66 THE ELECTRIC TELEGRAPH. 



axis of the handle H, which moves above the dial. A small 

 peg with a friction wheel runs in the groove, and imparts 

 a vibrating motion to the contact lever. The further end 

 of this lever is faced with platinum on each side, and makes 



Fig. 33. 



contact alternately with the screws p p, with p, when 

 the handle is over the even numbers, and with p' when it 

 covers the uneven. 



The terminal c is connected with the positive pole of the 

 battery. It is also connected by a wire, /, to the contact 

 screw p '. The terminal R, on the left, is in permanent con- 

 nection by a wire, v, with the contact p, and is intended for 

 the wire leading to the receiving instrument. The terminal L 

 of the left line- wire communicates with the contact lever, N. 

 The point of N touches, at pleasure, either the contact s, to 

 which the alarm is connected, or r, which is in communica- 

 tion with the revolving disc, and through this and the friction 

 wheel and 1 1' with battery and earth, or, lastly, it may touch 

 the end of a metallic strip marked " communication directed 

 On the other side of the dial is a similar lever, N, connected 

 with the terminal L of the line on the right. N may be 

 placed on s, the alarm, or on r, which, like r, is connected 



