**Charles Briot** was a French mathematician who worked on elliptic functions. He also published on light and heat.

- Briot was two years ahead of Bouquet at school and after leaving in 1837he taught for a year.
- In 1841 Briot completed the course for the agrégation in mathematics and he had improved on his position as the second best student which he achieved when he entered, for now he was placed first.
- Despite his marked academic success in research, Briot still wanted to follow his chosen career as a teacher and it was as a teacher of mathematics in a Lycée that he began his career.
- In 1851 Briot returned to Paris where he taught at various Lycées.
- At this Lycée, Briot taught the special mathematics course designed to prepare pupils to take the entrance examinations for the École Normale Supérieure and the École Polytechnique.
- When Briot moved to the Lycée Saint-Louis he continued to teach the same special mathematics courses there.
- Briot undertook research on analysis, heat, light and electricity.
- Of course Pasteur was a great scientist, but Briot had an additional reason to hold him in high esteem for, like himself and his friend Bouquet, Pasteur was brought up in the Doubs region of France.
- The way that these two versions had been discovered was fascinating to Briot, for Pasteur had investigated acid crystals showing that there were two forms, one of which rotated plane polarised light in a certain direction while the other rotated plane polarised light to the same degree but in the opposite direction.
- Then Briot applied these properties of crystals discovered by Pasteur to the aether which he believed was a crystalline substance.
- Briot, however, developed a sophisticated mathematical theory to study these properties, and although his work has no great importance to physics, the analysis he had to develop during his working out of the theory led to significant results in the integral calculus and also in the theory of elliptic and abelian functions.
- In 1859 Briot and Bouquet published their important two volume treatise on doubly periodic functions.
- In 1879 Briot, this time in a single author work, produced his treatise on abelian functions.
- The physical motivation for the mathematical theories which gave rise to this work in analysis was published by Briot in 1864 when he published his work on light, Essai sur la théorie mathématique de la lumière Ⓣ(Essay on the mathematical theory of light) and five years later when he published his work on heat, Théorie mécanique de la chaleur Ⓣ(Mechanical theory of heat).
- We noted above that Briot was a dedicated teacher and as such he wrote a great number of textbooks for his students.
- This was certainly a tradition in France at this time and it was natural for a teacher of Briot's quality to write up his courses as textbooks.
- For his outstanding contributions to mathematics the Académie des Sciences in Paris awarded Briot their Poncelet Prize in 1882 shortly before he died.

Born 19 July 1817, St Hippolyte, Doubs, Franche-Comté, France. Died 20 September 1882, Bourg-d'Ault, France.

View full biography at MacTutor

Astronomy

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive