chap, ix.] MAGNETS. 91 



POLES, and to vanish at the middle, where there is a 

 NEUTKAL ZOXE, or indifference point. 



Attraction and repulsion. It has been said 

 that a freely suspended magnet always turns so as to 

 set one pole towards the north pole of the earth, and 

 the other towards the south pole. If now a second 

 magnet be brought near, it is found that on presenting 

 the pole of the second that points north to the similar 

 pole of the first, freely suspended, the latter is at once 

 repelled ; but if the south pole of the second be pre- 

 sented to the north pole of the other, they attract one 

 another. Thus, like poles repel, but unlike poles at- 

 tract. An explanation of the invariable tendency of 

 a magnet to point north and south is, therefore, forth- 



coming. 



It is supposed that the earth is a magnet which 

 acts on freely suspended magnets in the way men- 

 tioned, attracting by each pole the unlike pole of the 

 magnet, and repelling by each pole the like pole of 

 the magnet. Thus, the north pole of the earth will 

 attract the south pole of a magnet, and repel the north : 

 and the south pole of the earth will attract the north, 

 and repel the south, of a magnet. Thus, the pole of a 

 freely suspended magnet that points north is actually 

 the south pole of the magnet. Owing to this circum- 

 stance, confusion in the designation of the poles of a 

 magnet has arisen. Thus, the one pole is called the 

 north-pointing, or north-seeking pole, and with that 

 there is no difficulty. But because this is actually the 

 south pole of the magnet it has been called the austral 

 pole, and the south-seeking pole has been called boreal. 

 .French writers speak of aiistral and boreal. In Eng- 

 lish, usually, by north pole is meant the pole that 

 points north, and by south pole the one that points 

 south. For convenience sake the pole of a magnet 

 that points north is usually marked, and is, there- 

 fore, also called the marked pole. 



