Gaspard-Gustave de Coriolis

Gaspard-Gustave de Coriolis was born in Paris in 1792, the son of a Royalist officer who fled the Revolution to Nancy when the boy was still small. He entered the École Polytechnique in 1808 — second in his class — and the École des Ponts et Chaussées the following year, training as a civil engineer. He taught mechanics at the Polytechnique for the rest of his life, took the chair of machine theory at the École Centrale in 1832, and served as director of studies at the Polytechnique from 1838 until his death five years later.

His public legacy is in the technical meaning he gave to three words. In 1829's Du Calcul de l'Effet des Machines he coined travail ("work") as the integral of force over distance, fixing in place the definition every physicist still uses. He replaced Leibniz's vis viva with the modern kinetic energy ½mv², halving the prefactor and putting energy bookkeeping on a rational footing. And in 1835's Sur les équations du mouvement relatif des systèmes de corps he derived, for the first time, the complete equations of motion in a rotating reference frame — identifying the two non-inertial acceleration terms we now call centrifugal and Coriolis.

Coriolis was explicit that these forces were computational conveniences, not real physical interactions. His interest was industrial: waterwheels, turbines, and the billiard-table kinematics that appear in his last book, Théorie Mathématique des Effets du Jeu de Billard (1835). He never connected his mathematical result to weather or ballistics; that leap came decades later, when meteorologists studying trade winds and artillery officers calculating long-range gunnery rediscovered his equations and realised they explained what they had been observing. The force that now bears his name was invented to balance an accounting equation in rotating machinery and only afterwards found the planet it belonged to.