372 FRAGMENTS OF SCIENCE. 



needle was attracted in your first experiment ; and from 

 this you may at once deduce the consequence that, after the 

 steel has been magnetized, the repulsive action of a magnet 

 must be always less than its attractive action. For the 

 repulsion is opposed by the inductive action of the magnet 

 on the steel, while the attraction is assisted by the same 

 inductive action. Make this clear to your minds, and 

 verify it by your experiments. In some cases you can 

 actually make the attraction due to the temporary mag- 

 netism overbalance the repulsion due to the permanent 

 magnetism, and thus cause two poles of the same kind 

 apparently to attract each other. When, however, good 

 hard magnets act on each other from a sufficient distance, 

 the inductive action practically vanishes, and the repulsion 

 of like poles is sensibly equal to the attraction of unlike 

 ones. 



I dwell thus long on elementary principles, because 

 they are of the first importance, and it is the temptation 

 of this age of unhealthy cramming to neglect them. Now 

 follow me a little further. In examining the distribution 

 of magnetism in your strip of steel, you raised the needle 

 slowly from bottom to top, and found what we called a 

 neutral point at the centre. Now does the magnet really 

 exert no influence on the pole presented to its centre ? 

 Let us see. 



Fig. 1. 



Dn 



Let S N, Fig. 1, be your magnet, and let n represent a 

 particle of north magnetism placed exactly opposite the 



