344 SCIENCE PROGRESS 



be detected? A gratuitous statement this, not a likely one; 

 but for the present it must pass. The electromagnetic influence 

 of two bodies moving side by side has not yet been detected 

 except by means of apparatus stationary in respect of both 

 bodies — thus introducing relative motion. Whether the plates 

 of a charged condenser fixed to each other and to the earth — 

 i.e. moving only with the earth — do really attract each other 

 differently or have a different capacity or anything of the kind 

 by reason of that motion remains a point not yet settled by 

 observation. 



So, naturally, the supporters of the doctrine of relativity 

 have a great deal to say in support of their position ; certainly 

 they can contend that no experiment has yet assailed it. 



The weak point of their position — and fortunate it is that 

 it has this weak point, for thereby it cannot remain as a per- 

 manent bugbear in the path of science unless it has a real and 

 substantial justification, in which case it will be no bugbear 

 but the truth — the weak point is that any year an experiment 

 may be made with a positive result ; unlikely though such a thing 

 seems at present, by reason of curiously compensating causes. 



Whenever that happens, the bubble will be pricked ; and 

 physicists in general — not the loyal few alone but the adven- 

 turous spirits who have struck out in rash metaphysical 

 directions of their own — will return to their allegiance and 

 once more interpret physical nature in terms of an omnipresent, 

 universally-connecting, perfectly-continuous medium, the Ether 

 of Space. 



