Italian mathematician who was a student of Galileo. In 1635, he stated Cavalieri's Principle, which states that if two solids have the same height, and if their cross sections taken parallel to and at equal distances from their bases are always equal, then the solids have the same volume. This was a stepping stone towards calculus.

Additional biographies: MacTutor (St. Andrews), Dublin Trinity College, Firenze, Bonn