Magnetism > Nova demonstratio
By using the properties of spherical loadstones to defend the Copernican system in De Magnete (1600), William Gilbert (1544-1603) made magnetism an important part of the 17th-century debates over celestial physics. Heliocentrists like Johannes Kepler and Galileo Galilei adapted Gilbert's theorization of the magnet to explain the heavenly forces propelling the planets around the sun. In response, Athanasius Kircher (1601 or 1602-1680), Jacquess Grandami (1588–1672) and other geocentrists used their own experiments to prove the impossibility of the Earth's rotation. Grandami placed a spherical loadstone in a container of water. When disturbed, the magnet repositioned itself. He offered this as proof that the Earth's magnetism makes it inclined to be stationary. Nova demonstratio inmobilitatis terrae petita ex virtute magnetica (1645) documents Grandami's experiments with descriptions and illustrations.
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M. R. Baldwin, "Magnetism and the Anti-Copernican Polemic," History of Astronomy 16.3 (1985): 155-172.
