第10章

Afterthisthetravellersflewnorthwardatgreatspeedintheupperregionsoftheair,fortheywereanxioustohastentheirjourney。Theyfoundnothingbutunbrokensea,andnottilltheyreachedlatitudeeighty—sevenwasthereasignofice。Theythensawsomesmallbergsandfieldice,butinnogreatquantities。

Astheiroutsidethermometer,whenjustabovetheplacidwater——fortherewerenowaveshere——registeredtwenty—onedegreesFahrenheit,theyaccountedforthisscarcityoficebytheabsenceoflandonwhichfreshwatercouldfreeze,andbythefactthatitwasnotcoldenoughtocongealtheverysaltsea—water。

Finallytheyreachedanotherarchipelagoafewhundredmilesinextent,thelargerislandsofwhichwerecoveredwithasheetofice,attheedgesofwhichsmallicebergswerebeingformedbybreakingoffandslowlyfloating。Findingasmallislandonwhichthecoatingwasthin,theygroundedtheCallisto,andsteppedoutforthefirsttimeinseveraldays。Theairwassostillthatasmallpieceofpaperreleasedataheightofsixfeetsankslowlyandwentasstraightasthestringofaplumb—line。Thesunwasbisectedbythelineofthehorizon,andappearedtobemovingabouttheminacircle,withonlyitsupperhalfvisible。AsJupiter"snorthernhemispherewaspassingthroughitsautumnalequinox,theyconcludedtheyhadlandedexactlyatthepole。

"Nowtoworkonourexperiment,"saidCortlandt。"Iwonderhowwemaybestgetbelowthefrozensurface？"

"Wecanexplodeasmallquantityofdynamite,"repliedBearwarden,"afterwhichthediggingwillbecomparativelyeasy。"

WhileCortlandtandBearwardenpreparedthemine,Ayraultbroughtoutapickaxe,twoshovels,andthebatteryandwireswithwhichtoignitetheexplosive。TheymadetheirpreparationswithinonehundredfeetoftheCallisto,ormuchnearerthananequivalentamountofgunpowdercouldhavebeendischarged。

"Thisrecallsanoldlaboratoryexperiment,orratherlecture,"

saidCortlandt,astheycompletedthearrangements,"fortheillustrationisnotasarulecarriedout。Explodetwopoundsofpowderonanironsafeinaroomwiththewindowsclosed,andthewindowswillbeblownout,whilethesaferemainsuninjured。

Explodeanequivalentamountofdynamiteontopofthesafe,anditwillbedestroyed,whiletheglasspanesarenotevencracked。

Thisillustratesthedifferenceinrapiditywithwhichtheexplosionstakeplace。Totheintenselyrapidactionofdynamitetheairaffordsasmuchresistanceasasolidsubstance,whiletheexplosionofthepowderissoslowthattheairhastimetomoveaway;hencethedestructionofthewindowsinthefirstcase,andthesafeinthesecond。"

Whentheyhadmovedbeyondthedangerline,Bearwarden,astheparty"spractisingengineer,pressedthebutton,andtheexplosiondidtherest。Theyfoundthatthegroundwasfrozentoadepthofbutlittlemorethanafoot,belowwhichitbecameperceptiblywarm。Plyingtheirshovelsvigorously,theyhadsoondugtheholesodeepthatitsedgeswereabovetheirheads。Whenthefloorwastenfeetbelowthesurroundinglevelthethermometerregisteredsixty。

"Thisisscarcelyafairtest,"saidCortlandt,"sincetheheatrisesandislostasfastasgivenoff。Letusthereforeclosetheopeningandseeinwhattimeitwillmeltanumberofcubicfeetofice。"

Accordinglytheyclimbedout,threwinaboutacart—loadofice,andcoveredtheopeningwithtwooftheCallisto"sthickrugs。

Inhalfanhouralltheicehadmelted,andinanotherhalfhourthewaterwashot。

"Noarcticexpeditionneedfreezetodeathhere,"saidBearwarden,"sinceallamanwouldhavetodowouldbetoburrowafewfeettobeaswarmastoast。"

Astheislandonwhichtheyhadlandedwasatonesideofthearchipelago,butwasitselfattheexactpole,itfollowedthatthecentreofthearchipelagowasnotthepartfarthestnorth。

Thisinameasureaccountedfortheslightthicknessoficeandsnow,fortheisobariclineswouldslope,andconsequentlywhatwindtherewaswouldflowtowardstheinteriorofthearchipelago,whosesurfacewascolderthanthesurroundingocean。

Themoistair,however,comingalmostentirelyfromthesouth,wouldlosemostofitsmoisturebycondensationinpassingovertheice—ladenland,andso,likethecloudsovertheregioneastoftheAndes,wouldhavebutlittlelefttoletfallonthisextremenorthernpart。Theblanketingeffectofagreatthicknessofsnowwouldalsocause,thelowerstrataoficetomelt,bykeepingintheheatconstantlygivenoffbythewarmplanet。

"Ithinktherecanbenoquestion,"saidCortlandt,"that,asaresultofJupiter"sgreatflatteningatthepolesandthedrawingofthecrust,whichmovesfasterinJupiter"srotationthananyotherpart,towardstheequator,thecrustmustbeparticularlythinhere;for,wereitasthinallover,therewouldbenospaceforthecoal—beds,which,judgingfromthepurityoftheatmosphere,mustbeveryextensive。Further,wecanrecallthatthewaterinthehotspringnearwhichwealighted,whichevidentlycamefromafargreaterdepththanwehavehere,wasnotashotasthis。Theconclusionisclearthatelsewheretheinternalheatisnotasnearthesurfaceashere。"

"ThemoreIseeofJupiter,"exclaimedBearwardenenthusiastically,"themorecharmedIbecome。ItalmostexactlysupplieswhatIhavebeenconjuringupasmyideaofaperfectplanet。Itscompensationsofhighlandneartheequator,andlowwitheffectiveinternalheatatthepoles,areideal。Thegradualslopeofitscontinentalelevations,onaccountoftheirextent,willeasetheworkofoperatingrailways,andtheatmosphere"sdensitywillbejustthethingforourflyingmachines,whileNaturehassuppliedallsourcesofpowersolavishlythatnoundertakingwillbetoogreat。Thoughlandasyet,tojudgebyourphotographs,occupiesonlyaboutoneeighthofthesurface,weknow,fromtheexperienceoftheotherplanets,thatthisisboundtoincrease;sothat,ifthehumanracecanperpetuateitselfonJupiterlongenough,itwillundoubtedlyhaveonefourthoralargerproportionforoccupation,thoughthelandalreadyupheavedcomprisesfullyfortytimestheareaofourentireglobe,which,asweknow,isstillthree—fourthswater。"

"SincewehavereachedwhatwemightcalltheendofJupiter,andstillhavetime,continuedAyrault,"letusproceedtoSaturn,wherewemayfindevenstrangerthingsthanhere。Ihopedwecouldinvestigatethegreatredspot,butamconvincedwehaveseenthebeginningofoneinTwentiethCenturyArchipelago,andwhat,underfavourableconditions,willberecognizedassuchonearth。"

Itwasjustsixterrestrialweekssincetheyhadsetout,andthereforeFebruary2donearth。

"Itwouldbebest,inanycase,tostartfromJupiter"sequator,"

saidCortlandt,"forthestraightlineweshouldmakefromthesurfaceherewouldbeatrightanglestoSaturn。Weshallprobably,inspiteofourselves,swingafewdegreesbeyondtheline,andsocangetabird"s—eyeviewofsomeportionofthesouthernhemisphere。"

"AllaboardforSaturn！"criedBearwardenenthusiastically,inhisjovialway。"Thiswillbeajourney。"

CHAPTERXIV。

THESCENESHIFTS。

HavingreturnedtherugstotheCallisto,theyappliedthemaximumpowerofthebatteriestorising,closedallopeningswhenthebarometerregisteredthirty,andmovedoffintospace。

WhenSeveralthousandmilesabovethepole,theydivertedpartofthepowertoattractingthenearestmoonthatwasintheplaneofJupiter"sequator,andbythetimetheirupwardmotionhadceasedweremovingwellinitsdirection。Theirrapidmotionaidedtheworkofresistinggravity,sincetheircarhadinfactbecomeasmallmoon,revolving,likethoseofUranusorthatofNeptune,inanorbitvaryinggreatlyfromtheplaneoftheecliptic。Astheyflewsouthataheightrangingfromtwothousandtothreethousandmiles,theplanetrevolvedbeforethem,andtheyhadachanceofobtainingathoroughview。TherewerebutafewscatteredislandsonthesideoftheNorthernhemisphereoppositetothatoverwhichtheyhadreachedthepole,andinthevaryingcoloursofthewater,whichtheyattributedtotemperatureortosomesubstanceinsolution,theyrecognizedwhattheyhadalwayshearddescribedonearthasthebandsofJupiter,encirclingtheplanetwithgreatbelts,thecolourvaryingwiththelatitude。

Ataboutlatitudeforty—fivethesebandswerepurple,farthersouthlightolivegreen,andattheequatorabrownorange。

Shortlyaftertheyswungacrosstheequatortheoceanagainbecamepurple,andatthesametimeawell—definedandverybrilliantwhitespotcameintoview。Itsbrightnessshowedslightvariationsinintensity,thoughitsgeneralshaperemainedunchanged。Ithadanotherpeculiarity,inthatitpossessedafairlyrapidmotionofitsown,asitmovedeastwardacrossthesurfaceoftheocean。ItexhibitedallthephenomenaofthestormtheyhadwatchedincrossingSecretaryDeepwatersBay,butcoveredalargerarea,andwasfarmoreviolent。Theirglassesshowedthemvastsheetsofspraydrivenalongattremendousspeed,whilethesurfacewasmilkywhite。

"This,"saidBearwarden,pickingupabook,"solvestomymindthemysteryofthewhitespotdescribedbytheEnglishwriterChambers,in1889,asfollows:

""Duringthelastfewyearsabrilliantwhitespothasbeenvisibleontheequatorialborderofthegreatsouthernbelt。A

curiousfactinconnectionwiththisspotis,thatitmoveswithavelocityofsometwohundredandsixtymilesperhourgreaterthantheredspot。Denningobtainedonehundredandsixty—nineobservationsofthisbrightmarkingduringtheyears1880—1883,anddeterminedtheperiodasninehours,fiftyminutes,eightandsevententhsseconds（fiveandahalfminuteslessthanthatoftheredspot）。Althoughthelatterisnowsomewhatfaint,thewhitespotgivespromiseofremainingvisibleformanyyears。

Duringtheyear1886alargenumberofobservationsofJupiterweremadeattheDearbornObservatory,Chicago,U。S。,byProf。

G。W。Hough,usingtheeighteen—and—a—half—inchrefractoroftheobservatory。Inasmuchastheseobservationsarenotonlyofhighintrinsicinterest,butareinconflict,tosomeextent,withpreviousrecords,asomewhatfullabstractofthemwillbeuseful:Theobjectofgeneralinterestwasthegreatredspot。

Theoutline,shape,andsizeofthisremarkableobjecthasremainedwithoutmaterialchangefromtheyear1879,whenitwasfirstobservedhere,untilthepresenttime。Accordingtoourobservations,duringthewholeofthisperiodithasshownasharpandwell—definedoutline,andatnotimehasitcoalescedorbeenjoinedtoanybeltinitsproximity,ashasbeenallegedbysomeobservers。Duringtheyear1885themiddleofthespotwasverymuchpalerincolourthanthemargins,causingittoappearasanellipticalring。Theringformhascontinueduptothepresenttime。Whiletheoutlineofthespothasremainedveryconstant,thecolourhaschangedmateriallyfromyeartoyear。Duringthepastthreeyears（1884—"86）ithasattimesbeenveryfaint,soasbarelytobevisible。Thepersistenceofthisobjectforsomanyyearsleadsmetoinferthattheformerlyacceptedtheory,thatthephenomenaseenonthesurfaceoftheplanetareatmospheric,isnolongertenable。Thestatementsooftenmadeintext—books,thatinthecourseofafewdaysormonthsthewholeaspectoftheplanetmaybechanged,isobviouslyerroneous。Theovalwhitespotsonthesouthernhemisphereoftheplanet,ninedegreessouthoftheequator,havebeensystematicallyobservedateveryoppositionduringthepasteightyears。Theyaregenerallyfoundingroupsofthreeormore,butareratherdifficulttoobserve。Therotationperioddeducedfromthemisnearlythesameasfromthegreatredspot。

Thesespotsusuallyhaveaslowdriftinlongitudeofaboutfivesecondsdailyinthedirectionoftheplanet"srotation,whenreferredtothegreatredspot;correspondingtoarotationperiodoftwentysecondslessthanthelatter。"

"Thisshows,"continuedBearwarden,"thataslongagoastowardsthecloseofthenineteenthcenturytheoldideathatwesawnothingbutthecloudsinJupiter"satmospherewasbeginningtochange;andalsohowcloselythetwoEnglishwritersandProf。

Houghwerestudyingthesubject,thoughtheirviewsdidnotentirelyagree。Awhitespotismerelyastorm—centrepassingroundandroundtheplanet,thewindrunningalittleaheadofthesurface,whichaccountsforitsrapidrotationcomparedwiththeredspot,whichisafixture。Acriticmaysaywehavenosuchwindsonearth;towhichIreply,thatwindsonaplanetofJupiter"ssize,withitsrateofrotation——thoughitis480,000,000milesfromthesunandtheinternalheatissonearthesurface——andwithlandandwaterarrangedastheyare,mayandindeedmustbeverydifferentfromthoseprevailingonearth,theconditionsproducingandaffectingthembeingsochanged。

Thoughthestorm—centremovestwohundredandsixtymilesanhour,thewindneednotblowatthatrate。"

Latertheysawseveralsmallerspotsdriftingeastward,butconcludedthatanyseaworthyshipmightpasssafelythroughthem,for,thoughtheywerehurricanesofgreatviolence,thewavesweresmall。

"Therewouldbelessdanger,"saidBearwarden,"ofshippingseasherethanthereisonearth;theprincipalrisktotravellerswouldbethatofbeingblownfromthedeck。Onaccountoftheair"sweightinconnectionwithitsvelocity,thiswouldnecessitatesomeprecaution。"

Thenextobjectofinterestwasthegreatredspot。Itproved,asCortlandthadpredicted,tobeacontinent,withatthattimenospecialcolour,thoughtheyeasilyrecognizeditbycomparingitsoutlineswiththoseofthespotinthemap。Itslength,astheyalreadyknew,wastwenty—seventhousandmiles,anditsbreadthabouteightthousandmiles,sothatitcontainedmoresquaremilesthantheentiresurfaceoftheearth,landandwaterincluded。

"Itisclear,"saidCortlandt,"thatatsomeseasonofJupiter"slongyearachangetakesplacethataffectsthecolouroftheleaves——somedroughtorprolongednorther;foritisobviousthatthatisthesimplestexplanation。Inlikemannerwemayexpectthatatsometimesmorewhitespotswillmoveacrosstheoceanthanatothers。"

"Onaccountofthesizeofthesecontinentsandoceans,"saidBearwarden,"itiseasytobelievethatmanyclimaticconditionsmayprevailherethatcanscarcelyexistonearth。Butwhatamagnificentworldtodevelop,withitsgreatrivers,lakes,andmountainsshowingateventhisdistance,andwhatnaturalresourcesmustbelyingtheredormant,awaitingourcall！Thisconstantlyrecurstomymind。Thesubjugationandthoroughopeningupofthisredspotcontinentwillprobablysupplymoreinterestingproblemsthanstraighteningtheaxisoftheearth。"

"Atournextvisit,"repliedAyrault,"whenwehaveestablishedregularinterplanetarylinesoftravel,wemayhaveanopportunitytoexamineitmoreclosely。"Thentheyagainattractedthenearestmoonbeyondwhichtheyhadswung,increasedtherepulsiononJupiter,andsoaredawaytowardsSaturn。

"WehaveastrikingillustrationofJupiter"senormousmass,"

saidCortlandt,astheapparentdiameterofthemightyplanetrapidlydecreased,"inthefactthatnotwithstandingitsnumerousmoons,itstillrotatessorapidly。Weknowthattheearth"sdayswereformerlybuthalforaquarteraslongasnow,havinglastedbutsixoreighthours。Theexplanationoftheelongationissimple:theearthrotatesinabouttwenty—fourhours,whilethemoonencirclesitbutonceinnearlytwenty—eightdays,sothatoursatelliteiscontinuallydrawingtheoceansbackwardagainstitsmotion。Thesetidalbrakesactingthroughthefrictionofthewateronthebottom,itsunequalpressure,andtheimpactofthewavesontheshore,arecontinuallyretardingitsrotation,sothatthedayisafractionofasecondlongernowthanitwasinthetimeofCaesar。ThissameactionisofcoursetakingplaceinJupiterandthegreatplanets,inthiscasetherebeingfivemoonsatwork。Ourmoon,weknow,rotatesonitsaxisbutoncewhileitrevolvesabouttheearth,thisbeingnodoubtduetoitsowncomparativesmallnessandthegreatattractionoftheearth,whichmusthaveproducedtremendoustidesbeforethelunaroceansdisappearedfromitssurface。"

Incrossingtheorbitsofthesatellites,theypassednearGanymede,Jupiter"slargestmoon。

"This,"saidCortlandt,"wasdiscoveredbyGalileoin1610。Itisthreethousandfourhundredandeightymilesindiameter,whileourmoonisbuttwothousandonehundredandsixty,revolvesatadistanceofsixhundredandseventy—eightthousandthreehundredmilesfromJupiter,completesitsrevolutioninsevendaysandfourhours,andhasaspecificgravityof1。87。"

Inpassing,theyobservedthatGanymedepossessedanatmosphere,andcontinentsandoceansoflargearea。

"Here,"saidBearwarden,"wehaveabodywithadiameteraboutfivehundredmilesgreaterthantheplanetMercury。Itssize,lightspecificgravity,atmosphere,andoceansseemtoindicatethatitislessadvancedthanthatplanet,yetyouthinkJupiterhashadalongerseparateexistencethantheplanetsnearerthesun？"

"Undoubtedly,"saidCortlandt。"Jupiterwascondensedwhileinthesolar—systemnebula,andbeganitsindividualexistenceanditsevolutionarycareerlongbeforeMercurywasformed。ThematternowinGanymede,however,doubtlessremainedpartoftheJupiter—systemnebulatillafterMercury"screation,and,beingpartofsogreatamass,didnotcoolveryrapidly。IshouldsaythatthissatellitehasaboutthesamerelationtoJupiterthatJupiterhastothesun,andisthereforeyoungerinpointoftimeaswellasofdevelopmentthanthemostdistantCallisto,andolder,atalleventsinyears,thanEuropaandIo,bothofwhicharenearer。ThissuppositioniscorroboratedbythefactthatEuropa,thesmallestofthesefour,isalsothedensest,havingaspecificgravityof2。14,itssmallnesshavingenabledittoovertakeGanymedeindevelopment,notwithstandingthelatter"sstart。Inthefaceoftheevidencebeforeuswemustbelievethis,orelsethat,perhaps,asinthecaseoftheasteroidHilda,somethinglikeacollisionhasrejuvenatedit。Thismightaccountforitssize,andfortheNauticalAlmanac"sstatementthatthereisa"smallandvariable"inclinationtoitsorbit,whileIoandEuroparevolveexactlyintheplaneofJupiter"sequator。"

TheyhadaboutaslongajourneybeforethemastheyhadalreadymadeingoingfromtheearthtoJupiter。Thegreatplanetsoonappearedasahugecrescent,sinceitwasbetweenthemandthesun;itsmoonsbecameasfifth—andsixth—magnitudestars,andintheeveningofthenextdayJupiter"sdiskbecameinvisibletotheunaidedeye。Sincetherewerenowaystations,intheshapeofplanetsorasteroids,betweenJupiterandSaturn,theykeptthemaximumrepulsiononJupiteraslongaspossible,andmovedattremendousspeed。SaturnwassomewhatinadvanceofJupiterinitsorbit,sothattheircoursefromtheearthhadbeenalongtwosidesofatrianglewithanobtuseanglebetween。Duringthenextfourterrestrialdaystheysightedseveralsmallcomets,butspentmostoftheirtimewritingouttheirJovianexperiences。

DuringthesixthdaySaturn"srings,althoughnotasmuchtiltedastheywouldbelaterintheplanet"sseason,presentedamostsuperbsight,whiletheyspuninthesun"srays。Soonafterthistheeightmoonsbecamevisible,and,whileslightlyreducingtheCallisto"sspeed,theycrossedtheorbitsofIapetus,Hyperion,andTitan,whentheyknewtheywerebutsevenhundredandfiftythousandmilesfromSaturn。

"Iamanxioustoascertain,"saidCortlandt,"whetherthecompositionofyonderringsissimilartothatofthecometthroughwhichwepassed。Iamsuretheyshinewithmorethanreflectedlight。"

"Wehavebeeninthehabit,"saidAyrault,"ofassociatingheatwithlight,butitisobviousthereissomethingfarmoresubtleaboutcometarylightandthatofSaturn"srings,bothofwhichseemtohavetheirbirthintheintensecoldofinterplanetaryspace。"

PassingclosetoMimas,Saturn"snearestmoon,theysupplementeditsattraction,afterswingingby,bytheirownstrongpull,bringingtheirspeeddowntodeadslowastheyenteredtheoutsidering。Atdistancesoftenofhalfamiletheyfoundmeteoricmasses,sometimeslumpsthesizeofahouse,oftennolargerthanapples,whilesmallparticleslikegrainsofsandmovedbetweenthem。Thereweretwomotions。TheringrevolvedaboutSaturn,andtheparticlesvibratedamongthemselves,evidentlykeptapartbyamutualrepulsion,whichseemedbothtoincreaseanddecreasefasterthangravitation;foronapproachingoneanothertheyweremorestronglyrepelledthanattracted,butwhentheyseparatedtherepulsiondecreasedfasterthantheattraction,sothatafteratimedivergenceceased,andtheyremainedatfixeddistances。

TheCallistosoonbecameimbuedwithmotionalso,butnothingeverstruckit。Whenanylargemasscameunusuallynear,bothitandtheircaremittedlight,andtheyrapidlyseparated。Thesunlightwasnotasstronghereasithadbeenwhentheyenteredthecomet,andastheypenetratedfarthertheywerebetterabletoobservetheomnipresentluminosity。Theyweresomewhatpuzzledbytheapproachofcertainlight—centres,whichseemedtocontainnothingbutthisconcentratedbrightness。Occasionallyoneofthesecentreswouldglowverybrightlynearthem,andsimultaneouslyrecede。AtsuchtimestheCallistoalsoglowed,anditselfrecoiledslightly。Atfirstthetravellerscouldnotaccountforthis,butfinallytheyconcludedthatthecentresmustbemeteoricmassesconsistingentirelyofgases,possessingweightthoughinvisible。

"Wehaveagaintoface,"saidCortlandt,"thatsingularlawthattillrecentlywedidnotsupposeexistedonearth。Allkindsofsuppositionshavebeenadvancedinexplanationoftheserings。

Somewritershavetheirthickness,lookedatfromthethinedge,asfourhundredmiles,someonehundred,andsomebutforty。Oneastronomerofthenineteenthcentury,amanofconsiderableeminence,wasconvincedthattheyconsistedofsheetsofliquid。

Now,itshouldbeobviousthatnoliquidcouldmaintainitselfhereforaminute,foritwouldeitherfallupontheplanetasacrushinghail,or,ifdependentforitsshapeonitsowntenacity,itwouldbreakifformedofthetougheststeel,onaccountofthetremendousweight。Anynumberoftheorieshavebeenadvancedbyanynumberofmen,butinweightwehavetherub。NoonehasevershownhowtheseinnumerablefragmentsmaintainthemselvesataheightofbutafewthousandmilesaboveSaturn,withstandingthegiant"sgravitation—pull。Theirrateofrevolution,thoughrapid,doesnotseemfastenoughtosustainthem。NeitherhaveIeverseenitexplainedwhythesmallfragmentsdonotfalluponthelargeones,thoughmanyastronomershavepicturedthecompositionoftheseringsaswefindtheyexist。Nordoweknowwhythemoleculesofagasaredrivenfartherapartbyheat,whiletheiractivityisalsoincreased,thoughifthisactivitywererevolutionaboutoneanothertodevelopthecentrifugal,itwouldnotneedtobeasstrongthenaswhentheyarecoldandnearertogether。Theremaybeexplanations,butIhavefoundnoneinanyoftheliteratureI

haveread。Itseemstomethatallthisleadstobutoneconclusion,viz。:apergyistheconstantandvisiblecompanionofgravitation,onthesegreatplanetsJupiterandSaturn,perhapsonaccountofsomepeculiarinfluencetheypossess,andalsoincomets,inthecaseoflargemasses,whileonearthitappearsnaturallyonlyamongmolecules——thoseofgasesandeveryothersubstance。"

"Ishouldgoastepfurther,"saidBearwarden,"andsayourearthhasthepeculiarity,sinceitdoesnotpossesstheinfluencenecessarytogeneratenaturallyagreatorevenconsiderabledevelopmentofapergy。Theelectricityofthunderstorms,northernlights,andotherforcesseemstobeproducedfreely,butasregardsapergyourplanet"snaturalproductivenessappearstobesmall。"

Theomnipresentluminositycontinued,buttheglowwasscarcelybrightenoughtobeperceivedfromtheearth。

"Ibelieve,however,"saidBearwarden,referringtothis,"thatwheneverasatellitepassesnearthesefragments,preferablywhenitenterstheplanet"sshadow,sincethatwillremoveitsownlight,itwillcreatesuchactivityamongthemastomaketheluminosityvisibletothelargetelescopesorgelatineplatesonearth。"

"Now,"saidAyrault,"thatwehaveevolvedenoughtheoriestokeepastronomersbusyforsometime,iftheyattempttodiscussthem,Isuggestthatwealightandleavetheabstractfortheconcrete。"

Whereupontheypassedthroughtheinnerringandrapidlysanktotheground。

BOOKIII。

CHAPTERI。

SATURN。

Landingonaplaceabouttendegreesnorthoftheequator,sothattheymightobtainagoodviewofthegreatrings——sinceON

thelineonlythethinedgewouldbevisible——theyopenedaport—holewiththesamecautiontheyhadexercisedonJupiter。

Againtherewasarushofair,showingthatthepressurewithoutwasgreaterthanthatwithin;butonthisoccasionthebarometerstoppedatthirty—eight,fromwhichtheycalculatedthatthepressurewasnineteenpoundstothesquareinchontheirbodies,insteadoffifteenasatsea—levelonearth。Thisdifferencewassoslightthattheyscarcelyfeltit。TheyalsodiscardedtheapergeticoutfitsthathadbeensousefulonJupiter,asunnecessaryhere。Theairwasanicyblast,andthoughtheyquicklyclosedtheopening,theinterioroftheCallistowasconsiderablychilled。

"Weshallwantourwinterclothes,"saidBearwarden;"itmightbemorecomfortableforusexactlyontheequator,thoughthesceneatnightwillbefarfinerhere,ifwecanstandtheclimate。

Doubtlessitwillalsobewarmersoon,forthesunhasbutjustrisen。"

"Isuspectthisismerelyoneofthecoldwavesthatrushtowardstheequatoratthisseason,whichcorrespondstoaboutthe10thofourSeptember,"repliedCortlandt。"ThepolesofSaturnmustbeintenselycoldduringitslongwinteroffourteenandthreequarteryears,for,theaxisbeinginclinedtwenty—sevendegreesfromtheperpendicularofitsorbit,thepoleturnedfromthesunismoreshutofffromitsheatthanours,andinadditiontothisthemeandistance——morethaneighthundredandeightymillionmiles——isverygreat。Sincethechemicalcompositionoftheairwehaveinhaledhasnottroubledourlungs,itisfairtosupposeweshallhavenodifficultyinbreathing。"

Havingdressedthemselvesmorewarmly,andseenbyathermometertheyhadplacedoutsidethatthetemperaturewasthirty—eightdegreesFahrenheit,whichhadseemedverycoldcomparedwiththewarmthinsidetheCallisto,theyagainopenedtheport—hole,thistimeleavingitopenlonger。Whattheyhadfeltbeforewasevidentlymerelyasuddengust,fortheairwasnowcomparativelycalm。

Findingthatthedoctor"spredictionastothesuitabilityoftheairtotheirlungswascorrect,theyventuredout,closingthedoorastheywent。

Expecting,asonJupiter,tofindprincipallyvertebratesofthereptileandbirdorder,theycarriedgunsandcartridgesloadedwithbuckshotandNo。1,trustingforsolid—ballprojectilestotheirrevolvers,whichtheyshovedintotheirbelts。Theyalsotooktest—tubesforexperimentsontheSaturnianbacilli。

Hangingabucketunderthepipeleadingfromtheroof,tocatchanyrainthatmightfall——fortheyrememberedthescarcityofdrinking—wateronJupiter——theysetoutinasouthwesterlydirection。

Walkingalong,theynoticedonallsidestallliliesimmaculatelypureintheirwhiteness,andmushroomsandtoadstoolsnearlyafoothigh,theformerhavingadeliciousflavourandextremefreshness,asthoughonlyanhourold。Theyhadseennoanimallife,orevensignofit,andwerewonderingatitsdearth,whensuddenlytwolargewhitebirdsrosedirectlyinfrontofthem。

Likethought,BearwardenandAyraulthadtheirgunsup,snappingthethumb—piecesover"safe"andpullingthetriggersalmostsimultaneously。Bearwarden,havingdoublebuckshot,killedhisbirdatthefirstfire;butAyrault,havingonlyNo。1,hadtogivehisthesecondbarrel,almostalldamageinbothcasesbeinginthehead。Oncomingclosetotheirvictimstheyfoundthemtomeasuretwelvefeetfromtiptotip,andtohaveatremendousthicknessoffeathersanddown。

"Fromthelooksofthesebeauties,"saidBearwarden,"Ishouldsaytheyprobablyinhabitedaprettycoldplace。"

"Theyaredoubtlessnorthernbirds,"saidCortlandt,"thathavejustcomesouth。Itiseasytobelievethatthedepthtowhichthetemperaturemayfallintheupperairofthisplanetmustbesomethingstartling。"

Astheyturnedfromthecranes,towhichspeciesthebirdsseemedtobelong,theybecamemutewithastonishment。Everymushroomhaddisappeared,butthetoadstoolsstillremained。

"Isitpossiblewedidnotseethem？"gaspedAyrault。

"Wemustinadvertentlyhavewalkedsomedistancesincewesawthem,"saidCortlandt。

"TheywerewhatIlookedforwardtoforlunch,"exclaimedBearwarden。

Theyweregreatlyperplexed。Themushroomswereallaboutthemwhentheyshotthebirds,whichstilllaywheretheyhadfallen。

"Wemustbeveryabsent—minded,"saidthedoctor,"orperchanceourbrainsareaffectedbytheair。Wemustanalyzeittoseeifitcontainsourownproportionofoxygenandnitrogen。Therewasagooddealofcarbonic—acidgasonJupiter,butthatwouldhardlyconfuseoursenses。Thestrangethingis,thatweallseemtohavebeenimpressedthesameway。"

Concludingthattheymusthavebeenmistaken,theycontinuedontheirjourney。

Allabouttheyheardacurioushumming,asthatofbees,orlikethemurmuringofprayersinaresonantcathedral。Thinkingitwasthewindinthegreattreesthatgrewsinglyaroundthem,theypaidnoattentiontoituntil,emergingonanopenplainandfindingthatthesoundcontinued,theystopped。

"Now,"saidBearwarden,"thisismorecuriousthananythingwefoundonJupiter。Herewehaveanincessantandratherpleasantsound,withnovisiblecause。"

"Itmaypossiblybesomepeculiarityofthegrass,"repliedCortlandt,"though,shoulditcontinuewhenwereachsandyorbaresoil,Ishallbelieveweneedadoseofquinine。"

"IFEELperfectlywell,"saidAyrault;"howisitwithyou？"

Eachfindingthathewasinanormalstate,theyproceeded,determined,ifpossible,todiscoverthesourcefromwhichthesoundscame。SuddenlyBearwardenraisedhisguntobringdownalong—beakedhawk;butthebirdflewoff,andhedidnotshoot。

"Plaguetheluck！"saidhe;"IwentblindjustasIwasabouttopull。Ahazeseemedtocoverbothbarrels,andcompletelyscreenedthebird。"

"TheCallistowillsoonbehiddenbythosetrees,"saidCortlandt。"Ithinkwehadbettertakeourbearings,for,ifourcrackshotisgoingtomisslikethat,wemaywantcannedprovisions。"

Accordingly,hegotouthissextant,tookthealtitudeofthesun,gotcross—bearingsandafewangles,andbegantomakearoughcalculation。Forseveralminutesheworkedindustriously,usedtherubberattheendofhispencil,triedagain,andthenscratchedout。"ThathummingconfusesmesothatIcannotworkcorrectly,"saidhe,"whilethemostirrelevantthingsentermymindinspiteofme,andmixupmyfigures。"