[499] H. A., 28, 131, 1901.

[500] Observatory, 38, 381, 1915.

[501] Mt. W. Contr. 199, 1918.

[502] Harper and Young, J. R. A. S. Can., 18, 9, 1924.

[503] Observatory, 38, 381, 1915.

[504] Chapter XIII, [p. 178].

[505] Observatory, 38, 381, 1915.

[506] Chapter III, [p. 36].

[507] Chapter III, [p. 35].

[508] See above, [p. 193].