68 NOMOS. 



movements ? M. Ampere, we answer, has furnished 

 the clue to the explanation, and we now know that 

 the movements must result from the reactions which 

 necessarily take place between the current surround- 

 ing the magnet and the current which streams from 

 the conductor to the magnet. 



In explaining the movement of a magnet around 

 a conductor, it is necessary to bear several things in 

 mind. It must be borne in mind that the currents 

 of the magnet and conductor are not confined to 

 these bodies ; but that they extend to an indefinite 

 distance beyond them, in, as it were, an atmosphere 

 of currents. (See p. 56.) It must be borne in mind 

 that these overflowing currents are more disposed 

 to pass towards the nearest point of neighbouring 

 bodies than to the space between these bodies a 

 fact which is well exemplified in the working of the 

 common electrical machine. It must be borne in 

 mind that a current may overflow indifferently from 

 the conductor to the magnet, or from the magnet to 

 the conductor, but not in both directions simulta- 

 neously, for it is not possible that contrary currents 

 can co-exist in the same place without mutual neu- 

 tralization, or without the weaker giving place to the 

 stronger. In explaining the movements of a magnet 

 around a conductor we assume, then, that the cur- 

 rents of the magnet are not confined to that body, 

 but that they extend indefinitely beyond it, in, as it 

 were, an atmosphere of currents. We also assume 

 that currents overflow, not from the magnet to the 

 conductor, but from the conductor to the magnet, 

 and that they converge upon the nearest point of the 



