Siméon Denis Poisson
(1781-1840)

Siméon Denis Poisson was a great French mathematician. He made many contributions to both mathematics and mechanics, and his name is preserved in numerous ways besides Poisson’s ratio. For instance, we have Poisson’s equation in partial differential equations and the Poisson distribution in theory of probability. Based upon his own theory for the behavior of materials, he calculated the lateral strain of a bar in tension and found it to be one-fourth of the longitudinal strain.

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