Torricelli, Evangelista (1608–1647)
Torricelli was born in Piancaldoni in the Romagna, on October 15, 1608. He was brought up by an uncle who lived in Faenza and who put him under Jesuit tuition. When he was 20 he was sent to Rome, where he studied mathematics. Galileo's theories on force and motion caught 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 later, he was appointed mathematician to the grand-duke, and professor to the Florentine Academy. Here he resided till his death on October 25, 1647.
Torricelli's great discovery was the interpretation of the previously known fact that will rise in a suction-pump only to a height of about 32 feet – the idea that the column of fluid is sustained by the pressure on the open surface of fluid. The vacuum in the barometer was historically known as the Torricellian vacuum; and the barometer of this type 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.
Torricelli and the mercury barometer
Torricelli measured the height of the mercury column from day to day and concluded that it varied with the weather. His idea that this was tied up with air pressure was verified by young Blaise Pascal, who succeeded in showing that the column was shorter in rarefied mountain air. Since it could be used for measuring air pressures, Torricelli's mercury column was the first barometer.
Related category• PHYSICISTS
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