the dominion of the air-第2章

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his　speculations　standing　on　a　giant's　shoulders。　　Torricelli；　with　his　closed　bent　tube；　had　just　shown　the　world　how　heavily　the　air　lies　above　us。　　It　then　required　little　mathematical　skill　to　calculate　what　would　be　the　lifting　power　of　any　vessel　void　of　air　on　the　earth's　surface。　　Thus　Lana　proposed　the　construction　of　an　air　ship　which　possibly　because　of　its　　　picturesquesness　has　won　him　notoriety。　　But　it　was　a　fraud。　　We　have　but　to　conceive　a　dainty　boat　in　which　the　aeronaut　would　sit　at　ease　handling　a　little　rudder　and　a　simple　sail。　　These；　though　a　schoolboy　would　have　known　better；　he　thought　would　guide　his　vessel　when　in　the　air。

So　much　has　been　claimed　for　Father　Lana　and　his　mathematical　and　other　attainments　that　it　seems　only　right　to　insist　on　the　weakness　of　his　reasoning。　　An　air　ship　simply　drifting　with　the　wind　is　incapable　of　altering　its　course　in　the　slightest　degree　by　either　sail　or　rudder。　　It　is　simply　like　a　log　borne　along　in　a　torrent；　but　to　compare　such　a　log　properly　with　the　air　ship　we　must　conceive　it　WHOLLY　submerged　in　the　water　and　having　no　sail　or　other　appendage　projecting　into　the　air；　which　would；　of　course；　introduce　other　conditions。　　If；　however；　a　man　were　to　sit　astride　of　the　log　and　begin　to　propel　it　so　that　it　travels　either　faster　or　slower　than　the　stream；　then　in　that　case；　either　by　paddle　or　rudder；　the　log　could　be　guided；　and　the　same　might　be　said　of　Lana's　air　boat　if　only　he　had　thought　of　some　adequate　paddle；　fan；　or　other　propeller。　　But　he　did　not。　　One　further　explanatory　sentence　may　here　be　needed；　for　we　hear　of　balloons　which　are　capable　of　being　guided　to　a　small　extent　by　sail　and　rudder。　　In　these　cases；　however；　the　rudder　is　a　guide　rope　trailing　on　earth　or　sea；　so　introducing　a　fresh　element　and　fresh　conditions　which　are　easy　to　explain。

Suppose　a　free　balloon　drifting　down　the　wind　to　have　a　sail　suddenly　hoisted　on　one　side；　what　happens？　　The　balloon　will　simply　swing　till　this　sail　is　in　front；　and　thus　continue　its　straightforward　course。　　Suppose；　however；　that　as　soon　as　the　side　sail　is　hoisted　a　trail　rope　is　also　dropped　aft　from　a　spar　in　the　rigging。　　The　tendency　of　the　sail　to　fly　round　in　front　is　now　checked　by　the　dragging　rope；　and　it　is　constrained　to　remain　slanting　at　an　angle　on　one　side；　at　the　same　time　the　rate　of　the　balloon　is　reduced　by　the　dragging　rope；　so　that　it　travels　slower　than　the　wind；　which；　now　acting　on　its　slant　sail；　imparts　a　certain　sidelong　motion　much　as　it　does　in　the　case　of　a　sailing　boat。

Lana　having　in　imagination　built　his　ship；　proceeds　to　make　it　float　up　into　space；　for　which　purpose　he　proposes　four　thin　copper　globes　exhausted　of　air。　　Had　this　last　been　his　own　idea　we　might　have　pardoned　him。　　We　have；　however；　pointed　out　that　it　was　not；　and　we　must　further　point　out　that　in　copying　his　great　predecessor　he　fails　to　see　that　he　would　lose　enormous　advantage　by　using　four　globes　instead　of　one。　　But；　beyond　all；　he　failed　to　see　what　the　master　genius　of　Bacon　saw　clearlythat　his　thin　globes　when　exhausted　must　infallibly　collapse　by　virtue　of　that　very　pressure　of　the　air　which　he　sought　to　make　use　of。

It　cannot　be　too　strongly　insisted　on　that　if　the　too　much　belauded　speculations　of　Lana　have　any　value　at　all　it　is　that　they　throw　into　stronger　contrast　the　wonderful　insight　of　the　philosopher　who　so　long　preceded　him。　　By　sheer　genius　Bacon　had　foreseen　that　the　emptied　globe　must　be　filled　with　SOMETHING；　and　for　this　something　he　suggests　〃ethereal　air〃　or　〃liquid　fire；〃　neither　of　which；　we　contend；　were　empty　terms。　　With　Bacon's　knowledge　of　experimental　chemistry　it　is　a　question；　and　a　most　interesting　one；　whether　he　had　not　in　his　mind　those　two　actual　principles　respectively　of　gas　and　air　rarefied　by　heat　on　which　we　launch　our　balloons　into　space　to…day。

Early　progress　in　any　art　or　science　is　commonly　intermittent。　　It　was　so　in　the　story　of　aeronautics。　　Advance　was　like　that　of　the　incoming　tide；　throwing　an　occasional　wave　far　in　front　of　its　rising　flood。　　It　was　a　phenomenal　wave　that　bore　Roger　Bacon　and　left　his　mark　on　the　sand　where　none　other　approached　for　centuries。　　In　those　centuries　men　were　either　too　priest…ridden　to　lend　an　ear　to　Science；　or；　like　children；　followed　only　the　Will…o'…the…Wisp　floating　above　the　quagmire　which　held　them　fast。　　They　ran　after　the　stone　that　was　to　turn　all　to　gold；　or　the　elixir　that　should　conquer　death；　or　the　signs　in　the　heavens　that　should　foretell　their　destinies；　and　the　taint　of　this　may　be　traced　even　when　the　dark　period　that　followed　was　clearing　away。　　Four　hundred　years　after　Roger's　death；　his　illustrious　namesake；　Francis　Bacon；　was　formulating　his　Inductive　Philosophy；　and　with　complete　cock…sureness　was　teaching　mankind　all　about　everything。　　Let　us　look　at　some　of　his　utterances　which　may　help　to　throw　light　on　the　way　he　regarded　the　problem　we　are　dealing　with。

〃It　is　reported；〃　Francis　Bacon　writes；　〃that　the　Leucacians　in　ancient　time　did　use　to　precipitate　a　man　from　a　high　cliffe　into　the　sea；　tying　about　him；　with　strings；　at　some　distance；　many　great　fowles；　and　fixing　unto　his　body　divers　feathers；　spread；　to　breake　the　fall。　　Certainly　many　birds　of　good　wing　（as　Kites　and　the　like）　would　beare　up　a　good　weight　as　they　flie。　　And　spreading　of　feathers；　thin　and　close；　and　in　great　breadth；　will　likewise　beare　up　a　great　weight；　being　even　laid　without　tilting　upon　the　sides。　　The　further　extension　of　this　experiment　of　flying　may　be　thought　upon。〃

To　say　the　least；　this　is　hardly　mechanical。　　But　let　us　next　follow　the　philosopher　into　the　domain　of　Physics。　　Referring　to　a　strange　assertion；　that　〃salt　water　will　dissolve　salt　put　into　it　in　less　time　than　fresh　water　will　dissolve　it；〃　he　is　at　once　ready　with　an　explanation　to　fit　the　case。　　〃The　salt；〃　he　says；　〃in　the　precedent　water　doth　by　similitude　of　substance　draw　the　salt　new　put　in　unto　it。〃　　Again；　in　his　finding；　well　water　is　warmer　in　winter　than　summer；　and　〃the　cause　is　the　subterranean　heat　which　shut　close　in　（as　in　winter）　is　the　more；　but　if　it　perspire　（as　it　doth　in　summer）　it　is　the　less。〃　　This　was　Bacon　the　Lord。　　What　a　falling　offfrom　the　experimentalist's　point　of　viewfrom　Bacon　the　Friar！　　We　can　fancy　him　watching　a　falcon　poised　motionless　in　the　sky；　and　reflecting　on　that　problem　which　to　this　day　fairly　puzzles　our　ablest　scientists；　settling　the　matter　in　a　sentence：　　〃The　cause　is　that　feathers　doe　possess　upward　attractions。〃　　During　four　hundred　years　preceding　Lord　Verulam　philosophers　would　have　flown　by　aid　of　a　broomstick。　　Bacon　himself　would　have　merely　parried　the　problem　with　a　platitude！

At　any　rate；　physicists；　even　in　the　brilliant　seventeenth　century；　made　no　material　progress　towards　the　navigation　of　the　air；　and　thus　presently　let　the　simple　mechanic　step　in　before　them。　　Ere　that　century　had　closed　something　in　the　nature　of　flight　had　been　accomplished。　　It　is　exceedingly　hard　to　arrive　at　actual　fact；　but　it　seems　pretty　clear　that　more　than　one　individual；　by　starting　from　some　eminence；　could　let　himself　fall　into　space　and　waft　himself　away　for　some　distance　with　fair　success　and　safety；　It　is　stated　that　an　English　Monk；　Elmerus；　flew　the　space　of　a　furlong　from　a　tower　in　Spain；　a　feat　of　the　same　kind　having　been　accomplished　by　another　adventurer　from　the　top　of　St。　Mark's　at　Venice。

In　these　attempts　it　would　seem　that　the　principle　of　the　parachute　was　to　some　extent　at　least　brought　into　play。　　If　also　circumstantial　accounts　can　be　credited；　it　would　appear　that　a　working　model　of　a　flying　machine　was　publicly　exhibited　by　one　John　Muller　before　the　Emperor　Charles　V。　at　Nuremberg。　　Whatever　exaggeration　or　embellishment　history　may　be　guilty　of　it　is　pretty　clear　that　some　genuine　attempts　of　a　practical　and　not　unsuccessful　nature　had　been　made　here　and　there；　and　these　prompted　the　flowery　and　visionary　Bishop　Wilkins　already　quoted　to　predict　confidently　that　the　day　was　approaching　when　it　〃would　be　as　common　for　a　man　to　call　for　his　wings　as　for　boots　and　spurs。〃

We　have　now　to　return　to　the　〃tame　goose〃　method；　which　found　its　best　a