THE EMPIRE OF THE AUI. 461 



or roctaii.uular forms, wirli ai'i'ia! rafts in the shape of an arrow, with 

 irreguhii' forms even. pro\ ided always that lie can shift the center of 

 gravity as retpiired; pro\ideil also, that the sustaining' snrl'ace be snlli- 

 cient in extent, and that the si>eed of the wind, or the speed of the 

 ;ero])lane, shall be about -2 miles ])vv hour. 



The j)roblcm. thus broadly stated, leads to sonn^ curious conse(|Uences, 

 Eventually, when success is achie\ed. we shall j)erhaps be <piite 

 surprised to see some second-hand apparatus circulating;' in the air; 

 some a'roplanes full of holes and rents, patclu'd u]), damai^ed and 

 mended, holdin.u' together by the ^racc of Providence, and yet glidinjj;' 

 along" after a fashion. These w ill n(»t be the best to resist the \icissi- 

 tndes of the wind, but they will get along Just the sajue. >>()W. what 

 is thei)roof of this :' 1 haxc conferred liberty upon kites and upon 

 Egyptian Nultuies whose llying surfaces were in deplorable condition; 

 some with wings almost [>lucke(l to bare ])oles, sonu' with a wing and a 

 half only (this lack of counterpoise in their sustaining surfaces ti'ou- 

 bles them greatly). I rt'memb<M' a particadar jxdican \\ ho glided upon 

 an incredible ])aii' of wings, lie had lost six or se\ en ])rintary feathers 

 at least, and the rest of his plumage was far from complete. Vvt, 

 when the wind blew fresh, he launched out from slojjing ground and 

 sonuitimes succeeded in getting under way. Once fairly u]) in air, In^ 

 became most surprising. (Hiding upon his ragged wings he would 

 skim within a yard of the observer, his ne<;k bent back, his head rest- 

 ing upon Ids shoulders with an air ol' sn[)reme impertinence. He 

 would go out for a tour over the sea, would come back to insj)ect the 

 nuxrket, and comjilete his perigrinations by settling down on the 

 waves. A most curious thing it was to see this creature, which was 

 quite tanu', pass close at hand, very swiftly, near the spectators. He 

 l)roduced a stiaiige sensation by gliding by with ease and no exertion. 

 It was a foretastii of the pleasures of a-rial sj)eed — a sort of class-room 

 gliding, in which the bird-jjrofessor was (eaching tin' beholdci's the art 

 of sailing lliglit. 



After all these digi'essions, the main question which conu's up is the 

 following: What is the least suiTace reouired to sustain a man and 

 ai)paratus, weighing 17()])ounds? 



I'lu' exa(;t answer must be, ascertained by experiment : butwcnuiy 

 even now say that it ])robably will astonish by its niedio(;i-ity. My 

 own idea is that Sii square fe(^t will snlUce, as a nnninuim, to sustain 

 170 jtounds in sailing flight. 



* * * * * * # 



ASprcKhifioii.s (IS to resiclt.s — Alter having discussed the bemdits to be 

 derived from the conquest of the air. Ictus now consider the ])ertur- 

 bations which it may cause. Let us see whether there is not some blot 

 on the other side of the shield; tor so important an achievemeid as 

 this new mode of locomotion can not take place without producing dis- 

 turbances. 



