Leonardo da Vinci, the great Italian artist and scientist, who lived in the fifteenth century, spent years experimenting with the idea of flying. He made a number of sketches of wings to be fitted to the arms and legs of man. His plan for a parachute was soundly worked out and his idea that the wings of a flying machine should be patterned after the wings of the bat found expression in the doped fabric covering of our early airplanes.