82 On Aerial Navigation. 
of the sine of the angle of incidence,—it will require about 
12450 pounds to produce this rate of conveyance in Mr. Evans’s 
balloon; and hence the power he allows is not one-fourth part 
of what is required. This apparatus would, however, according 
to my calculation, travel with the speed of about 8} miles per 
hour*, which is quite sufficient to show the utility of the princi- 
ple, whether the mistake be in Mr. Evans’s figures or my own. 
A few years ago I made many experiments upon the power 
of iticlined planes, some of which exceeded 300 square feet in 
area: an account of these may be seen in Mr. Nicholson’s Jour- 
nal for November 1809, and February and March 1810.” It 
may be affirmed with confidence from these experiments, that in 
obliquely descending the efficacy and steerage of the inclined 
plane have been completely ascertained. My object was to leave - 
out the unwieldy bulk of balloons altogether, and to make use 
of the intlined plane propelled by a light first mover. Although 
my attention has hitherto been diverted from making further 
experiments, I am fully convinced that this mode of aerial na- 
vigation is practicable, and will, ere long, be accomplished. In 
the mean time I shall be glad to promote any promising ex- 
periments upon the steerage of balloons, and therefore offer the 
following observations through the medium of your Magazine. 
In considering the means for obviating the relative resistance 
of balloons in passing swiftly through the air, the leading ge- 
neral principle is evidently to increase their dimensions far be- 
yond the limits hitherte adopted. The weight of their super- 
ficial materials, and the resistance they meet with, being as the 
squares of their diameters; whereas their power of support be- 
ing as the cubes of these diameters, it follows that their power 
may be made to bear any required proportion to their resistance. 
Thus a balloon of one yard in diameter meets with ten times 
more resistance, in proportion to its power, than a balloon of ten 
vards in diameter. 
The next consideration is, that a globe is by no means the best 
shape for obviating resistance; a greater extension in the line 
of its path, with a corresponding diminution in the section per- 
pendicular to it, may be adopted with great advantage. Keeping 
in view these two leading principles, the former of which places 
the proper scale of experiments beyond the expense that indivi- 
duals choose to appropriate to such purposes, I propose that 
the following plan be adopted by those desirous of promoting 
this noble art :—First, that a subscription be entered into for 
* An error in the paper of Mr, Evans was corrected in our number for 
December, making the velocity 10} miles per hour. 
obtaining 
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