H. xii.] DUE TO RAPID MOTION 125 



it starts no longer in a direction perpendicular to 

 the surface, when it is in rapid motion, but sets 

 out obliquely, with a deflexion towards the equator, 

 so as to give the arrangement above described ; like 

 trunks of trees on a cliff or landslide which preserve 

 their roots in situ and gradually adjust their growth 

 to the vertical direction without being any longer 

 perpendicular to the soil. 



As a matter of fact the question all depends on 

 what hypothesis we make as to the intrinsic struc- 

 ture of the electron. If we liken it to a perfectly 

 conducting body with an electric charge, the charge 

 must be confined to its surface ; and it may be 

 proved, as Heaviside did. that the distribution will 

 remain uniform (cf. Larmor, dEther and Matter, 

 p. 154). Or it might be likened to a solid globe 

 of uniform electrification. It may be something of 

 which we have as yet no conception : but the 

 experiments of Kaufmann probably suffice to prove 

 that, whatever the structure is, it is symmetrical 

 around a centre, after the general manner of a 

 stratified spherical distribution. 



On the other hand these considerations can be 

 avoided by treating the charge merely as a 

 geometrical point from which the lines of force 

 emanate, and ignoring its size or possible conducting 

 power. This is the keynote of I/armor's treatment 

 throughout his book ^Ether and Matter, and also 

 in his earlier papers : in dealing with atomic structure 

 it implies that the electrons in the atom are at 

 distances apart which are great compared with their 

 radii. Cf. the fundamental investigation of Chapter 

 XL to be referred to below. We could hardly tell 

 a priori which treatment would best correspond 

 with fact, but it will turn out (see Chap. XIII.) that 



