396 



SCIENCE. 



[N. S. Vol. XXII. No. 501. 



Poincare should not be forgotten: If, says 

 Poincare, compatibly with the principle of 

 the conservation of energy and of least 

 action, any single ether mechanism is a 

 possibility, there must at the same time 

 be an infinity of others. 



THE ELECTRONIC THEORY. 



The splendid triumph of the electronic 

 theory is quite of recent date, although 

 Davy discovered the electric arc in 1821 

 and although many experiments were made 

 on the conduction of gases by Faraday 

 (1838), Riess, Gassiot (1858, et seq.) and 

 others. The marvelous progress which the 

 subject has made begins with the observa- 

 tions of the properties of the cathode ray 

 by Pliicker and Hittorf (1868), brilliant- 

 ly substantiated and extended later by 

 Crookes (1879). Hertz (1892) and more 

 specifically Lenard (1894) observed the 

 passage of the cathode rays into the at- 

 mosphere. Perrin (1895) showed them 

 to be negatively charged, Rontgen (1895) 

 shattered them against a solid obstacle 

 generating the X-ray. Goldstein (1886) 

 discovered the anodal rays. 



Schuster's (1890) original determination 

 of the charge carried by the ion per gram 

 was soon followed by others utilizing both 

 the electrostatic and the magnetic deviation 

 of the cathode torrent and by Lorentz 

 (1895) using the Zeeman effect. J. J. 

 Thomson (1898) succeeded in measuring 

 the charge per corpuscle and its mass, and 

 the velocities following Thomson (1897) 

 and Wiechert (1899), are known under 

 most varied conditions. 



But all this rapid advance, remarkable 

 in itself, became startlingiy so when viewed 

 correlatively with the new phenomena of 

 radioactivity, discovered by Becquerel 

 (1896), wonderfully developed by M. and 

 Madame Curie (1898, et seq.), by J. J. 

 Thomson and his pupils, particularly by 

 Rutherford (1899, et seq.). From the 



Curies came radium (1898) and the ther- 

 mal effect of radioactivity (1903), from 

 Thomson much of the philosophical pre- 

 vision which revealed the lines of sim- 

 plicity and order in a bewildering chaos of 

 facts, and from Rutherford the brilliant 

 demonstration of atomic disintegration 

 (1903) which has become the immediate 

 trust of the twentieth century. Even if 

 the ultimate significance of such profound 

 researches as Larmor's (1891) 'Ether and 

 Matter' can not yet be discerned, the evi- 

 dences of the transmutation of matter are 

 assured, and it is with these that the cen- 

 tury will immediately have to reckon. 



The physical manifestations accompany- 

 ing the breakdown of atomic structure, as- 

 toundingly varied as these prove to be, 

 assume fundamental importance when it 

 appears that the ultimate issue involved is 

 nothing less than a complete reconstruction 

 of dynamics on an electromagnetic basis. 

 It is now confidently affirmed that the mass 

 of the electron is wholly of the nature of 

 electromagnetic inertia, and hence, as Abra- 

 hard (1902), utilizing Kaufmann's data 

 (1902) on the increase of electromagnetic 

 mass with the velocity of the corpuscle, 

 has shown, the Lagrangian equations of 

 motion may be recast in an electromagnetic 

 form. This profound question has been 

 approached independently by two lines of 

 argument, one beginning with Heaviside 

 (1889), who seems to have been the first to 

 compute the magnetic energy of the elec- 

 tron, J. J. Thomson (1891, 1893), Morton 

 (1896), Searle (1896), Sutherland (1899) ; 

 the other with H. A. Lorentz (1895), 

 Wiechert (1898, 1899), Des Coudres 

 (1900), Drude (1900), Poincare (1900), 

 Kaufmann (1901), Abraham (1902). Not 

 only does this new electronic tendency in 

 physics give an acceptable account of heat, 

 light, the X-ray, etc., but of the Lagrangian 

 function and of Nev/ton 's laAvs. 



