ELEMENTARY MAGNETISM. 349 



treats: it is repelled. Make the same experiment with 

 the two points; you obtain the same result, the sus- 

 pended needle is repelled. Now cause the dissimilar 

 ends to act on each other you have attraction point 

 attracts eye, and eye attracts point. Prove the reci- 

 procity of this action by removing the suspended 

 needle, and putting the other in its place. You ob- 

 tain the same result. The attraction, then, is mutual, 

 and the repulsion is mutual. You have thus demon- 

 strated in the clearest manner the fundamental law of 

 magnetism, that like poles repel, and that unlike poles 

 attract, each other. You may say that this is all easily 

 understood without doing; but do it, and your knowl- 

 edge will not be confined to what I have uttered here. 



I have said that one end of your bar-magnet has a 

 mark upon it; lay several silk fibres together, so as to 

 get sufficient strength, or employ a thin silk ribbon, 

 and form a loop large enough to hold your magnet. 

 Suspend it; it turns its marked end towards the north. 

 This marked end is that which in England is called the 

 north pole. If a common smith has made your mag- 

 net, it will be convenient to determine its north pole 

 yourself, and to mark it with a file. Vary your experi- 

 ments by causing your magnetised darning-needle to 

 attract and repel your large magnet; it is quite com- 

 petent to do so. In magnetising the needle, I have 

 supposed the point to be the last to quit the marked 

 end of the magnet; the point of the needle is a south 

 pole. The end which last quits the magnet is always 

 opposed in polarity to the end of the magnet with 

 which it has been last in contact. 



You may perhaps learn all this in a single hour; 

 but spend several at it, if necessary; and remember, 

 understanding it is not sufficient: you must obtain a 

 manual aptitude in addressing Nature. If you speak 



