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CHAPTER XII. 



The Laws of Magnetism. 



MAGNETISM has no very obvious or apparently 

 extensive office in the mechanism of the atmos- 

 phere and the earth : but the mention of it may 

 be introduced, because its ascertained relations 

 to the other powers which exist in the system are 

 well suited to show us the connexion subsisting 

 throughout the universe, and to check the sus- 

 picion, if any such should arise, that any law of 

 nature is without its use. The parts of creation 

 when these uses are most obscure, are precisely 

 those parts when the laws themselves are least 

 known. 



When indeed we consider the vast service of 

 which magnetism is to man, by supplying him 

 with that invaluable instrument the mariner's 

 compass, many persons will require no further 

 evidence of this property being introduced into 

 the frame of things with a worthy purpose. 

 As however, we have hitherto excluded use in the 

 arts from our line of argument, we shall not here 

 make any exception in favour of navigation, and 

 what we shall observe belongs to another view of 

 the subject. 



Magnetism has been discovered in modern 

 times to have so close a connexion with galva- 



w. 5 i 



