JEtlier and Electrons. 697 



A wave-propagation involving no bodily motion for aether- 

 eleinents, as suggested in § 5, might conceivably be realized 

 in a medium incapable of experiencing a bodily shearing- 

 stress, or of yielding to compressional stress : that is, in a 

 medium constituted of frictionless incompressible fluid, which 

 must necessarily be in motion. A further condition for 

 such a medium appears to be a certain heterogeneity, as 

 for example when coreless vortices are present. On this 

 subject I hope to present some considerations in a later 

 communication. 



Strain-figures and Electrons. 



8. In 1891 a paper was read before the Physical Society 

 of London *, wherein an attempt was made to account for 

 some of the properties of matter by means of a theory of 

 " strain-figures," the equations of motion of a strain-figure 

 o£ general specification being established. The intervening 

 years having seen the initiation and development of the 

 electronic theory of matter, the main feature of the view put 

 forward in the paper referred to will be understood from the 

 briefest restatement. It was suggested " that a given portion 

 of matter consists, not of any individual portion of aetherial 

 or other substance, but of modifications in the structure or 

 energy or other qualities of the aether ; and when matter 

 moves, it is merely these modifications of structure or of 

 energy or of other qualities which are transferred from one 

 portion of the aether to another." No attempt was made to 

 connect the inertia or other properties of atomic matter with 

 any electromagnetic phenomena, and in fact, as it was assumed 

 that the inertia of a given body was strictly invariable, the 

 conclusion was drawn that the strain concerned w r as probably 

 related closely to gravitation. I was not at that time aware 

 of Professor J. J. Thomson's memoir " On the Electric and 

 Magnetic Effects produced by the Motion o£ Electrified 

 Bodies " f , which forms the starting-point as well as the 

 permanent basis for an electronic theory of matter. 



9. The especial object of this " strain-figure " theory was 

 to reconcile the mobility of matter with the apparently perfect 

 elastic properties of the aether, and from this point of view 

 it may be interesting to compare the strain-figure of 1891 

 with subsequent specifications of the electron. The suggested 



* C. V. Burton, " A Theory concerning' the Constitution of Matter," 

 Phil. Mao-. February 1892. 

 t Phil.' Mag. April 1881. 



