is than a subscription was raised, and
M. Charles, Professor of Experimental Philosophy, was appointed, with
the assistance of M. Roberts, to superintend the construction of a
suitable balloon and its inflation by the proposed new method.

The task was one of considerable difficulty, owing partly to the
necessity of procuring some material which would prevent the escape of
the lightest and most subtle gas known, and no less by reason of the
difficulty of preparing under pressure a sufficient quantity of gas
itself. The experiment, sound enough in theory, was eventually carried
through after several instructive failures. A suitable material was
found in "lustring," a glossy silk cloth varnished with a solution of
caoutchouc, and this being formed into a balloon only thirteen feet in
diameter and fitted without other aperture than a stopcock, was after
several attempts filled with hydrogen gas prepared in the usual way by
the action of dilute sulphuric acid on scrap iron.

The preparations completed, one last and all-important mistake was
made by closing the stop-cock before the balloon was dismissed, the
disastrous and unavoidable result of this being at the time overlooked.

On August 25, 1783, the balloon was liberated on the Champ de Mars
before an enormous concourse, and in less than two minutes had reached
an elevation of half a mile, when it was temporarily lost in cloud,
through which, however, it penetrated, climbing into yet higher cloud,
when, disappearing from sight, it presently burst and descended to earth
after remaining in the air some three-quarters of an hour.

The bursting of this little craft taught the future balloonist his first
great lesson, namely, that on leaving earth he must open the neck of
his balloon; and the reason of this is obvious. While yet on earth the
imprisoned gas of a properly filled balloon distends the silk by virtue
of its expansive force, and in spite of the enormous outside pressure
which the weight of air exerts upon it. Then, as the balloon rises
high in the air and the outside pressure grows less, the struggling gas
within, if allowed no vent, stretches the balloon more and more until
the slender fabric bursts under the strain.

At the risk of being tedious, we have dwelt at some length on the
initial experiments which in less than a single year had led to the
discovery and development of two distinct methods--still employed and in
competition with each other--of dismiss