the germ of the invention of the balloon lies in the discovery of mr cavendish, made in 1766, that hydrogen gas, called inflammable air, is at least seven times lighter than atmospheric air. founding on this fact, dr black of edinburgh proved by experiment that a very thin bag, filled with this gas, would rise to the ceiling of a room.
in dr thomson’s history of chemistry, an anecdote, related by mr benjamin bell, refers to this as follows:—
“soon after the appearance of mr cavendish’s paper on hydrogen gas, in which he made an approximation to the specific gravity of that body, showing that it was at least ten times lighter than common air, dr black invited a party of friends to supper, informing them that he had a curiosity to show them. dr hutton, mr clerk of eldin, and sir george clerk of penicuik, were of the number. when the company invited had arrived, he took them into a room where he had the allantois of a calf filled with hydrogen gas, and, upon setting it at liberty, it immediately ascended and adhered to the ceiling. the phenomenon was easily accounted for; it was taken for granted that a small black thread had been attached to the allantois, that the thread passed through the ceiling, and that some one in the apartment above, by pulling the thread, elevated it to the ceiling, and kept it in its position! this explanation was so plausible, that it was agreed to by the whole company, though, like many other plausible theories, it turned out wholly fallacious, for, when the allantois was brought down, no thread whatever was found attached to it. dr black explained the cause of the ascent to his admiring friends; but such was his carelessness of his own reputation, that he never gave the least account of this curious experiment even to his class, and several years elapsed before this obvious property of hydrogen gas was applied to the elevation of balloons.”
cavallo made the first practical attempts with hydrogen gas six years later, but he only succeeded in causing soap-bubbles to ascend.
at last the art of aerial navigation was discovered in france, and in 1782 the first ascent was made. the triumph was achieved by stephen and joseph montgolfier, sons of a wealthy paper-maker who dwelt at annonay, on the banks of a rivulet which flows into the rhone, not far from lyons.
these brothers were remarkable men. although bred in a remote provincial town, and without the benefit of a liberal education, they were possessed in a high degree of ingenuity and the spirit of observation. they educated themselves, and acquired an unusually large stock of information, which their inventive and original minds led them to apply in new fields of speculation. they were associated in business with their father, a man who passed his quiet days like a patriarch amidst a large family and a numerous body of dependants, until he reached the advanced age of ninety-three.
stephen 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 diluted sulphuric acid upon iron filings. their balloon, which was made of thin silk, varnished with a solution of elastic gum, was a much nearer approach to the balloon of modern days than that of montgolfier. it was a great success; it rose and remained suspended at a height of 100 feet, in which state it was conveyed with acclamation to the place des victoires, where it rested and underwent some repairs. at midnight it was conveyed in solemn procession by torchlight, and guarded by a detachment of horse, to the champ de mars, where, on the following day, the whole world of paris turned out to witness another ascent. the balloon went up to the sound of cannon, and in two minutes reached a height of 3000 feet, when it was lost for a time in a dark cloud, but speedily reappeared still higher. after a flight of fifteen miles, performed in three-quarters of an hour, it sunk to the ground in a field near ecouen, where it was secured by the peasants.
the parisians now appeared to become balloon-mad. the royal academy of sciences invited joseph montgolfier to repeat his experiments, and another balloon was prepared by him of coarse linen with a paper lining, which, however, was destroyed by incessant and violent rain before it could be tried. undeterred by this, another was constructed by him, which ascended from versailles on the 19th of september 1783.
this balloon deserves peculiar notice as being the first which carried up living creatures. a sheep, a cockerel, and a duck, were the first aeronauts! they ascended to a height of about 1500 feet; remained suspended for a time, and descended some two miles off in perfect safety—indeed we may say in perfect comfort, for the sheep was discovered to be quietly feeding when it returned to the earth!
the practicability of ballooning being now fairly established, men soon began to venture their own persons in the frail cars. a young and enthusiastic naturalist named rozier leaped into the car of another of montgolfier’s balloons soon after this, and ascended in safety to an elevation of about 300 feet, but on this occasion the balloon was held down by ropes. the ice, however, was broken, and bolder attempts quickly followed.
