168 THE ELECTRIC TELEGRAPH. 



ing the letters a and b. The bottom of the composing-stick 

 is provided with a row of teeth, which lock into the worm of 

 an endless screw on the shaft which turns the inductor- coil. 

 Thus, while the inductor-coil is turned, and the alternate 

 currents generated, the types are moved forward with a 

 corresponding velocity, and make and break contact by lifting 

 and letting fall respectively the point of the contact lever. 



Fig. 91 gives an elevation of the contacts, with the lever 

 and part of the composing-stick containing the three letters 



Fig. 91. 



a, b, and c. c', c'' is the composing- rule, moved along in 

 the direction indicated by the arrow, by the rotation of the 

 screw T, and is held in its place by the roller r. The lever 

 L, L 1 is held back against the contact 1, when not raised by 

 the types, by means of the spring s. The figure, however, 

 shows the point L lifted up by the broad tooth of the letter 

 A, and the arm L 1 , therefore, pressed against the contact 

 screw 2. The types are straightened, in the event of getting 

 shifted upwards, by passing under the spring s 1 . 



The transmitter is fixed upon a table, underneath which is 

 a fly-wheel and pulley, whose strap turns the shaft of the 

 inductor and screw T. A common crank and treadle, like 

 that of a lathe, imparts motion to the system. 



The composing-rules are about two feet long, and consist 

 each of a straight, rigid piece of metal one- sixteenth inch 

 thick and one-half inch broad, with a thin elastic piece, not 

 quite so broad, screwed on lengthways. The types are put 



