The foregoing sketches by the great artist were made toward the year 1500, and there the science stood for nearly three centuries. Much speculation followed, but no substantial progress. Mathematicians proved by figures the inadequacy of the human muscle to achieve human flight. Dreamers demonstrated the same by launching themselves from high places, and breaking their bones on the unfeeling earth, before unpitying crowds. Finally came the balloon, giving a new impetus to an embryo art. The earliest of Da Vinci’s aëronautic ideas to be practically realized was the parachute. The exact date of its first employment is not exactly known. In the year 1617 Fauste Veranzio published in Venice a good technical description of the construction and operation of the parachute, accompanied by a clear illustration, as shown in Fig. 28. But the first authentic account of a parachute descent of a human being is that given by Sebastien Lenormand. This dauntless inventor, on December 26, 1783, descended from the tower of the Montpelier Observatory, holding in either hand an umbrella sixty inches in diameter. A few days later he sent to the Academy of Lyons the following description of his improved parachute, illustrated in Fig. 29: “I make a circle 14 feet in diameter with a heavy cord; I attach firmly all around, a cone of linen whose height is 6 feet; I double this cone with paper laid on the linen to render it impermeable to air; or better, instead of linen, taffeta covered with gum elastic. I place all about the cone small cords, which are attached below to a wicker frame, and forming with this frame an inverse truncated cone. Upon this frame I place myself. By this means I avoid the ribs and handle of the umbrella, which would add considerable weight. I am sure to risk so little that I offer to make the experiment myself, after once having tried the parachute with different weights to make sure of its solidity.” [Illustration: FIG. 28.—VERANZIO’S PARACHUTE.] Previous to Lenormand’s experiments, Blanchard, the aëronaut, had dropped small parachutes from his balloon, sometimes carrying animals, but never a human being. For unaccountable reasons the world had to wait fourteen years longer to see a man make the new familiar parachute descent from a balloon. On October 22, 1797, in presence of a large crowd Jacques Garnerin ascended in a closed parachute to a height of 3,000 feet, then cut loose. The people were astonished and appalled; but they soon saw the umbrella-shaped canvas spread open and oscillate in the sky with its human freight. As it was but eight yards in diameter, it descended rapidly and struck the ground with violence, throwing Garnerin from his seat. He escaped with a bruised foot, mounted a horse, and returned to the starting point, where he received a lively ovation. [Illustration: FIG. 29.—LENORMAND’S PARACHUTE, 1784.]