76 Faraday on new Electro-Magnetieal Motions, 



reversed, and the needle powerfully endeavours to pass the 

 opposite way. 



It is evident from this that the centre of the active portion of 

 either limb of the needle, or the true pole, as it may be called, 

 is not at the extremity of the needle, but may be represented 

 by a point generally in the axis of the needle, at some little dis- 

 tance from the end. It was evident, also, that this point had a 

 tendency to revolve round the wire, and necessarily, therefore, 

 the wire round this point ; and as the same effects in the op- 

 posite direction took place with the other pole, it was evident 

 that each pole had the power of acting on the wire by itself, 

 and not as any part of the needle, or as connected with the 

 opposite pole. 



By attending to fig. 3, which represents sections of the wire 

 in its different positions to the needle, all this will be plain ; the 

 active poles are represented by two dots, and the arrow-heads 

 shew the tendency of the wire in its positions to go round 

 these poles. 



Several important conclusions f^ow from these facts ; such as 

 that there is no attraction between the wire and either pole of a 

 magnet; that the wire ought to revolve round a magnetic pole, and 

 a magnetic pole round the wire ; that both attraction and re- 

 pulsion of connecting wires, and probably magnets, are com- 

 pound actions ; that true magnetic poles are centres of action 

 induced by the whole bar, S^c. Sfc. Such of these as I have 

 been able to confirm by experiment, shall be stated, with their 

 proofs. 



The revolution of the wire and the pole round each other 

 being the first important thing required to prove the nature of 

 the force mutually exerted by them, various means were tried 

 to succeed in producing it. The difficulty consisted in making 

 a suspension of part of the wire sufficiently delicate for the mo- 

 tion, and yet affording sufficient mass of matter for contact. 

 This was overcome in the following manner : — A piece of brass 

 wire had a small button of silver soldered on to its end, a little 

 cup was hollowed in the silver, and the metal being amal- 

 gamated, it would then retain a drop of mercury in it, though 



