The time was at hand, however, when Montgolfier, who had always maintained that the true usefulness of the balloon would be in warfare, was given the opportunity of seeing his contention verified. On the breaking out of the French Revolution, balloon corps were at once pressed into the service of the army. Napoleon Bonaparte carried with him some balloons on his Egyptian campaign, partly for the purpose of making observations, and partly to impress the Arabs with the superiority of Christian armies. A school of aeronautics was established at Meudon, and some fifty young men, sworn to secrecy, assigned to it. Balloons were constructed, tested, and distributed among the different divisions of the army, and one of these was used for reconnoitering the position of the Austrian forces just before the battle of Fleurus. In the course of the day two ascents were made in this balloon, which was held captive by several thousand feet of cable. The second ascent drew the fire of the enemy's cannon, but the range was too great and no harm was done. Meanwhile the French general, Jourdain, was furnished most valuable information by these aerial voyages. The Revolutionary wars were also responsible, indirectly, for the invention of the parachute. It will be recalled that even as early as the fifteenth century, Leonardo da Vinci had conceived the idea of a kind of parachute; and that Blanchard had a spread-canvas arrangement to produce a similar effect attached to some of his balloons. It was not until 1799, however, that the folding umbrella-like parachute was invented, the inventor, Garnerin, having developed the idea in trying to devise some means of escape from the fortress of Buda, Hungary, where he was being kept prisoner after one of the battles in the North between the Revolutionary forces and the Austrians and Prussians. Although he did not actually effect his escape in this dramatic manner, he finally proved that he had not dreamed in vain during his imprisonment by demonstrating the entire practicality of the parachute. Garnerin's first practical test of his invention was made in October, 1797, when he ascended to the height of six thousand feet in a balloon to which was attached a parachute of the ordinary umbrella type still used. At that altitude he cut loose the balloon which rushed upward until it exploded, while the parachute, dropping rapidly at first, finally settled slowly and gently to the earth, without injury to the inventor. PROGRESS IN MECHANICAL FLIGHT