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CHAPTER IV. 



DISCOVERY OF ELECTRO-MAGNETIC ACTION. 

 OERSTED. 



THE impulse which the discovery of galvanism, v 

 in 1791, and of the voltaic pile, in 1800, had 

 given to the study of electricity as a mechanical 

 science, had nearly died away in 1820. It was in 

 that year that M. Oersted, of Copenhagen, an-/ 

 nounced that the conducting wire of a voltaic circuit 

 acts upon a magnetic needle; and thus recalled 

 into activity that endeavour to connect magnetism 

 with electricity, which, though apparently on many 

 accounts so hopeful, had hitherto been attended 

 with no success. Oersted found that the needle 

 has a tendency to place itself at right angles to the / 

 wire ; a kind of action altogether different from 

 any which had been suspected. 



This observation was of vast importance ; and 

 the analysis of its conditions and consequences em- 

 ployed the best philosophers in Europe immediately 

 on its promulgation. It is impossible, without great 

 injustice, to refuse great merit to Oersted as the 

 author of the discovery. We have already said, 

 that men appear generally inclined to believe re- 

 markable discoveries to be accidental, and the dis- 

 covery of Oersted has been spoken of as a casual 

 insulated experiment 1 . Yet Oersted had been look- 

 1 See Soliciting ueber Faraday's EntdecJtvng, p. 27. 



