[11] Holden, op. cit., p. 39.
[12] Memoir of Caroline Herschel, p. 37.
[13] See Holden's Sir William Herschel, p. 54.
[14] An Original Theory or New Hypothesis of the Universe, London, 1750. See also De Morgan's summary of his views in Philosophical Magazine, April, 1848.
[15] Allgemeine Naturgeschichte und Theorie des Himmels, 1755.
[16] Cosmologische Briefe, Augsburg, 1761.
[17] The System of the World, p. 125, London, 1800 (a translation of Cosmologische Briefe). Lambert regarded nebulæ as composed of stars crowded together, but not as external universes. In the case of the Orion nebula, indeed, he throws out such a conjecture, but afterwards suggests that it may form a centre for that one of the subordinate systems composing the Milky Way to which our sun belongs.
[18] Opera Inedita, t. i., p. 79.
[19] Phil. Trans., vol. lxxiii. (1783), p. 273. Pierre Prévost's similar investigation, communicated to the Berlin Academy of Sciences four months later, July 3, 1783, was inserted in the Memoirs of that body for 1781, and thus seems to claim a priority not its due. Georg Simon Klügel at Halle gave about the same time an analytical demonstration of Herschel's result. Wolf, Gesch. der Astronomie, p. 733.
[20] Phil. Trans., vol. xcv., p. 233.