FOOTNOTES:

[1] _R. S. Phil Trans_., 1810 and 1817-24.

[2] One of the most valuable contributions to our knowledge of stellar
parallaxes is the result of Gill's work (_Cape Results_, vol. iii.,
part ii., 1900).

[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 orbital 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 Institution, 1908. Also Gill's
presidential address to the British Association, 1907.

[10] _Brit. Assoc. Rep._, 1905.

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