16 Aérial 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’ wings, 
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. 
_— §: 
we A Paen oe a 
PELL | | I 
BN 3 A d 
ae TG <i 
i = 
E meas 
A 
p> am8 | fam, 
ae) | | Pe | | PS F 
r | ‘ ; Cc & owed 
Figure 1.—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 downwards so that the wing can be raised with a great 
