CHAPTER X. 



THE ELECTRON THEORY OF CONDUCTION 

 AND OF RADIATION. 



MEANWHILE the probability of the existence of elec- 

 trons and the possibility of regarding them as the 

 basis of all electric and of most other material 

 phenomena, had seized hold of the imagination of 

 several mathematical physicists, notably of Professor 

 H. A. Lorentz and of Dr. J. Larmor. The former, 

 who was first in the field (1892 and 1895), was 

 driven in this direction by the problem of the 

 astronomical aberration of light and the optics of 

 moving media treated from the electric standpoint. 

 The latter reached the same goal independently, from 

 the dynamics of the free ether, on the basis of 

 MacCullagh and Kelvin, which required discrete 

 mobile sources of disturbance (electrons) as a basis for 

 development. Both these philosophers endeavoured 

 to trace all electric properties to the behaviour of 

 electrons, usually of course in association with 

 material atoms ; while Larmor's procedure also im- 

 pelled him to make intelligible by conceptual ' models' 

 the dynamical possibility of a structure in the ether 

 which should have the properties of an electron, 

 whether positive or negative, the two being treated 

 as mirror images of each other and so to reduce a 



