ELEMENTARY MAGNETISM 871 



entire upper half attracts the opposite end. Supposing 

 the north end of your little needle to be that attracted 

 below, you infer that the entire lower half of your mag- 

 netized strip exhibits south magnetism, while the entire 

 upper half exhibits north magnetism. So far, then, you 

 have determined the distribution of magnetism in your 

 strip of steel. 



You look at this fact, you think of it; in its sugges- 

 tiveness the value of an experiment chiefly consists. The 

 thought naturally arises: *'What will occur if I break my 

 strip of steel across in the middle? Shall I obtain two 

 magnets each possessing a single pole?" Try the experi- 

 ment; break your strip of steel, and test each half as you 

 tested the whole. The mere presentation of its two ends 

 in succession to your test-needle suffices to show that you 

 have not sl magnet with a single pole — ^that each half pos- 

 sesses two poles with a neutral point between them. And 

 if you again break the half into two other halves, you 

 will find that each quarter of the original strip exhibits 

 precisely the same magnetic distribution as the whole 

 strip. You may continue the breaking process: no mat- 

 ter how small your fragment may be, it still possesses 

 two opposite poles and a neutral point between them. 

 Well, your hand ceases to break where breaking becomes 

 a mechanical impossibility; but does the mind stop there? 

 No: you follow the breaking process in idea when you 

 can no longer realize it in fact; your thoughts wander 

 amid the very atoms of your steel, and you conclude that 

 each atom is a magnet, and that the force exerted by the 

 strip of steel is the mere summation, or resultant, of the 

 forces of its ultimate particles. 



Here, then, is an exhibition of power which we can 



