[ 201 ] ( K 



XYII. On the Theory of Moving Electrons and Electric 

 Charges. By J. Larmor*. 



IN an interesting paper by Mr. W. B. Morton, communi- 

 cated by the Physical Society to the Philosophical 

 Magazine for June, there is a criticism of a portion of 

 my paper on u A Dynamical Theory of the Electric and 

 Luminiferous Medium "f> which if valid would affect its whole 

 tenor. As, however, the formulae of that paper were to a 

 considerable extent obtained by two independent trains of 

 reasoning, it would have to be shown that both were wrong 

 before an error could be fully substantiated. As a matter of 

 fact, Mr. Morton's criticism arises from his reading into the 

 analysis assumptions which are not there, but which had been 

 used, with the proper limitations to secure accuracy, in 

 another place in the previous part of the paper. As the point 

 is really fundamental, and as the analytical statement in the 

 memoir is no doubt too brief to convey at once a grasp of the 

 procedure employed, without somewhat detailed consideration 

 on the reader's part, I beg leave to offer the following general 

 explanation. 



The facts of chemical physics point to electrification being 

 distributed in an atomic manner, so that an atom of electricity, 

 say an electron, has the same claims to separate and permanent 

 existence as an atom of matter. The fundamental question 

 then is, how far the conception of separate isolated electrons, 

 pervading the aether of free space, can provide an explanation 

 of electrodynamic and optical phenomena. In the paper re- 

 ferred to I have gone further back, and have considered the 

 question how far such a simple underlying scheme is able by 

 itself to provide an explanation of physical phenomena in 

 general ; for it will obviously not be permissible to import 

 into our dynamical notion of an atom of matter more than 

 simple electric properties, unless these latter prove to be in- 

 sufficient to include all actual knowledge of its relations. 

 The conclusion arrived at in the memoir is that there is 

 nothing in the ascertained laws of general physics which 

 points to insufficiency in that scheme ; while there are some 

 experimental results which somewhat militate against the 

 existence of interatomic forces of any kind other than those 

 included in it. 



The main feature of the theory referred to is that the aether 



* Communicated by the Physical Society. 



t Phil. Trans. 1894 (A) , pp. 719-822, and 1895! (A), pp. 695-743. 



