FOOTNOTES:

[476] Russell, Science, 39, 791, 1914.

[477] R. H. Fowler and Milne, M. N. R. A. S., 83, 403, 1923.

[478] Harrison, unpub.

[479] H. C. 258, 1924.

[480] Payne, Proc. N. Ac. Sci., 11, 192, 1925.

[481] Clarke and Washington, Proc. N. Ac. Aci., 8, 108, 1922.

[482] Russell, Science, 39, 791, 1914.

[483] Pub. Dom. Ap. Obs., 1, 325, 1922.

[484] Jeffreys, The Earth, 1924.