The balloon was then dilated to an alarming degree, and M. Garnerin, having been prevented by the turbulence of the mob, before his ascent, from regulating those parts of his apparatus which were meant to conduct the gas away from the lamps on its escape, was totally incapable of managing his balloon. He had no alternative left, therefore, but with one hand to make an opening two feet in diameter, through which the inflammable air was discharged in great quantities; and, with the other, to extinguish as many of the lamps as he could possibly reach. The æronaut was now without a regulating valve, and the balloon, subject to every caprice of the whirlwind, was tossed about from current to current. When the storm impelled him downwards, he was forced to throw out his ballast, to restore the ascending tendency; and at last, every resource being exhausted, no expedient was left him to provide against future exigencies. In this forlorn condition, the balloon rose through thick clouds, and afterwards sunk; and the car, having struck against the ground, with a violent impulse rebounded from it to a considerable altitude. The fury of the storm dashed him against the mountains, and, after many rude agitations and severe shocks, he was reduced to a state of temporary insensibility. On recovering from his perilous situation he reached Mont Tonnerre, in a storm of thunder. A very short time after his anchor hooked in a tree; and, in seven hours and a half, after a voyage which had nearly proved fatal to him, he landed at the distance of three hundred miles from Paris. The advantages hitherto derived from ærial navigation have by no means proved adequate to the expectations excited by the novelty and promising aspect of the science. This failure, in their utility, may in a great degree be ascribed to the art of steering balloons being yet undiscovered. And we may here add, that no probability exists that the art will ever be attained. The French, indeed, once instituted an academy for the purpose of improving the state of æronautics, and a corps of fifty young men were selected, and for a time trained to the service. A balloon thirty-two feet in diameter was provided, and in favorable weather was often sent up to the distance of from one hundred and sixty to two hundred and forty yards, with some of the young æronauts in it. The institution, however, is now abandoned. Balloons are uniformly constructed of silk lustring. From the price of this article, the expense of only a moderate sized balloon is great. A balloon of only twelve feet in diameter will require fifty square yards; a balloon thirty feet in diameter requires three hundred and fourteen yards of cloth, and when filled its ascensive power will be five hundred and eighty-one pounds.