ELECTRICITY AND MAGNETISM 



the way to the establishment of the science of electro- 

 dynamics; although it was by the French savant 

 Andre Marie Ampere (1775-1836) that the science was 

 actually created, and this within the space of one week 

 after hearing of Oersted's experiment in deflecting the 

 needle. Ampere first received the news of Oersted's 

 experiment on September u, 1820, and on the iSth 

 of the same month he announced to the Academy the 

 fundamental principles of the science of electro-dynam- 

 ics seven days of rapid progress perhaps unequalled 

 in the history of science. 



Ampere's distinguished countryman, Arago, a few 

 months later, gave the finishing touches to Oersted's 

 and Ampere's discoveries, by demonstrating conclu- 

 sively that electricity not only influenced a magnet, 

 but actually produced magnetism under proper cir- 

 cumstances a complemental fact most essential in 

 practical mechanics. 



Some four years after Arago' s discovery, Sturgeon 

 made the first "electro -magnet" by winding a soft 

 iron core with wire through which a current of elec- 

 tricity was passed. This study of electro-magnets 

 was taken up by Professor Joseph Henry, of Albany, 

 New York, who succeeded in making magnets of enor- 

 mous lifting power by winding the iron core with sev- 

 eral coils of wire. One of these magnets, excited by 

 a single galvanic cell of less than half a square foot 

 of surface, and containing only half a pint of dilute 

 acids, sustained a weight of six hundred and fifty 

 pounds. 



Thus by Oersted's great discovery of the intimate 

 relationship of magnetism and electricity, with further 



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