the　most　part；　aim　at　the　mechanical　solution　of　the　problem　connected　with　the　soaring　flight　of　a　bird。
  The　theoretical　solution　of　the　same　problem　had　been　attacked　by　Professor　Langley　in　a　masterly　monograph；　entitled　〃The　Internal　Work　of　the　Wind。〃　　By　painstaking　experiment　with　delicate　instruments；　specially　constructed；　the　Professor　shows　that　wind　in　general；　so　far　from　being；　as　was　commonly　assumed；　mere　air　put　in　motion　with　an　approximately　uniform　velocity　in　the　same　strata；　is；　in　reality；　variable　and　irregular　in　its　movements　beyond　anything　which　had　been　anticipated；　being　made　up；　in　fact；　of　a　succession　of　brief　pulsations　in　different　directions；　and　of　great　complexity。　　　These　pulsations；　he　argues；　if　of　sufficient　amplitude　and　frequency；　would　be　capable；　by　reason　of　their　own　〃internal　work；〃　of　sustaining　or　even　raising　a　suitably　curved　surface　which　was　being　carried　along　by　the　main　mean　air　stream。　　This　would　account　for　the　phenomenon　of　〃soaring。〃　　Lord　Rayleigh；　discussing　the　same　problem；　premises　that　when　a　bird　is　soaring　the　air　cannot　be　moving　uniformly　and　horizontally。　　Then　comes　the　natural　question；　Is　it　moving　in　ascending　currents？　　Lord　Rayleigh　has　frequently　noticed　such　currents；　particularly　above　a　cliff　facing　the　wind。　　Again；　to　quote　another　eminent　authority；　Major　Baden…Powell；　on　an　occasion　when　flying　one　of　his　own　kites；　found　it　getting　to　so　high　an　angle　that　it　presently　rose　absolutely　overhead；　with　the　string　perpendicular。　　He　then　took　up　a　heavy　piece　of　wood；　which；　when　tied　to　the　string；　began　to　rise　in　the　air。　　He　satisfied　himself　that　this　curious　result　was　solely　due　to　a　strong　uptake　of　the　air。
  But；　again；　Lord　Rayleigh；　lending　support　to　Professor　Langley's　argument；　points　out　that　the　apparent　cause　of　soaring　may　be　the　non…uniformity　of　the　wind。　　The　upper　currents　are　generally　stronger　than　the　lower；　and　it　is　mechanically　possible　for　a　bird；　taking　advantage　of　two　adjacent　air　streams；　different　in　velocity；　to　maintain　itself　in　air　without　effort　on　its　own　part。
  Lord　Rayleigh；　proceeding　to　give　his　views　on　artificial　flight；　declares　the　main　problem　of　the　flying　machine　to　be　the　problem　of　the　aerial　plane。　　He　states　the　case　thus：　〃Supposing　a　plane　surface　to　be　falling　vertically　at　the　rate　of　four　miles　an　hour；　and　also　moving　horizontally　at　the　rate　of　twenty　miles　an　hour；　it　might　have　been　supposed　that　the　horizontal　motion　would　make　no　difference　to　the　pressure　on　its　under　surface　which　the　falling　plane　must　experience。　　We　are　told；　however；　that　in　actual　trial　the　horizontal　motion　much　increases　the　pressure　under　the　falling　plane；　and　it　is　this　fact　on　which　the　possibility　of　natural　and　artificial　flight　depends。
  Ere　this　opinion　had　been　stated　by　Lord　Rayleigh　in　his　discourse　on　〃Flight；〃　at　the　Royal　Institution；　there　were　already　at　work　upon　the　aero…plane　a　small　army　of　inventors；　of　whom　it　will　be　only　possible　in　a　future　chapter　to　mention　some。　Due　reference；　however；　should　here　be　made　to　Mr。　W。　F。　Wenham；　of　Boston；　U。S。A。；　who　had　been　at　work　on　artificial　flight　for　many　years；　and　to　whose　labours　in　determining　whether　man's　power　is　sufficient　to　raise　his　own　weight　Lord　Rayleigh　paid　a　high　tribute。　　As　far　back　as　1866　Mr。　Wenham　had　published　a　paper　on　aerial　locomotion；　in　which　he　shows　that　any　imitation　by　man　of　the　far…extended　wings　of　a　bird　might　be　impracticable；　the　alternative　being　to　arrange　the　necessary　length　of　wing　as　a　series　of　aero…planes；　a　conception　far　in　advance　of　many　theorists　of　his　time。
  But　there　had　been　developments　in　aerostation　in　other　lines；　and　it　is　time　to　turn　from　the　somewhat　tedious　technicalities　of　mechanical　flight　and　the　theory　or　practice　of　soaring；　to　another　important　means　for　traversing　the　airthe　parachute。　This　aerial　machine；　long　laid　aside；　was　to　lend　its　aid　to　the　navigation　of　the　air　with　a　reliability　never　before　realised。　　Professor　Baldwin；　as　he　was　termed；　an　American　aeronaut；　arrived　in　England　in　the　summer　of　1888；　and　commenced　giving　a　series　of　exhibitions　from　the　Alexandra　Palace　with　a　parachute　of　his　own　invention；　which；　in　actual　performance；　seems　to　have　been　the　most　perfect　instrument　of　the　kind　up　to　that　time　devised。　　It　was　said　to　be　about　18　feet　in　diameter；　whereas　that　of　Garnerin；　already　mentioned；　had　a　diameter　of　some　30　feet；　and　was　distinctly　top…heavy；　owing　to　its　being　thus　inadequately　ballasted；　for　it　was　calculated　that　its　enormous　size　would　have　served　for　the　safe　descent；　not　of　one　man；　but　of　four　or　five。　　Baldwin's　parachute；　on　the　contrary；　was　reckoned　to　give　safe　descent　to　250　lbs。；　which　would　include　weight　of　man　and　apparatus；　and　reduce　the　ultimate　fall　to　one　not　exceeding　8　feet。　The　parachute　was　attached　to　the　ring　of　a　small　balloon　of　12；000　cubic　feet；　and　the　Professor　ascended；　sitting　on　a　mere　sling　of　rope；　which　did　duty　for　a　car。
  Mr。　Thomas　Moy；　who　investigated　the　mechanics　of　the　contrivance；　estimated　that　after　a　drop　of　16　feet；　the　upward　pressure；　amounting　to　over　2　lb。　per　square　foot；　would　act　on　a　surface　of　not　less　than　254　square　feet。　　There　was；　at　the　time；　much　foolish　comment　on　the　great　distance　which　the　parachute　fell　before　it　opened；　a　complete　delusion　due　to　the　fact　that　observers　failed　to　see　that　at　the　moment　of　separation　the　balloon　itself　sprang　upward。
  CHAPTER　XXII。　　THE　STORY　OF　THE　SPENCERS。
  It　has　been　in　the　hands　of　the　Spencers　that　the　parachute；　as　also　many　other　practical　details　of　aeronautics；　has　been　perfected；　and　some　due　sketch　of　the　career　of　this　family　of　eminent　aeronauts　must　be　no　longer　delayed。
  Charles　Green　had　stood　godfather　to　the　youngest　son　of　his　friend　and　colleague；　Mr。　Edward　Spencer；　and　in　later　years；　as　though　to　vindicate　the　fact；　this　same　son　took　up　the　science　of　aeronautics　at　the　point　where　his　father　had　left　it。　　We　find　his　name　in　the　records　of　the　Patent　Office　of　1868　as　the　inventor　of　a　manumetric　flying　machine；　and　there　are　accounts　of　the　flying　leaps　of　several　hundred　feet　which　he　was　enabled　to　take　by　means　of　the　machine　he　constructed。　　Again；　in　1882　we　find　him　an　inventor；　this　time　of　the　patent　asbestos　fire　balloon；　by　means　of　which　the　principal　danger　to　such　balloons　was　overcome。
  At　this　point　it　is　needful　to　make　mention　of　the　third　generationthe　several　sons　who　early　showed　their　zeal　and　aptitude　for　perpetuating　the　family　tradition。　　It　was　from　his　school　playground　that　the　eldest　son；　Percival；　witnessed　with　intense　interest　what　appeared　like　a　drop　floating　in　the　sky　at　an　immense　altitude。　　This　proved　to　be　Simmons's　balloon；　which　had　just　risen　to　a　vast　elevation　over　Cremorne　Gardens；　after　having　liberated　the　unfortunate　De　Groof；　as　mentioned　in　a　former　chapter。　　And　one　may　be　sure　that　the　terrible　reality　of　the　disaster　that　had　happened　was　not　lost　on　the　young　schoolboy。　　But　his　wish　was　to　become　an　aeronauts；　and　from　this　desire　nothing　deterred　him；　so　that　school　days　were　scarcely　over　before　he　began　to　accompany　his　father　aloft；　and　in　a　very　few　years；　i。e。　in　1888；　he　had　assumed　the　full　responsibilities　of　a　professional　balloonist。
  It　was　in　this　year　that　Professor　Baldwin　appeared　in　England；　and　it　is　easy　to　understand　that　the　parachute　became　an　object　of　interest　to　the　young　Spencer；　who　commenced　on　his　own　account　a　series　of　trials　at　the　Alexandra　Palace；　and　it　was　now；　also；　that　chance　good　fortune　came　his　way。　　An　Indian　gentleman；　who　was　witness　of　his　experiments；　and　convinced　that　a　favourable　field　for　their　further　development　existed　in　his　own　country；　proposed　to　the　young　aspirant　that　he　should　accompany　him　to　India；　with　equipment　suited　for　the　making　of　a　successful　campaign。
  Thus　it　came　about　that　in　the　early　days　of　1889；　in　the　height　of　the　season；　Mr。　Percival　Spencer　arrived　at　Bombay；　and　at　once　commenced　professional　business　in　earnest。　　Coal　gas　being　here　available；　a　maiden　ascent　was　quickly　arranged；　and　duly　announced　to　take　place　at　the　Government　House；　Paral；　the　chief　attraction　being　the　parachute　descent；　the　first　ever　attempted　in　India。
  This　preliminary　exhibition　proving　in　all　ways　a　complete　success；　Mr。　Spencer；　after　a　few　repetitions　of　his　performance；　repaired　to　Calcutta；　but　here　great　difficulties　were　experienced　in　the　matter　of　gas。　　The　coal　gas　available　was　inadequate；　and　when　recourse　was　had　to　pure　hydrogen　the　supply　proved　too　sluggish。　　At　the　advertised　hour　of　departure　the　balloon　was　not　sufficiently　inflated；　while　the　spectators　were　growing　impatient。　　It　was　at　this　critical　moment　that　Mr。　Spencer　resolved　on　a　surprise。　　Suddenly　casting　off　the　parachute；　and　seated　on　a　mere　sling　below　the　half…inflated　balloon；　without　ballast；　without　grapnel；　and　unprovided　with　a　valve；　he　sailed　away　over　the　heads　of　the　multitude。
  The　afternoon　was　already　far　advanced；　and　the　short　tropical　twilight　soon　gave　way　to　darkness；　when　the　intrepid　voyager　disappeared　completely　from　sight。　　Excitement　was　intense