Adhémar Barré de Saint-Venant

Adhémar Barré de Saint-Venant, born on August twenty-third, seventeen ninety-seven, at the château de Fortoiseau in Villiers-en-Bière, France, was a distinguished mathematician, chemist, and engineer. He was the son of Jean Barré de Saint-Venant, a colonial officer, and Marie-Thérèse Josèphe Laborie. Following in his father's footsteps, he entered the prestigious École Polytechnique at the young age of sixteen, where he studied under the renowned Gay-Lussac and graduated in eighteen sixteen.

Throughout his career, Barré de Saint-Venant made significant contributions to the fields of mechanics and hydraulics. He is best known for developing the Saint-Venant equations, a fundamental set of equations in modern hydraulic engineering, which describe unsteady open channel flow. His work also includes the correct derivation of the Navier–Stokes equations for viscous flow, where he was the first to identify the coefficient of viscosity as a crucial factor in flow dynamics.

In addition to his engineering achievements, he engaged in a notable dispute with Hermann Grassmann over the development of vector calculus, which he claimed to have conceived in eighteen thirty-two, prior to Grassmann's publication. Barré de Saint-Venant's career was marked by various roles, including a position as a civil engineer at the Corps des Ponts et Chaussées and a brief tenure as the chair of Agricultural Engineering at the Agronomic Institute of Versailles.

His later years were spent teaching mathematics at the École des Ponts et Chaussées, where he succeeded the esteemed Coriolis. In eighteen sixty-eight, he was elected to the Académie des Sciences, succeeding Poncelet, and continued his research until his death in January eighteen eighty-six in Saint-Ouen, Loir-et-Cher. His legacy is further honored by the title of 'Count' bestowed upon him by Pope Pius IX in eighteen sixty-nine.