the dominion of the air-第14部分

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In　1840；　three　years　after　the　tragic　adventure　connected　with　Mr。　Cocking's　parachute　trial；　we　find　Charles　Green　giving　his　views　as　to　the　practicability　of　carrying　out　a　ballooning　enterprise　which　should　far　excel　all　others　that　had　hitherto　been　attempted。　　This　was　nothing　less　than　the　crossing　of　the　Atlantic　from　America　to　England。　　There　is　no　shadow　of　doubt　that　the　adventurous　aeronaut　was　wholly　in　earnest　in　the　readiness　he　expressed　to　embark　on　the　undertaking　should　adequate　funds　be　forthcoming；　and　he　discusses　the　possibilities　with　singular　clearness　and　candour。　　He　maintains　that　the　actual　difficulties　resolve　themselves　into　two　only：　　first；　the　maintenance　of　the　balloon　in　the　sky　for　the　requisite　period　of　time；　and；　secondly；　the　adequate　control　of　its　direction　in　space。　　With　respect　to　the　first　difficulty；　he　points　out　the　fact　to　which　we　have　already　referred；　namely；　that　it　is　impossible　to　avoid　the　fluctuations　of　level　in　a　balloon's　course；　〃by　which　it　constantly　becomes　alternately　subjected　to　escape　of　gas　by　expansion；　and　consequent　loss　of　ballast；　to　furnish　an　equivalent　diminution　of　weight。〃　　Taking　his　own　balloon　of　80；000　cubic　feet　by　way　of　example；　he　shows　that　this；　fully　inflated　on　the　earth；　would　lose　8；000　cubic　feet　of　gas　by　expansion　in　ascending　only　3；000　feet。　　Moreover；　the　approach　of　night　or　passage　through　cloud　or　falling　rain　would　occasion　chilling　of　the　gas　or　accumulation　of　moisture　on　the　silk；　in　either　case　necessitating　the　loss　of　ballast；　the　store　of　which　is　always　the　true　measure　of　the　balloon's　life。

To　combat　the　above　difficulty　Green　sanguinely　relies　on　his　favourite　device　of　a　trail　or　guide　rope；　whose　function；　being　that　of　relieving　the　balloon　of　a　material　weight　as　it　approaches　the　earth；　could；　he　supposed；　be　made　to　act　yet　more　efficiently　when　over　the　sea　in　the　following　manner。　　Its　length；　suspended　from　the　ring；　being　not　less　than　2；000　feet；　it　should　have　attached　at　its　lower　end　at　certain　intervals　a　number　of　small；　stout　waterproof　canvas　bags；　the　apertures　of　which　should　be　contrived　to　admit　water；　but　to　oppose　its　return。　　Between　these　bags　were　to　be　conical　floats；　to　support　any　length　of　the　rope　that　might　descend　on　the　sea。　　Now；　should　the　balloon　commence　descending；　it　would　simply　deposit　a　certain　portion　of　rope　on　the　water　until　it　regained　equilibrium　at　no　great　decrease　of　altitude；　and　would　thus　continue　its　course　until　alteration　of　conditions　should　cause　it　to　recommence　rising；　when　the　weight　of　water　now　collected　in　the　bags　would　play　its　part　in　preventing　the　balloon　from　soaring　up　into　space。　　With　such　a　contrivance　Green　allowed　himself　to　imagine　that　he　could　keep　a　properly　made　balloon　at　practically　the　same　altitude　for　a　period　of　three　months　if　required。

The　difficulty　of　maintaining　a　due　course　was　next　discussed；　and　somewhat　speedily　disposed　of。　　Here　Green　relied　on　the　results　of　his　own　observation；　gathered　during　275　ascents；　and　stated　his　conviction　that　there　prevails　a　uniformity　of　upper　wind　currents　that　would　enable　him　to　carry　out　his　bold　projects　successfully。　　His　contention　is　best　given　in　his　own　words：？

〃Under　whatever　circumstances；〃　he　says；　〃I　made　my　ascent；　however　contrary　the　direction　of　the　winds　below；　I　uniformly　found　that　at　a　certain　elevation；　varying　occasionally；　but　always　within　10；000　feet　of　the　earth；　a　current　from　the　west　or　rather　from　the　north　of　west；　invariably　travailed；　nor　do　I　recollect　a　single　instance　in　which　a　different　result　ensued。〃　　Green's　complete　scheme　is　now　sufficiently　evident。　　He　was　to　cross　the　Atlantic　practically　by　the　sole　assistance　of　upper　currents　and　his　guide　rope；　but　on　this　latter　expedient；　should　adverse　conditions　prevail；　he　yet　further　relied；　for　he　conceived　that　the　rope　could　have　attached　to　its　floating　end　a　water　drag；　which　would　hold　the　balloon　in　check　until　favouring　gales　returned。

Funds；　apparently；　were　not　forthcoming　to　allow　of　Mr。　Green's　putting　his　bold　method　to　the　test；　but　we　find　him　still　adhering　with　so　much　zeal　to　his　project　that；　five　years　later；　he　made；　though　again　unsuccessfully；　a　second　proposal　to　cross　the　Atlantic　by　balloon。　　He　still　continued　to　make　many　and　most　enterprising　ascents；　and　one　of　a　specially　sensational　nature　must　be　briefly　mentioned　before　we　pass　on　to　regard　the　exploits　of　other　aeronauts。

It　was　in　1841　on　the　occasion　of　a　fete　at　Cremorne　House；　when　Mr。　Green；　using　his　famous　Nassau　balloon；　ascended　with　a　Mr。　Macdonnell。　　The　wind　was　blowing　with　such　extreme　violence　that　Rainham；　in　Essex；　about　twenty　miles　distant；　was　reached　in　little　more　than　a　quarter　of　an　hour；　and　here；　on　nearing　the　earth；　the　grapnel；　finding　good　hold；　gave　a　wrench　to　the　balloon　that　broke　the　ring　and　jerked　the　car　completely　upside　down；　the　aeronauts　only　escaping　precipitation　by　holding　hard　to　the　ropes。　　A　terrific　steeplechase　ensued；　in　which　the　travellers　were　dragged　through　stout　fencing　and　other　obstacles　till　the　balloon；　fairly　emptied　of　gas；　finally　came　to　rest；　but　not　until　some　severe　injuries　had　been　received。



CHAPTER　VIII。　JOHN　WISETHE　AMERICAN　AERONAUT。


By　this　period　the　domination　of　the　air　was　being　pursued　in　a　fresh　part　of　the　world。　　England　and　her　Continental　neighbours　had　vied　with　each　in　adding　to　the　roll　of　conquests；　and　it　could　hardly　other　be　supposed　that　America　would　stand　by　without　taking　part　in　the　campaign　which　was　now　being　revived　with　so　much　fresh　energy　in　the　skies。

The　American　champion　who　stepped　forward　was　Mr。　John　Wise；　of　Lancaster；　Pa。；　whose　career；　commencing　in　the　year　1835；　we　must　now　for　a　while　follow。　　Few　attempts　at　ballooning　of　any　kind　had　up　to　that　time　been　made　in　all　America。　　There　is　a　record　that　in　December；　1783；　Messrs。　Rittenhouse　and　Hopkins；　Members　of　the　Philosophical　Academy　of　Philadelphia；　instituted　experiments　with　an　aerial　machine　consisting　of　a　cage　to　which　forty…seven　small　balloons　were　harnessed。　　In　this　strange　craft　a　carpenter；　by　name　Wilcox；　was　induced　to　ascend；　which；　it　is　said；　he　did　successfully；　remaining　in　the　air　for　ten　minutes；　when；　finding　himself　near　a　river；　he　sought　to　come　to　earth　again　by　opening　several　of　his　balloons。　　This　brought　about　an　awkward　descent；　attended；　however；　by　no　more　serious　accident　than　a　dislocated　wrist。　　Mr。　Wise；　on　the　other　hand；　states　that　Blanchard　had　won　the　distinction　of　making　the　first　ascent　in　the　New　World　in　1793　in　Philadelphia　on　which　occasion　Washington　was　a　spectator；　and　a　few　years　afterwards　other　Frenchmen　gave　ex　hibitions；　which；　however；　led　to　no　real　development　of　the　new　art　on　this；　the　further　side　of　the　Atlantic。　　Thus　the　endeavours　we　are　about　to　describe　were　those　of　an　independent　and；　at　the　same　time；　highly；　practical　experimentalist；　and　on　this　account　have　a　special　value　of　their　own。

The　records　that　Wise　has　left　of　his　investigations　begin　at　the　earliest　stage；　and　possess　the　charm　of　an　obvious　and　somewhat　quaint　reality。　　They　commence　with　certain　crude　calculations　which　would　seem　to　place　no　limit　to　the　capabilities　of　a　balloon。　　Thus；　he　points　out　that　one　of　〃the　very　moderate　size　of　400　feet　diameter〃　would　convey　13；000　men。　　〃No　wonder；　then；〃　he　continues；　〃the　citizens　of　London　became　alarmed　during　the　French　War；　when　they　mistook　the　appearance　of　a　vast　flock　of　birds　coming　towards　the　Metropolis　for　Napoleon's　army　apparently　coming　down　upon　them　with　this　new　contrivance。〃

Proceeding　to　practical　measures；　Wise's　first　care　was　to　procure　some　proper　material　of　which　to　build　an　experimental　balloon　of　sufficient　size　to　lift　and　convey　himself　alone。　　For　this　he　chose　ordinary　long…cloth；　rendered　gas…tight　by　coats　of　suitable　varnish；　the　preparation　of　which　became　with　him；　as；　indeed；　it　remains　to　this　day；　a　problem　of　chief　importance　and　difficulty。　　Perhaps　it　hardly　needs　pointing　out　that　the　varnish　of　a　balloon　must　not　only　be　sufficiently　elastic　not　to　crack　or　scale　off　with　folding　or　unavoidable　rough　usage；　but　it　must　also　be　of　a　nature　to　resist　the　common　tendency　of　such　substances　to　become　adherent　or　〃tacky。〃　　Wise　determined　on　bird　lime　thinned　with　linseed　oil　and　ordinary　driers。　　With　this　preparation　he　coated　his　material　several　times　both　before　and　after　the　making　up；　and　having　procured　a　net；　of　which　he　speaks　with　pride；　and　a　primitive　sort　of　car；　of　which　he　bitterly　complains；　he　thought　himself　sufficiently　equipped　to　embark　on　an　actual　ascent；　which　he　found　a　task　of　much　greater　practical　difficulty　than　the　mere　manufacture　of　his　air　ship。　　For　the　inflation　by　hydrogen　of　so　small　a　balloon　as　his　was　he　made　more　than　ample　provision　in　procuring　no　less　than　fifteen　casks　of　130　gallons　capacity　each。　　He　also　duly　secured　a　suitable　filling　ground　at　the　corner　of　Ninth　and　Green　Streets；　Philadelphia；　but　he　made　a　miscalculation　as　to　the　time　the　inflation　would　demand；　and　this　led　to　unforeseen　complications；　for　as　yet　he　knew　not　the　way　of　a　crowd　which　comes　to　witness　a　balloon　ascent。

Having　all　things　in　readiness；　and　prudently　waiting　for　fair　weather；　he　embarked　on　his　grand　experiment　on　the　2nd　of　May；　1835；　announcing　4　p。m。　as　the　hour　of　departure。　　But　by　that　time　the　inflation；　having　only　proceeded　for　three　hours；　the　balloon　was　but　half　full；　and　then　the　populace　began　to　behave　as　in　such　circumstances　they　always　will。　　They　were　incredulous；　and　presently　grew　troublesome。　　In　vain　the　harnessing　of　the　car　was　proceeded　with　as　though　all　were　well。　　For　all　was　not　well；　and　when　the　aeronaut　stepped　into　his　car　with　only　fifteen　pounds　of　sand　and　a　few　instruments　he　must　have　done　so　with　much　misgiving。　　Still；　he　had　friends　around　who　might　have　been　useful　had　they　been　less　eager　to　help。　　But　these　simply　crowded　round　him；　giving　him　no　elbow　room；　nor　opportunity　for　trying　the　〃lift〃　of　his　all…too…empty　globe。　　Moreover；　some　would　endeavour　to　throw　the　machine　upward；　while　others　as　strenuously　str