PHYSICAL FORCES 125 



iron filings be spread upon a piece of paper or a thin 

 sheet of glass, and the magnet be moved above on the 

 under surface of the paper or glass, the iron filings will 

 follow the magnet so that its influence is clearly trans- 

 mitted through such bodies. 



The magnets first known consisted of a certain mineral 

 called "loadstone" which is especially abundant in 

 Sweden and in Asia Minor. Loadstones attract iron 

 and steel, while they themselves consist of an iron ore- 

 that is, of iron, in union with certain other substances, 

 or at least, resolvable into such. 



Artificial steel magnets can be made from loadstone 

 by rubbing them against that mineral, but they are now 

 also made in other ways. A piece of pure iron, by contact 

 with a natural or artificial magnet, will itself become 

 magnetised and attract iron filings, steel needles, &c., so 

 long as it remains in such contact, but it does rot 

 permanently retain its magnetic power. Such is not the 

 case with steel, which by contact, or rubbing, will become 

 itself permanently magnetised. 



It is the ends of the magnets which mainly attract, 

 the bent part produces hardly any effect. But the 

 actions of the two ends are never alike. 



If a magnetised steel needle be freely suspended and 

 allowed to- oscillate till it becomes motionless, then if one 

 end, A, of a horse-shoe magnet be brought near to one, 

 X, of the two ends of the needle, the needle will be 

 attracted and rotate so as to bring that end, X, as close 

 as possible to, or in contact with, the end, A, of the 

 magnet. Then, if the other end, B, of the magnet be 

 brought near that same end, X, of the needle, instead of 

 being attracted, it will thereby be repelled. Yet that 

 same end, B, of the magnet will attract the opposite end 

 (or opposite pole Y) of the needle, which will, on the 



