Gabriel Lamé (1795-1890) is largely considered to be the greatest French mathematician of the 19th century. He made great contributions to the fields of number theory, thermodynamics, and applied mathematics, and is perhaps best known for his introduction of and development of curvilinear coordinates.
Gabriel Lamé was born in 1795 at the tail end of the French Revolution. He was bright at an early age and enrolled in Ecole Polytechnique in 1813, graduating in 1817. Even during these undergraduate years Lamé wrote several research papers, publishing his first in Gergonne's Journal in 1816. After his stay at Ecole Polytechnique, Gabriel went on to study engineering at Ecole des Mines in Paris, graduating in 1820. While there, he published a somewhat influential paper detailing a method he had invented to calculate the angles between faces of crystals.
In 1820, at the request of the French government and other French engineers, Gabriel went to Russia for five years. The czar there at the time, Alexander I, was very interested in building Russian science, mathematics, and engineering, and thus persuaded European nations to send some of their intellectuals there to help build the foundations of academics in Russia. Lamé would stay there for some twelve years, years which would be highly productive after he adapted himself to the climate. He gave lectures while there on analysis, physics, mechanics, chemistry, and engineering topics, and published papers in a wide variety of fields and in both Russian and French. He also studied and promoted Cauchy's research in analysis and gained some note in using Cauchy's work to criticize a proof of Taylor's theorem.
Lamé returned to Paris in 1832 and early in the year began an engineering firm, but by the end of the year he had returned to academia, accepting the physics chair at Ecole Polytechnique. He didn't restrict himself to just academics for the rest of his career; instead, he often applied his engineering skills to real world problems. He was appointed France's chief engineer of mines in 1836 and played a large role in several major railroading projects in the country throughout the rest of his life.
Lamé was elected to the Académie des Sciences in 1843, and in 1844 he left his chair of physics at the Ecole Polytechnique, accepting a position at the Sorbonne in mathematical physics and probability. He was appointed to the chair of mathematical physics and probability at the Sorbonne in 1851 and remained in that position for the rest of his professional career.
His work was widely varied, covering many areas of mathematics. His most important mathematical contribution may have been curvilinear coordinates, which provided a simple way to work with curves. He would go on to use these to develop Laplace transforms and equations to describe the flow of heat. He also worked on Fermat's Last Theorem, eventually proving the case where n = 7. In addition, he also studied differential geometry, engineering (especially elasticity, where two elastic constants are named after him, and crystalline diffusion), and number theory, where he proved that the number of divisions in the Euclidean algorithm never exceeds five times the number of digits in the smaller number.
Lamé's great contributions to several fields won him great adulation outside of France, but inside France, his stature was much lower. French mathematicians considered him to be too practical, whereas French scientists considered him to be too theoretical, so he never won strong acceptance from either camp.
Lamé passed away in 1890 in Paris at the age of 95. He contributed greatly to many areas of mathematics and physics throughout his career, and was well thought of by many in both fields.