the dominion of the air-第7章

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he　remainder　of　his　descent；　though　leisurely；　occupying；　in　fact；　some　twelve　minutes；　appeared　to　the　spectators　to　be　attended　with　uncertainty；　owing　to　a　swinging　motion　set　up　in　the　car　to　which　he　was　clinging。　　But　the　fact　remains　that　he　reached　the　earth　with　only　slight　impact；　and　entirely　without　injury。

It　appears　that　Garnerin　subsequently　made　many　equally　successful　parachute　descents　in　France；　and　during　the　short　peace　of　1802　visited　London；　where　he　gave　an　exhibition　of　his　art。　　From　the　most　reliable　accounts　of　his　exploit　it　would　seem　that　his　drop　was　from　a　very　great　height；　and　that　a　strong　ground　wind　was　blowing　at　the　time；　the　result　of　which　was　that　wild；　wide　oscillations　were　set　up　in　the　car；　which　narrowly　escaped　bringing　him　in　contact　with　the　house　tops　in　St。　Pancreas；　and　eventually　swung　him　down　into　a　field；　not　without　some　unpleasant　scratches。

Nor　was　Garnerin　the　only　successful　parachutist　at　this　period。　　A　Polish　aeronaut；　Jordaki　Kuparento；　ascended　from　Warsaw　on　the　24th　of　July；　1804　in　a　hot　air　balloon；　taking　up；　as　was　the　custom；　an　attached　furnace；　which　caused　the　balloon　to　take　fire　when　at　a　great　height。　　Kuparento；　however；　who　was　alone；　had　as　a　precaution　provided　himself　with　a　parachute；　and　with　this　he　seems　to　have　found　no　difficulty　in　effecting　a　safe　descent　to　earth。

It　was　many　years　after　this　that　fresh　experimentalists；　introducing　parachutes　on　new　lines　and　faulty　in　construction；　met　with　death　or　disaster。　　Enough；　however；　has　already　been　said　to　show　that　in　the　early　years　we　are　now　traversing　in　this　history　a　perfectly　practicable　parachute　had　become　an　accomplished　fact。　　The　early　form　is　well　described　by　Mr。　Monck　Mason　in　a　letter　to　the　Morning　Herald　in　1837；　written　on　the　eve　of　an　unrehearsed　and　fatal　experiment　made　by　Mr。　Cocking；　which　must　receive　notice　in　due　course。　　〃The　principle；〃　writes　Mr。　Monck　Mason；　〃upon　which　all　these　parachutes　were　constructed　is　the　same；　and　consists　simply　of　a　flattened　dome　of　silk　or　linen　from　24　feet　to　28　feet　in　diameter。　　From　the　outer　margin　all　around　at　stated　intervals　proceed　a　large　number　of　cords；　in　length　about　the　diameter　of　the　dome　itself；　which；　being　collected　together　in　one　point　and　made　fast　to　another　of　superior　dimensions　attached　to　the　apex　of　the　machine；　serve　to　maintain　it　in　its　form　when　expanded　in　the　progress　of　the　descent。　　To　this　centre　cord　likewise；　at　a　distance　below　the　point　of　junction；　varying　according　to　the　fancy　of　the　aeronaut；　is　fixed　the　car　or　basket　in　which　he　is　seated；　and　the　whole　suspended　from　the　network　of　the　balloon　in　such　a　manner　as　to　be　capable　of　being　detached　in　an　instant　at　the　will　of　the　individual　by　cutting　the　rope　by　which　it　is　made　fast　above。〃

It　followed　almost　as　a　matter　of　course　that　so　soon　as　the　balloon　had　been　made　subject　to　something　like　due　control；　and　thus　had　become　recognised　as　a　new　machine　fairly　reduced　to　the　service　of　man；　it　began　to　be　regarded　as　an　instrument　which　should　be　made　capable　of　being　devoted　to　scientific　research。　　Indeed；　it　may　be　claimed　that；　among　the　very　earliest　aeronauts；　those　who　had　sailed　away　into　the　skies　and　brought　back　intelligent　observations　or　impressions　of　the　realm　of　cloud…land；　or　who　had　only　described　their　own　sensations　at　lofty　altitudes；　had　already　contributed　facts　of　value　to　science。　　It　is　time　then；　taking　events　in　their　due　sequence；　that　mention　should　be　made　of　the　endeavours　of　various　savants；　who　began　about　the　commencement　of　the　nineteenth　century　to　gather　fresh　knowledge　from　the　exploration　of　the　air　by　balloon　ascents　organised　with　fitting　equipment。　　The　time　had　now　come　for　promoting　the　balloon　to　higher　purposes　than　those　of　mere　exhibition　or　amusement。　　In　point　of　fact；　it　had　already　in　one　way　been　turned　to　serious　practical　account。　　It　had　been　used　by　the　French　during　military　operations　in　the　revolutionary　war　as　a　mode　of　reconnoitring；　and　not　without　success；　so　that　when　after　due　trial　the　war　balloon　was　judged　of　value　a　number　of　similar　balloons　were　constructed　for　the　use　of　the　various　divisions　of　the　French　army；　and；　as　will　be　told　in　its　proper　place；　one；　at　least；　of　these　was　put　to　a　positive　test　before　the　battle　of　Fleurus。

But；　returning　to　more　strictly　scientific　ascents；　which　began　to　be　mooted　at　this　period；　we　are　at　once　impressed　with　the　widespread　influence　which　the　balloon　was　exercising　on　thinking　minds。　　We　note　this　from　the　fact　that　what　must　be　claimed　to　be　the　first　genuine　ascent　for　scientific　observation　was　made　in　altogether　fresh　ground；　and　at　so　distant　a　spot　as　St。　Petersburg。

It　was　now　the　year　1804；　and　the　Russian　Academy　had　determined　on　attempting　an　examination　of　the　physical　condition　of　the　higher　atmosphere　by　means　of　the　balloon。　　The　idea　had　probably　been　suggested　by　scientific　observations　which　had　already　been　made　on　mountain　heights　by　such　explorers　as　De　Luc；　Saussure；　Humboldt；　and　others。　　And　now　it　was　determined　that　their　results　should　be　tested　alongside　such　observations　as　could　be　gathered　in　the　free　heaven　far　removed　from　any　disturbing　effects　that　might　be　caused　by　contiguity　to　earth。　　The　lines　of　enquiry　to　which　special　attention　was　required　were　such　as　would　be　naturally　suggested　by　the　scientific　knowledge　of　the　hour；　though　they　may　read　somewhat　quaintly　to…day。　　Would　there　be　any　change　in　the　intensity　of　the　magnetic　force？　　Any　change　in　the　inclination　of　the　magnetised　needle？　　Would　evaporation　find　a　new　law？　　Would　solar　rays　increase　in　power？　　What　amount　of　electric　matter　would　be　found？　　What　change　in　the　colours　produced　by　the　prism？　　What　would　be　the　constitution　of　the　higher　and　more　attenuated　air？　　What　physical　effect　would　it　have　on　human　and　bird　life？

The　ascent　was　made　at　7。15　on　a　summer　evening　by　M。　Robertson　and　the　Academician；　M。　Sacharof；　to　whom　we　are　indebted　for　the　following　resume　of　notes；　which　have　a　special　value　as　being　the　first　of　their　class。　　Rising　slowly；　a　difference　of　atmosphere　over　the　Neva　gave　the　balloon　a　downward　motion；　necessitating　the　discharge　of　ballast。　　As　late　as　8。45　p。m。　　a　fine　view　was　obtained　of　the　Newski　Islands；　and　the　whole　course　of　the　neighbouring　river。　　At　9。20　p。m。；　when　the　barometer　had　fallen　from　30　inches　to　23　inches；　a　canary　and　a　dove　were　dismissed；　the　former　falling　precipitately；　while　the　latter　sailed　down　to　a　village　below。　　All　available　ballast　was　now　thrown　out；　including　a　spare　great　coat　and　the　remains　of　supper；　with　the　result　that　at　9。30　the　barometer　had　fallen　to　22　inches；　and　at　this　height　they　caught　sight　of　the　upper　rim　of　the　sun。　　The　action　of　heart　and　lungs　remained　normal。　　No　stars　were　seen；　though　the　sky　was　mainly　clear；　such　clouds　as　were　visible　appearing　white　and　at　a　great　height。　　The　echo　of　a　speaking　trumpet　was　heard　after　an　interval　of　ten　seconds。　　This　was　substantially　the　outcome　of　the　experiments。　　The　practical　difficulties　of　carrying　out　prearranged　observations　amid　the　inconvenience　of　balloon　travel　were　much　felt。　　Their　instruments　were　seriously　damaged；　and　their　results；　despite　most　painstaking　and　praiseworthy　efforts；　must　be　regarded　as　somewhat　disappointing。

But　ere　the　autumn　of　the　same　year　two　other　scientific　ascents；　admirably　schemed　and　financed　at　the　public　expense；　had　been　successfully　carried　out　at　Paris　in　a　war　balloon　which；　as　will　be　told；　had　at　this　time　been　returned　from　military　operations　in　Egypt。　　In　the　first　of　these；　Gay　Lussac　ascended　in　company　with　M。　Biot；　with　very　complete　equipment。　　Choosing　ten　o'clock　in　the　morning　for　their　hour　of　departure；　they　quickly　entered　a　region　of　thin；　but　wet　fog；　after　which　they　shot　up　into　denser　cloud；　which　they　completely　surmounted　at　a　height　of　6；500　feet；　when　they　described　the　upper　surface　as　bearing　the　resemblance；　familiar　enough　to　aeronauts　and　mountaineers；　as　of　a　white　sea　broken　up　into　gently　swelling　billows；　or　of　an　extended　plain　covered　with　snow。

A　series　of　simple　experiments　now　embarked　upon　showed　the　behaviour　of　magnetised　iron；　as　also　of　a　galvanic　pile　or　battery；　to　remain　unaltered。　　As　their　altitude　increased　their　pulses　quickened；　though　beyond　feeling　keenly　the　contrast　of　a　colder　air　and　of　scorching　rays　of　the　sun　they　experienced　no　physical　discomfort。　　At　11；000　feet　a　linnet　which　they　liberated　fell　to　the　earth　almost　helplessly；　while　a　pigeon　with　difficulty　maintained　an　irregular　and　precipitate　flight。　　A　carefully　compiled　record　was　made　of　variations　of　temperature　and　humidity；　and　they　succeeded　in　determining　that　the　upper　air　was　charged　with　negative　electricity。　　In　all　this　these　two　accomplished　physicists　may　be　said　to　have　carried　out　a　brilliant　achievement；　even　though　their　actual　results　may　seem　somewhat　meagre。　　They　not　only　were　their　own　aeronauts；　but　succeeded　in　arranging　and　carrying　out　continuous　and　systematic　observations　throughout　the　period　of　their　remaining　in　the　sky。

This　voyage　was　regarded　as　such　a　pronounced　success　that　three　weeks　later；　in　mid…September；　Gay　Lussac　was　induced　to　ascend　again；　this　time　alone；　and　under　circumstances　that　should　enable　him　to　reach　an　exceptionally　high　altitude。　　Experience　had　taught　the　advisability　of　certain　modifications　in　his　equipment。　　A　magnet　was　ingeniously　slung　with　a　view　of　testing　its　oscillation　even　in　spite　of　accidental　gyrations　in　the　balloon。　　Thermometers　and　hygrometers　were　carefully　sheltered　from　the　direct　action　of　the　sun；　and　exhausted　flasks　were　supplied　with　the　object　of　bringing　down　samples　of　upper　air　for　subsequent　analysis。

Again　it　was　an　early　morning　ascent；　with　a　barometer　on　the　ground　standing　at　30。6　inches；　and　a　slightly　misty　air。　　Lussac　appears　to　have　accomplished　the　exceedingly　difficult　task　of　counting　the　oscillations　of　his　magnet　with　satisfaction　to　himself。　　At　10；000　feet　twenty　vibrations　occupied　83　seconds；　as　compared　with　84。33　seconds　at　the　earth's　surface。　　The　variation　of　the　compass　remained　unaltered；　as　also　the　behaviour　of　magnetised　iron　at　all　altitudes。　　Keeping　his　balloon　under　perfect　control；　and　maintaining　a　uniform　and　steady　ascent；　he　at　the　same　time　succeeded　in　compiling　an　accurate　table　of　readings　recording　atmospheric　pressure；　temperature　and　humidity；　and　it　is　interesting　to　find　that　he　was　confronted　with　an　apparent　anomaly　which　will　commonly　present　itself　to　the　aeronaut　observer。　　Up　to　12；000　feet　the　temperature　had　decreased　consistently　from　82　degrees　to　47　degrees；　after　which　it　increased　6　degrees　in　the　next　2；000　feet。　　This　by　no　means　uncommon　experience　shall　be　presently　discussed。　　The　balloon　was　now　steadily　manoeuvred　up　to　18；636　feet；　at　which　height　freezing　point　was　practically　reached。　　Then　with　a　further　climb　20；000　feet　is　recorded；　at　which　altitude　the　ardent　philosopher　could　still　attend　to　his　magnetic　observations；　nor　is　his　arduous　and　unassisted　task　abandoned　here；　but　with　marvellous　pertinacity　he　yet　struggl