**Jean Le Rond d'Alembert**, was born on November 17, 1717, and died on October 29, 1783.

He was a French mathematician and physicist who developed the early stages of CALCULUS, formalized the new science of mechanics, and was the science editor of Diderot's Encyclopedia. With DIDEROT and VOLTAIRE, he was one of the leading figures of enlightenment in France.

D'Alembert grew up in Paris. In 1741 he was admitted to the Paris Academy of Science, where he worked for the rest of his life.

D'Alembert appears with Daniel BERNOULLI, Alexis CLAIRAUT, and Leonhard EULER as one of the leading scientists of his time. He was one of the first to understand the importance of FUNCTIONS and the concept of limits for calculus, and also pioneered the use of differential equations in physics.

It also helped resolve the physics controversy over kinetic energy conservation by improving Newton's definition of force in his *Dynamique betrayal* (1742), which articulates d'Alembert's principle of mechanics. He also studied hydrodynamics, rigid body mechanics, and the three-body problem in astronomy.