第1章

类别:其他 作者:Rev. J. M. Bacon字数:13130更新时间:18/12/18 14:00:38
CHAPTERI。 THEDAWNOFAERONAUTICS。 \"Hethatwouldlearntoflymustbebroughtuptotheconstantpracticeofitfromhisyouth,tryingfirstonlytousehiswingsasatamegoosewilldo,sobydegreeslearningtorisehighertillheattainuntoskillandconfidence。\" SowroteWilkins,BishopofChester,whowasreckonedamanofgeniusandlearninginthedaysoftheCommonwealth。ButsosoonaswecometoinquireintothematterwefindthatthisgoodBishopwasborrowingfromtheideasofotherswhohadgonebeforehim;and,lookbackasfaraswewill,mankindisdiscoveredtohaveentertainedpersistentandoftenplausibleideasofhumanflight。Andthoseideashadinsomesortofway,forgoodorill,takenpracticalshape。Thus,aslongagoasthedayswhenXenophonwasleadingbackhiswarriorstotheshoresoftheBlackSea,anderetheGaulshadfirstburnedRome,therewasaphilosopher,Archytas,whoinventedapigeonwhichcouldfly,partlybymeansofmechanism,andpartlyalso,itissaid,byaidofanauraorspirit。Andherearisesaquestion。Wasthisauraagas,ordidmenuseitasspiritualistsdotoday,asmerelyawordtoconjurewith? Fourcenturieslater,inthedaysofNero,therewasamaninRomewhoflewsowellandhighastolosehislifethereby。 Here,atanyrate,wasanhonestman,orthestorywouldnothaveendedthus;butoftherest——andtherearemanywhoinearlyagesaspiredtotheattainmentofflight——wehavenomorereasontocredittheirclaimsthanthoseofcharlatanswhoflourishineveryage。 Inmedievaltimesweareseriouslytoldbyasaintlywriter(St。Remigius)offolkswhocreatedcloudswhichrosetoheavenbymeansof\"anearthenpotinwhichalittleimphadbeenenclosed。\"Weneednomore。Thatwasanageofflyingsaints,asalsoofflyingdragons。Flyinginthosedaysofyoremayhavebeenrealenoughtothemultitude,butitwasatbestdelusion。InthegoodoldtimesitdidnotneedthegeniusofaMaskelynetodoa\"levitation\"trick。Wecanpicturethesceneata\"flyingseance。\"Ontheonesidethedecidedlyprofessionalshowmanpossessedofsufficientlowcunning;ontheothertheignorantandhighlysuperstitiousaudience,eagertohearorseesomenewthing——thesameaudiencethat,deceivedbyasimpletrickofschoolboyscience,wouldlistentosupernaturalvoicesintheirgroves,ororacularutterancesintheirtemples,orwatchtheurnsofBacchusfillthemselveswithwine。Surelyfortheireyesitwouldneednomorethanthesimplestphantasmagoria,ormaybeonlyalittleblackthread,tomakeapigeonriseandfly。 Itisinterestingtonote,however,thatinthecaselastcitedthereisunquestionablyanallusiontosomecrudeformoffirework,andwhatmorelikelyorbettercalculatedtoimpresstheignorant!Ourfireworkmakersstillmanufacturea\"littleDevil。\"Pyrotechnicisasoldashistoryitself;wehaveanexcellentdescriptionofarocketinadocumentatleastasancientastheninthcentury。AndthataspeciesofpyrotechnywasresortedtobythosewhosoughttoimitateflightwehaveproofinthefollowingrecipeforaflyingbodygivenbyaDoctor,ekeaFriar,inParisinthedaysofourKingJohn:—— \"Takeonepoundofsulphur,twopoundsofwillowcarbon,sixpoundsofrocksaltgroundveryfineinamarblemortar。 Place,whenyouplease,inacoveringmadeofflyingpapyrustoproducethunder。Thecoveringinordertoascendandfloatawayshouldbelong,graceful,wellfilledwiththisfinepowder;buttoproducethunderthecoveringshouldbeshort,thick,andhalffull。\" Nordoesthisrecipestandalone。Takeanothersample,ofwhichchapterandversearetobefoundintheMSS。ofaJesuit,GaspardSchott,ofPalermoandRome,bornthreehundredyearsago:—— \"Theshellsofhen—eggs,ifproperlyfilledandwellsecuredagainstthepenetrationoftheair,andexposedtosolarrays,willascendtotheskiesandsometimessufferanaturalchange。 Andiftheeggsofthelargerdescriptionofswans,orleatherballsstitchedwithfinethongs,befilledwithnitre,thepurestsulphurquicksilver,orkindredmaterialswhichrarifybytheircaloricenergy,andiftheyexternallyresemblepigeons,theywilleasilybemistakenforflyinganimals。\" Thusitwouldseemthat,huntingbackinhistory,therewerethreemainideasonwhichwould—beaeronautsofoldexercisedtheiringenuity。Therewasthelast—mentionedmethod,which,bytheway,JulesVernepartlyreliesonwhenhetakeshisheroestothemoon,andwhichinitshighestpracticaldevelopmentmaybeseenannuallyonthenightof\"Brock’sBenefit\"attheCrystalPalace。Thereis,again,the\"tamegoose\"method,towhichwemustreturnpresently;and,lastly,thereisathirdmethod,towhich,asalsotothebrilliantgeniuswhoconceivedit,wemustwithoutfurtherdelaybeintroduced。Thismaybecalledthemethodof\"ahollowglobe。\" RogerBacon,Melchisedeck—fashion,cameintoexistenceatIlchesterin1214ofparentagethatishardtotrace。Hewas,however,abornphilosopher,andpossessedofintellectandpenetrationthatplacedhimincalculablyaheadofhisgeneration。Amanofmarvellousinsightandresearch,hegrasped,andasfaraspossiblecarriedout,ideaswhichdawnedonothermenonlyaftercenturies。Thus,manyofhisutteranceshavebeenprophetic。Itisprobablethatamonghischemicaldiscoverieshere—inventedgunpowder。Itiscertainthathedivinedthepropertiesofalens,anddivingdeepintoexperimentalandmechanicalsciences,actuallyforesawthetimewhen,inhisownwords,\"menwouldconstructenginestotraverselandandwaterwithgreatspeedandcarrywiththempersonsandmerchandise。\"ClearlyinhisdreamsBaconsawtheAtlanticnotmerelyexplored,butonitsbosomtheWhiteStarlinersbreakingrecords,contemptuousofitsangriestseas。Hesaw,too,afutureDumontcirclingintheair,andnotonlyinadeadcalm,butholdinghisownwiththefeatheredrace。Hetellshisdreamthus:\"Theremaybemadesomeflyinginstrumentsothatamansittinginthemiddleoftheinstrumentandturningsomemechanismmayputinmotionsomeartificialwingswhichmaybeattheairlikeabirdflying。\" Buthelivedtoolongbeforehistime。Hisruinlaynotonlyinhissuperiorgenius,butalsoinhisfearlessoutspokenness。 HepresentlyfellunderthebanoftheChurch,throughwhichhelostalikehislibertyandthemeansofpursuinginvestigation。 Haditbeenotherwisewemayfairlybelievethatthe\"admirableDoctor,\"ashewascalled,wouldhavebeenthefirsttoshowmankindhowtonavigatetheair。Hisideasareperfectlyeasytograsp。Heconceivedthattheairwasatruefluid,andassuchmusthaveanupperlimit,anditwouldbeonthisuppersurface,hesupposed,asonthebosomoftheocean,thatmanwouldsailhisair—ship。Afine,boldguesstruly。Hewouldwatchthecirruscloudssailinggrandlytenmilesabovehimonsomestreamthatneverapproachednearer。Upthere,inhisimagination,wouldbetossingthewavesofouroceanofair。 Waitforsomelittlebettercylindersofoxygenandanimprovedfoot—warmer,andafutureCoxwellwillgoaloftandsee;butastoanuppersea,itistrulythere,andwemayvisitandviewitssun—littossingbillowsstretchingouttoalimitlesshorizonatsuchtimesasthenetherworldisshroudedindensestgloom。Bacon’smethodofreachingsuchanupperseaashepostulatedwas,aswehavesaid,byahollowglobe。 \"Themachinemustbealargehollowglobe,ofcopperorothersuitablemetal,wroughtextremelythinsoastohaveitaslightaspossible,\"and\"itmustbefilledwithetherealairorliquidfire。\"Thiswaswritteninthethirteenthcentury,anditisscarcelyedifyingtofindfourhundredyearsafterthistheJesuitFatherLana,whocontrivedtomakehisnameliveinhistoryasatheoriserinaeronautics,arrogatingtohimselftheboldconceptionoftheEnglishFriar,withcertainunfortunatedifferences,however,whichinfairnesswemusthereclearlypointout。Lanaproclaimedhisspeculationsstandingonagiant’sshoulders。Torricelli,withhisclosedbenttube,hadjustshowntheworldhowheavilytheairliesaboveus。Itthenrequiredlittlemathematicalskilltocalculatewhatwouldbetheliftingpowerofanyvesselvoidofairontheearth’ssurface。ThusLanaproposedtheconstructionofanairshipwhichpossiblybecauseofitspicturesquesnesshaswonhimnotoriety。Butitwasafraud。Wehavebuttoconceiveadaintyboatinwhichtheaeronautwouldsitateasehandlingalittlerudderandasimplesail。These,thoughaschoolboywouldhaveknownbetter,hethoughtwouldguidehisvesselwhenintheair。 SomuchhasbeenclaimedforFatherLanaandhismathematicalandotherattainmentsthatitseemsonlyrighttoinsistontheweaknessofhisreasoning。Anairshipsimplydriftingwiththewindisincapableofalteringitscourseintheslightestdegreebyeithersailorrudder。Itissimplylikealogbornealonginatorrent;buttocomparesuchalogproperlywiththeairshipwemustconceiveitWHOLLYsubmergedinthewaterandhavingnosailorotherappendageprojectingintotheair,whichwould,ofcourse,introduceotherconditions。If,however,amanweretositastrideofthelogandbegintopropelitsothatittravelseitherfasterorslowerthanthestream,theninthatcase,eitherbypaddleorrudder,thelogcouldbeguided,andthesamemightbesaidofLana’sairboatifonlyhehadthoughtofsomeadequatepaddle,fan,orotherpropeller。Buthedidnot。Onefurtherexplanatorysentencemayherebeneeded;forwehearofballoonswhicharecapableofbeingguidedtoasmallextentbysailandrudder。Inthesecases,however,therudderisaguideropetrailingonearthorsea,sointroducingafreshelementandfreshconditionswhichareeasytoexplain。 Supposeafreeballoondriftingdownthewindtohaveasailsuddenlyhoistedononeside,whathappens?Theballoonwillsimplyswingtillthissailisinfront,andthuscontinueitsstraightforwardcourse。Suppose,however,thatassoonasthesidesailishoistedatrailropeisalsodroppedaftfromasparintherigging。Thetendencyofthesailtoflyroundinfrontisnowcheckedbythedraggingrope,anditisconstrainedtoremainslantingatanangleononeside;atthesametimetherateoftheballoonisreducedbythedraggingrope,sothatittravelsslowerthanthewind,which,nowactingonitsslantsail,impartsacertainsidelongmotionmuchasitdoesinthecaseofasailingboat。 Lanahavinginimaginationbuilthisship,proceedstomakeitfloatupintospace,forwhichpurposeheproposesfourthincopperglobesexhaustedofair。Hadthislastbeenhisownideawemighthavepardonedhim。Wehave,however,pointedoutthatitwasnot,andwemustfurtherpointoutthatincopyinghisgreatpredecessorhefailstoseethathewouldloseenormousadvantagebyusingfourglobesinsteadofone。But,beyondall,hefailedtoseewhatthemastergeniusofBaconsawclearly——thathisthinglobeswhenexhaustedmustinfalliblycollapsebyvirtueofthatverypressureoftheairwhichhesoughttomakeuseof。 ItcannotbetoostronglyinsistedonthatifthetoomuchbelaudedspeculationsofLanahaveanyvalueatallitisthattheythrowintostrongercontrastthewonderfulinsightofthephilosopherwhosolongprecededhim。BysheergeniusBaconhadforeseenthattheemptiedglobemustbefilledwithSOMETHING,andforthissomethinghesuggests\"etherealair\"or\"liquidfire,\"neitherofwhich,wecontend,wereemptyterms。WithBacon’sknowledgeofexperimentalchemistryitisaquestion,andamostinterestingone,whetherhehadnotinhismindthosetwoactualprinciplesrespectivelyofgasandairrarefiedbyheatonwhichwelaunchourballoonsintospaceto—day。 Earlyprogressinanyartorscienceiscommonlyintermittent。 Itwassointhestoryofaeronautics。Advancewaslikethatoftheincomingtide,throwinganoccasionalwavefarinfrontofitsrisingflood。ItwasaphenomenalwavethatboreRogerBaconandlefthismarkonthesandwherenoneotherapproachedforcenturies。Inthosecenturiesmenwereeithertoopriest—riddentolendaneartoScience,or,likechildren,followedonlytheWill—o’—the—Wispfloatingabovethequagmirewhichheldthemfast。Theyranafterthestonethatwastoturnalltogold,ortheelixirthatshouldconquerdeath,orthesignsintheheavensthatshouldforetelltheirdestinies; andthetaintofthismaybetracedevenwhenthedarkperiodthatfollowedwasclearingaway。FourhundredyearsafterRoger’sdeath,hisillustriousnamesake,FrancisBacon,wasformulatinghisInductivePhilosophy,andwithcompletecock—surenesswasteachingmankindallabouteverything。Letuslookatsomeofhisutteranceswhichmayhelptothrowlightonthewayheregardedtheproblemwearedealingwith。 \"Itisreported,\"FrancisBaconwrites,\"thattheLeucaciansinancienttimedidusetoprecipitateamanfromahighcliffeintothesea;tyingabouthim,withstrings,atsomedistance,manygreatfowles;andfixinguntohisbodydiversfeathers,spread,tobreakethefall。Certainlymanybirdsofgoodwing(asKitesandthelike)wouldbeareupagoodweightastheyflie。Andspreadingoffeathers,thinandclose,andingreatbreadth,willlikewisebeareupagreatweight,beingevenlaidwithouttiltinguponthesides。Thefurtherextensionofthisexperimentofflyingmaybethoughtupon。\" Tosaytheleast,thisishardlymechanical。ButletusnextfollowthephilosopherintothedomainofPhysics。Referringtoastrangeassertion,that\"saltwaterwilldissolvesaltputintoitinlesstimethanfreshwaterwilldissolveit,\"heisatoncereadywithanexplanationtofitthecase。\"Thesalt,\" hesays,\"intheprecedentwaterdothbysimilitudeofsubstancedrawthesaltnewputinuntoit。\"Again,inhisfinding,wellwateriswarmerinwinterthansummer,and\"thecauseisthesubterraneanheatwhichshutclosein(asinwinter)isthemore,butifitperspire(asitdothinsummer) itistheless。\"ThiswasBacontheLord。Whatafallingoff——fromtheexperimentalist’spointofview——fromBacontheFriar!Wecanfancyhimwatchingafalconpoisedmotionlessinthesky,andreflectingonthatproblemwhichtothisdayfairlypuzzlesourablestscientists,settlingthematterinasentence:\"Thecauseisthatfeathersdoepossessupwardattractions。\"DuringfourhundredyearsprecedingLordVerulamphilosopherswouldhaveflownbyaidofabroomstick。Baconhimselfwouldhavemerelyparriedtheproblemwithaplatitude! Atanyrate,physicists,eveninthebrilliantseventeenthcentury,madenomaterialprogresstowardsthenavigationoftheair,andthuspresentlyletthesimplemechanicstepinbeforethem。Erethatcenturyhadclosedsomethinginthenatureofflighthadbeenaccomplished。Itisexceedinglyhardtoarriveatactualfact,butitseemsprettyclearthatmorethanoneindividual,bystartingfromsomeeminence,couldlethimselffallintospaceandwafthimselfawayforsomedistancewithfairsuccessandsafety,ItisstatedthatanEnglishMonk,Elmerus,flewthespaceofafurlongfromatowerinSpain,afeatofthesamekindhavingbeenaccomplishedbyanotheradventurerfromthetopofSt。Mark’satVenice。 Intheseattemptsitwouldseemthattheprincipleoftheparachutewastosomeextentatleastbroughtintoplay。Ifalsocircumstantialaccountscanbecredited,itwouldappearthataworkingmodelofaflyingmachinewaspubliclyexhibitedbyoneJohnMullerbeforetheEmperorCharlesV。atNuremberg。 Whateverexaggerationorembellishmenthistorymaybeguiltyofitisprettyclearthatsomegenuineattemptsofapracticalandnotunsuccessfulnaturehadbeenmadehereandthere,andthesepromptedthefloweryandvisionaryBishopWilkinsalreadyquotedtopredictconfidentlythatthedaywasapproachingwhenit\"wouldbeascommonforamantocallforhiswingsasforbootsandspurs。\" Wehavenowtoreturntothe\"tamegoose\"method,whichfounditsbestandboldestexponentinahumblecraftsman,bynameBesnier,livingatSable,abouttheyear1678。Thismechanicalgeniuswasbytradealocksmith,andmusthavebeenpossessedofsufficientskilltoconstructanefficientapparatusoutofsuchmaterialsascametohishand,ofthesimplestpossibledesign。Itmaybecomparedtotheearliesttypeofbicycle,theancient\"boneshaker,\"nowalmostforgottensavebythosewho,likethewriter,hadexperienceofitonitsfirstappearance。Besnier’swings,asitwouldappear,wereessentiallyapairofdouble—bladedpaddlesandnothingmore,roughlyresemblingthedouble—paddleofanold—fashionedcanoe,onlythebladeswerelarge,roughlyrectangular,andcurvedorhollowed。Theoperatorwouldcommencebystandingerectandbalancingthesepaddles,oneoneachshoulder,sothatthehollowsofthebladesshouldbetowardstheground。Theforwardpartofeachpaddlewasthengraspedbythehands,whilethehinderpartofeachwasconnectedtothecorrespondingleg。This,presumably,wouldbeeffectedafterthearmshadbeenraisedvertically,thelegattachmentbeingcontrivedinsomewaywhichexperiencewoulddictate。 Theflyerwasnowfullyequipped,andnothingremainedforhimsavetomountsomeeminenceand,throwinghimselfforwardintospaceandassumingthepositionofaflyingbird,tocommenceflappingandbeatingtheairwithareciprocalmotion。First,hewouldbuffettheairdownwardswiththeleftarmandrightlegsimultaneously,andwhiletheserecoveredtheirpositionwouldstrikewiththerighthandandleftleg,andsoonalternately。Withthiscrudemethodtheenterprisinginventorsucceededinraisinghimselfbyshortstagesfromoneheighttoanother,reachingthusthetopofahouse,whencehecouldpassoverothers,orcrossariverorthelike。 Theperfectingofhissystembecamethensimplyaquestionofpracticeandexperience,andhadyoungathletesonlybeentrainedfromearlyyearstothenewartitseemsreasonabletosupposethatsomecrudeapproachtohumanflightwouldhavebeeneffected。Modificationsandimprovementsinconstructionwouldsoonhavesuggestedthemselves,aswasthecasewiththebicycle,whichinitslatestdevelopmentscanscarcelyberecognisedasspringingfromtheprimitive\"bone—shaker\"ofthirty—threeyearsago。Wewouldsuggesttheideatothemoderninventor。Hewillinthesedays,ofcourse,findlightermaterialstohand。Thenhewilladoptsomelinkmotionforthelegsinplaceofleatherthongs,andwillhingethepaddlebladessothattheyopenoutwiththeforwardstroke,butcollapsewiththereturn。Thenlookonanotherthirty—threeyears——afreshgeneration——andouryouthofbothsexesmayfindapopularrecreationingracefulaerialexercise。Thepaceisnotlikelytobeexcessive,andmolestationsfromdisguisedpolicemen——notphysicallyadapted,bytheway,torapidflight——neednotbeapprehended。 OneofthebesttestsofBesnier’smeasureofsuccessissuppliedbythefactthathehadpupilsaswellasimitators。 FirstonthislistmustbementionedaMr。Baldwin,anamewhich,curiouslyenough,twiceoverinmoderntimescomesintotherecordsofboldaerialexploits。Thisindividual,itappears,purchasedaflyingoutfitofBesnierhimself,andsurpassedhismasterinachievement。AlittlelateroneDantecontrivedsomemodificationofthesameapparatus,withwhichhepursuedthenewmodeofprogresstillhemetwithafracturedthigh。 ButwhatevertheimitatorsofBesniermayhaveaccomplished,tothehonestsmithmustbeaccordedthefullcreditoftheirsuccess,andwithhissimple,butbrilliant,recordleftatfloodmark,thetideofprogressebbedbackagain,whilemankindruminatedoverthegreatprobleminapparentinactivity。Butnotforlong。Theair—pumpaboutthisperiodwasgiventotheworld,andchemistswerealreadybusyinvestigatingthenatureofgases。Cavallowasexperimentingonkindredlines,whileinourownlandtherivalgeniusesofPriestleyandCavendishwereclearingthewaytomakewithrespecttotheatmospherethemostimportantdiscoveryyetdreamedof。Inrecordingthisdawnofanewera,however,weshouldcertainlynotforgethow,acrosstheAtlantic,hadarisenaRumfordandaFranklin,whoselaboursweredestinedtothrowanall—importantsidelightonthepagesofprogresswhichwehavenowtochronicle。 CHAPTERII。THEINVENTIONOFTHEBALLOON。 ItwasaNovembernightoftheyear1782,inthelittletownofAnnonay,nearLyons。Twoyoungmen,StephenandJosephMontgolfier,therepresentativesofafirmofpapermakers,weresittingtogetherovertheirparlourfire。Whilewatchingthesmokecurlingupthechimneyonepropoundedanideabywayofasuddeninspiration:\"Whyshouldn’tsmokebemadetoraisebodiesintotheair?\" Theworldwaswaitingforthisutterance,which,itwouldseem,wasonthetipofthetonguewithmanyothers。Cavendishhadalreadydiscoveredwhathedesignated\"inflammableair,\"thoughnoonehadasyetgivenititslatertitleofhydrogengas。 Moreover,intreatingofthisgas——Dr。BlackofEdinburgh,asmuchasfifteenyearsbeforethedatewehavenowarrivedat,hadsuggestedthatitshouldbemadecapableofraisingathinbladderintheair。Withashademoreofgoodfortune,ormaybewithamodicummoreofleisure,thelearnedDoctorwouldhavewontheinventionoftheballoonforhisowncountry。 Cavallocamealmostnearer,andactuallyputtingthesameideaintopractice,hadsucceededinthespringof1782inmakingsoapbubblesblownwithhydrogengasfloatupwards。Buthehadaccomplishednomorewhen,asrelated,intheautumnofthesameyearthebrothersMontgolfierconceivedthenotionofmakingbodies\"levitate\"bythesimplerexpedientoffillingthemwithsmoke。 Thiswasthecrudeidea,theapplicationofwhichintheirhandswassoonmarkedwithnotablesuccess。Theirowntradesuppliedreadyandsuitablematerialsforafirstexperiment,and,makinganoblongbagofthinpaperafewfeetinlength,theyproceededtointroduceacloudofsmokeintoitbyholdingcrumpledpaperkindledinachafingdishbeneaththeopenmouth。Whatasubjectistherehereforanimaginativepainter!Asthesmokycloudformedwithin,thebagdistendeditself,becamebuoyant,andpresentlyfloatedtotheceiling。 Thesimpletrialprovedacompletesuccess,due,asitappearedtothem,totheascensivepowerofacloudofsmoke。 Aninterestingandmoredetailedversionofthestoryisextant。Whiletheexperimentwasinprogressaneighbour,thewidowofatradesmanwhohadbeenconnectedinbusinesswiththefirm,seeingsmokeescapingintotheroom,enteredandstoodwatchingtheproceedings,whichwerenotunattendedwithdifficulties。Thebag,halfinflated,wasnoteasytoholdinpositionoverthechafingdish,andrapidlycooledandcollapsedonbeingremovedfromit。Thewidownotingthis,asalsotheperplexityoftheyoungmen,suggestedthattheyshouldtrytheresultoftyingthedishonatthebottomofthebag。Thiswastheonethingwantedtosecuresuccess,andthatgoodlady,whoseverynameisunhappilylost,deservesanhonouredplaceinhistory。Itwasunquestionablytheadoptionofherideawhichlaunchedthefirstballoonintospace。 Thesameexperimentrepeatedintheopenairprovingayetmorepronouncedsuccess,moreelaboratetrialswerequicklydeveloped,andtheinfantballoongrewfast。Oneworthyofthename,sphericalinshapeandofsome600cubicfeetcapacity,wasnowmadeandtreatedasbefore,withtheresultthatereitwasfullyinflateditbrokethestringsthathelditandsailedawayhundredsoffeetintotheair。Theinfantwasfastbecomingaprodigy。Encouragedbytheirfreshsuccess,theinventorsatoncesetaboutpreparationsfortheconstructionofamuchlargerballoonsomethirty—fivefeetdiameter(thatis,ofabout23,000cubicfeetcapacity),tobemadeoflinenlinedwithpaperandthismachine,launchedonafavourabledayinthefollowingspring,rosewithgreatswiftnesstofullyathousandfeet,andtravellednearlyamilefromitsstartingground。 Enough;thetimewasalreadyripeforapublicdemonstrationofthenewinvention,andaccordinglythe5thofthefollowingJunewitnessedtheascentofthesameballoonwithdueceremonyandadvertisement。Specialpainsweretakenwiththeinflation,whichwasconductedoverapitabovewhichtheballoonenvelopewasslung;andinaccordancewiththeviewthatsmokewasthechiefliftingpower,thefuelwascomposedofstrawlargelymixedwithwool。Itisrecordedthatthemanagementofthefurnaceneededtheattentionoftwomenonly,whileeightmencouldhardlyholdtheimpatientballooninrestraint。Theinflation,inspiteofthefactthatthefuelchosenwasscarcelythebestforthepurpose,wasconductedremarkableexpedition,andonbeingreleased,thecrafttravelledoneandahalfmilesintotheair,attainingaheightestimatedatover6,000feet。 Fromthistimethetideofeventsintheaeronauticalworldrollsoninfullflood,almosteveryhalf—yearmarkingafreshepoch,untilanewdepartureintheinfantartofballooningwasalreadyonthepointofbeingreached。IthadbeenerroneouslysupposedthattheascentoftheMontgolfierballoonhadbeendue,nottotherarefactionoftheairwithinit——whichwasitstruecause——buttotheevolutionofsomelightgasdisengagedbythenatureofthefuelused。Itfollowed,therefore,almostasamatterofcourse,thatchemists,who,asstatedinthelastchapter,werealreadyacquaintedwithso—called\"inflammableair,\"orhydrogengas,graspedthefactthatthisgaswouldservebetterthananyotherforthepurposesofaballoon。AndnosoonerhadthenewsoftheMontgolfiers’successreachedParisthanasubscriptionwasraised,andM。Charles,ProfessorofExperimentalPhilosophy,wasappointed,withtheassistanceofM。Roberts,tosuperintendtheconstructionofasuitableballoonanditsinflationbytheproposednewmethod。 Thetaskwasoneofconsiderabledifficulty,owingpartlytothenecessityofprocuringsomematerialwhichwouldpreventtheescapeofthelightestandmostsubtlegasknown,andnolessbyreasonofthedifficultyofpreparingunderpressureasufficientquantityofgasitself。Theexperiment,soundenoughintheory,waseventuallycarriedthroughafterseveralinstructivefailures。Asuitablematerialwasfoundin\"lustring,\"aglossysilkclothvarnishedwithasolutionofcaoutchouc,andthisbeingformedintoaballoononlythirteenfeetindiameterandfittedwithoutotheraperturethanastopcock,wasafterseveralattemptsfilledwithhydrogengaspreparedintheusualwaybytheactionofdilutesulphuricacidonscrapiron。 Thepreparationscompleted,onelastandall—importantmistakewasmadebyclosingthestop—cockbeforetheballoonwasdismissed,thedisastrousandunavoidableresultofthisbeingatthetimeoverlooked。 OnAugust25,1783,theballoonwasliberatedontheChampdeMarsbeforeanenormousconcourse,andinlessthantwominuteshadreachedanelevationofhalfamile,whenitwastemporarilylostincloud,throughwhich,however,itpenetrated,climbingintoyethighercloud,when,disappearingfromsight,itpresentlyburstanddescendedtoearthafterremainingintheairsomethree—quartersofanhour。 Theburstingofthislittlecrafttaughtthefutureballoonisthisfirstgreatlesson,namely,thatonleavingearthhemustopentheneckofhisballoon;andthereasonofthisisobvious。 Whileyetonearththeimprisonedgasofaproperlyfilledballoondistendsthesilkbyvirtueofitsexpansiveforce,andinspiteoftheenormousoutsidepressurewhichtheweightofairexertsuponit。Then,astheballoonriseshighintheairandtheoutsidepressuregrowsless,thestrugglinggaswithin,ifallowednovent,stretchestheballoonmoreandmoreuntiltheslenderfabricburstsunderthestrain。 Attheriskofbeingtedious,wehavedweltatsomelengthontheinitialexperimentswhichinlessthanasingleyearhadledtothediscoveryanddevelopmentoftwodistinctmethods——stillemployedandincompetitionwitheachother——ofdismissingballoonsintotheheavens。Wearenowpreparedtoenterfullyintotheromantichistoryofoursubjectwhichfromthispointrapidlyunfoldsitself。 SomeelevenmonthsonlyafterthetwoMontgolfierswerediscoveredtoyingwiththeirinflatedpaperbag,theyoungerofthetwobrotherswasengagedtomakeanexhibitionofhisnewartbeforetheKingatVersailles,andthiswasdestinedtobethefirstoccasionwhenaballoonwastocarryalivingfreightintothesky。Thestatelystructure,whichwasgorgeouslydecorated,toweredsomeseventyfeetintotheair,andwasfurnishedwithawickercarinwhichthepassengersweredulyinstalled。Thesewerethreeinnumber,asheep,acock,andaduck,andamidtheacclamationsofthemultitude,roseafewhundredfeetanddescendedhalfamileaway。Thecockwasfoundtohavesustainedanunexplainedmishap:itslegwasbroken;butthesheepwasfeedingcomplacently,andtheduckwasquackingwithmuchapparentsatisfaction。 Now,whoamongmortalswillcomeforwardandwinthehonourofbeingthefirsttosailtheskies?M。PilitredeRozieratoncevolunteered,andbythemonthofNovemberanewairshipwasbuilt,74feethigh,48feetinlargestdiameter,and15 feetacrosstheneck,outsidewhichawickergallerywasconstructed,whileanironbrazierwasslungbelowall。Buttotrimtheboatproperlytwopassengerswereneeded,anddeRozierfoundareadycolleagueintheMarquisd’Arlandes。Bywayofprecaution,deRoziermadeafewpreliminaryascentswiththeballoonheldcaptive,andthenthetwointrepidFrenchmentooktheirstandonoppositesidesofthegallery,eachfurnishedwithbundlesoffueltofeedthefurnace,eachalsocarryingalargewetspongewithwhichtoextinguishtheflameswheneverthemachinemightcatchfire。Oncastingofftheballoonrosereadily,andreaching3,000feet,driftedawayonanuppercurrent。 Therestofthenarrative,muchcondensedfromaletteroftheMarquis,writtenaweeklater,runssomewhatthus:\"Ourdeparturewasatfifty—fourminutespastone,andoccasionedlittlestiramongthespectators。Thinkingtheymightbefrightenedandstandinneedofencouragement,Iwavedmyarm。 M。deRoziercried,’Youaredoingnothing,andwearenotrising!’Istirredthefire,andthenbegantoscantheriver,butPilitrecriedagain,’Seetheriver;wearedroppingintoit!’Weagainurgedthefire,butstillclungtotheriverbed。