[Footnote 676: _Comptes Rendus_, t. lxiii., p. 647.] [Footnote 677: _Ibid._, t. lxxxvi., p. 317. Some half dozen of these identifications have proved fallacious.] [Footnote 678: _Chemistry of the Sun_, p. 143.] [Footnote 679: _Amer. Jour. of Science_, vol. xxxiv., p. 348.] [Footnote 680: _Berlin Abhandlungen_, 1889.] [Footnote 681: _Amer. Jour. of Science_, vol. xli., p. 243. See Appendix, Table II.] [Footnote 682: _Astrophy. Jour._, vol. ix., p. 219; Fowler, _Knowledge_, vol. xxiii., p. 11.] [Footnote 683: _Amer. Jour, of Science_, vol. xiv., p. 89; _Nature_, vol. xvi., p. 364; _Month. Not._, vol. xxxix., p. 440.] [Footnote 684: _Month. Not._, vol. xxxviii., p. 473; Trowbridge and Hutchins, _Amer. Jour. of Science_, vol. xxxiv., p. 263.] [Footnote 685: Scheiner, _Die Spectralanalyse_, p. 180.] [Footnote 686: _Comptes Rendus_, t. lxvii., p. 1123.] [Footnote 687: Rev. A. L. Cortie, _Month. Not._, vol. li., p. 18.] [Footnote 688: Young, _The Sun_, p. 135; Hale, _Astr. and Astrophysics_, vol. xi., p. 312 Buss, _Jour. Brit. Astr. Ass._, vol. ix., p. 253.] [Footnote 689: _Phil. Trans._, vol. clxx., p. 46.] [Footnote 690: _Comptes Rendus_, t. xcvii., p. 555; t. ci., p. 1145.] [Footnote 691: Liveing and Dewar, _Astr. and Astrophysics_, vol. xi., p. 705.] [Footnote 692: _Comptes Rendus_, t. lx., p. 213; t. lxiii., p. 289.] [Footnote 693: _Ibid._, t. cviii., p. 1035.] [Footnote 694: _Ibid._, t. cxi., p. 431.] [Footnote 695: _Astroph. Jour._, vols. iv., p. 317; vi., p. 426.] [Footnote 696: _Trans. Roy. Soc. Edin._, vol. xxxii., p. 452.] [Footnote 697: _Comptes Rendus_, t. cxi., p. 941; Huggins, _Proc. Roy. Soc._, vol. xlvi., p. 168.] CHAPTER V _TEMPERATURE OF THE SUN_ Newton was the first who attempted to measure the quantity of heat received by the earth from the sun. His object in making the experiment was to ascertain the temperature encountered by the comet of 1680 at its passage through perihelion. He found it, by multiplying the observed heating effects of direct sunshine according to the familiar rule of the "inverse squares of the distances," to be about 2,000 times that of red-hot iron.[698]