Sophie Germain, (1776-1831) French mathematician, number theorist and physicist. She overcame her lack of formal training, discrimination against her sex and middle class social status to become an important mathematician. Her work was particularly significant in number theory, including Fermat's Last Theorem, and the theory of elasticity. She corresponded with Lagrange, Gauss and Legendre. In 1816 she won the Grand Prize from the Paris Academy of Sciences for her essay on elasticity theory. She was the first woman to attend the Academy of Sciences in her own right and the first woman invited to attend sessions at the Institut de France. This portrait is based on a pencil sketch of a memorial plaque by Mme. Cheagray.