2 , Second Letter from Dr. Hare to Prof. Faraday. 



aware that when in a discussion, which due attention to brevity- 

 must render unceremonious, diversities of opinion are exhibited, 

 much magnanimity is requisite in the party whose opinions are 

 assailed ; but I trust that both of us have truth in view above all 

 other objects, and that so much of your new doctrine as tends to 

 promote that end, will not be invalidated by a criticism which 

 though free, is intended to be perfectly fair and friendly. 



In paragraph (ii,) your language is as follows, " wy theory of 

 induction makes no assertion as to the nature of electricity, nor 

 at all questions any of the theories respecting that subject.''^ Ow- 

 ing to this avowed omission to state your opinions of the nature 

 of electricity as preliminary to the statement of your " theory, ^^ 

 and because I was unable to reconcile that theory with those pre- 

 viously accredited, I received the impression that you claimed no 

 aid from any imponderable principle. It appeared to me that 

 there was no room for the agency of any such principle, if induc- 

 tion were an action of contiguous ponderable particles, consisting 

 of a species of polarity. It seemed to follow, that what we call 

 electricity, could be nothing more than a polarity, in the ponder- 

 able particles, directly caused by those mechanical or chemical 

 frictions, movements, or reactions by which ponderable bodies 

 are electrified. You have correctly inferred that I had not seen 

 the fourteenth series of your researches, containing certain para- 

 graphs. From them it appears that the polarity, on which so 

 much stress has been laid, is analogous to that which has long 

 been known to arise in a mass, about which the electric equilibri- 

 um has been subverted, by the inductive influence of the electri- 

 city accumulated upon another mass. This is clearly explained 

 in paragraph iv of your letter, by the illustration, agreeably to 

 which three bodies. A, B, C, are situated in a line, in the order in 

 which they are named, in proximity, but not in contact. " A is 

 electrified positively and then C is uninsulated." It is evident 

 that you are correct in representing that under these circumstan- 

 ces the extremities of B will be oppositely excited, so as to have 

 a reaction with any similarly excited body, analogous to that 

 which takes place between magnets ; since the similarly excited 

 extremities of two such bodies, would repel each other ; while 

 those dissimilarly excited, would be reciprocally attractive. Hence 

 no doubt the word polarity is conceived by you to convey an idea 

 of the state of the body B. If I may be allowed to propose an 



