Aérial Navigation. 23 
Having explained my theory of aérial navigation, I will now endeav- 
or to illustrate its princples more clearly by an example. Suppose an 
oval balloon, thirty feet long and twenty two feet high or wide, was 
filled with the lightest inflammable air, so as to raise four hundred 
and twenty pounds, independently of the weight of itself, net-like en- 
velope, pilot and passenger cars, and wings, as represented in figure 
2, sixteen feet in diameter.. ‘Two men enter the passenger car, both 
weighing two hundred and eighty pounds, and one the pilot car weigh- 
ing one hundred and forty, making in all four hundred and twenty. 
Now it is evident that the ascensive power exactly balances or equals 
that of gravity and that the smallest weight added to either, will give 
it the ascendency or the least percussion of the wings, and consequent- 
ly reaction of the air, will cause the whole to ascend till equilibrated 
in the air. Now both being in equilibrium, suppose twenty pounds of 
ballast, (as any number can be added that can be raised with ease 
by the percussion of the wings,) to be put in the passenger car, which 
will give to gravity so much the ascendency. In order to descend, 
vertically, in a calm atmosphere, the pilot, standing upright in 
the center of his car, must, by the wings, strike the air, with suf- 
ficient force to raise the twenty pounds. Having ascended suffi- 
ciently to descend vertically, the pilot has only to cease moving the 
wings, and the _— . the: twenty“pounds will bring the acct ves- 
sel or machine down he must keep 
the handles of the winks Feet, and all the air under them will have 
to pass through the space he occupies at their center, while, if fast, 
the handles must be held down and all the air under them will rush 
out at their sides, as the valves of the wings on each side of the 
axles, all close air tight, in descent. 
Having now shown the manner of vertical ascent and descent, I 
will explain the manner of progression. ‘There are four ways of dri- 
ving or impelling this vessel or machine through the air; by gravity, 
oblique percussion, the wind, and percussion from vertical wings, and 
three kinds of progression, ascensive, descensive and direct. The 
balloon being elevated as far as required to reach any place; the pi- 
lot, in order to impel it there, must stop moving the wings and step a 
little from the center of his car or line of gravity toward it, which will 
cause the wings to incline, while the twenty pounds will impel it for- 
ward, as it were, down an inclined plain to the intended place. ‘The 
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This is descensive progression. F 
