THE LATEST STAGE 237 



cathode rays. We may, in fact, resolve the concep- 

 tion of electricity into that of matter, or the conception 

 of matter into that of electricity. It is impossible to 

 say that one of these conceptions is more fundamental 

 than the other. Owing to our muscular sense, the 

 forces required to set matter in motion are direct 

 sense-perceptions, and thus to our minds matter 

 seems more familiar than electricity ; but, had we 

 an electrical sense, as the fish torpedo may possibly 

 possess, we might find the positions reversed, and 

 think it simpler to paint our picture of nature in 

 electrical colours. Thus clearly we see how the 

 structure of our minds, nay of our bodies too, affects 

 our scheme of science. 



Another consequence of the theories we are con- 

 sidering is of philosophic interest. A corpuscle or 

 electron, as we have seen, owes its apparent mass to 

 the field of electromagnetic momentum it carries with 

 it. Now, while this momentum remains constant at 

 all ordinary speeds, the mathematical equations show 

 that it should increase very rapidly as the velocity 

 of light is approached. If that velocity could be 

 reached, the apparent mass would be infinite, for no 

 exertion of force could cause any further increase in 

 velocity. 



Now, in the next section, we shall describe the 

 phenomena of radio-activity in which corpuscles 

 are found moving with speeds which in some cases 

 approach to within some five per cent, of the velocity 

 of light. By measuring their deflection by electric 

 and magnetic forces, the mass of these particles can 

 be measured, and it is of great interest to find that 

 once more our scheme of science corresponds with 



