Torricelli, Evangelista, << `tawr` ih CHEHL ee, eh `vahn` jeh LEE stah >> (1608-1647), was an Italian physicist and mathematician. Torricelli is best known for his invention of the mercury barometer (a device that measures the pressure of the atmosphere). He described this device in 1644. Torricelli also improved the telescope. He studied geometry and motion, and wrote of his research findings in Opera geometrica (1644). His work in geometry helped later mathematicians develop integral calculus, a system of mathematics.
Torricelli was born on Oct. 15, 1608, in Faenza. He was a friend and disciple of the Italian astronomer and physicist Galileo. A unit of pressure, the torr, is named for Torricelli. He died on Oct. 25, 1647. See also Barometer ; Hydraulics (Laws of hydrodynamics) .
