After many experiments with steam, smoke, and hydrogen gas, with which they tried ineffectually to inflate large paper bags, they finally succeeded with heated air, and on June 5, 1783, they sent up a great paper hot-air balloon, 35 feet in diameter. It rose to a height of 1,000 feet, but soon came to earth again upon cooling. It appears that the Montgolfiers were wholly ignorant of the fact that it was the rarefying of the air by heating that caused their balloon to rise, and they made no attempt to keep it hot while the balloon was in the air. [Illustration: An early Montgolfier balloon.] About the same time the French scientist, M. Charles, decided that hydrogen gas would be better than hot air to inflate balloons. Finding that this gas passed readily through paper, he used silk coated with a varnish made by dissolving rubber. His balloon was 13 feet in diameter, and weighed about 20 pounds. It was sent up from the Champ de Mars on August 29, 1783, amidst the booming of cannon, in the presence of 300,000 spectators who assembled despite a heavy rain. It rose swiftly, disappearing among the clouds, and soon burst from the expansion of the gas in the higher and rarer atmosphere--no allowance having been made for this unforeseen result. It fell in a rural region near Paris, where it was totally destroyed by the inhabitants, who believed it to be some hideous form of the devil. The Montgolfiers had already come to Paris, and had constructed a balloon of linen and paper. Before they had opportunity of sending it up it was ruined by a rainstorm with a high wind. They immediately built another of waterproof linen which made a successful ascension on September 19, 1783, taking as passengers a sheep, a cock, and a duck. The balloon came safely to earth after being up eight minutes--falling in consequence of a leak in the air-bag near the top. The passengers were examined with great interest. The sheep and the duck seemed in the same excellent condition as when they went up, but the cock was evidently ailing. A consultation of scientists was held and it was the consensus of opinion that the fowl could not endure breathing the rarer air of the high altitude. At this juncture some one discovered that the cock had been trodden upon by the sheep, and the consultation closed abruptly. The Montgolfier brothers were loaded with honors, Stephen receiving the larger portion; and the people of Paris entered enthusiastically into the sport of making and flying small balloons of the Montgolfier type. Stephen began work at once upon a larger balloon intended to carry human passengers. It was fifty feet in diameter, and 85 feet high, with a capacity of 100,000 cubic feet. The car for the passengers was swung below from cords in the fashion that has since become so familiar.