the dominion of the air-第21章

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Wise；　by　his　expedient　of　tying　ribbons　at　different　points　to　his　trail　rope；　would　obtain　much　more　correct　and　constant　information　respecting　those　general　streams　through　which　the　pendant　rope　was　moving。　　A　similar　expedient　adopted　by　the　same　ingenious　aeronaut　is　worthy　of　imitation；　namely；　that　of　tying　ribbons　on　to　a　rod　projecting　laterally　from　the　car。　　These　form　a　handy　and　constant　telltale　as　to　the　flight　of　the　balloon；　for　should　they　be　fluttering　upwards　the　sky　sailor　at　once　knows　that　his　craft　is　descending；　and　that　he　must　act　accordingly。

The　material；　pure　silk；　which　was　universally　adopted　up　to　and　after　the　period　we　are　now　regarding；　is　not　on　every　account　to　be　reckoned　the　most　desirable。　　In　the　first　place；　its　cost　alone　is　prohibitive；　and　next；　although　lighter　than　any　kind　of　linen；　strength　for　strength；　it　requires　a　greater　weight　of　varnish；　which；　moreover；　it　does　not　take　so　kindly　as　does　fabric　made　of　vegetable　tissue。　　Further；　paradoxical　as　it　may　appear；its　great　strength　is　not　entirely　an　advantage。　　There　are　occasions　which　must　come　into　the　experience　of　every　zealous　aeronaut　when　his　balloon　has　descended　in　a　rough　wind；　and　in　awkward　country。　　This　may；　indeed；　happen　even　when　the　ascent　has　been　made　in　calm。　　Squalls　of　wind　may　spring　up　at　short　notice；　or　after　traversing　only　two　or　three　counties　a　strong　gale　may　be　found　on　the　earth；　though　such　was　absent　in　the　starting　ground。　　This　is　more　particularly　the　case　when　the　landing　chances　to　be　on　high　ground　in　the　neighbourhood　of　the　sea。　　In　these　circumstances；　the　careful　balloonist；　who　will　generally　be　forewarned　by　the　ruffle　on　any　water　he　may　pass；　or　by　the　drift　of　smoke；　the　tossing　of　trees；　or　by　their　very　rustling　or　〃singing〃　wafted　upwards　to　him；　will；　if　possible；　seek　for　his　landing　place　the　lee　of　a　wood　or　some　other　sheltered　spot。　　But；　even　with　all　his　care；　he　will　sometimes　find　himself；　on　reaching　earth；　being　dragged　violently　across　country　on　a　mad　course　which　the　anchor　cannot　check。　　Now；　the　country　through　which　he　is　making　an　unwilling　steeplechase　may　be　difficult；　or　even　dangerous。　　Rivers；　railway　cuttings；　or　other　undesirable　obstacles　may　lie　ahead；　or；　worse　yet；　such　a　death　trap　as　in　such　circumstances　almost　any　part　of　Derbyshire　affords；　with　its　stone　walls；　its　precipitous　cliffs；　and　deep　rocky　dells。　　To　be　dragged　at　the　speed　of　an　express　train　through　territory　of　this　description　will　presently　mean　damage　to　something；　perhaps　to　telegraph　poles；　to　roofs；　or　crops；　and　if　not；　then　to　the　balloon　itself。　　Something　appertaining　to　it　must　be　victimised；　and　it　is　in　all　ways　best　that　this　should　be　the　fabric　of　the　balloon　itself。　　If　made　of　some　form；　or　at　least　some　proportion　of　linen；　this　will　probably　rend　ere　long；　and；　allowing　the　gas　to　escape；　will　soon　bring　itself　to　rest。　　On　the　other　hand；　if　the　balloon　proper　is　a　silk　one；　with　sound　net　and　in　good　condition；　it　is　probable　that　something　else　will　give　way　first；　and　that　something　may　prove　to　be　the　hapless　passenger　or　passengers。

And　here　be　it　laid　down　as　one　first　and　all…important　principle；　that　in　any　such　awkward　predicament　as　that　just　described；　if　there　be　more　than　one　passenger　aboard；　let　none　attempt　to　get　out。　　In　the　first　place；　he　may　very　probably　break　a　limb　in　so　doing；　inasmuch　as　the　tangle　of　the　ropes　will　not　allow　of　his　getting　cut　readily；　or；　when　actually　on　the　ground；　he　may　be　caught　and　impaled　by　the　anchor　charging　and　leaping　behind。　　But；　worse　than　all；　he　may；　in　any　case；　jeopardise　the　lives　of　his　companions；　who　stand　in　need　of　all　the　available　weight　and　help　that　the　car　contains　up　to　the　moment　Of　coming　to　final　rest。

We　have　already　touched　on　the　early　notions　as　to　the　means　of　steering　a　balloon。　　Oars　had　been　tested　without　satisfactory　result；　and　the　conception　of　a　rotary　screw　found　favour　among　theorists　at　this　time；　the　principle　being　actually　tried　with　success　in　working　models；　which；　by　mechanical　means；　could　be　made　to　flit　about　in　the　still　air　of　the　lecture　room；　but　the　only　feasible　method　advocated　was　that　already　alluded　to；　which　depended　on　the　undesirable　action　of　a　trail　rope　dragging　over　the　ground　or　through　water。　　The　idea　was；　of　course；　perfectly　practical；　and　was　simply　analogous　to　the　method　adopted　by　sailors；　who；　when　floating　with　the　stream　but　without　wind；　are　desirous　of　gaining　〃steerage　way。〃　　While　simply　drifting　with　the　flood；　they　are　unable　to　guide　their　vessel　in　any　way；　and　this；　in　practice；　is　commonly　effected　by　simply　propelling　the　vessel　faster　than　the　stream；　in　which　case　the　rudder　at　once　becomes　available。　　But　the　same　result　is　equally　well　obtained　by　slowing　the　vessel；　and　this　is　easily　accomplished　by　a　cable；　with　a　small　anchor　or　other　weight　attached；　dragging　below　the　vessel。　　This　cable　is　essentially　the　same　as　the　guide…rope　of　the　older　aeronauts。

It　is　when　we　come　to　consider　the　impressions　and　sensations　described　by　sky　voyagers　of　bygone　times　that　we　find　them　curiously　at　variance　with　our　own。　　As　an　instance；　we　may　state　that　the　earth；　as　seen　from　a　highflying　balloon；　used　to　be　almost　always　described　as　appearing　concave；　or　like　a　huge　basin；　and　ingenious　attempts　were　made　to　prove　mathematically　that　this　must　be　so。　　The　laws　of　refraction　are　brought　in　to　prove　the　fact；　or；　again；　the　case　is　stated　thus：　　Supposing　the　extreme　horizon　to　be　seen　when　the　balloon　is　little　more　than　a　mile　high；　the　range　of　view　on　all　sides　will　then　be；　roughly；　some　eighty　miles。　　If；　then；　a　line　were　drawn　from　the　aerial　observer　to　this　remote　distance；　that　line　would　be　almost　horizontal；　so　nearly　so　that　he　cannot　persuade　himself　that　his　horizon　is　otherwise　than　still　on　a　level　with　his　eye；　yet　the　earth　below　him　lies；　as　it　seems；　at　the　bottom　of　a　huge　gulf。　　Thus　the　whole　visible　earth　appears　as　a　vast　bowl　or　basin。　　This　is　extremely　ingenious　reasoning；　and　not　to　be　disregarded；　but　the　fact　remains　that　in　the　experience　of　the　writer　and　of　many　others　whom　he　has　consulted；　there　is　no　such　optical　illusion　as　I　have　just　discussed；　and　to　their　vision　it　is　impossible　to　regard　the　earth　as　anything　but　uniformly　flat。

Another　impression　invariably　insisted　on　by　early　balloonists　is　that　the　earth；　on　quitting　it；　appears　to　drop　away　into　an　abyss；　leaving　the　voyagers　motionless；　and　this　illusion　must；　indeed；　be　probably　universal。　　It　is　the　same　illusion　as　the　apparent　gliding　backwards　of　objects　to　a　traveller　in　a　railway　carriage；　only　in　this　latter　case　the　rattling　and　shaking　of　the　carriage　helps　the　mind　to　grasp　the　real　fact　that　the　motion　belongs　to　the　train　itself；　whereas　it　is　otherwise　with　a　balloon；　whose　motion　is　so　perfectly　smooth　as　to　be　quite　imperceptible。

Old　ideas；　formed　upon　insufficient　observations；　even　if　erroneous；　were　slow　to　die。　　Thus　it　used　to　be　stated　that　an　upper　cloud　floor　adapted　itself　to　the　contour　of　the　land　over　which　it　rested；　giving　what　Mr。　Monck　Mason　has　called　a　〃phrenological　estimate〃　of　the　character　of　the　earth　below；　the　clouds；　〃even　when　under　the　influence　of　rapid　motion；　seeming　to　accommodate　themselves　to　all　variations　of　form　in　the　surface　of　the　subjacent　soil；　rising　with　its　prominences　and　sinking　with　its　depressions。〃　　Probably　few　aeronauts　of　the　present　time　will　accept　the　statement。

It　used　commonly　to　be　asserted；　and　is　so　often　to　this　day；　that　a　feeling　as　of　sea…sickness　is　experienced　in　balloon　travel；　and　the　notion　has　undoubtedly　arisen　from　the　circumstances　attending　an　ascent　in　a　captive　balloon。　　It　were　well；　now　that　ballooning　bids　fair　to　become　popular；　to　disabuse　the　public　mind　of　such　a　wholly　false　idea。　　The　truth　is　that　a　balloon　let　up　with　a　lengthy　rope　and　held　captive　will；　with　a　fitful　breeze；　pitch　and　sway　in　a　manner　which　may　induce　all　the　unpleasant　feelings　attending　a　rough　passage　at　sea。　　It　may　do　worse；　and　even　be　borne　to　earth　with　a　puff　of　wind　which　may　come　unexpectedly；　and　considerably　un