motion he is the movable fulcrum. Absolute stability, therefore, is
not a necessary condition of a fulcrum; it is sufficient that there
be, between the resistant force and the motive force, a difference of
intensity in favour of the former. Thus, in water, the fulcrum, being
liquid, is necessarily pliant and movable; yet it is quite possible,
as every child knows, to obtain in this element purchase sufficient to
steer the largest ships.

'In the air, which is a gas, the fulcrum being gaseous, must also be
movable; but although the air, being the most elastic body with which
we are acquainted, is therefore the least apt to furnish a fulcrum,
yet, as compressed air is capable of bursting the strongest metallic
receptacles, splitting the solid rock, and rending the bosom of the
earth, it would seem that we have only to act upon the air through
pressure, in order to obtain the requisite purchase from which to
steer.

'Foremost among those who are thus endeavouring to render the balloon
manageable, is M. Pétin of Paris, who has devoted fifteen years to the
study of this subject, the last three years to lecturing upon it in
the principal towns of France, and who has unfortunately expended the
whole of his resources in constructing an air-ship intended to
demonstrate, on a small scale, the possibility of steering according
to the system which he has elucidated. We say on a small scale; for
though the dimensions of the curious construction in question,
intended to carry two hundred passengers, will appear large to those
of our readers whose ideas of ballooning have never gone beyond the
ordinary ascensions so much in vogue at the present day, they are yet
of almost microscopic minuteness when compared with the developments
of which M. Pétin and his friends conceive his plans to be