Perhaps these struggles to use wings suggested to the tight-rope walker Allard the possibility of performing a novel stunt. At any rate, in 1660 he successfully made several glides for exhibition purposes in France. Seventeen years later another Frenchman named Bosnier also made spectacular glides. These experiments, however, led to the invention of the glider, which finally developed into the aeroplane or the heavier-than-air machine. A glider consists of a rigid rectangular plane constructed of frail framework, similar to a kite, and covered with linen or cloth, much like the wing of a modern aeroplane. This plane surface might be a dozen or more feet long and two or more feet wide. The early experimenters jumped off hills with this plane fastened to their arms or shoulders, and balancing themselves in the centre, glided several feet over the ground, keeping their equilibrium by means of their feet. Later two planes fastened together like a box-kite were employed, with the flier stretched out on his stomach on the lower planes. Lillienthal and even the Wright brothers learned most about longitudinal and lateral balance by gliding on gliders of the last type. A great deal of sport can be had with these man-carrying kites even to-day. The experiments of the two French brothers, Joseph and Jacques Montgolfier, with paper bags inflated with hot air started a new period of development in aeronautics, for the paper bags suggested the silk ones, which were, of course, much lighter. On September 19, 1783, they gave an exhibition before the royal family at Versailles. The authors of the first ascension, the first actual step in the conquest of the air, were two Frenchmen, Marquis d’Arlandes and Pilâtre de Roziers, who made the first ascension near Paris on November 21, 1783. From that time on free ballooning became a very popular sport. The escaping of the hot air or gas, forcing the balloon to descend too suddenly, led to the invention of the parachute as a means of descending slowly from the collapsing bag. The possibility of using this type of balloon for observation purposes was realized by the French, and the first recorded battle that the captive balloon was employed in was at Fleurus June 26, 1794, thus supplying “aerial eyes” for the French army to observe the movements of the Austrians.