74, 75; for a germ of the same thought in Lucretius, see his De Natura Rerum, lib.
v, pp.187-194, 447-454; for Bruno's conjecture (in 1591), see Jevons, Principles of Science, London, 1874, vol.ii, p.

36; for Kant's statement, see his Naturgeschichte des Himmels; for his part in the nebular hypothesis, see Lange, Geschichte des Materialismus, vol.i, p.266; for the value of Plateau's beautiful experiment, very cautiously estimated, see Jevons, vol.ii, p.

36; also Elisee Reclus, The Earth, translated by Woodward, vol.i, pp.

14-18, for an estimate still more careful; for a general account of discoveries of the nature of nebulae by spectroscope, see Draper, Conflict between Religion and Science; for a careful discussion regarding the spectra of solid, liquid, and gaseous bodies, see Schellen, Spectrum Analysis, pp.

100 et seq.; for a very thorough discussion of the bearings of discoveries made by spectrum analysis upon the nebular hypothesis, ibid., pp.