Part 12 (1/2)

[3] Taking the velocity of light at 186,000 miles a second, and the earth's mean distance at 93,000,000 miles, 1 light year=5,865,696,000,000 miles or 63,072 astronomical units; 1 astronomical unit a year=2.94 miles a second; and the earth's...o...b..tal velocity=18.5 miles a second.

[4] Ast. Nacht., 1889.

[5] R. S. Phil. Trans., 1718.

[6] Mem. Acad. des Sciences, 1738, p. 337.

[7] R. S Phil. Trans., 1868.

[8] _R.S. Phil Trans._, 1783.

[9] See Kapteyn's address to the Royal Inst.i.tution, 1908. Also Gill's presidential address to the British a.s.sociation, 1907.

[10] _Brit. a.s.soc. Rep._, 1905.

[11] R. S. Phil. Trans., 1803, 1804.

[12] Ibid, 1824.

[13] Connaisance des Temps, 1830.

[14] _R. A. S. Mem._, vol. xlvii., p. 178; _Ast. Nach._, No. 3,142; Catalogue published by Lick Observatory, 1901.