226 SCIENCE AND METHOD. 



IV. 



I 



Consequences of the Principle of 

 Relativity. 



We have seen above the reasons that incline us to 

 regard the Principle of Relativity as a general law of 

 Nature. Let us see what consequences the principle 

 will lead us to if we regard it as definitely proved. 



First of all, it compels us to generalize the hypo- 

 thesis of Lorentz and Fitz-Gerald on the contraction 

 of all bodies in the direction of their transposition. 

 More particularly, we must extend the hypothesis to 

 the electrons themselves. Abraham considered these 

 electrons as spherical and undeformable, but we shall 

 have to admit that the electrons, while spherical when 

 in repose, undergo Lorentz's contraction when they 

 are in motion, and then take the form of flattened 

 ellipsoids. 



This deformation of the electrons will have an 

 influence upon their mechanical properties. In fact, 

 I have said that the displacement of these charged 

 electrons is an actual convection current, and that 

 their apparent inertia is due to the self-induction of 

 this current, exclusively so in the case of the negative 

 electrons, but whether exclusively or not in the case of 

 the positive electrons we do not yet know. 



On these terms the compensation will be perfect, 

 and in conformity with the requirements of the 

 Principle of Relativity, but only upon two con- 

 ditions : — 



I. That the positive electrons have no real mass, 

 but only a fictitious electro-magnetic mass ; or at least 



