Augustin Louis Cauchy
(1789-1857)

Augustin Louis Cauchy was one of the greatest mathematicians. Born in Paris, he entered the École Polytechnique at the age of 16, where he studied under Lagrange, Laplace, Fourier, and Poisson. He was quickly recognized for his mathematical prowess, and at age 27 he became a professor at the École and a member of the Academy of Sciences. His major works in pure mathematics were in group theory, number theory, series, integration, differential equations, and analytical functions. In applied mathematics, he introduced the concept of stress as we know it today, developed the equations of theory of elasticity, and introduced the notion of principal stresses and principal strains.

From Mechanics of Materials, 4th Ed., by J.M. Gere and S.P. Timoshenko, PWS Publishing, 1997, pp. 835-42.