Mr. W. R. Browne on Action at a Distance. 439 



red ways in which it can act upon it are two, viz. either by 

 projecting a third body from contact with itself into contact 

 with B, or by diverting some third body which, if not diverted, 

 would have come into contact with B. 



If action at a distance does not exist, all the actions between 

 all the bodies of the universe must be explicable, by impact, 

 on one of these three hypotheses. If any phenomenon takes 

 place which cannot be so explained, then action at a distance 

 does exist. It may be added that, if it is shown to exist in 

 any one instance and at any distance, there is no probability 

 against its existence in any other instance and at any other 

 distance. It is no less wonderful, and no more wonderful, 

 that two bodies should act on each other across the hundred 

 millionth of an inch, than that they should act on each other 

 across a hundred million of miles. In fact it is easy to con- 

 ceive a creature so large, or so small, that the difference be- 

 tween these two distances would appear to it quite insignificant. 



Let us now take the above three hypotheses and see whether 

 all the actions in the universe can be explained by them. 



First, as to the direct impact of one interacting body A 

 upon another B. This may no doubt explain certain obvious 

 cases, as the stoppage of a falling body when it reaches the 

 earth ; but it is equally obvious that there are many others, 

 such as gravity, magnetism, &c, which it cannot explain. In 

 fact, it will be granted that in these and many other cases 

 there is an apparent action between bodies at a distance; and 

 our business is to see whether it is real or apparent only. 



Secondly, with reference to the projection of other bodies 

 from A against B. It is clear that the actions thus produced 

 can be actions of repulsion only: therefore this principle 

 cannot explain any case of attraction. Moreover the power 

 by which A is able to project these bodies against B itself re- 

 quires explanation. If they have previously been at rest in 

 relation to A, then A can only project them by some innate 

 explosive power totally different from impact. And if any one 

 suggests that the bodies have previously been in motion with 

 respect to A, and that they are projected by elastic reaction 

 from A, then he must be asked to give an explanation of elas- 

 ticity from impact only, and without introducing action at a 

 distance. In any case it seems clear that this principle will 

 not carry us very far in explaining the actions of the 

 universe. 



Thirdly, we have the principle that A may stop certain 



other bodies, which would otherwise have impinged upon B. 



This principle, as is well known, was applied by Le Sage to 



explain the facts of gravitation *. His hypothesis was that 



* SirW. Thomson, Phil. Mag. May 1873. 



21 2. 



