Up in the Clouds | Page 6

devoted himself chiefly to the study of mathematics, Joseph to chemistry; and they were accustomed to form their plans in concert. It appears that they had long contemplated, with philosophical interest, the floating and ascent of clouds in the air, and when they heard of or read Cavendish's theories in regard to different kinds of air, it at once struck them that by enclosing some gas lighter than the atmosphere in a bag, a weight might be raised from the earth into the air.
The brothers Montgolfier were men of that vigorous stamp who act promptly on receiving their convictions. At once they set about experimenting, and constructed large bags of paper,--the substance which naturally came readiest to their hands, and which appeared to them to be best suited to their purpose. These were filled with hydrogen gas, which raised them to the ceiling; but, owing to the escape of the gas through the pores and cracks of the case, those embryo balloons descended in a few minutes. Instead of varnishing the paper to prevent the escape of the gas, and supposing, erroneously, that the fault lay in the latter, they sought about for a new gas more suitable to the paper. This they found, as they supposed, in the gas which resulted from the combustion of wet straw and wool, which had an upward tendency, they thought, on account of its electrical properties, which caused it to be repelled from the ground. It is scarcely necessary now to point out that the true cause of the upward tendency lay in the rarefaction of the air by the heat of the fire, and that hot air has a tendency to rise because its bulk is greatly increased beyond the same quantity of the surrounding cold air.
Although wrong in assigning the cause of the result, they were right in the application of it. While on a visit to Avignon Joseph Montgolfier procured a silk bag having a small opening at its lower end, and a capacity of about fifty cubic feet. Under the orifice some paper was burnt; the air inside was heated and expanded so as to fill the bag, which, when let go, soared rapidly up to the height of seventy or eighty feet, where it remained until the air cooled and allowed it to descend. Thus did the first balloon ascend in the month of November 1782.
Delighted with their success, the indefatigable brothers resolved to make further experiment on a larger scale. They procured a quantity of packcloth or coarse linen, formed it into a globe about ninety feet in circumference, lined it with paper, and lighted a fire under it in an iron choffer. This balloon went up with a force which they estimated as equivalent to 500 pounds.
After this the Montgolfiers appeared to have become ambitious of accomplishing greater things, and giving to their discoveries publicity; for we are told that, "they invited the members of the provincial meeting of the states of the Vivarais, then assembled at Annonay, to witness the first public aerial ascent. On the 5th June 1783, amidst a very large concourse of spectators, the spherical bag or balloon, consisting of different pieces of linen, merely buttoned together, was suspended from cross poles. Two men kindled a fire under it, and kept feeding the flame with small bundles of chopped straw. The loose bag gradually swelled, assuming a graceful form, and in the space of five minutes it was completely distended, and made such an effort to escape that eight men were required to hold it down.
"On a signal being given the stays were slipped, and the balloon instantly rose with an accelerating motion till it reached some height, when its velocity continued uniform, and carried it to an elevation of more than a mile. All was admiration and transport. Amidst the shouts of unbounded applause, the progress of the artificial cloud retiring from sight arrested every eye. It was hurried along by the wind; but its buoyant force being soon spent, it remained suspended only ten minutes, and fell gently in a vineyard at a distance of about a mile and a half from the place of its ascension. So memorable a feat lighted up the glow of national vanity, and the two Montgolfiers were hailed and exalted by the spontaneous impulse of their fellow-citizens."
This event created a sensation not only in France but over the whole of Europe. In Paris, particularly, the effect on all classes was so great that they determined to have the experiment repeated, set a subscription on foot, and appointed a scientific man named Charles, and two brothers of the name of Robert, to construct a balloon. This they did, but instead of applying the Montgolfier motive power--heated air--they used hydrogen gas, procured by the action of