ON THE PHYSICAL VIKW OK NAJ ll:i:. 



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The t«-nii 



requisites were supplied before the close of the ceuturv, 

 Here and abroad, the term electron, introduced l»y l)r 

 .Tohnstone Stoney ^ about ten years ago, has been gener- "eieciruu. 

 ally accepted to denote the ultimate particle of elec- 

 tricity, tlie atom of electricity — positive or negative — 

 of Helmholtz. Mathematical theories have been Wfjrked 

 out independently abroad by Prof. H. A. Lorentz - of 

 Leyden, and in this country by Dr Joseph Larmor"^ (;f 

 Cambridge.'* 



^ See 'British Association Report.' 

 1891, p. r.74, "On the Cause of 

 Double Lines in Spectra," by G. 

 Johnstone Stone}' : " The lines of 

 the spectrum of a gas are due to 

 some events which occur within 

 the molecules, and which are able 

 to affect the ether. These events 

 may be Hertzian discharges be- 

 tween molecules that are differ- 

 ently electrified, or they may be 

 the moving about of those irre- 

 movable electric charges, the sup- 

 position of which offers the simplest 

 explanation of Faraday's law of 

 electrolysis. . . . Several consider- 

 ations suggest that the source of the 

 spectral lines is to be sought not 

 in the Hertzian discharges, but 

 in the carrying about of the 

 fixed electric clmrges, which, for 

 convenience, may be called the 

 electrons." 



- Prof. Lorentz's principal writ- 

 ings are the two memoirs, ' ' La 

 Theorie dlectromaguetique de 

 Maxwell et son Application aux 

 Corps mouvants" (Leyden, 1892), 

 and " Versuch einer Theorie der 

 electrischen und optischen Erschei- 

 nungen in bewegten Korpern " 

 (Leyden, 189.o). His first labours, 

 indeed, go back to the year 1880. 



•* Dr Larmor's principal publi- 

 cations are, "A Dynamical Theory of 

 the Electric and Luminiferous Med- 

 ium" ('Philos. Transactions," 1894) ; 



VOL. II. 



Part ii., "Theory of Electrons," 

 1895; Part iii., "Relations with 

 Material Media," 1898 ; and his 

 Adams Prize Essay, " .i-Ether and 

 Matter, a Development of the 

 Dynamical Relations of the .lEther 

 to Material Systems on the Basis 

 of the Atomic Constitution of 

 Matter" (Cambridge, 1900). Dr 

 Larmor's several shorter pa])er8 

 and addresses, to which I shall 

 refer, are very hel[)ful as intro- 

 ducing one into this novel domain 

 of science. 



■* A little later than Lorentz and 

 Larmor, Dr Wiechert of Konigs- 

 berg began (in 1896) a series of 

 publications on the same subject, 

 with the aim of making the Max- 

 welliaii conceptions more definite. 

 With him, also, the problem narrows 

 itself down to a reconciliation of 

 the continuity of the ether with 

 the atomic nature of ponderable 

 matter, and of the electrical charges 

 attached to it. His views, to- 

 gether with a historicid ana- 

 lysis of the labours of his great 

 predecessors. Coulomb, Ampere, 

 Biot and Savart, Neumann, Far- 

 aday, Maxwell (including the 

 formal simplifications introduced 

 into Maxwell's scheme by 0. 

 Heaviside, Hertz, and Poynting), 

 Von Helmh«)ltz, and H. A. Lorentz, 

 are very concisely set out in a 

 memorial essay entitled ' Gruud- 



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