CHAPTER X.
THE SECOND AERIAL VOYAGE.
(1st December 1783.—Charles and Robert at the Tuileries.)
The first ascent of Roziers and Arlandes was a feat of hardihood almost unique. The men's courage was, so to speak, their only guarantee. Thanks to the balloon, however, they accomplished one of the most extraordinary enterprises ever achieved by our race.
On the day after the experiment of the Champ de Mars (27th of August), Professor Charles—who had already acquired celebrity at the Louvre, by his scientific collection and by his rank as an official instructor—and the Brothers Robert, mechanicians, were engaged in the construction of a balloon, to be inflated with hydrogen gas, and destined to carry a car and one or two passengers. For this ascent Charles may be said to have created all at once the art of aerostation as now practiced, for he brought it at one bound to such perfection that since his day scarcely any advance has been made upon his arrangements. His simple yet complete invention was that of the valve which gives escape to the hydrogen gas, and thus renders the descent of the balloon gentle and gradual; the car that carries the travellers; the ballast of sand, by which the ascent is regulated and the fall is moderated; the coating of caoutchouc, by means of which the material of the balloon is rendered airtight and prevents loss of gas; and, finally, the use of the barometer, which marks at every instant, by the elevation or
