[Footnote 412: _Cape Observations_, p. 435, _note_.]
[Footnote 413: _Month. Not._, vol. x., p. 158.]
[Footnote 414: _Rosa Ursina_, lib. iii., p. 348.]
[Footnote 415: _Observations at Redhill_, p. 8.]
[Footnote 417: _Rosa Ursina_, lib. iv., p. 601. Both Galileo and Scheiner spoke of the _apparent_ or "synodical" period, which is about one and a third days longer than the _true_ or "sidereal" one. The difference is caused by the revolution of the earth in its orbit in the same direction with the sun's rotation on its axis.]
[Footnote 418: _Rosa Ursina_, lib. iii., p. 260.]
[Footnote 419: Faye, _Comptes Rendus_, t. lx., p. 818.]
[Footnote 420: _Ibid._, t. xii., p. 648.]
[Footnote 421: _Proc. Am. Ass. Adv. of Science_, 1885, p. 85.]
[Footnote 422: _Observations at Redhill_, p. 221.]
[Footnote 423: _Am. Jour. of Science_, vol. xi., p. 169.]
[Footnote 424: _Month. Not._, vol. xix., p. 1.]
[Footnote 425: _Vierteljahrsschrift der Naturfors. Gesellschaft_ (Zürich), 1859, p. 252.]
[Footnote 426: Lockyer, _Chemistry of the Sun_, p. 428.]
[Footnote 427: Maunder, _Knowledge_, vol. xv., p. 130.]
[Footnote 428: _Month. Mon._, vol. l., p. 251.]
[Footnote 429: Maunder, _Knowledge_, vol. xvii., p. 173.]
[Footnote 430: _Astr. Nach._, No. 1,315.]
[Footnote 431: As late as 1866 an elaborate treatise in its support was written by F. Coyteux, entitled _Qu'est-ce que le Soleil? Peut-il être habité?_ and answering the question in the affirmative.]
[Footnote 432: The subsequent researches of Plücker, Frankland, Wüllner, and others, showed that gases strongly compressed give an absolutely unbroken spectrum.]
[Footnote 433: _Comptes Rendus_, t. lx., pp. 89, 138.]
[Footnote 435: _Bull. Meteor. dell Osservatorio dell Coll. Rom._, Jan. 1, 1864, p. 4.]
[Footnote 436: _Quart. Jour. of Science_, vol. i., p. 222.]
[Footnote 437: _Ann. de Chim. et de Phys._, t. xxii., p. 127.]
[Footnote 438: _Phil. Trans._, vol. clix., p. 575.]
[Footnote 439: _Les Mondes_, Dec. 22, 1864, p. 707.]
[Footnote 440: _Comptes Rendus_, t. lx., p. 147.]
[Footnote 441: _Proc. Roy. Society_, vol. xvi., p. 29.]
[Footnote 442: _Recherches sur le Spectre Solaire_, p. 38.]
[Footnote 443: _Am. Jour. of Science_, 1881, vol. xxi., p. 41. Hastings stipulated only for some member of the triad, carbon, silicon, and boron.]