130 



Electro-Magnetic Rotations. 



This apparatus is represented in Fig. 1. Let A B represent a 

 coil of metallic ribbon, C D a magnet revolving upon an axis in 

 its centre. Upon connecting the extremities, F and G with a 



Figure 1. 



galvanic battery, the magnet will be thrown at right angles to the 

 coil by tangential action of the current ; when it reaches this 

 point, the pin E upon the magnet C D moves a lever which turns 

 an apparatus for reversing the current in the coil. The motion in 

 the magnet is then continued until it reaches a half revolution, 

 when the pin E moves the lever in the opposite direction, and 

 changing the direction of the current again, the magnet is im- 

 pelled as at first. The motions of this magnet were rapid, being 

 about one hundred and twenty revolutions in a minute, although 

 weighing six pounds, and would continue half an hour without 

 much diminution with the same charge of the battery. 



Fig. 2, represents an apparatus by means of which the ribbon 

 may be made to revolve around the magnet. Let A B represent 



Figure 2. 



a galvanic magnet suspended upon an axis G. The wires E F, 

 are the extremities of the wire which is wound around the mag- 

 net, and which pass through a copper tube which serves as an 

 axis for the revolving part of the apparatus. These wires are^ 



