Paul Guldin

Paul Guldin (1577 to 1643), born Habakkuk Guldin at Mels, was a Swiss Jesuit mathematician and astronomer who died at Graz. Although of Jewish descent, his parents were Protestants and brought him up in that faith. He was a professor of mathematics in Graz and Vienna and was noted for his association with Johannes Kepler. He discovered the Guldinus theorem, also known as the Pappus-Guldinus theorem or Pappus's centroid theorem, which determines the surface and the volume of a solid of revolution: the volume generated by a plane figure rotated about a line equals the product of its area and the length of the circumference described by its centre of gravity, published in Centrobaryca in 1641. A similar statement in the works of Pappus of Alexandria had been printed in 1588, 1589 and 1602, which led to a debate over whether he was a plagiarist. He also wrote a critique of Cavalieri's method of indivisibles.