is he states with truth that, "a balloon which
presents to the action of the atmosphere a volume of from 22,000 to
42,000 [cubic] feet of a gas from ten to fifteen times lighter than air,
is, by its very nature, smitten with incapacity to struggle against the
slightest current, no matter what may be the resisting motive force
which may be imparted to it. Both by its constitution, and by the
medium which drives it hither and thither at the pleasure of the winds,
it can never become a vessel. It is a buoy, and remains a buoy."

Discarding, therefore, with contempt, the balloon as an aerial
locomotive, he announces his belief that it is the _screw_ which is
destined to drive us, or clamber with us, into the blue vault above, and
convey us from place to place. And here it is right to assure the
reader that the theoretical power of the screw to accomplish the end in
view is not a disputable question. It has been practically proved by
models, and the only point that remains to be settled is the possibility
of applying the power to machines large enough to carry human beings
with a sufficient degree of safety to warrant risking the attempt.

Monsieur Nadar sets out with a statement which he deems self-evident,
namely, that, "in order to contend against the air, we must be
specifically heavier than the air"--a truth which was also, we are told,
announced by the first Napoleon in the epigrammatic sentence, "There can
be no progress without resistance." From this the Frenchman proceeds to
prove that, in order to command the air, it is necessary to support
one's-self upon it, instead of being at its mercy; that we can only rest
upon that which resists, and that the air itself furnishes us amply with
the needful resistance--it being "the same atmosphere which overturns
walls, tears up by the root trees a century old, and enables ships to
ascend impetuous currents." Glowing with the ardour of a man whose
faith is refreshingly great, he tells us that the time has at last come
when the atmosphere must yield to man. "It is for man," he says, "to
restrain and subdue this insolent and abnormal rebellion, which has for
so many years laughed at our vain efforts. We are in turn about to make
it serve us as a slave, just as the water on which we launch the ship,
as the solid earth on which we press the wheel!"

There is a toy called the _spiralifer_, which is common enough in towns,
and which is, doubtless, known to almost every one