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THE BALLOON.
Two very decided failures, of late--those of Mr. Henson and Sir George
Cayley--had much weakened the public interest in the subject of aerial
navigation. Mr. Henson's scheme (which at first was considered very
feasible even by men of science,) was founded upon the principle of an
inclined plane, started from an eminence by an extrinsic force, applied
and continued by the revolution of impinging vanes, in form and number
resembling the vanes of a windmill. But, in all the experiments made
with models at the Adelaide Gallery, it was found that the operation of
these fans not only did not propel the machine, but actually impeded
its flight. The only propelling force it ever exhibited, was the mere
impetus acquired from the descent of the inclined plane; and this
impetus carried the machine farther when the vanes were at rest, than
when they were in motion--a fact which sufficiently demonstrates their
inutility; and in the absence of the propelling, which was also the
sustaining power, the whole fabric would necessarily descend.
This consideration led Sir George Cayley to think only of adapting
a propeller to some machine having of itself an independent power of
support--in a word, to a balloon; the idea, however, being novel,
or original, with Sir George, only so far as regards the mode of its
application to practice. He exhibited a model of his invention at the
Polytechnic Institution. The propelling principle, or power, was here,
also, applied to interrupted surfaces, or vanes, put in revolution.
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