Evangelista Torricelli

Evangelista Torricelli was an Italian physicist and mathematician, born in Rome in 1608 to a poor family from Faenza, and a student of Benedetto Castelli, who had himself been taught by Galileo. He worked as Castelli's secretary, met Galileo in the last months of the older man's life, and in 1642 was asked by Grand Duke Ferdinando II de' Medici to succeed Galileo as grand-ducal mathematician. He is best known for inventing the mercury barometer. His work grew out of the puzzle that a suction pump could raise water only about 10 metres, and he proposed that we live in a sea of air that exerts pressure. In 1643 his mercury tube experiment produced the first recorded permanent vacuum, now called a Torricellian vacuum. The torr is named after him. He died in 1647.