[17] See Maxwell’s Electricity and Magnetism, vol. i. p. 350 (2nd ed., 1881).
[18] “On the Physical Units of Nature,” Phil. Mag., 1881, [5], 11, p. 381. Also Trans. Roy. Soc. (Dublin, 1891), 4, p. 583.
[19] See Sir W. Thomson, Proc. Roy. Soc. Lond., 1856, 8, p. 152; or Maxwell, Elect. and Mag., vol. ii. p. 831.
[20] See Lord Rayleigh, Proc. Roy. Soc. Lond., 1884, 37, p. 146; Gordon, Phil. Trans., 1877, 167, p. 1; H. Becquerel, Ann. Chim. Phys., 1882, [3], 27, p. 312.
[21] Perkin’s Papers are to be found in the Journ. Chem. Soc. Lond., 1884, p. 421; 1886, p. 177; 1888, p. 561; 1889, p. 680; 1891, p. 981; 1892, p. 800; 1893, p. 75.
[22] The Work of Hertz (London, 1894).
[23] L’Ottica delle oscillazioni elettriche (Bologna, 1897).
[24] Les Oscillations électriques (Paris, 1894).
[25] Recent Researches in Electricity and Magnetism (Oxford, 1892).
[26] See J.J. Thomson, Proc. Roy. Inst. Lond., 1897, 15, p. 419; also Phil. Mag., 1899, [5], 48, p. 547.