cold air; the necessity of feeding the fire, and watching it
without a moment's cessation, as it hangs in the rechaud over the
middle of the car, rendered this sort of air travelling subject
to many dangers and difficulties. Recently, M. Eugene Godard has
obviated a portion of this difficulty by fitting a chimney, like
that which is found of such incalculable service in the case of
the Davy lamp. It is principally on account of this improvement
that the Montgolfiere has risen so highly in popular esteem.

Generally it is not pure hydrogen that is made use of in the
inflation of balloons. Aeronauts content themselves with the gas
which we burn in our streets and houses, and thus it suffices, in
inflating the balloon, to obtain from the nearest gas-works the
quantity of gas necessary, and to lead it, by means of a pipe or
tube, from the gasometer to the mouth or neck of the machine.

The balloon is made of long strips of silk, sewn together, and
rendered air-tight by means of a coating of caoutchouc. A valve
is fitted to the top, and by means of it the aeronaut can descend
to the earth at will, by allowing some quantity of the gas to
escape. The car in which he sits is suspended to the balloon by
a network, which covers the whole structure. Sacks of sand are
carried in this car as ballast, so that, when descending, if the
aeronaut sees that he is likely to be precipitated into the sea
or into a lake, he throws over the sand, and his air-carriage,
being thus lightened, mounts again and travels away to a more
desirable resting-place. The idea of the valve, as well as that
of the sand ballast, is due to the physician Charles. They
enable the aeronaut to ascend or descend with facility. When he
wishes to mount, he throws over his ballast; when he wants to