Evangelista Torricelli (1608-1647), Italian physicist, inventing the barometer. After working on the dynamics of falling bodies with Benedetto Castelli (1578-1643), Torricelli was appointed assistant to Galileo. He succeeded Galileo as mathematician to the court of Tuscany. Torricelli was interested in pure maths and experimental physics, but he is best remembered for his invention of the mercury barometer and his discovery of atmospheric pressure in 1644. He later noticed that small variations in the height of the column of mercury supported by atmospheric pressure were related to changes in the weather. Engraving from The Atmosphere (1873) by Camille Flammarion.