Henry Cavendish

about 1766, discovered the great levity of hydrogen gas—slightly over 14 times le than that of atmospheric air—and the following year Dr. Black, of Edinburgh, announced in his lectures that a thin bladder, filled with this gas, must ascend into the air. Cavallo made the requisite experiments in 1782, and found that a bladder was too heavy, paper not air-tight, but that soap-bubbles filled with hydrogen rose to the ceiling of the room, where they burst. The first succe ful balloon was made by the Montgolfier brothers, sons of Peter Monitgolfier, a_paper manufacturer of Annonay, France. It was a parallelepiped or six-sided bag of silk, containing 40 cubic ft.; inflated with hot air from burning paper it | rose to a height of 36 ft. The brothers, after seeing a petticoat sail to the ceiling when left to dry by a fire, had conceived the idea that a bag filled with a cloud-like substance, such as smoke, would float in the air. Larger machines were constructed with greater succe in ascension, a straw fire, fed by chopped wool from time to Aeronautics: time, being kindled under the aperture of the balloon to produce the smoke cloud; the true cause of ascension, the rarefaction of the heated air, was not discovered till a later period. The Montgolfier succe es led to Charles’ experiments with hydrogen gas. Within a short tinfe several captive ascents by human beings were succe fully made in heated air balloons, and on Noy. 21, 1783, Pilatre de Rozier and the Marquis d’Arlandes made the first independent aerial expedition rising 3,000 ft. and descending safely, though not without being exposed to considerable danger, 9,000 ft. from their starting point. Ten days later, on Dec. 1, Me rs, Charles and Roberts ascended in a hydrogen balloon fitted with a safety_valve, and travelled over 31 miles. Over 52: balloon ascents are recorded in 1784.