the dominion of the air-第54节

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imitive　form　of　balloon；　the　Montgolfier；　might　not　be　the　most　valuable。　　Instead　of　being　made；　as　the　war　balloon　is　now；　of　fragile　material；　and　filled　with　costly　gas　difficult　to　procure；　and　which　has　to　be　conveyed　in　heavy　and　cumbersome　cylinders；　a　hot　air　balloon　could　be　rapidly　carried　by　hand　anywhere　where　a　few　men　could　push　their　way。　　It　is　of　strong　material；　readily　mended　if　torn；　and　could　be　inflated　for　short　ascents；　if　not　by　mere　brush　wood；　then　by　a　portable　blast　furnace　and　petroleum。

But　there　is　a　further　use　for　balloons　in　warfare　not　yet　exploited。　　The　Siege　of　Paris　showed　the　utility　of　free　balloons；　and　occasions　arise　when　their　use　might　be　still　further　extended。　　The　writer　pointed　out　that　it　might　have　been　very　possible　for　an　aeronaut　of　experience；　by　choosing　the　right　weather　and　the　right　position　along　the　British　lines；　to　have　skilfully　manoeuvred　a　free　balloon　by　means　of　upper　currents；　so　as　to　convey　all…important　intelligence　to　besieged　Mafeking；　and　he　proved　that　it　would　have　sufficed　if　the　balloon　could　have　been　〃tacked〃　across　the　sky　to　within　some　fifteen　miles　of　the　desired　goal。

The　mode　of　signalling　which　he　proposed　was　by　means　of　a　〃collapsing　drum；〃　an　instrument　of　occasional　use　in　the　Navy。　　A　modification　of　this　instrument；　as　employed　by　the　writer；　consisted　of　a　light；　spherical；　drum…shaped　frame　of　large　size；　which；　when　covered　with　dark　material　and　hung　in　the　clear　below　the　car　of　a　lofty　balloon；　could　be　well　seen　either　against　blue　sky　or　grey　at　a　great　distance。　　The　so…called　drum　could；　by　a　very　simple　contrivance；　readily　worked　from　the　car；　be　made　to　collapse　into　a　very　inconspicuous　object；　and　thus　be　capable　of　displaying　Morse　Code　signals。　　A　long　pause　with　the　drum　extendedlike　the　long　wave　of　a　signalling　flagwould　denote　a　〃dash；〃　and　a　short　pause　a　〃dot；〃　and　these　motions　would　be　at　once　intelligible　to　anyone　acquainted　with　the　now　universal　Morse　Code　system。

Provided　with　an　apparatus　of　the　kind；　the　writer　made　an　ascent　from　Newbury　at　a　time　when　the　military　camps　were　lying　on　Salisbury　Plain　at　a　distance　of　nearly　twenty　miles　to　the　south…west。　　The　ground　wind　up　to　2；500　feet　on　starting　was　nearly　due　north；　and　would　have　defeated　the　attempt；　again；　the　air　stream　blowing　above　that　height　was　nearly　due　east；　which　again　would　have　proved　unsuitable。　　But　it　was　manifestly　possible　to　utilise　the　two　currents；　and　with　good　luck　to　zig…zag　one's　course　so　as　to　come　within　easy　signalling　distance　of　the　various　camps；　and；　as　a　matter　of　fact；　we　actually　passed　immediately　over　Bulford　Camp；　with　which　we　exchanged　signals；　while　two　other　camps　lay　close　to　right　and　left　of　us。　　Fortune　favouring　us；　we　had　actually　hit　our　mark；　though　it　would　have　been　sufficient　for　the　experiment　had　our　course　lain　within　ten　miles　right　or　left。

Yet　a　further　use　for　the　balloon　in　warfare　remains　untried　in　this　country。　　Acting　under　the　advice　of　experts　in　the　Service；　the　writer；　in　the　early　part　of　the　present　year；　suggested　to　the　Admiralty　the　desirability　of　experimenting　with　balloons　as　a　means　of　detecting　submarine　engines　of　war。　　It　is　well　known　that　reefs　and　shoals　can　generally　be　seen　from　a　cliff　or　mast　head　far　more　clearly　than　from　the　deck　or　other　position　near　the　surface　of　the　water。　　Would　not；　then；　a　balloon；　if　skilfully　manoeuvred；　serve　as　a　valuable　post　of　observation？　　The　Admiralty；　in　acknowledging　the　communication；　promised　to　give　the　matter　their　attention；　but　by　the　month　of　June　the　Press　had　announcements　of　how　the　self…same　experiments　had　been　successfully　carried　through　by　French　authorities；　while　a　few　days　later　the　Admiralty　wrote；　〃For　the　present　no　need　is　seen　for　the　use　of　a　captive　balloon　to　detect　submarines。〃

Among　many　and　varied　ballooning　incidents　which　have　occurred　to　the　writer；　there　are　some　which　may　not　unprofitably　be　compared　with　certain　experiences　already　recorded　of　other　aeronauts。　　Thunderstorms；　as　witnessed　from　a　balloon；　have　already　been　casually　described；　and　it　may　reasonably　be　hoped　that　the　observations　which　have；　under　varying　circumstances；　been　made　at　high　altitudes　may　throw　some　additional　light　on　this　familiar；　though　somewhat　perplexing；　phenomenon。

To　begin　with；　it　seems　a　moot　point　whether　a　balloon　caught　in　a　thunderstorm　is；　or　is　not；　in　any　special　danger　of　being　struck。　　It　has　been　argued　that　immunity　under　such　circumstances　must　depend　upon　whether　a　sufficiently　long　time　has　elapsed　since　the　balloon　left　the　earth　to　allow　of　its　becoming　positively　electrified　by　induction　from　the　clouds　or　by　rain　falling　upon　its　surface。　　But　there　are　many　other　points　to　be　considered。　　There　is　the　constant　escape　of　gas　from　the　mouth；　there　is　the　mass　of　pointed　metal　in　the　anchor；　and；　again；　it　is　conceivable　that　a　balloon　rapidly　descending　out　of　a　thunderstorm　might　carry　with　it　a　charge　residing　on　its　moistened　surface　which　might　manifest　itself　disastrously　as　the　balloon　reached　the　earth。

Instances　seem　to　have　been　not　infrequent　of　balloons　encountering　thunderstorms；　but；　unfortunately；　in　most　cases　the　observers　have　not　had　any　scientific　training；　or　the　accounts　which　are　to　hand　are　those　of　the　type　of　journalist　who　is　chiefly　in　quest　of　sensational　copy。

Thus　there　is　an　account　from　America　of　a　Professor　King　who　made　an　ascent　from　Burlington；　Iowa；　just　as　a　thunderstorm　was　approaching；　with　the　result　that；　instead　of　scudding　away　with　the　wind　before　the　storm；　he　was　actually；　as　if　by　some　attraction；　drawn　into　it。　　On　this　his　aim　was　to　pierce　through　the　cloud　above；　and　then　follows　a　description　which　it　is　hard　to　realise：〃There　came　down　in　front　of　him；　and　apparently　not　more　than　50　feet　distant；　a　grand　discharge　of　electricity。〃　　Then　he　feels　the　car　lifted；　the　gas　suddenly　expands　to　overflowing；　and　the　balloon　is　hurled　through　the　cloud　with　inconceivable　velocity；　this　happening　several　times；　with　tremendous　oscillations　of　the　car；　until　the　balloon　is　borne　to　earth　in　a　torrent　of　rain。　　We　fancy　that　many　practical　balloonists　will　hardly　endorse　this　description。

But　we　have　another；　relating　to　one　of　the　most　distinguished　aeronauts；　M。　Eugene　Godard；　who；　in　an　ascent　with　local　journalists；　was　caught　in　a　thunderstorm。　　Here　we　are　toldpresumably　by　the　journaliststhat　〃twice　the　lightning　flashed　within　a　few　yards　of　the　terror…stricken　crew。〃

Once　again；　in　an　ascent　at　Derby；　a　spectator　writes：〃The　lightning　played　upon　the　sphere　of　the　balloon；　lighting　it　up　and　making　things　visible　through　it。〃　　This；　however；　one　must　suppose；　can　hardly　apply　to　the　balloon　when　liberated。

But　a　graphic　description　of　a　very　different　character　given　in　the　〃Quarterly　Journal　of　the　Royal　Meteorological　Society〃　for　January；　1901；　is　of　real　value。　　It　appears　that　three　lieutenants　of　the　Prussian　Balloon　Corps　took　charge　of　a　balloon　that　ascended　at　Berlin；　and；　when　at　a　height　of　2；300　feet；　became　enveloped　in　the　mist；　through　which　only　occasional　glimpses　of　earth　were　seen。　　At　this　point　a　sharp；　crackling　sound　was　heard　at　the　ring；　like　the　sparking　of　a　huge　electrical　machine；　and；　looking　up；　the　voyagers　beheld　sparks　apparently　some　half…inch　thick；　and　over　two　feet　in　length；　playing　from　the　ring。　　Thunder　was　heard；　butand　this　may　have　significanceonly　before　and　after　the　above　phenomenon。

Another　instructive　experience　is　recorded　of　the　younger　Green　in　an　ascent　which　he　made　from　Frankfort…on…the…Maine。　　On　this　occasion　he　relates　that　he　encountered　a　thunderstorm；　and　at　a　height　of　4；400　feet　found　himself　at　the　level　where　the　storm　clouds　were　discharging　themselves　in　a　deluge。　　He　seems　to　have　had　no　difficulty　in　ascending　through　the　storm　into　the　clear　sky　above；　where　a　breeze　from　another　quarter　quickly　carried　him　away　from　the　storm　centre。

This　co…existence；　or　conflict　of　opposite　currents；　is　held　to　be　the　common　characteristic；　if　not　the　main　cause；　of　thunderstorms；　and　tallies　with　the　following　personal　experience。　　It　was　in　typical　July　weather　of　1900　that　the　writer　and　his　son；　accompanied　by　Admiral　Sir　Edmund　Fremantle　and　Mr。　Percival　Spencer；　made　an　evening　ascent　from　Newbury。　　It　had　been　a　day　of　storms；　but　about　5　p。m。；　after　what　appeared　to　be　a　clearing　shower；　the　sky　brightened；　and　we　sailed　up　into　a　cloudless　heaven。　　The　wind；　at　3；000　feet；　was　travelling　at　some　thirty　miles　an　hour；　and　ere　the　distance　of　ten　miles　had　been　covered　a　formidable　thunder　pack　was　seen　approaching　and　coming　up　dead　against　the　wind。　　Nothing　could　be　more　evident　than　that　the　balloon　was　travelling　rapidly　with　a　lower　wind；　while　the　storm　was　being　borne　equally　rapidly　on　an　upper　and　diametrically　opposite　current。　　It　proved　one　of　the　most　severe　thunderstorms　remembered　in　the　country。　　It　brooded　for　five　hours　over　Devizes；　a　few　miles　ahead。　　A　homestead　on　our　right　was　struck　and　burned　to　the　ground；　while　on　our　left　two　soldiers　were　killed　on　Salisbury　Plain。　　The　sky　immediately　overhead　was；　of　c