238 ELECTRO-MAGNETISM. 



Magnetism may be produced in any bar of steel, 

 either by rubbing it with a loadstone, or by placing it in 

 a certain position in relation to the magnetic currents of 

 the earth, and, by a blow or any other means, disturbing 

 its molecular arrangement. This principle appears to 

 involve the iron as with an atmosphere, and to inter- 

 penetrate it. By one magnet we may induce magnetism 

 in any number of iron bars without its losing any of its 

 original force. As we have observed of the electrical 

 forces already considered, the magnet constantly presents 

 two points in which there is a difference manifested by 

 the circumstance that they are always drawn with con- 

 siderable power towards the north or south poles of the 

 earth. That this power is of the same character as the 

 electricity which we have been considering, is now most 

 satisfactorily proved. By involving a bar of soft iron 

 which, being without any magnetic power, is incapable 

 of sustaining even an ounce weight, with a coil of 

 copper wire, through which a galvanic current is passing, 

 the bar will receive, by induction from the current, an 

 enormous accession of power, and will, so long as the 

 current flows around it, sustain many hundred pounds 

 weight, which, the moment the current is checked, fall 

 away from it in obedience to the law of gravity. Thus 

 the mere flow of this invisible agent around a mass of 

 metal possessing no magneto-attractive power, at once 

 imparts this life-like influence to it, and as long as the 

 current is maintained, the iron is endowed with this 

 surprising energy. 



This discovery, which we owe to the genius of 

 Oersted, and which has, indeed, given rise to a new 

 science, electro-magnetism, may be regarded as one of 

 the most important additions made to our knowledge. 



Current electricity is magnetic ; iron is not necessary 

 to the production of magnetic phenomena, although by 

 its presence we secure a greater amount of power. The 



