PHYSICAL AND MATHEMATICAL SCIENCES. 239
was often desirable to find such a point. Bouillauddevised several methods for finding such a centre, andmade calculations, founded on that hypothesis, whichwere, perhaps, accurate enough for his purpose. Dr.Seth Ward, then professor of astronomy at Oxford, andafterwards bishop of Salisbury, improved greatly uponthese methods, by assuming the focus in which the sunis not situated as the centre about which the motion ofthe planet is uniform. In orbits of small excentricity,this fiction affords a rule very nearly approximating tothe truth. Dr. Ward , however, appears to have re-garded it rather as a real theory of the nature of theplanetary motions. Indeed, very few, if any, of theastronomers of that day seem to have studied or com-pletely understood the discoveries of Kepler, from whichthey ought to have seen, at once, that, however conve-nient the fiction of a centre of uniform, motion may befor the purposes of computation, yet the law of natureis no other than that which Kepler discovered, of a mo-tion, about the focus in which the sun is situated ; notuniform in linear velocity, but uniform in the areas ofthe sectors which the radius passes over. Riccioli, inenumerating various hypotheses, does not so much asmention Kepler’s discovery. His work, entitled the“ New Almagest,” is an elaborate account of the stateof astronomical knowledge in the middle of the seven-teenth century. He was, however, an enemy to theCopernican theory; and, though he states the reasoningsfor and against it, yet he estimates the evidence, not bythe weight, but by the number, of the arguments. Hewas exceedingly anxious to prop the falling system ofepicycles, and betrays, in the midst of much accuracyand ingenuity, a mind either totally incapable of com-prehending discoveries like those which were now be-ginning to enlighten the world, or, what is perhaps notimprobable, a determination to shut his eyes againstthem, and a design to blind others. He was a priestand a Jesuit .