FOOTNOTES:
[1] Communicated by Sir Ernest Rutherford, F.R.S.
[2] Phil. Mag. xxvi. pp. 1, 476, 857 (1918) and xxvii. p. 506 (1914). These papers will be referred to as I., II., III., & IV. respectively. See [Transcriber’s Notes]
[3] van den Broek, Phys. Zeit. xiv. p. 32 (1913).
[4] See Rutherford, Phil. Mag. xxvii. p. 488 (1914).
[5] See J. H. Jeans, “Report on Radiation and the Quantum Theory,” Phys. Soc. London, 1914.
[6] Nicholson, Month. Not, Roy. Astr. Soc. lxxii. p. 679 (1912).
[7] Einstein and Haas, Verh. d. D. Phys. Ges. xvii. p. 152 (1915). That such a mechanical rotational effect was to be expected on the electron theory of magnetism was pointed out several years ago by O. W. Richardson, Phys. Review, xxvi. p. 248 (1908). Richardson tried to detect this effect but without decisive results.
[8] Nicholson, Phil. Mag. xxvii. p. 541 and xxviii. p. 90 (1914).
[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.
[17] Stark, loc. cit. pp. 51, 54, 55, & 56.
[18] On this view we should expect the Rydberg constant in (13) to be not exactly the same for all elements, since the expression (5) depends to a certain extent on the mass of the nucleus. The correction is very small; the difference in passing from hydrogen to an element of high atomic weight being only 0.05 per cent. (see IV. p. 7). In a recent paper (Proc. Roy. Soc. A. xci. p. 255, 1915), Nicholson has concluded that this consequence of the theory is inconsistent with the measurements of the ordinary helium spectrum. It seems doubtful, however, if the measurements are accurate enough for such a conclusion. It must be remembered that it is only for high values of
that the theory indicates values of
very nearly unity; but for such values of
, the terms in question are very small, and the relative accuracy in the experimental determination not very high. The only spectra for which a sufficiently accurate determination of
seems possible at present are the ordinary hydrogen spectrum and the helium spectrum considered in the [former section], and in these cases the measurements agree very closely with calculation.
[19] Fowler, Phil. Trans. Roy. Soc. A. 214. p. 225 (1914).
[20] Fowler, loc. cit. p. 262, see also II. p. 15.
[21] Stark, loc. cit. pp. 67-75.
[22] Rau, loc. cit.
[23] Franck & Hertz, Verh. d. D. Phys. Ges. xv. p. 34 (1918).
[24] Cuthbertson, Proc. Roy. Soc. A. lxxxiv. p. 18 (1910).
[25] Franck and Hertz, Verh. d. D. Phys. Ges. xvi. pp. 457, 512 (1914).
[26] Paschen, Ann. d. Phys. xxxv. p. 860 (1911).
[27] Stark, Ann. d. Phys. xlii. p. 239 (1913).
[28] This value is of the same order of magnitude as the value 12.5 volts recently found by McLennan and Henderson (Proc. Roy. Soc, A. xci. p. 485, 1915) to be the minimum voltage necessary to produce the usual mercury spectrum. The interesting observations of single-lined spectra of zinc and cadmium given in their paper are analogous to Franck and Hertz’s results for mercury, and similar considerations may therefore possibly also hold for them.
[29] Moseley, Phil. Mag. xxvi. p. 1024 (1918); and xxvii. p. 703 (1914).
[30] Nicholson, Phil. Mag. xxvii. p. 562 (1914).
[31] Kossel, Verh. d. Deutsch. Phys. Ges. xvi. p. 953 (1914).
[32] Malmer, Phil. Mag. xxviii. p. 787 (1914).
[33] See Kossel, loc. cit. p. 960.
[34] Bragg, Phil. Mag. xxix. p. 407 (1915).
[35] Barkla, Nature, xcv. p. 7 (1915). In this note Barkla proposes an explanation of his experimental results which in some points has great similarity to Kossel’s theory.