Page:The New International Encyclopædia 1st ed. v. 01.djvu/195

AERONAUTICS. multitude, they raised a balloon 35 feet in diameter to a height of 1500 feet. This balloon, nearly spherical in shape, was made of packcloth, covered with paper, and was heated by a small iron grate placed beneath it, in which ten pounds of moist straw and wool were burned.

The news of this extraordinary experiment soon reached Paris, where it produced a great sensation. A commission was appointed by the Academy of Sciences to report upon it. Public curiosity, however, could not await the tardy decision of this body, and accordingly a subscription was raised to defray the expense of repeating the Annonay experiment. Such was the excitement that the subscription was filled in a few days, and the construction of the balloon was intrusted to the brothers Robert, famous philosophical instrument makers of the day, and to Professor Charles, a young but experienced physicist. As the detailed account of the Annonay ascent had not reached Paris, and as nothing was therefore known of the Mont- golfier gas. Charles fixed upon hydrogen as the gas most likely to insure success. It was, how- ever, a formidable undertaking to produce it in sufficient abundance for a balloon, as it was at that time only prepared in small quantities in the lecture room and laboratory. By ingenuity and perseverance combined he triumphed over this difficulty, and succeeded in filling, in the course of four days, a silk globe 12 feet in diameter. This balloon was transferred to the Champs de Mars, the largest open space in Paris, where, on August 27, 1783, it ascended in the presence of 300,000 spectators, half the popula- tion of the city. At the instance of the commis- sion already referred to, Étienne Montgolfier constructed a fire-balloon 72 feet high and 41 feet in diameter. It ascended before the commis- sion on September 12, 1783, but being held cap- tive it was much injured by a violent wind which blew at the time, and after it descended it was finally broken up by heavy rains. Another was made, of nearly the same dimensions, which as- cended on the nineteenth of the same month at Versailles, the king and royal family witnessing the spectacle. This ascent is worthy of note, from the fact that a sheep, a cock, and a duck were placed in an osier basket attached to the lower part of the balloon, and that these first aërial voyagers reached the ground again in safety.

The balloon was now an accomplished fact, and it began to be discussed whether it might not he serviceable as an airship for bearing men aloft as passengers. The solution of this ques- tion was first given by Pilâtre de Rozier. In a montgolfière, as the heated air-balloon was called, 74 feet high and 48 feet in diameter, sup- porting at its base a gallery of wicker-work, he, in company with the Marquis d'Arlandes, made the first aërial voyage, November 21, 1783. They remained in the air twenty-five minutes, and sailed across the Seine and over a consider- able part of Paris. The year 1783, so fertile in the annals of aëronautics, witnessed an addi- tional, and even more satisfactory, triumph. On December 1, Professor Charles, along with Robert, rose from the Tuileries gardens with a hydrogen balloon — then called a Charlière — made with the proceeds of a public subscription. This balloon was made of alternately red and yellow gores of silk sewed together and coated with caoutchouc varnish. It was covered with a

net which supported the car, and was furnished with a valve, a barometer, and sand-ballast, and was, in fact, a complete aërial machine. In con- sequence of the danger attending the use of fire- balloons, and the engrossing attention which they demand of the aëronaut, they have now en- tirely given way to the hydrogen or coal-gas bal- loons for long voyages. Before they became obsolete several remarkable voyages were made in them. The same Pilâtre de Rozier made 30 leagues in one of them, the longest voyage ever executed in a montgolfière. Among the names of the first professional aëronauts, those of Lunardi, Blanchard, and Garnerin deserve spe- cial note. Lunardi was the first who made an ascent in Great Britain; and Blanchard, along with an American, Dr. Jeffries, crossed the Eng- lish Channel from Dover to Calais in circum- stances of almost unparalleled danger, January 7, 1785. Garnerin first descended from a balloon by a parachute (q.v.), October 22, 1797. It is much to be regretted that the first aëronaut, Pilâtre de Rozier, fell a victim to a blind de- votion to his art. In order to outvie Blanchard, he constructed a compound machine, consisting of a hydrogen balloon above and a montgolfière below, and started from Boulogne, accompanied by a young physicist named Romain, on the morning of June 5, 1785. He had not ascended many minutes when, as it afterward appeared, on attempting to open the valve of the hydrogen balloon by the rope attached to it, he caused a rent of several yards in it, so that it emptied itself almost immediately, and fell on the mont- golfière beneath. The fire in the latter not being kindled, the whole machine fell with a frightful rapidity to the earth, and the ill-fated aëronauts perished on the spot whence they had arisen.

As stated above, the second balloon built by Professor Charles embodied all the essentials of the ordinary balloon of the present day. Briefly described, the balloon, as it is commonly employed, is a large pear-shaped bag, made of any pliable cloth, usually alpaca or cotton (though silk is the best), covered with a varnish, made by dissolving caoutchouc in oil of turpen- tine, to render it air-tight. The common size of this bag varies from 20 to 30 feet in equatorial diameter, with a proportionate height. The mouth or neck of this bag is just large enough to enable a man to get inside to make any neces- sary repairs, and is, of course, turned downward when the balloon is inflated, A network of hempen or cotton twine is accurately fitted to the balloon, and the ends of the separate cords, of which it is formed, are tied to a circular hoop placed a few feet below the neck. The car, gen- erally a large wicker-basket, is suspended by ropes from this hoop and hangs at a consider- able distance below, so that the aëronaut may be removed from the vicinity of the gas. The net-work serves to distribute the weight of the car and its charge equally over the whole upper surface of the balloon. One of the most impor- tant requisites in the construction is the valve, which is introduced into the top of the balloon. It consists of a wooden or metal clapper, from one foot to three feet in diameter, opening in- ward, and kept closed by springs. A rope at- tached to this valve descends through the neck into the car, where, to prevent accidental open- ing, it is allowed to dangle freely. The equip- ment of the car comprises the ballast, or sand- bags, by emptying which the balloon may be light-