the dominion of the air-第51部分

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　of　trials：　first；　that　the　theory　of　aerial　echoes　thrown　back　from　empty　space；　which　physicists　have　held　to　exist　constantly；　and　to　be　part　of　the　cause　of　thunder；　will　have　to　be　abandoned；　and；　secondly；　that　from　some　cause　yet　to　be　fully　explained　the　echo　back　from　the　earth　is　always　behind　its　time。

But　balloons　have　revealed　further　suggestive　facts　with　regard　to　sound；　and　more　particularly　with　regard　to　the　varying　acoustic　properties　of　the　air。　　It　is　a　familiar　experience　how　distant　sounds　will　come　and　go；　rising　and　falling；　often　being　wafted　over　extraordinary　distances；　and　again　failing　altogether；　or　sometimes　being　lost　at　near　range；　but　appearing　in　strength　further　away。　　A　free　balloon；　moving　in　the　profound　silence　of　the　upper　air；　becomes　an　admirable　sound　observatory。　　It　may　be　clearly　detected　that　in　certain　conditions　of　atmosphere；　at　least；　there　are　what　may　be　conceived　to　be　aerial　sound　channels；　through　which　sounds　are　；momentarily　conveyed　with　abnormal　intensity。　　This　phenomenon　does　but　serve　to　give　an　intelligible　presentment　of　the　unseen　conditions　existing　in　the　realm　of　air。

It　would　be　reasonable　to　suppose　that　were　an　eye　so　constituted　as　to　be　able　to　see；　say；　cumulus　masses　of　warmer　air；　strata　mottled　with　traces　of　other　gases；　and　beds　of　invisible　matter　in　suspension；　one　might　suppose　that　what　we　deem　the　clearest　sky　would　then　appear　flecked　with　forms　as　many　and　various　as　the　clouds　that　adorn　our　summer　heavens。

But　there　is　matter　in　suspension　in　the　atmosphere　which　is　very　far　from　invisible；　and　which　in　the　case　of　large　towns　is　very　commonly　lying　in　thick　strata　overhead；　stopping　back　the　sunlight；　and　forming　the　nucleus　round　which　noisome　fogs　may　form。　　Experimenting　with　suitable　apparatus；　the　writer　has　found　on　a　still　afternoon　in　May；　at　2；000　feet　above　Kingston　in　Surrey；　that　the　air　was　charged　far　more　heavily　with　dust　than　that　of　the　London　streets　the　next　day；　and；　again；　at　half　a　mile　above　the　city　in　the　month　of　August　last　dust；　much　of　it　being　of　a　gross　and　even　fibrous　nature；　was　far　more　abundant　than　on　grass　enclosures　in　the　town　during　the　forenoon　of　the　day　following。

An　attempt　has　been　made　to　include　England　in　a　series　of　international　balloon　ascents　arranged　expressly　for　the　purpose　of　taking　simultaneous　observations　at　a　large　number　of　stations　over　Europe；　by　which　means　it　is　hoped　that　much　fresh　knowledge　will　be　forthcoming　with　respect　to　the　constitution　of　the　atmosphere　up　to　the　highest　levels　accessible　by　balloons　manned　and　unmanned。　　It　is　very　much　to　be　regretted　that　in　the　case　of　England　the　attempt　here　spoken　of　has　rested　entirely　on　private　enterprise。　　First　and　foremost　in　personal　liberality　and　the　work　of　organisation　must　be　mentioned　Mr。　P。　Y。　Alexander；　whose　zeal　in　the　progress　of　aeronautics　is　second　to　none　in　this　country。　　Twice　through　his　efforts　England　has　been　represented　in　the　important　work　for　which　Continental　nations　have　no　difficulty　in　obtaining　public　grants。　　The　first　occasion　was　on　November　8th；　1900；　when　the　writer　was　privileged　to　occupy　a　seat　in　the　balloon　furnished　by　Mr。　Alexander；　and　equipped　with　the　most　modern　type　of　instruments。　　It　was　a　stormy　and　fast　voyage　from　the　Crystal　Palace　to　Halstead；　in　Essex；　48　miles　in　40　minutes。　　Simultaneously　with　this；　Mr。　Alexander　dismissed　an　unmanned　balloon　from　Bath；　which　ascended　8；000　feet；　and　landed　at　Cricklade。　　Other　balloons　which　took　part　in　the　combined　experiment　were　two　from　Paris；　three　from　Chalais　Meudon；　three　from　Strasburg；　two　from　Vienna；　two　from　Berlin；　and　two　from　St。　Petersburg。

The　section　of　our　countrymen　specially　interested　in　aeronauticsa　growing　communityis　represented　by　the　Aeronautical　Society；　formed　in　1865；　with　the　Duke　of　Argyll　for　president；　and　for　thirty　years　under　the　most　energetic　management　of　Mr。　F。　W。　Brearey；　succeeding　whom　as　hon。　secs。　　have　been　Major　Baden…Powell　and　Mr。　Eric　S。　Bruce。　　Mr。　Brearey　was　one　of　the　most　successful　inventors　of　flying　models。　　Mr。　Chanute；　speaking　as　President　of　the　American　Society　of　Civil　Engineers；　paid　him　a　high　and　well…deserved　compliment　in　saying　that　it　was　through　his　influence　that　aerial　navigation　had　been　cleared　of　much　rubbish　and　placed　upon　a　scientific　and　firm　basis。

Another　community　devoting　itself　to　the　pursuit　of　balloon　trips　and　matters　aeronautical　generally　is　the　newly…formed　Aero　Club；　of　whom　one　of　the　most　prominent　and　energetic　members　is　the　Hon。　C。　S。　Rolls。

It　had　been　announced　that　M。　Santos…Dumont　would　bring　an　air　ship　to　England；　and　during　the　summer　of　the　present　year　would　give　exhibitions　of　its　capability。　　It　was　even　rumoured　that　he　might　circle　round　St。　Paul's　and　accomplish　other　aerial　feats　unknown　in　England。　　The　promise　was　fulfilled　so　far　as　bringing　the　air　ship　to　England　was　concerned；　for　one　of　his　vessels　which　had　seen　service　was　deposited　at　the　Crystal　Palace。　　In　some　mysterious　manner；　however；　never　sufficiently　made　clear　to　the　public；　this　machine　was　one　morning　found　damaged；　and　M。　Santos…Dumont　has　withdrawn　from　his　proposed　engagements。

In　thus　doing　he　left　the　field　open　to　one　of　our　own　countrymen；　who；　in　his　first　attempt　at　flight　with　an　air　ship　of　his　own　invention　and　construction；　has　proved　himself　no　unworthy　rival　of　the　wealthy　young　Brazilian。

Mr。　Stanley　Spencer；　in　a　very　brief　space　of　time；　designed　and　built　completely　in　the　workshops　of　the　firm　an　elongated　motor　balloon；　75　feet　long　by　20　feet　diameter；　worked　by　a　screw　and　petrol　motor。　　This　motor　is　placed　in　the　prow；　25　feet　away　from；　and　in　front　of；　the　safety　valve；　by　which　precaution　any　danger　of　igniting　the　escaping　gas　is　avoided。　　Should；　however；　a　collapse　of　the　machine　arise　from　any　cause；　there　is　an　arrangement　for　throwing　the　balloon　into　the　form　of　a　parachute。　　Further；　there　is　provided　means　for　admitting　air　at　will　into　the　balloon；　by　which　the　necessity　for　much　ballast　is　obviated。

Mr。　Spencer　having　filled　the　balloon　with　pure　hydrogen；　made　his　first　trial　with　this　machine　late　in　an　evening　at　the　end　of　June。　　The　performance　of　the　vessel　is　thus　described　in　the　Westminster　Gazette：〃The　huge　balloon　filled　slowly；　so　that　the　light　was　rapidly　failing　when　at　last　the　doors　of　the　big　shed　slid　open　and　the　ship　was　brought　carefully　out；　her　motor　started；　and　her　maiden　voyage　commenced。　　With　Mr。　Stanley　Spencer　in　the　car；　she　sailed　gracefully　down　the　football　field；　wheeled　round　in　a　circlea　small　circle；　tooand　for　perhaps　a　quarter　of　an　hour　sailed　a　tortuous　course　over　the　heads　of　a　small　but　enthusiastic　crowd　of　spectators。　　The　ship　was　handicapped　to　some　extent　by　the　fact　that　in　their　anxiety　to　make　the　trial　the　aeronauts　had　not　waited　to　inflate　it　fully；　but　still　it　did　its　work　well；　answered　its　helm　readily；　showed　no　signs　of　rolling；　and；　in　short；　appeared　to　give　entire　satisfaction　to　everybody　concernedso　much　so；　indeed；　that　Mr。　Stanley　Spencer　informed　the　crowd　after　the　ascent　that　he　was　quite　ready　to　take　up　any　challenge　that　M。　Santos　Dumont　might　throw　down。〃　Within　a　few　weeks　of　this　his　first　success　Mr。　Spencer　was　able　to　prove　to　the　world　that　he　had　only　claimed　for　his　machine　what　its　powers　fully　justified。　　On　a　still　September　afternoon；　ascending　alone；　he　steered　his　aerial　ship　in　an　easy　and　graceful　flight　over　London；　from　the　Crystal　Palace　to　Harrow。



CHAPTER　XXIX。　　CONCLUSION。


The　future　development　of　aerostation　is　necessarily　difficult　to　forecast。　　Having　reviewed　its　history　from　its　inception　we　have　to　allow　that　the　balloon　in　itself；　as　an　instrument　of　aerial　locomotion；　remains　practically　only　where　it　was　120　years　ago。　　Nor；　in　the　nature　of　the　case；　is　this　to　be　wondered　at。　　The　wind；　which　alone　guides　the　balloon；　is　beyond　man's　control；　while；　as　a　source　of　lifting　power；　a　lighter　and　therefore　more　suitable　gas　than　hydrogen　is　not　to　be　found　in　nature。

It　is；　however；　conceivable　that　a　superior　mode　of　inflation　may　yet　be　discovered。　　Now　that　the　liquefaction　of　gases　has　become　an　accomplished　fact；　it　seems　almost　theoretically　possible　that　a　balloonist　may　presently　be　able　to　provide　himself　with　an　unlimited　reserve　of　potential　energy　so　as　to　be　fitted　for　travel　of　indefinite　duration。　　Endowed　with　increased　powers　of　this　nature；　the　aeronaut　could　utilise　a　balloon　for　voyages　of　discovery　over　regions　of　the　earth　which　bar　man's　progress　by　any　other　mode　of　travel。　　A　future　Andree；　provided　with　a　means　of　maintaining　his　gas　supply　for　six　weeks；　need　have　no　hesitation　in　laying　his　course　towards　the　North　Pole；　being　confident　that　the　winds　must　ultimately　waft　him　to　some　safe　haven。　　He　could；　indeed；　well　afford；　having　reached　the　Pole；　to　descend　and　build　his　cairn；　or　even　to　stop　a　week；　if　he　so　desired；　before　continuing　on　his　way。

But　it　may　fairly　be　claimed　for　the　balloon；　even　as　it　now　is；　that　a　great　and　important　future　is　open　to　it　as　a　means　for　exploring　inaccessible　country。　　It　may；　indeed；　be　urged　that　Andree's　task　was；　in　the　very　nature　of　the　case；　well　nigh　impracticable；　and　his　unfortunate　miscarriage　will　be　used　as　argument　against　such　a　method　of　exploration。　　But　it　must　always　be　remembered　that　in　Andree's　case　the　rigours　of　climate　which　he　was　compelled　to　face　were　the　most　serious　of　all　obstacles　to　balloon　travel。　　The　extreme　cold　would　not　only　cause　constant　shrinkage　of　the　gas；　but　would　entail　the　deposition　of　a　weight　of　moisture；　if　not　of　snow；　upon　the　surface　of　the　balloon；　which　must　greatly　shorten　its　life。

It　would　be　entirely　otherwise　if　the　country　it　were　sought　to　explore　were　in　lower　latitudes；　in　Australia；　or　within　the　vast　unknown　belt　of　earth　lying　nearer　the　equator。　　The　writer's　scheme　for　exploring　the　wholly　unknown　regions　of　Arabia　is　already　before　the　public。　　The　fact；　thought　to　be　established　by　the　most　experienced　aeronauts　of　old　times；　and　already　referred　to　in　these　pages；　that　at　some　height　a　strong　west　wind　is　to　be　found　b