosphericdisturbancewasthecauseofthem? Icouldnotanswerthatquestionatthemoment. Hungerandfatiguemademeincapableofreasoning. Adescentofsevenhoursconsecutivelyisnotmadewithoutconsiderableexpenditureofstrength.Iwasexhausted. Theorderto'halt'thereforegavemepleasure. Hanslaidourprovisionsuponablockoflava,andweatewithagoodappetite. Butonethingtroubledme,oursupplyofwaterwashalfconsumed. Myunclereckoneduponafreshsupplyfromsubterraneansources,buthithertowehadmetwithnone. Icouldnothelpdrawinghisattentiontothiscircumstance. "Areyousurprisedatthiswantofsprings?"hesaid. "Morethanthat,Iamanxiousaboutit;wehaveonlywaterenoughforfivedays." "Don'tbeuneasy,Axel,weshallfindmorethanwewant." "Whenwehaveleftthisbedoflavabehindus.Howcouldspringsbreakthroughsuchwallsasthese?" "Butperhapsthispassagerunstoaverygreatdepth.Itseemstomethatwehavemadenogreatprogressvertically." "Becauseifwehadgonedeepintothecrustofearth,weshouldhaveencounteredgreaterheat." "Accordingtoyoursystem,"saidmyuncle."Butwhatdoesthethermometersay?" "Hardlyfifteendegrees(59°Fahr),ninedegreesonlysinceourdeparture." "Well,whatisyourconclusion?" "Thisismyconclusion.Accordingtoexactobservations,theincreaseoftemperatureintheinterioroftheglobeadvancesattherateofonedegree(14/5°Fahr.)foreveryhundredfeet. Butcertainlocalconditionsmaymodifythisrate. ThusatYakoutskinSiberiatheincreaseofadegreeisascertainedtobereachedevery36feet. Thisdifferencedependsupontheheat–conductingpoweroftherocks. Moreover,intheneighbourhoodofanextinctvolcano,throughgneiss,ithasbeenobservedthattheincreaseofadegreeisonlyattainedatevery125feet. Letusthereforeassumethislasthypothesisasthemostsuitabletooursituation,andcalculate." "Well,docalculate,myboy." "Nothingiseasier,"saidI,puttingdownfiguresinmynotebook."Ninetimesahundredandtwenty–fivefeetgivesadepthofelevenhundredandtwenty–fivefeet." "Bymyobservationweareat10,000feetbelowthelevelofthesea." "Yes,orfiguresareofnouse." TheProfessor'scalculationswerequitecorrect. Wehadalreadyattainedadepthofsixthousandfeetbeyondthathithertoreachedbythefootofman,suchastheminesofKitzBahlinTyrol,andthoseofWuttembourginBohemia. Thetemperature,whichoughttohavebeen81°(178°Fahr.)wasscarcely15°(59°Fahr.).Herewascauseforreflection. 
