Galileo'S ‘Platonic’ Cosmogony and Kepler's Prodromus

The research for this paper was funded by the John Simon Guggenheim Memorial Foundation.

Galileo , Dialogue, tr. S. Drake ( Berkely , 1953), 234; Two new sciences, tr. S. Drake ( Madison , 1973), 158–9.

Dialogue, 30.

Two new sciences, 233–4.

Mersenne , Harmonie universelle (Paris, 1637; repr. 1963), i, 103–7.

Galileo computed the speed that would be acquired in fall from the Moon to the Earth as nearly 100,000 m.p.h. (Dialogue, 224). The orbital speed of the Earth was but a tiny fraction of that, though the theory required it to have fallen much farther.

See Cohen I. B. (ed.), Isaac Newton's papers and letters on natural philosophy (Cambridge, Mass., 1958), 284–7, 296–8.

Cf. Drake S. , “Galileo's Discovery of the Law of Falling Bodies”, Scientific American (May, 1973), 86, box 2, for Galileo's attempt to use this concept in mid-1604.

Cf. Galileo , Opere, ed. Favaro A. (Florence, 1890–1909), x, 90.

Ibid., 104; Kepler , Gesammelte Werke, ed. Caspar M. (Munich, 1949), xiv, 445.

Dialogue, 29.

Cf. Opere, xv, 179.

See, for example, Sambursky S. , “Galileo's Attempt at a Cosmogony”, Isis, liii (1962), 460–4; Cohen I. B. , “Galileo, Newton, and the Divine Order of the Solar System”, Galileo man of science, ed. McMullin E. (New York, 1967), esp. pp. 210–11.