Wonderful Balloon Ascents; Or, The Conquest of the Skies

To wings, however, aerial adventurers mostly adhered. The Marquis de Racqueville flew from a window of his hotel, on the banks of the Seine, and fell into a boat full of washerwomen on the river. All these unfortunate attempts were lampooned, burlesqued on the stage, and pursued with the mockery of the public. Up to this time, therefore, the efforts of man to conquer the air had miscarried. They were conducted on a wrong principle, the machinery employed being heavier than the air itself But, even before the time of Montgolfier, the principles of aerostation began to be recognised, though nothing was actually done in the way of acting upon them. Thus, in 1767, Professor Black, of Edinburgh, announced in his class that a vessel, filled with hydrogen, would rise naturally in the air; but he never made the experiment, regarding the fact as capable of being employed only for amusement. Finally, Cavallo, in 1782, communicated to the Royal Society of London the experiments he had made, and which consisted in filling soap-bubbles with hydrogen. The bubbles rose in the atmosphere, the gas which filled them being lighter than air. Chapter III. The Theory of Balloons. A certain proposition in physics, known as the “Principle of Archimedes,” runs to the following effect:--“Every body plunged into a liquid loses a portion of its weight equal to the weight of the fluid which it displaces.” Everybody has verified this principle, and knows that objects are much lighter in water than out of it; a body plunged into water being acted upon by two forces--its own weight, which tends to sink it, and resistance from below, which tends to bear it up. But this principle applies to gas as well as to liquids--to air as well as to water. When we weigh a body in the air, we do not find its absolute weight, but that weight minus the weight of the air which the body displaces. In order to know the exact weight of an object, it would be necessary to weigh it in a vacuum.