CH. XXXV. 



ELECTRO MAGNETISM. 



343 



a series of experiments by which he proved that an electric 

 current passing near a magnetic needle will always make it 

 turn round so as to lie ACROSS the path of the current. 



For example, if the bar of copper wire a b, supported on 

 the glass rods <?, e, be so placed that the end b points to the 

 north and a to the south, then the magnetic needle c will 

 lie exactly in a line with the bar, because a magnet always 

 points north and south. But if the two ends of the copper 

 rod #, b, are fixed to the wires of a voltaic battery d> Fig. 54, 

 so that an electric current runs along the rod from a to , 

 then the north end of the needle will begin to move away 

 from the north towards the west, that is towards the left side 



FIG. 54. 



Magnet turned by an Electric Current. 



a. , Rod of copper wire, c, Magnetic needle, d. Voltaic pile (explained p. 263). 

 e e, Glass supports to prevent the current running down to the ground. 



of the current ; and it will turn more and more as the current 

 grows stronger, till it lies right across it, pointing direct east 

 and west. 



This was a very grand fact, and it has become the begin- 

 ning of a new science called electro-magnetism, for it shows 

 that electricity and magnetism act upon each other in some 

 peculiar way. Oersted did not publish an account of his 

 experiments until 1820, and then the whole of Europe rang 

 with the news of the discovery. 



Ampere, 1775-1864. One of the first men who heard 



