Mr. Rainey's Reply to Dr. Ritchie's Remarks. 469 



deposit, I trust more information in a short time will be laid 

 before the members of the Camden Literary and Scientific 

 Institution. 



Highgate, April 23, 1836. 



LXXXVII. Reply to Dr. Ritchie's Remarks on Mr. Rainey's 

 Theory of Magnetic Reaction. By G. Rainey, Member of 

 the Royal College of Surgeons.* 



T~\R. RITCHIE, in his reply to my last letter, appears to 

 have attached a meaning to my explanation totally dif- 

 ferent to that which it was intended to convey. Dr. Ritchie 

 asserts that I take for granted " that a piece 

 of soft iron B, placed in the direction of one 

 side of the horse-shoe magnet A, will have a 

 magnetic power represented by h, induced in 

 its remote extremity, while the power of the 

 pole S still retains its inducing power." As 

 I cannot suppose that Dr. Ritchie has so far 

 intentionally mistaken my meaning as to at- r— 

 tribute to me the adoption of a postulate at ^ 

 variance with common sense, I must suppose 

 this mistake to have originated in some verbal 

 obscurity, or want of perspicuity in my 

 phraseology. As I have failed so far in making my meanino- 

 intelligible, and being allowed the indulgence of a second trial, 

 I will endeavour to be more explicit, as I am particularly 

 anxious that nothing like technical disputation should prolong 

 this controversy. Dr. Ritchie says "that S cannot induce a 

 power on a piece of soft iron, without having its own power 

 diminished by an equal quantity." This is a fact which I am 

 most ready to admit, and which I never doubted; and accord- 

 ing to this fact, when the contiguous end of B has received 

 all the magnetism S is capable of inducing, the magnetism at 

 this end will be represented by b, which is equal to a in its 

 inducing power, though of an opposite kind. 



When magnetism is induced in ferruginous matter by the 

 contact of either pole of a permanent magnet, the remote ex- 

 tremity instantly assumes a magnetic state, opposite in kind 

 to the contiguous one, and consequently similar to the mag- 

 netism of the inducing pole. Now, as the one magnetism 

 always induces that of a dissimilar kind, the magnetism of 

 the remote end of B may be considered to result immediately 

 from the induction which has been produced upon the conti- 



* Communicated by the Author. 



