Background
He was born Oct. 15, 1608, in Faenza, Italy. The family was very poor.
He was born Oct. 15, 1608, in Faenza, Italy. The family was very poor.
In 1627 he went to Rome and studied mathematics under Benedetto Castelli. He then entered young Torricelli into a Jesuit College in 1624. He then became Galileo's pupil.
After reading the works of Galileo on motion, he composed a treatise on the same subject entitled Trattato del moto. He then became Galileo's secretary, and later succeeded him as professor of mathematics and philosophy in Florence.
In 1643, Torricelli expanded on the findings of Galileo, proving that air has weight and that a suction pump cannot raise water more than about 33 feet (10 meters). Aided by Vincenzo Viviani (1622 - 1703), Torricelli discovered that when a tube closed at one end, having a length greater than 30 inches (76 cm), is filled with mercury and inverted in a dish, the mercury in the tube reaches a height of approximately 30 inches (the height varies with atmospheric changes), leaving a vacuum in the upper end of the tube. From this, Torricelli inferred that the pressure of the atmosphere on any area is equal to the pressure that a column of mercury 30 inches high would have on the same area. His apparatus was, in effect, the first barometer, and many barometers at present are identical with Torricelli's tube.
Torricelli is also known for a theorem which states that if a hole is opened in the side of an open vessel filled with a liquid, the velocity of the resulting liquid jet, neglecting exit losses, is the same as if the liquid had fallen freely through a distance equivalent to the height of the surface of the liquid above the hole.
("Lezioni accademiche" from Evangelista Torricelli. Matema...)