Torricelli's barometer experiment, 1644.
© Science Museum / Science & Society Picture Library
Torricelli's barometer experiment, 1644. Evangelista Torricelli (1608-1647), the Italian mathematician and physicist, was the inventor of the mercury barometer. The experiment pictured is a particularly famous one in which the existence of atmospheric presure is experimentally demonstrated. After working as his personal asistant Torricelli succeeded Galileo to the post of mathemetician to the court of Tuscany.