CH. ix.J SIZE OF ELECTRON 95 



verified later on by direct experiment.) Again, the 

 & 



ratio had been determined for the cathode ray 

 m 



particles, and for the carriers of negative electricity 

 from incandescent filaments and from metal plates 

 illuminated by ultra-violet light at low pressures, 

 and it will be remembered that in all these cases the 



p 



same value of was obtained, thereby justifying 



the surmise that the charge on an electron was the 

 same as that on an ion produced by ultra-violet 

 light, and therefore the same as on a negative ion 

 produced by X-rays." 



Estimate of Size. 



On the hypothesis that the flying or vibrating 

 fragment is a material corpuscle charged with 

 electricity, so that it has a duplex constitution and 

 a compound kind of inertia, part material and part 

 electrical, no further progress can be made. But on 

 the hypothesis that the flying or vibrating particle is 

 an electron a charge of electricity and nothing 

 else a constituent of an atom but with no material 

 nucleus so that the whole of atomic properties 

 might possibly turn out to be due to an aggregate 

 of electrons of opposite sign, of which one or two 

 are comparatively free and detachable on this 

 hypothesis a determination of the mass of a 

 corpuscle carries with it, as a consequence, a de- 

 termination of its size also. 



Because, as has already been pointed out, any 

 required amount of self-induction can be conferred on 

 a wire by making it fine enough, and any required 

 amount of energy can be conferred upon an electric 



