MAGNETIC ATTRACTION AND EEPULSION. 709 



on each other diminishes as the distance between them 

 increases, and the mutual action of those currents which 

 are near to each other will therefore have -a preponder- 

 ance over that of currents more remote from one 

 another. 



In fig. 359 A and B, the north poles of the two 

 electro -magnets a and b are again denoted by n^ n^ and 

 the south poles by s^ s. 2 , and the magnets are supposed 

 to be placed at right angles to each other. The two 

 portions which in this position are nearest to each 

 other are two edges, viz., the right edge at one end of a, 

 and the Jeft edge of one end of 6, and the current in 

 either magnet flows along these edges in a downward 

 direction, hence attraction takes place between the 

 contrary poles s l and rc 2 ; attraction takes place, for 

 the same reason, between n^ and s. 2 , but it is insensible 

 in consequence of the distance between these two poles. 

 In the position B the currents in the nearest edges flow 

 in a contrary direction, hence there is repulsion be- 

 tween 5j and 5 2 . 



Finally, if the electro -magnets are placed side by side 

 or one above the other, as in fig. 360, and contrary 

 poles are on the same side, as at A, the currents flow 

 in the same direction in those portions of the two 

 magnets nearest to each other, that is, in the lower side 

 of a, or the upper side of b ; mutual attraction is the 

 consequence. But if, as at B, like poles are on the 

 same side, then the nearest portions of the current in 

 either magnet are opposed; hence the magnets repel 

 each other. 



For the contrivance fig. 353 a piece of glass tubing, 8 or 9 cm long 

 and 5 cm wide, and some insulated copper wire, O mm> 6 thick without 



