OTNOTES:

[Footnote 3: _Phil. Trans._, vol. xxx., p. 737.]

[Footnote 4: Out of eighty stars compared, fifty-seven were found to
have changed their places by more than 10". Lesser discrepancies were at
that time regarded as falling within the limits of observational error.
_Tobiae Mayeri Op. Inedita_, t. i., pp. 80, 81, and Herschel in _Phil.
Trans._, vol. lxxiii., pp. 275-278.]

[Footnote 5: _Posthumous Works_, p. 701.]

[Footnote 6: Arago in _Annuaire du Bureau des Longitudes_, 1842, p.
313.]

[Footnote 7: Bradley to Halley, _Phil. Trans._, vol. xxxv. (1728), p.
660. His observations were directly applicable to only two stars,
Gamma Draconis and Eta Ursae Majoris, but some lesser ones
were included in the same result.]

[Footnote 8: Holden, _Sir William Herschel, his Life and Works_, p. 17.]

[Footnote 9: _Phil. Trans._, vol. ci., p. 269.]

[Footnote 10: Caroline Lucretia Herschel, born at Hanover, March 16,
1750, died in the same place, January 9, 1848. She came to England in
1772, and was her brother's devoted assistant, first in his musical
undertakings, and afterwards, down to the end of his life, in his
astronomical labours.]

[Footnote 11: Holden, _op. cit._, p. 39.]

[Footnote 12: _Memoir of Caroline Herschel_, p. 37.]

[Footnote 13: See Holden's _Sir William Herschel_, p. 54.]

[Footnote 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.]

[Footnote 15: _Allgemeine Naturgeschichte und Theorie des Himmels_,
1755.]

[Footnote 16: _Cosmologische Briefe_, Augsburg, 1761.]

[Footnote 17: _The System of the World_, p. 125, London, 1800 (a
translation of _Cosmologische Briefe_). Lambert regarded nebulae 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.]

[Footnote 18: _Opera Inedita_, t. i., p. 79.]

[Footnote 19: _Phil. Trans._, vol. lxxiii. (1783), p. 273. Pierre
Prevost'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 Kluegel at Halle gave about the same time an analytical
demonstration o