First Hot-air .BaIkon: .,11Ontgol.Rre.—The Alontgolfiers, who were paper-manufacturers, and who were distinguished through their contrivance of the hydraulic ram, probably did not fully comprehend the principle of their invention; certainly they did not develop it so far as to use specifi cally light gases, etc.; but, as is well known, they received the happv in spiration for their invention by observing the ascending and moving clouds. " If such a cloud could be enclosed in a light envelope, this en velope would be carried through the air." This conclusion was the result of correct observation. "And as smoke "—thus, no doubt, further reasoned the inventors—" ascends like a cloud and moves onward, all that is required to raise a light balloon of paper or linen is to cause the smoke to pass into it from a fire kindled beneath." Paper, however, being too liable to tear, and the meshes of linen being too open, the 1\Iontgolfiers con structed a linen balloon lined with paper. On June 5, 1783, a globe of this description (fii. 6o, fig. I), Tx7 feet in circumference, inflated with hot air and gases of combustion, ascended at Annonay to the astonishing height of 1600 feet, and in ten minutes descended one and a half miles from its starting-point. This was the first successful experiment with the balloon, and the news of the event spread rapidly through all the countries of Europe. The balloon invented by the Montgolfiers was called a " fire balloon," or, as styled by the French, a nzontgoyi(Ve.
It is worthy of notice, in respect of the position of empiricism and science toward invention, that the Montgolfiers believed that the ascent of the balloon was caused by the smoke and gases of combustion with which it was inflated, and that they did not recognize that the balloon owed its lifting,-force to the air expanded and made lighter by the beat. of the smoke.
Experiments zvith Hydrogen Gas.—Science had now taken hold of the problem—or, rather, was led by the Montgolfiers in the right direction, long sought, but never before found. With the correct interpretation of the phenomenon of the rise of the hot-air balloon, the use of hydrogen sug gested itself; but there were doubts, from a scientific standpoint, of the possibility of preparing a sufficiently light and dense envelope to retain it. There were also fears of the inflammability of the hydrogen evolved in large quantities. The venture seems small enough at the present time, when we see hundreds of toy-balloons filled with hydrogen, or with ordi nary illmninating gas, carried about and occasionally flying in the air. We know, however, that the permeability' of the india-rubber of which they are made soon renders them useless, and therefore can form a conclu sion as to the difficulty at that time of preparing a gas-tight balloon of large dimensions—a task which even at present it is by no means easy to accompl ish.
Two brothers of the name of Robert, directed by M. Charles, professor of physics at the Conservatoire in Paris, endeavored by the use of taffeta covered with a thick coat of resinous varnish to fabricate a more dense, but nevertheless sufficiently light, envelope, and to give the balloon a firmer construction by covering it with a network of cords to which a gondola might be suspended. In the course of the first years of their experiments
they filled with hydrogen gas and liberated a number of balloons, whose aerial flights were followed by the public with intense interest. This in terest arose as much from the fantastic dreams and sanguine hopes which were associated with the near future of aerostation as from the more earn est reflections and quieter expectations which were induced by the prospect of a profitable application of the balloon to scientific purposes and to stra / tegical and other practical uses.
First Balloon: first was sent up from the Champ de Mars, in Paris, Aug,ust 27, 1783. This balloon, 13 feet in diameter, manufactured by the brothers Robert according to directions of M. Charles and inflated with hydrogen gas, rose rapidly about 3000 feet. At the expiration of threc-quarters of an hour it fell in a field about fifteen miles from the place of its ascension, where it was discovered by some peasants, who, fearing it was some uncanny thing that might do them harm, immediately tore it in shreds. A balloon of this description was then called an " air-balloon," because at that time hydrogen gas was known by the name of " inflammable air;" by the French the hydrogen balloon was styled a charh?re.
First first year after their invention the Montgolfiers were frequently engaged in sending up balloons filled with smoke or bot These ascensions, which were accompanied by festivities and the thunder of cannon, were watched with enthusiastic interest not only by Frenchmen, but also by the entire world. On the 19th of Septeniber, 1783, the Annonay experiment was repeated by Joseph Montgolfier at Ver sailles in the presence of the king, the queen, the court, and an immense concourse of spectators. Below the balloon there was suspended a basket or cage in which had been placed a duck, a cock, and a sheep. The bal loon rose to the height of about 13oo feet, and, with the animals—which were thus the first aeronauts—descended in safety two miles from the starting-point.
Pilatre de Raaler, a young- naturalist, was the first human being who ascended in a balloon. On October 15, 1783, and on several succeeding days, he mounted the gondola attached to a montgoyiere and made several experimental ascents at moderate heights, the balloon being held by ropes. He now resolved to undertake an aerial voyage in au unconfined balloon. Notwithstanding the opposition of Louis XVI., who at first would only consent that two condemned prisoners might be allowed to venture, De Rozier succeeded in overcoming- the king's objections and obtained per mission to nndertake the voyage. On November 21 of the same year, in company with the marquis D'Arlandes, he ascended from Paris in a free monIgolfit're (p. Go, Jig. 2), and after rising to a height of 3000 feet descended in safety five miles from the starting-point.