396 



MAGNETISM. 



1 he natural magnet or loadstone is an ore of iron, 

 of a blackish colour, and of a stony appearance. 

 It is worked extensively in many countries for iron ; 

 particularly in Norway and Sweden. 



This substance was known to the ancients; and 

 they had remarked its peculiar property of attracting 

 iron, though it does not appear that they were ac- 

 quainted with the wonderful property which it 

 also has, of turning to the pole when suspended 

 and left at liberty to move freely. 



Upon this remarkable circumstance does the 

 mariner's compass depend, an instrument which 

 enables them to conduct their vessels through vast 

 oceans out of the sight of land, in any given di- 

 rection ; and this directive property also guides the 

 miners in their subterranean excavations, and the 

 traveller through trackless deserts. 



It is not precisely known when and by whom 

 this directive property of the magnet was dis- 

 covered. The Chinese appear to have been ac- 

 quainted with it before it was known in Europe, 

 where it first appeared in the thirteenth century. 



Before that period, mariners scarcely ever ven- 

 tured out of sight of land, but contented them- 



