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III. On Action at a Distance. 

 By Oliver J. Lodge, D.Sc* 



THE idea of immediate action at a distance has been so 

 thoroughly condemned by Newton, Clerk Maxwell, and 

 other leaders of science in this country, that one cannot but 

 rejoice that Mr. Walter Browne has thought it worth while to 

 undertake its defence and to plead whatever can be pleaded on 

 its behalf, because there is a danger that in discarding too 

 completely any point of view some valuable truth may be 

 temporarily lost sight of at the same time. 



In his carefully constructed argument, communicated by 

 the Physical Society of London to *the December number of 

 the Philosophical Magazine, Mr. Browne has mainly occupied 

 himself with certain views concerning the aether, more especi- 

 ally with the one whose propoundment at the present time is a 

 natural consequence of the striking success of the kinetic 

 theory of gases, the one, namely, which regards every pheno- 

 menon in the universe as due to the bombardment of freely 

 flying atoms of various sizes and length of path. 



I am not anxious to defend this interesting hypothesis, which, 

 whether it ultimately maintain its ground or not, is sure to 

 find supporters; and I do not see that it very materially affects 

 the question as to whether there is or is not such a thing as 

 direct action of one body or another across a distance — because, 

 as Mr. Browne and others have observed, the magnitude of 

 the distance across which the action takes place is of no mo- 

 ment whatever. The real point in Mr. Browne's argument in 

 favour of action at a distance consists, I think, in the meta- 

 physical difficulties which he finds in assuming the existence 

 of immediate contact between two bodies under any circum- 

 stances. 



But I venture to think that, putting metaphysics entirely 

 on one side, we may prove in a perfectly simple and physical 

 manner that it is impossible for two bodies not in contact to 

 act directly on each other ; in other words, we can show that 

 action at a distance is incompatible either with the law of the 

 conservation of energy, or with Newton's " third law," or with 

 both. 



Let us state these two axioms, with the necessary definitions, 

 thus : — 



1st. If a body A act directly and solely on a body B, the 

 force with which A acts on B is equal and opposite to the force 

 with which B acts on A. 



2nd. If B yield to the force exerted by A, A is said to do 

 * Communicated by the Author. 



