Replica of Torricelli's first barometer, 1643.

Replica, Torricelli's first closed cistern barometer, Rome, Italy, 1643

Replica. The Italian mathematician, Evangelista Torricelli (1608-1647), was the first person to create a sustained vacuum and to discover the principle of the barometer. He worked as Galileo's assistant just before Galileo's death in 1641. In 1643, Torricelli experimented with vacuums to demonstrate that atmospheric pressure determines the height to which a fluid will rise in a tube when inverted over the same liquid. This concept led to the development of the barometer. This barometer is a replica of the four foot tube barometer that Torricelli used in this experiment.