16 



Aerial Navigation. 



The materials of which they are constructed, ought to be the light- 

 est, strongest, and most durable that can be procured, the different 

 parts compactly joined, and susceptible of considerable elasticity. 

 They can even be made, on this principle, so light as to be only a 

 very little heavier, in proportion to their surface, than birds' Tilings, 

 and equally creative. The wings are calculated to supersede the 

 utility of the Parachute, to accelerate or retard ascent or descent at 

 pleasure, to insure progression and prevent fatal consequences from 

 the rarefied or inflammable air envelopes' being burst or torn when 

 elevated high above the earth. 



Figure 1. 

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C « 



Figure!. — ^In this representation of the wings, AA, BFB, CC, 

 and DD represent a light, strong wooden frame, twice as long as wide. 

 EE, a strong rod firmly fastened by its ends to the middle of the 

 sides AA, CC, of the frame, which is to be the axle or pivot of the 

 wing. All the hair lines represent strong wires with which the frame 

 is woven and cross-woven to strengthen it, and on which the valves 

 are to be hung. The frame being constructed and wired, the valves 

 are then to be hung, whose purpose is to admit the passage of the 

 incumbent air dovvnwards so that the wing can be raised with a great 



