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LXIX. On Action at a Distance, and the Conservation of 

 Energy. By Oliver J. Lodge, D.&c* 



MB. BROWNE'S letter of last month scarcely calls for a 

 reply ; but it may be well, without opening up any 

 fresh points of controversy, to indicate the errors in his state- 

 ments quite briefly; and I trust that he will acquit me of 

 any desire to import personal animus into the controversy. 

 If I criticise his remarks in an unceremonious manner, it is 

 partly for the sake of conciseness, and also because, notwith- 

 standing all personal respect, I feel so strongly that his 

 reasoning is utterly wrong, that I should be conveying a 

 wrong impression if I used the language of compliment and 

 ceremony in attacking it. 



Mr. Browne first quotes my argument, by which as he 

 says I do solemnly imagine that I have " disposed for ever 

 of the idea of action at a distance," and then gives four fresh 

 confutations of it, which he labels a, b, c, and d. Let us 

 refer to them on page 380, and take them in order. 



(a) In the fifth and sixth lines of this paragraph it is 

 necessary to replace the word " of" by the words " generated 

 by this force in," to make it agree with the statement (in the 

 first two lines) of how force is measured. The concluding 

 three lines from " Hence " to the end may then be omitted. 



(b) Energy is undoubtedly a positive quantity; but gain 

 of energy may be either positive or negative. To be consis- 

 tent Mr. Browne ought to deny that distance travelled could 

 ever be reckoned negative, because the distance between two 

 places is an essentially positive quantity. But it looks child- 

 ish to have to point this out. 



(c) Two equal particles of finite mass impinging on one 

 another with equal opposite velocities of course exert an infi- 

 nite stress and stop instantaneously ; so there is no difficulty 

 with them. 



If Mr. Browne had chosen to consider the impact of two 

 finite bodies he would have been more troublesome, because 

 their action is complex : the particles which first touch stop 

 dead ; but the others are gradually stopped by actions trans- 

 mitted from particle to particle in a manner not by any means 

 yet precisely understood. 



But direct impact is an unfortunate example to fly to in 

 order to support action at a distance. 



(d) Here we come to the gist of the matter, and to the 

 "real and intrinsic vice" of my argument. He is getting 

 near the scent now when he implies that my statement of the 



* Communicated by the Author. 



