[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.
[15] _R. A. S., M. N._, vol. vi.
[16] _R. S. Phil. Trans._, vol. lxxiii., p. 484.
[17] _Astr. Nach._, No. 2,947.
[18] _R. S. E. Trans_., vol. xxvii. In 1901 Dr. Anderson discovered Nova Persei.
[19] _Astr. Nach_., No. 3,079.
[20] For a different explanation see Sir W. Huggins"s lecture, Royal Inst.i.tution, May 13th, 1892.
[21] For the early history of the proposals for photographic cataloguing of stars, see the _Cape Photographic Durchmusterung_, 3 vols. (_Ann. of the Cape Observatory_, vols. in., iv., and v., Introduction.)
[22] _R. S. Phil. Trans._, 1850, p. 499 _et seq._
[23] _Ibid_, vol. cliv., p. 437.
[24] _Brit. a.s.soc. Rep._, 1868, p. 165.