706 Dr. C. V. Burton : Notes 



on 



of the nature of electrons might furnish the justification. 

 Incidentally reference may be made to the sufficiently obvious 

 point that any theory which postulates symmetrical con- 

 trariety of properties for positive and negative electrons, even 

 though descriptive of a certain range of electromagnetic 

 phenomena, must fail to be ultimately satisfactory. 



18. It will probably be felt as a difficulty of a free strain- 

 figure theory of electron-constitution, that it is made to 

 appear at least kinematically possible to produce in free aether 

 a distribution of electric displacement which violates the 

 solenoidal or " circuital " condition : for example, in the 

 early stages of ideal genesis of a strain-figure (§ 9). This 

 difficulty, indeed, seems to arise in some form as soon as the 

 possibility of an isolated electron is assumed. To evade it 

 we may suppose the energy of non-circuital distributions of 

 electric displacement to be relatively very great ; or it may 

 even be suggested that the aether, though intrinsically capable 

 of transmitting waves of other than electromagnetic type, is 

 free from such disturbances because these are not produced 

 by the only available source of excitation, namely the motion 

 of electrons. But these attempts to deal with the difficulty 

 are clearly of the most tentative character. 



19. It can hardly be doubted that the uniformity which 

 characterizes all electrons of the same kind is an essential pro- 

 perty, and fundamentally related to the constitution of the 

 electron. From this point of view it does not seem easy to con- 

 ceive of an alternative to the free type of strain-figure, which 

 is imagined as existing in unconstrained equilibrium with the 

 surrounding comparatively unstrained medium. As I have 

 suggested previously*, if free strain-figures could exist in a 

 uniform (infinitely fine-textured) medium, only a limited 

 number of types of such strain-figures (say two for example) 

 would in general be possible as permanent forms ; the only 

 feature remaining undetermined for each type being expres- 

 sible as a single linear magnitude serving to define the scale 

 of the strain-figure. To secure definiteness of scale we must 

 suppose that there is some linear magnitude characteristic of 

 the medium, and capable of influencing the equilibrium- 

 conditions for a strain-figure; and apparently the only 

 possible basis for the existence of such a magnitude is a 

 certain coarseness of texture of the medium, or, in other 

 words, constitution on a scale not infinitely minute. 



20. As will be seen from the ideal genesis of a free strain- 

 figure outlined in § 19 above, we assume in the case of the 

 electron that a point is reached where the ordinary linear 



* Phil Mas. Feb. 1892. 



