Torricelli, Evangelista (1608-1647) was an Italian physicist and mathematician who is best known for his invention of the barometer. Torricelli was born on 15 October 1608 in Faenza and was educated, mainly in mathematics, at the Sapienza College, Rome. He was impressed by the works of Galileo and the respect became mutual when Galileo read Torricelli's De motu(1641), which dealt with movement. In that same year Galileo invited him to Florence, and after Galileo's death the following year became Professor of Mathematics at Florence, where he remained for the rest of his life. He died there on 25 October 1647. Galileo had been puzzled why a lift pump could not lift a column of water more than about 9 m/29.5 ft - current explanations were based on Nature's supposed abhorrence of a vacuum. Torricelli realized that the atmosphere must have weight, and the height of the water column is limited by atmospheric pressure. In 1643 he filled a long glass tube, closed at one end, with mercury and inverted it in a dish of mercury. Atmospheric pressure supported a column of mercury about 76 cm/30 in long; the space above the mercury was a vacuum. Mercury is nearly 14 times as dense as water, and the mercury column was only about one-fourteenth the height of the maximum water column. Torricelli also noticed that the height of the mercury column varied slightly from day to day and finally came to the conclusion that this was a reflection of variations in atmospheric pressure. Thus by 1644 he had developed the mercury barometer. Author not available, Torricelli, Evangelista (1608-1647). , The Hutchinson Dictionary of Scientific Biography, 01-01-1998. |