首页 >出版文学> The Works of Edgar Allan Poe>第7章
  “Thenextpointtoberegardedwasamatteroffargreaterimportance。Fromindicationsaffordedbythebarometer,wefindthat,inascensionsfromthesurfaceoftheearthwehave,attheheightof1,000feet,leftbelowusaboutone-thirtiethoftheentiremassofatmosphericair,thatat10,600wehaveascendedthroughnearlyone-third;andthatat18,000,whichisnotfarfromtheelevationofCotopaxi,wehavesurmountedone-halfthematerial,or,atallevents,one-halftheponderable,bodyofairincumbentuponourglobe。Itisalsocalculatedthatatanaltitudenotexceedingthehundredthpartoftheearth’sdiameterthatis,notexceedingeightymilestherarefactionwouldbesoexcessivethatanimallifecouldinnomannerbesustained,and,moreover,thatthemostdelicatemeanswepossessofascertainingthepresenceoftheatmospherewouldbeinadequatetoassureusofitsexistence。ButI
  didnotfailtoperceivethattheselattercalculationsarefoundedaltogetheronourexperimentalknowledgeofthepropertiesofair,andthemechanicallawsregulatingitsdilationandcompression,inwhatmaybecalled,comparativelyspeaking,theimmediatevicinityoftheearthitself;and,atthesametime,itistakenforgrantedthatanimallifeisandmustbeessentiallyincapableofmodificationatanygivenunattainabledistancefromthesurface。Now,allsuchreasoningandfromsuchdatamust,ofcourse,besimplyanalogical。
  Thegreatestheighteverreachedbymanwasthatof25,000feet,attainedintheaeronauticexpeditionofMessieursGay-LussacandBiot。Thisisamoderatealtitude,evenwhencomparedwiththeeightymilesinquestion;andIcouldnothelpthinkingthatthesubjectadmittedroomfordoubtandgreatlatitudeforspeculation。
  “But,inpointoffact,anascensionbeingmadetoanygivenaltitude,theponderablequantityofairsurmountedinanyfartherascensionisbynomeansinproportiontotheadditionalheightascendedasmaybeplainlyseenfromwhathasbeenstatedbefore,butinaratioconstantlydecreasing。Itisthereforeevidentthat,ascendashighaswemay,wecannot,literallyspeaking,arriveatalimitbeyondwhichnoatmosphereistobefound。Itmustexist,I
  argued;althoughitmayexistinastateofinfiniterarefaction。
  “Ontheotherhand,Iwasawarethatargumentshavenotbeenwantingtoprovetheexistenceofarealanddefinitelimittotheatmosphere,beyondwhichthereisabsolutelynoairwhatsoever。Butacircumstancewhichhasbeenleftoutofviewbythosewhocontendforsuchalimitseemedtome,althoughnopositiverefutationoftheircreed,stillapointworthyveryseriousinvestigation。OncomparingtheintervalsbetweenthesuccessivearrivalsofEncke’scometatitsperihelion,aftergivingcredit,inthemostexactmanner,forallthedisturbancesduetotheattractionsoftheplanets,itappearsthattheperiodsaregraduallydiminishing;thatistosay,themajoraxisofthecomet’sellipseisgrowingshorter,inaslowbutperfectlyregulardecrease。Now,thisispreciselywhatoughttobethecase,ifwesupposearesistanceexperiencedfromthecometfromanextremelyrareetherealmediumpervadingtheregionsofitsorbit。
  Foritisevidentthatsuchamediummust,inretardingthecomet’svelocity,increaseitscentripetal,byweakeningitscentrifugalforce。Inotherwords,thesun’sattractionwouldbeconstantlyattaininggreaterpower,andthecometwouldbedrawnnearerateveryrevolution。Indeed,thereisnootherwayofaccountingforthevariationinquestion。Butagain。Therealdiameterofthesamecomet’snebulosityisobservedtocontractrapidlyasitapproachesthesun,anddilatewithequalrapidityinitsdeparturetowardsitsaphelion。WasInotjustifiableinsupposingwithM。Valz,thatthisapparentcondensationofvolumehasitsorigininthecompressionofthesameetherealmediumIhavespokenofbefore,andwhichisonlydenserinproportiontoitssolarvicinity?Thelenticular-shapedphenomenon,alsocalledthezodiacallight,wasamatterworthyofattention。Thisradiance,soapparentinthetropics,andwhichcannotbemistakenforanymeteoriclustre,extendsfromthehorizonobliquelyupward,andfollowsgenerallythedirectionofthesun’sequator。Itappearedtomeevidentlyinthenatureofarareatmosphereextendingfromthesunoutward,beyondtheorbitofVenusatleast,andIbelievedindefinitelyfarther。{*2}Indeed,thismediumIcouldnotsupposeconfinedtothepathofthecomet’sellipse,ortotheimmediateneighborhoodofthesun。Itwaseasy,onthecontrary,toimagineitpervadingtheentireregionsofourplanetarysystem,condensedintowhatwecallatmosphereattheplanetsthemselves,andperhapsatsomeofthemmodifiedbyconsiderations,sotospeak,purelygeological。
  Havingadoptedthisviewofthesubject,Ihadlittlefurtherhesitation。GrantingthatonmypassageIshouldmeetwithatmosphereessentiallythesameasatthesurfaceoftheearth,Iconceivedthat,bymeansoftheveryingeniousapparatusofM。Grimm,Ishouldreadilybeenabledtocondenseitinsufficientquantityforthepurposesofrespiration。Thiswouldremovethechiefobstacleinajourneytothemoon。Ihadindeedspentsomemoneyandgreatlaborinadaptingtheapparatustotheobjectintended,andconfidentlylookedforwardtoitssuccessfulapplication,ifIcouldmanagetocompletethevoyagewithinanyreasonableperiod。Thisbringsmebacktotherateatwhichitmightbepossibletotravel。
  “Itistruethatballoons,inthefirststageoftheirascensionsfromtheearth,areknowntorisewithavelocitycomparativelymoderate。Now,thepowerofelevationliesaltogetherinthesuperiorlightnessofthegasintheballooncomparedwiththeatmosphericair;and,atfirstsight,itdoesnotappearprobablethat,astheballoonacquiresaltitude,andconsequentlyarrivessuccessivelyinatmosphericstrataofdensitiesrapidlydiminishingIsay,itdoesnotappearatallreasonablethat,inthisitsprogressupwards,theoriginalvelocityshouldbeaccelerated。Ontheotherhand,Iwasnotawarethat,inanyrecordedascension,adiminutionwasapparentintheabsoluterateofascent;althoughsuchshouldhavebeenthecase,ifonaccountofnothingelse,onaccountoftheescapeofgasthroughballoonsill-constructed,andvarnishedwithnobettermaterialthantheordinaryvarnish。Itseemed,therefore,thattheeffectofsuchescapewasonlysufficienttocounterbalancetheeffectofsomeacceleratingpower。Inowconsideredthat,providedinmypassageIfoundthemediumIhadimagined,andprovidedthatitshouldprovetobeactuallyandessentiallywhatwedenominateatmosphericair,itcouldmakecomparativelylittledifferenceatwhatextremestateofrarefactionIshoulddiscoveritthatistosay,inregardtomypowerofascendingforthegasintheballoonwouldnotonlybeitselfsubjecttorarefactionpartiallysimilarinproportiontotheoccurrenceofwhich,Icouldsufferanescapeofsomuchaswouldberequisitetopreventexplosion,but,beingwhatitwas,would,atallevents,continuespecificallylighterthananycompoundwhateverofmerenitrogenandoxygen。Inthemeantime,theforceofgravitationwouldbeconstantlydiminishing,inproportiontothesquaresofthedistances,andthus,withavelocityprodigiouslyaccelerating,Ishouldatlengtharriveinthosedistantregionswheretheforceoftheearth’sattractionwouldbesupersededbythatofthemoon。Inaccordancewiththeseideas,Ididnotthinkitworthwhiletoencumbermyselfwithmoreprovisionsthanwouldbesufficientforaperiodoffortydays。
  “Therewasstill,however,anotherdifficulty,whichoccasionedmesomelittledisquietude。Ithasbeenobserved,that,inballoonascensionstoanyconsiderableheight,besidesthepainattendingrespiration,greatuneasinessisexperiencedabouttheheadandbody,oftenaccompaniedwithbleedingatthenose,andothersymptomsofanalarmingkind,andgrowingmoreandmoreinconvenientinproportiontothealtitudeattained。{*3}Thiswasareflectionofanaturesomewhatstartling。Wasitnotprobablethatthesesymptomswouldincreaseindefinitely,oratleastuntilterminatedbydeathitself?
  Ifinallythoughtnot。Theiroriginwastobelookedforintheprogressiveremovalofthecustomaryatmosphericpressureuponthesurfaceofthebody,andconsequentdistentionofthesuperficialblood-vesselsnotinanypositivedisorganizationoftheanimalsystem,asinthecaseofdifficultyinbreathing,wheretheatmosphericdensityischemicallyinsufficientfortheduerenovationofbloodinaventricleoftheheart。Unlessfordefaultofthisrenovation,Icouldseenoreason,therefore,whylifecouldnotbesustainedeveninavacuum;fortheexpansionandcompressionofchest,commonlycalledbreathing,isactionpurelymuscular,andthecause,nottheeffect,ofrespiration。Inaword,Iconceivedthat,asthebodyshouldbecomehabituatedtothewantofatmosphericpressure,thesensationsofpainwouldgraduallydiminishandtoendurethemwhiletheycontinued,Ireliedwithconfidenceupontheironhardihoodofmyconstitution。
  “Thus,mayitpleaseyourExcellencies,Ihavedetailedsome,thoughbynomeansall,theconsiderationswhichledmetoformtheprojectofalunarvoyage。Ishallnowproceedtolaybeforeyoutheresultofanattemptsoapparentlyaudaciousinconception,and,atallevents,soutterlyunparalleledintheannalsofmankind。
  “Havingattainedthealtitudebeforementioned,thatistosaythreemilesandthree-quarters,Ithrewoutfromthecaraquantityoffeathers,andfoundthatIstillascendedwithsufficientrapidity;
  therewas,therefore,nonecessityfordischarginganyballast。Iwasgladofthis,forIwishedtoretainwithmeasmuchweightasI
  couldcarry,forreasonswhichwillbeexplainedinthesequel。Iasyetsufferednobodilyinconvenience,breathingwithgreatfreedom,andfeelingnopainwhateverinthehead。Thecatwaslyingverydemurelyuponmycoat,whichIhadtakenoff,andeyeingthepigeonswithanairofnonchalance。Theselatterbeingtiedbytheleg,topreventtheirescape,werebusilyemployedinpickingupsomegrainsofricescatteredfortheminthebottomofthecar。
  “Attwentyminutespastsixo’clock,thebarometershowedanelevationof26,400feet,orfivemilestoafraction。Theprospectseemedunbounded。Indeed,itisveryeasilycalculatedbymeansofsphericalgeometry,whatagreatextentoftheearth’sareaIbeheld。
  Theconvexsurfaceofanysegmentofasphereis,totheentiresurfaceofthesphereitself,astheversedsineofthesegmenttothediameterofthesphere。Now,inmycase,theversedsinethatistosay,thethicknessofthesegmentbeneathmewasaboutequaltomyelevation,ortheelevationofthepointofsightabovethesurface。“Asfivemiles,then,toeightthousand。”wouldexpresstheproportionoftheearth’sareaseenbyme。Inotherwords,Ibeheldasmuchasasixteen-hundredthpartofthewholesurfaceoftheglobe。Theseaappearedunruffledasamirror,although,bymeansofthespy-glass,Icouldperceiveittobeinastateofviolentagitation。Theshipwasnolongervisible,havingdriftedaway,apparentlytotheeastward。Inowbegantoexperience,atintervals,severepaininthehead,especiallyabouttheearsstill,however,breathingwithtolerablefreedom。Thecatandpigeonsseemedtosuffernoinconveniencewhatsoever。
  “Attwentyminutesbeforeseven,theballoonenteredalongseriesofdensecloud,whichputmetogreattrouble,bydamagingmycondensingapparatusandwettingmetotheskin。Thiswas,tobesure,asingularrecontre,forIhadnotbelieveditpossiblethatacloudofthisnaturecouldbesustainedatsogreatanelevation。Ithoughtitbest,however,tothrowouttwofive-poundpiecesofballast,reservingstillaweightofonehundredandsixty-fivepounds。Uponsodoing,Isoonroseabovethedifficulty,andperceivedimmediately,thatIhadobtainedagreatincreaseinmyrateofascent。Inafewsecondsaftermyleavingthecloud,aflashofvividlightningshotfromoneendofittotheother,andcausedittokindleup,throughoutitsvastextent,likeamassofignitedandglowingcharcoal。This,itmustberemembered,wasinthebroadlightofday。Nofancymaypicturethesublimitywhichmighthavebeenexhibitedbyasimilarphenomenontakingplaceamidthedarknessofthenight。Hellitselfmighthavebeenfoundafittingimage。Evenasitwas,myhairstoodonend,whileIgazedafardownwithintheyawningabysses,lettingimaginationdescend,asitwere,andstalkaboutinthestrangevaultedhalls,andruddygulfs,andredghastlychasmsofthehideousandunfathomablefire。Ihadindeedmadeanarrowescape。Hadtheballoonremainedaveryshortwhilelongerwithinthecloudthatistosayhadnottheinconvenienceofgettingwet,determinedmetodischargetheballast,inevitableruinwouldhavebeentheconsequence。Suchperils,althoughlittleconsidered,areperhapsthegreatestwhichmustbeencounteredinballoons。Ihadbythistime,however,attainedtoogreatanelevationtobeanylongeruneasyonthishead。