the Absurdity of Diamagnetic Polarity. 203 



that it will be necessary to impart or take away heat to keep 

 the temperature of the junction of the two bodies constant. 

 In other words, the theory gives both the difference of poten- 

 tial and the Peltier effect. 



Now it is important to remark that by merely assuming 

 our expressions for the energy and entropy to hold for stable 

 distributions and without making any further use of the con- 

 ception of unstable distributions, we can easily obtain the 

 very same expressions for the difference of potential and the 

 Peltier effect as before. 



In like manner, we have two methods of discussing the 

 question of a difference of potential and the law of the Thomson 

 effect, in the case of two unequally heated portions of the same 

 substance in contact, and both methods give the same results. 

 VII. Lastly, we have two ways of investigating Helmholtz's 

 theory of the galvanic battery, and both lead to the same 

 conclusions. This theory, it is true, has been questioned; 

 but the objections appear to rest on misconceptions; and, 

 besides, the theory does not seem to have been yet suffi- 

 ciently explained. However, I do not propose to consider 

 the subject any further at present, but merely wish to point 

 out that we have two ways of getting the same result. 



I have now, I consider, conclusively shown that my two 

 assumptions are legitimate; and yet, at the same time, I 

 acknowledge the importance of l)r. Lodge's objection, in 

 requiring us to examine the tacit assumptions which lie at 

 the root of all thermodynamical investigations of electricity 

 and magnetism. 



To conclude our discussion on diamagnetism, I observe 

 that, so far as I am aware, no one has ever attempted to 

 advance any serious theoretical or other arguments in favour 

 of the common notion of diamagnetism. The theory appears 

 to have owed its origin to the want of a theoretical examina- 

 tion of the subject, and to have been maintained from an 

 excusable veneration for an old theory and a belief in the 

 infallibility of the older scientists. Yet it has been occasion- 

 ally questioned from the first, Duhem, in his book on dia- 

 magnetic bodies, mentions Becquerel and Plucker as having 

 objected to the theory. Even in England there are persons 

 who have never accepted it, and Dr. Lodge himself seems to 

 be aware that it will not stand examination; for in his 

 criticism on my two previous papers on the subject, he 

 appears to rely chiefly on the strength of his rhetoric, and on 

 an appeal to the name of Faraday. 



I now proceed to the next part of the paper. 

 [To be continued.] 



