JEAN LE ROND D ALEMBERT' (1717-1783), French mathematician and philosopher, was born at Paris in November 1717.
He was called Jean le Rond from the church near which he was found; the surname Alembert was added by himself at a later period.
In 1744 Alembert applied this principle to the theory of the equilibrium and the motion of fluids (Trcite de l'equilibre et du mouvement des fluides), and all the problems before solved by geometricians became in some measure its corollaries.
Alembert was much interested in music both as a science and as an art, and wrote Elements de musique theorique et pratique (1779), which was based upon the system of P. Rameau with important modifications and differences.
Alembert persisted in his refusal, and the letter of Catherine was ordered to be engrossed in the minutes of the French Academy.