10 Mr. Faraday and Dr. P. Riess on the Action of 



hope you will give me an early note saying whether you object 

 or not. 



I anij yours very truly, 

 Prof. P. Riess, M. Faraday. 



^c. ^c. ^c. 



My dearest Sir, Berlin, December 10, 1855. 



In replying to the letter with which you have honoui-ed me, I 

 must at first claim your greatest indulgence for my English. I 

 mean not the errors which are easily corrected, but the improper 

 choice of words, which in theoretical controversies is of conse- 

 quence, and which I have no hope to avoid. Before I enter into 

 the discussion of your remarks concerning my paper on induc- 

 tion, it may not be improper to say a word upon the old theory 

 of static electricity. 



It appears to me, that a theory of a branch of the experimental 

 sciences should be deemed good, and not be abandoned, so long 

 as it is sufficient to account for all facts known by applying a 

 simple principle, be it paradoxical or not, and so long as it comes 

 not in contradiction with itself, or the theory of a congenial 

 branch. The old theory of light has been abandoned, not because 

 its principle of the emission of myriads of particles of light, 

 endued with the greatest velocity and many perplexing proper- 

 ties, was highly paradoxical, but because it was found incompe- 

 tent to account for the great class of phsenomena of diflVaction 

 and polarization. I see not the like in the old theory of elec- 

 tricitjr. It assumes, indeed, the action at a distance, and I agree 

 entirely with you that such an action is extremely difficult to 

 conceive ; but admit we not the like in the great theory of gra- 

 vitation ? and admit you not also this action in an extraordinary 

 case of induction in electricity ? The action at a distance con- 

 sists here in the attraction of electricity of one kind, and the 

 repulsion of the other in every particle of matter, and is un- 

 limited ; that is to say, if an electrified particle E acts upon a 

 particle of matter A, and a particle of matter B is placed any- 

 where, the action of E upon A is not hindered nor weakened, and 

 exists in the same amount as before. These premises granted, 

 the theory accounts for the phseuomena of static electricity in 

 the simplest manner. All these phsenomena are instances of the 

 arrangement of electricity upon the surface of bodies, and their 

 arrangement is made dependent upon the equilibrium of a num- 

 ber of forces which the electric particles exercise mutually on each 

 other. Thus the electrostatic problems are changed into problems 

 of pure mechanics, and the principles of this science find their 

 application. The advantage of this method is very great; it 

 gives the result of each experiment as the sum of single actions, 



