Borda, Jean Charles

Born May 4, 1733, in Dax; died Feb. 19, 1799, in Paris. French physicist and geodesist. A member of the Parisian Academy of Sciences. He served as an officer in the army and then in the navy. He determined the length of the seconds pendulum (1792) in Paris and developed a method for the precise determination of the period of oscillation of the pendulum. In 1766 he proposed a special nozzle (named for him) for increasing the flow rate of a liquid which is flowing from a container with a fixed outlet cross section. He proved the theorem in hydraulics which bears his name concerning the surging of a stream of liquid or gas. He developed one of the systems of vertical axes of astronomical-geodesical instruments.