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.
In the meantime Pilatre de Rozier had constructed a balloon on the hot-air principle, but with an arrangement to keep the air heated by a continuous fire in a pan under the mouth of the balloon. He made the first balloon ascent on record on October 15, 1783, rising to a height of eighty feet, in the captive balloon. On November 21, in the same year, de Rozier undertook an expedition in a free balloon with the Marquis d’Arlandes as a companion. The experiment was to have been made with two condemned criminals, but de Rozier and d’Arlandes succeeded in obtaining the King’s permission to make the attempt, and in consequence their names remain as those of the first aeronauts. They came safely to the ground after a voyage lasting twenty-five minutes. After this, ascensions speedily became a recognized sport, even for ladies.
The greatest altitude reached by these hot-air balloons was about 9,000 feet.
Pilatre de Rozier’s balloon.
The great danger from fire, however, led to the closer consideration of the hydrogen balloon of Professor Charles, who was building one of 30 feet diameter for the study of atmospheric phenomena. His mastery of the subject is shown by the fact that his balloon was equipped with almost every device afterward in use by the most experienced aeronauts. He invented the valve at the top of the bag for allowing the escape of gas in landing, the open neck to permit expansion, the network of cords to support the car, the grapnel for anchoring, and the use of a small pilot balloon to test the air-currents before the ascension. He also devised a barometer by which he was able to measure the altitude reached by the pressure of the atmosphere.
To provide the hydrogen gas required he used the chemical method of pouring dilute sulphuric acid on iron filings. The process was so slow that it took continuous action for three days and three nights to secure the 14,000 cubic feet needed, but his balloon was finally ready on December 1, 1783. One of the brothers Robert accompanied Charles, and they travelled about 40 miles in a little less than 4 hours, alighting at Nesles. Here Robert landed and Charles continued the voyage alone. Neglecting to take on board ballast to replace the weight of M. Robert, Charles was carried to a great height, and suffered severely from cold and the difficulty of breathing in the highly rarefied air. He was obliged to open his gas valve and descend after half an hour’s flight alone.
Blanchard, another French inventor, about this time constructed a balloon with the intention of being the first to cross the English Channel in the air. He took his balloon to Dover and with Dr. Jeffries, an American, started on January 7, 1785. His balloon was leaky and he had loaded it down with a lot of useless things in the way of oars, provisions, and other things. All of this material and the ballast had to be thrown overboard at the outset, and books and parts of the balloon followed. Even their clothing had to be thrown over to keep the balloon out of the sea, and at last, when Dr. Jeffries had determined to jump out to enable his friend to reach the shore, an upward current of wind caught them and with great difficulty they landed near Calais. The feat was highly lauded and a monument in marble was erected on the spot to perpetuate the record of the achievement.
De Rozier lost his life soon after in the effort to duplicate this trip across the Channel with his combination hydrogen and hot-air balloon. His idea seems to have been that he could preserve the buoyancy of his double balloon by heating up the air balloon at intervals. Unfortunately, the exuding of the hydrogen as the balloons rose formed an explosive mixture with the air he was rising through, and it was drawn to his furnace, and an explosion took place which blew the entire apparatus into fragments at an altitude of over 1,000 feet.