50 HISTORY OF MAGNETISM. 



these poles the north and the south pole, that in 

 two magnets the north pole of each attracts the 

 south pole and repels the north pole of the other. 

 This is, indeed, the cardinal fact on which our gene- 

 ralizations rest; and the reader will perceive at 

 once its resemblance to the leading phenomena of 

 statical electricity. 



But the doctrines of magnetism, like those of 

 heat, have an additional claim on our notice from 

 the manner in which they are exemplified in the 

 globe of the earth. The subject of terrestrial mag- 

 netism forms a very important addition to the 

 general facts of magnetic attraction and repulsion* 

 The property of the magnet by which it directs its 

 poles exactly or nearly north and south, when once 

 discovered, was of immense importance to the 

 mariner. It does not appear easy to trace with 

 certainty the period of this discovery. Passing over 

 certain legends of the Chinese, as at any rate not 

 bearing upon the progress of European science 2 , the 

 earliest notice of this property appears to be con- 

 tained in the Poem of Guyot de Provence, who 

 describes the needle as being magnetized, and then 

 placed in or on a straw, (floating on water, as I 

 presume :) 



Puis se torne la pointe toute 

 Centre 1'estoile sans doute; 



that is, it turns towards the pole-star. This ac- 

 count would .make the knowledge of this property 

 2 Enc. Met. art. Magnetism, p. 736. 



