Christopher Wren's De Corpore Saturni

Abstract We there discoursed . . . the Copernican Hypothesis, the Nature of Comets and new Stars, the Attendants on Jupiter, the Oval shape of Saturn, the Inequalities and Selenography of the Moon, the several Phases of Venus and Mercury, the Improvement of Telescopes, the grinding of Glasses for that purpose . . . THIS was written by John Wallis in 1678 in his Defence of the Royal Society and he was referring to the meetings held in London about 1645 by men interested in experimental philosophy. The ‘Oval shape of Saturn’ was a reference to what was then an important problem in astronomy: the explanation of the different appearances of Saturn. Among the men who were to become founding members of the Royal Society were a number who had an interest in this problem, John Wallis, Seth Ward, Dr Jonathan Goddard and Sir Paul Neile, who both kept operators at their houses for the grinding of lenses, John Wilkins, Laurence Rooke, William Balle, and Christopher Wren. Neile, Balle and Wren especially spent a great deal of time and effort on the problem in the 1650’s, effort that resulted in Wren’s hypothesis on Saturn, which is the subject of De Corpore Saturni.