ELEMENTARY MAGNETISM 379 



net really exert no influence on the pole presented to its 

 centre ? Let us see. 



Let s N, Fig. 11, be our magnet, and let n represent a 

 particle of north magnetism placed exactly opposite the 

 middle of the magnet. Of course this is an imaginary 

 case, as you can never in reality thus detach your north 

 magnetism from its neighbor. But, supposing us to haye 

 done so, what would be the action of the two poles of 

 the magnet on n't Your reply will, of course, be that 

 the pole s attracts n while the pole N repels it. Let the 

 magnitude and direction of the attraction be expressed by 



S I- \ 411 



FIG. 11. 



the line n ra, and the magnitude and direction of the 

 repulsion by the line n o. Now, the particle n being 

 equally distant from s and N, the line n o, expressing 

 the repulsion, will be equal to m n, which expresses the 

 attraction. Acted upon by two such forces, the particle n 

 must evidently move in the direction n p, exactly mid- 

 way between m n and n o. Hence you see that, although 

 there is no tendency of the particle n to move toward the 

 magnetic equator, there is a tendency on its part to move 

 parallel to the magnet. If, instead of a particle of north 

 magnetism, we placed a particle of south magnetism op- 

 posite to the magnetic equator, it would evidently be 

 urged along the line n q\ and if, instead of two separate 



