Irish mathematician who was born at midnight on August 3/4, 1805, so there is some confusion over his birthdate. As a child, his linguist uncle James taught him 14 languages (Bell 1986, p. 341). Hamilton taught himself mathematics at age 17, and discovered an error in Laplace's Celestial Mechanics. He predicted conical refraction in biaxial crystals, which was soon experimentally observed by Lloyd. Hamilton also extended the least action principle described earlier by Maupertuis.

Hamilton developed the mathematical theory of quaternions, which is an anticommutative algebra. Anticommutative algebra was later found to have important applications to quantum mechanics. The idea for quaternions occurred to Hamilton while he was walking along the Royal Canal on his way to a meeting of the Irish Academy, and was so pleased with his discovery that he scratched the fundamental formula of quaternion algebra,

into the stone of the Brougham bridge (Mishchenko and Solovyov 2000).

Hamilton was an alcoholic for the last third of his life.

Additional biographies: MacTutor (St. Andrews), Bonn, Dublin Trinity College