[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.

[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.