Alexis Claude Clairaut (1713-1765), French mathematician. Clairaut was a child prodigy, writing on geometry at age twelve, and being elected to the French Academy of Sciences in 1731 even though he was only eighteen and below the legal age. He proposed Clairaut's theorem, which concerned the gravitational field of a rotating body such as the Earth. He published theories concerning the Moon and also published theories about comets. 19th-century engraving.