Euler, Leonhard 1707-83
Swiss mathematician

Born in Basle, he studied mathematics there under Jean Bernoulli. In 1727 he went to St Petersburg to study at the Academy of Sciences newly founded by Catherine II, where he became Professor of Physics (1731) and then Professor of Mathematics (1733). In 1741 he moved to Berlin at the invitation of Frederick II, the Great, to be director of mathematics and physics in the Berlin Academy, but he returned to St Petersburg in 1766 after a disagreement with the king, and remained in Russia until his death. He published many books and papers on every aspect of pure and applied mathematics, physics and astronomy. He studied infinite series and differential equations, introduced or established many new functions, including the gamma function and elliptic integrals, and created the calculus of variations. His Introductio in analysin infinitorum (1748) and later treatises on differential and integral calculus and algebra became standard textbooks, and his notations such as e and i (the square root of -1) have been used ever since. In mechanics Euler studied the motion of rigid bodies in three dimensions, the construction and control of ships, and celestial mechanics. For the princess of Anhalt-Dessau he wrote Lettres � une princesse d'Allemagne (1768-72), a non-technical outline of the main physical theories of the time. His powerful memory enabled him to continue mathematical work though nearly blind.

Bibliography: Otto Speiss, Leonhard Euler (1929)