64- Prof. Faraday's Answer to Dr. Hare's Letter. 



which they both possess ; and that in both cases the effects 

 are consistent with my theory of induction. 



xxxvii. I now come to what ma^ be considered as queries 

 in your letter which I ought to answer. Paragraph 8 

 contains one. As I concede that particles on opposite sides 

 of a vacuum may perhaps act on each other, you ask, 

 " wherefore is the received theory of the mode in which 

 the excited surface of a Leyden jar induces in the opposite 

 surface a contrary state, objectionable?" My reasons for 

 thinking the excited surface does not directly induce upon the 

 opposite surface, &c., is, first, my belief that the glass con- 

 sists of particles conductive in themselves, but insulated as 

 respects each other (xvii.) ; and next, that in the arrangement 

 given iv., ix., or x., A does not induce directly on C, but 

 through the intermediate masses or particles of conducting 

 matter. 



xxxviii. In the next paragraph, the question is rather im- 

 plied than asked what do I mean by polarity? I had hoped 

 that the paragraphs 1669. 1670. 1671. 1672. 1679. 1686. 1687. 

 1688. J699. 1 700.4701. 1702. 1703. 1704. in the Researches, 

 would have been sufficient to convey my meaning, and I am 

 inclined to think you had not perhaps seen them when your 

 letter was written. They, and the observations already made 

 (v., xxvi.), with the case given (iv., v.), will, I think, be suffi- 

 cient as my answer. The sense of the word polarity is so 

 diverse when applied to light, to a crystal, to a magnet, to 

 the voltaic battery, and so different in all these cases to that 

 of the word when applied to the state of a conductor under 

 induction (v.), that I thought it safer to use the phrase "spe- 

 cies of polarity," than any other, which being more expres- 

 sive would pledge me further than I wished. 



xxxix. Paragraph 1 1 involves a mistake of my views. I 

 do not consider bodies which are charged by friction or 

 otherwise, as polarized, or as having their particles polarized 

 (iii., iv., xxvii.). This paragraph and the next do not re- 

 quire, therefore, any further remark, especially after what I 

 have said of polarity above (xxxviii.). 



xl. And now, my dear sir, I think I ought to draw my 

 reply to an end. The paragraphs which remain unanswered 

 refer, I think, only to differences of opinion, or else, not even 

 to differences, but opinions regarding which I have not ven- 

 tured to judge. These opinions I esteem as of the utmost 

 importance ; but that is a reason which makes me the rather 

 desirous to decline entering upon the reconsideration, inas- 

 much as on many of their connected points I have formed no 

 decided notion } but am constrained by ignorance and the 



