Small silver disc with glider design by Sir George Cayley, 1799.

UNITED KINGDOM - MAY 27: Reverse side engraved with an early design by Sir George Cayley (1773-1857) for a glider or heavier-than-air flying device. Cayley dedicated most of his life to the study and experiment of the basic principles of flight. He pioneered aerial navigation, was the founder of aerodynamics, and is widely considered to be the 'father' of fixed-wing flight. He was responsible for the first man-carrying glider (1853). His innovative 'Aerial Carriage' of 1843 incorporated four circular discs that were designed to raise the machine vertically, rather like a helicopter, whereupon they were to close and form circular wings. However, the design was never built. (Photo by SSPL/Getty Images)