[1] For definition see p. 22.
[2] Ibid.
[3] For definition see p. 18.
[4] For definition see p. 18.
[5] In his great book Copernicus says: “The movement of the heavenly bodies is uniform, circular, perpetual, or else composed of circular movements.” In this he proclaimed himself a follower of Pythagoras (see p. 14), as also when he says: “The world is spherical because the sphere is, of all figures, the most perfect” (Delambre, Ast. Mod. Hist., pp. 86, 87).
[6] Kepler tells us that Tycho Brahe was pleased with this device, and adapted it to his own system.
[7] Hist. Ast., vol. i., p. 354.
[8] Hist. of Phys. Ast., p. vii.
[9] “Est enim Astronomi proprium, historiam motuum coelestium diligenti et artificiosa observatione colligere. Deinde causas earundem, seu hypotheses, cum veras assequi nulla ratione possit ... Neque enim necesse est, eas hypotheses esse veras, imo ne verisimiles quidem, sed sufficit hoc usum, si calculum observationibus congruentem exhibeant.”