420 Prof. 0. Lodge on Absolute Velocity and 



But it may be objected that atoms can move ; and if they 

 move, their charges must go too ; and if their charges move, 

 the aether may be affected ; hence it appears as if motion of 

 matter could disturb aether after all. Let us get clear on 

 this point. On Larmor's theory, for instance, there need be 

 no material substratum at all, nothing but an agglomeration 

 of ionic charges or " electrons " with a definite configuration; 

 and this assemblage of elecirons constitutes an atom. Now 

 if there is an excess of free charge which vibrates or revolves, 

 or if the electrons move in any way differentially, that is an 

 electrical phenomenon, and it disturbs the aether and excites 

 or absorbs, or delays and therefore refracts, radiation ; but 

 if all the electrons move together, positive and negative 

 simultaneously, that is a material or mechanical phenomenon, 

 and need not excite the aether at a finite distance at all. 

 Similarly an electrical disturbance applied to water decom- 

 poses it, either actually or initially, setting up at least a 

 polarization no matter how small in amount ; whereas a 

 mechanical disturbance applied to water merely moves it 

 about, oxygen and hydrogen together. As I have suggested 

 long ago concerning these two processes, the first has an 

 analogue in the aether ; the second has none : aether can be 

 polarized or even sheared, but not moved. It may be that 

 the immobility is only approximate, that it behaves as if 

 its inertia were enormous but not infinite; but until further 

 facts are forthcoming, and for present purposes, I will assume 

 the immobility absolute, on the ground that the properties 

 of free aether usually seem to be of a perfect and not an 

 approximate order. 



The only tangential communication between aether and 

 matter is through the medium of what we call an electric 

 charge ; such charges are essentially of equal and opposite sign, 

 and imply some form of doubleness of constitution (right- and 

 left-handed strains on Larmor's theory) in the aether. In 

 purely electric and magnetic phenomena the aetherial consti- 

 tuents are sheared, either elastically or continuously, but their 

 " centre of gravity " is stationary ; and so even in those cases 

 the aether is immovable, while in mechanical phenomena there 

 is no necessary aetherial disturbance at all ; and hence in all 

 cases it is as a whole absolutely fixed. The only kinetic 

 energy it possesses is that of its constituents when being 

 sheared in opposite directions; this is electrokinetic energy*; 

 but of translatory or available mechanical kinetic energy it 

 has, i. e. it receives or delivers up, none. 



As to potential energy, — the energy of statical stress, 



* Larmor would express this differently, he would have translatory 

 energy with very great iuertia and therefore very small velocity. 



