, _Pop. Astr._, pp. 521-525.]

[Footnote 1160: _Proc. Roy. Soc._, vol. xxxiii., p. 393.]

[Footnote 1161: To this hostile argument, as urged by Mr. E. Douglas
Archibald, Sir W. Siemens opposed the increase of rotative velocity
through contraction (_Nature_, vol. xxv., p. 505). But contraction
cannot restore lost momentum.]

[Footnote 1162: _Stellar Evolution, and its Relations to Geological
Time_, 1889.]

[Footnote 1163: _Comptes Rendus_, t. lii., p. 481. See also Kirkwood,
_Observatory_, vol. iii., p. 409.]

[Footnote 1164: Fouche, _Comptes Rendus_, t. xcix., p. 903.]

[Footnote 1165: _Astroph. Jour._, vol. xiii., p. 338.]

[Footnote 1166: _Month. Not._, vol. xxix., p. 96.]

[Footnote 1167: _Pop. Astr._, p. 257.]

[Footnote 1168: _Sur l'Origine du Monde_, 1884.]

[Footnote 1169: Kirkwood adverted to it in 1864, _Am. Jour._, vol.
xxxviii., p. 1.]

[Footnote 1170: _Bull. Astr._, t. ii.]

[Footnote 1171: _Nature_, vol. xxxi., p. 506.]

[Footnote 1172: _Formation Mecanique du Systeme du Monde; Bull. Astr._,
t. xiv., p. 313 (O. Callandreau). See also, _Le Probleme Solaire_, by
l'Abbe Th. Moreux, 1900.]

[Footnote 1173: _Phil. Trans._, vol. clxxi., p. 713.]

[Footnote 1174: Mr. J. Nolan has pointed out (_Nature_, vol. xxxiv., p.
287) that the length of the equal day and month will be reduced to about
1,240 hours by the effects of _solar_ tidal friction.]

[Footnote 1175: _Phil. Trans._, vol. clxxi., p. 835.]

[Footnote 1176: _Nature_, vol. xxxiii., p. 368; see also Nolan, _Ibid._,
vol. xxxiv., p. 286.]

[Footnote 1177: _Phil. Trans._, vol. clxxviii., p. 422.]

[Footnote 1178: _Ibid._, vol. clxxii., p. 491.]

[Footnote 1179: _Ibid._, p. 530.]

[Footnote 1180: _Satellite Evolution_, Melbourne, 1895; _Knowledge_,
vol. xviii., p. 205.]

[Footnote 1181: _Phil. Trans._, vol. clxxii., p. 533.]

[Footnote 1182: This was perceived by M. Ed. Roche in 1872. _Mem. de
l'Acad. des Sciences de Montpellier_, t. viii., p. 247.]

[Footnote 1183: _Nature_, vol. xxxiv., p. 287.]

[Footnote 1184: _Bull. Astr._, t. ii., p. 223.]

[Footnote 1185: _Montpellier Mems._, t. viii., p. 242.]

[Footnote 1186: _Amer. Jour._, vol. xxxviii. (1864), p. 1.]

[Footnote 1187: Wolf, _Bull. Astr._, t. ii., p. 76.]

CHAPTER X

_RECENT COMETS_

On the 2nd of June, 1858, Giambattista Donati discovered at Florence a
feeble round nebulosity in the constellation