[320] Pub. Dom. Ap. Obs., 3, 7, 1925.

[321] H. C. 258, 1924.

[322] Chapter VIII, [p. 126].

[323] Mt. W. Contr., in press.

[324] Walters, J. Wash. Ac. Sci., 14, 408, 1924.

[325] Russell, Ap. J., 55, 119, 1922.

[326] Menzel, H. C. 258, 1924.

[327] Ap. J., 9, 214, 1899.

[328] Russell, Ap. J., 55, 119, 1922.

[329] Menzel, H. C. 258, 1924.