Torricelli, EVANGELISTA

Torricelli, EVANGELISTA, mathematician and philosopher, was born at Piancaldoli in the Romagna, 15th October 1608. He was brought up by an uncle who resided at Faenza, and who put him under the tuition of the Jesuits. When twenty years old he was sent to Rome, and there devoted himself to mathematical studies. Galileo's theories on force and motion engaged his attention, and led to his writing a Trattato del Moto (about 1641), and to his being invited by Galileo (1641) to visit him; on the old philosopher's death, three months afterwards, he was appointed mathematician to the grand-duke, and professor to the Florentine Academy. Here he resided till his death, 25th October 1647. His great discovery was the interpretation of the previously known fact that water will rise in a suction-pump only to the height of about 32 feet—the idea that the column of fluid is sustained by the pressure of the atmosphere on the open surface of fluid (see BAROMETER). The vacuum in the barometer is the Torricellian vacuum; and the barometer is sometimes called the Torricellian tube. Torricelli also effected the quadrature of the cycloid—in this he was anticipated by Roberval—and made other mathematical discoveries. To him is due the fundamental principles of Hydromechanics (q.v., Vol. VI. p. 32); and he made and greatly improved both telescopes and microscopes.