202 Mr. J. Larmor on the Theory of 



is not matter, as ordinarily assumed, nor in any way like 

 matter ; it is the uniform substratum (analytical basis, if one 

 is disposed to use that term, for it can never be the direct 

 object of perception) in which the atoms of matter consist as 

 permanent configurations of strain and motion. As was to be 

 expected, the relations of inertia and elasticity of this uniform 

 medium are simpler than those of matter, which is merely a 

 molecular aggregate involved in its constitution. In fact, 

 the only way to arrive at a scheme of the relations between 

 aether and matter which shall be a complete dynamical 

 theory and not merely descriptive, is to abolish the apparent 

 duality in the phenomena, either by taking as here the mole- 

 cules of matter to constitute singularities (in the mathe- 

 matical tense of the theory of functions) in the uniform 

 aether, or else by trying to make out the aether to be ordinary 

 matter, and so giving up any attempt to explain why matter 

 is molecularly constituted. This molecular constitution of 

 matter is essential to the former theory, just as it is to all 

 other theories or illustrations, like the A r ortex theories, which 

 hypothecate a uniform underlying medium ; it is quite 

 unintelligible — or rather quite unexplained — on the latter 

 type of theory. 



But however these things may be, the point criticised by 

 Mr. Morton does not involve any considerations so refined, 

 or — as possibly may be said — so ambiguous. The sections to 

 which he objects claim to be a reconstruction of ordinary 

 electrodynamic theory on the basis of permanent electrons 

 associated with the " atoms of matter. Whatever view one 

 may entertain as to the presence of qualities other than electric 

 in the atom, all are 1 think now-a-days agreed that the electron 

 is there. And whatever view one may have as to the validity 

 and sufficiency of an aether with simple rotational elasticity, 

 the formal equations to which that theory leads for free space 

 are just those equations of Maxwell which Hertz's experi- 

 mental work has fully verified. The problem of electrodynamics 

 is then that of the free aether, whose properties are represented 

 analytically by these acknowledged equations, disturbed by 

 the action of the electrons of material atoms moving about in 

 it. The original Amperean electrodynamics, proceeding by 

 consideration of elements of current, has not proved valid or 

 sufficient in matters involving electric radiation, or even 

 ordinary electrodynamic force. A most successful modification 

 of it was that proposed by Weber, in which elements of current 

 were replaced, as the fundamental object of consideration, by 

 moving electric particles which acted on each other at a dis- 

 tance according to a law of force involving their velocities. 



