[9] Fowler, Month. Not. Roy. Astr. Soc. lxxiii. Dec. 1912.

[10] Evans, Nature, xcii. p. 5 (1913); Phil. Mag. xxix. p. 284 (1915).

[11] For

we get a series in the extreme ultraviolet of which some lines have recently been observed by Lyman (Nature, xcv. p. 343, 1915).

[12] See Nature, xcii. p. 231 (1913).

[13] See also Stark, Verh. d. D. Phys. Ges. xvi. p. 468 (1914).

[14] Rau, Sitz. Ber. d. Phys. Med. Ges. Würzburg (1914).

[15] Merton, Nature, xcv. p. 65 (1915); Proc. Roy. Soc. A. xci. p. 389 (1915).

[16] Stark, Elektrische Spektralanalyse chemischer Atome, Leipzig, 1914.