Sophie Germain (1776-1831) was one of the first distinguished female mathematicians of the modern era. Largely self-taught, she won the admiration and friendship of Legendre and Gauss (whose work also appears in this series). Germain is best known for her work on number theory, notably Fermat’s Last Theorem, but she played an important part in establishing the foundations of elasticity. This book, described by her slightly younger contemporary Navier as ‘a work which few men are able to read and which only one woman was able to write’, contains her research on the topic, which was awarded a prize by the Paris Academy of Sciences. This work was published in Paris in 1821.