Benedetto Castelli

Benedetto Castelli (1578–1643), born Antonio Castelli in Brescia, was an Italian Benedictine monk, mathematician and physicist, and the closest pupil of Galileo Galilei. He assisted Galileo's study of sunspots and took part in discussions of Copernican theory.

In 1613 he took Galileo's old mathematics chair at the University of Pisa, and in 1625 Pope Urban VIII called him to teach at the Sapienza in Rome.

His studies of running water issued in the treatise On the Measurement of Running Waters, a foundation of modern hydraulics. His pupils included Torricelli, Borelli and Cavalieri. He died in Rome.