. Recent Theories of Electricity. 205 



matter are attributes of electricity. Tbis hypothesis can mean 

 nothing else than tliat the Lucretian atom, the centres of 

 force of Boscovich, the vortices of Kelvin and all the atomic 

 models (made of weights and springs and strings), have failed 

 and become useless as aids to the imagination. 



Sir J. Larmor defines this new atom as a protion *, " in 

 whole or in part a nucleus of intrinsic strain in the aether, a 

 place at which the continuity of the medium has been broken 

 and cemented together again (to use a crude but effective 

 image) without accurately fitting the parts, so that there is a 

 residual strain all round the place." This strain is not of 

 the character of mechanical elasticity, since the " ultimate f 

 element of material constitution is taken to be an electric 

 charge or nucleus of permanent setherial strain instead of a 

 vortex ring : . . . . The molecule is composed simply of a 

 system, probably large in number, of positive and negative 

 protions in a state of steady orbital motion round each 

 other : . . . . And, moreover, we may imagine complex 

 structures composed of these primary systems as units, for 

 example successive concentric rings of positive or negative 

 electrons sustaining each other in position/'' 



Positive and negative electrons differ only in their orbital 

 motion from each other and their forces are all of the elec- 

 trical type. Prof. Sir J. J. Thomson pictures the atoms of 

 the various chemical elements as nuclei of free positive elec- 

 tricity holding in electrical equilibrium free negative charges, 

 placed in various geometrical designs. The degree of stability 

 is determined by the radioactivity of each element. Professor 

 Lorentz considers the protion to be a small particle charged 

 with electricity and probably a local modification of the aether ; 

 but his work on electromagnetic mass leads one to the opinion 

 that he believes electricity to be the real essence of the 

 material universe. Professor Abraham and the modern 

 school of German physicists are frankly endeavouring to 

 give a purely electromagnetic foundation to the mechanism 

 of the electron and to mechanical actions in general. 



Now to me, and I believe to many men of science, the 

 chief and indeed only value of an atomic theory is to give a 

 concrete, though crude, image of matter reduced to its 

 simplest conditions. The word electricity gives me no such 

 image of matter ; it conveys absolutely no idea of materiality 

 nor even of space or time relations. What the originators 

 of the electrical atom have done is apparently to transpose 

 the words, matter and electricity, tacitly giving to the latter 



* 'JEther and Matter,' p. 26. 

 t L. c. p. 27 passim. 



