PHYSICS OF NINETEENTH CENT.-ELECTR1CITY. 561 



been marked by an unparalleled series of wonderful discoveries. That 

 the practical applications to every-day life of certain of these discoveries 

 now realize the wildest marvels of the magician is a fact known to all, 

 and enhances the interest with which the first principles of electro- 

 magnetism must be regarded. 



CErsted announced his discovery in a short pamphlet published in 



FIG. 272. 



Latin in July, 1820. The Royal Society of London and other learned 

 bodies acknowledged the merit of the discoverer by awards of medals 

 and other distinctions. He was also raised to the highest scientific 

 and social position in his native country. CErsted's name will always 

 be remembered in connection with the memorable event represented 

 in our illustration, but he made also not a few valuable contributions 



FIG. 273. 



to the physical and chemical sciences, and his scientific and philoso- 

 phical writings attained a wide popularity, especially the work trans- 

 lated into English under the title "The Soul in Nature." 



It behoves us now to state with exactness the conditions of CErsted's 

 fundamental electro-magnetic experiment. Let A B (Fig. 272) repre- 

 sent a magnetic needle poised on a pivot, and in its position of rest, 

 in which it points nearly north and south (at least, it does so in Western 

 Europe). The end of the needle pointing towards the north is sup- 

 posed to be that marked A, and the needle to be lower than the spec- 

 tator's eye. F F' is a copper wire held above the needle and parallel 

 with it. Now a copper wire has of itself no effect on the needle, but 



3G 



