54 THE POPULAR SCIENCE MONTHLY. 



of two light aluminum arms, making a right angle with each 

 other. Each of these arms is attached to its operating drum by 

 means of a cord passing around the drum, so that the rotation of 

 this moves the arm to and fro in the direction of its length after 

 the manner of the ordinary bow drill. The drums are given a 

 tendency to rotate by a small electric motor located in the case of 

 the receiver, and as this rotation is controlled by the polarized 

 relays, which are in turn operated by the current impulses sent 

 out by the transmitting pen, it will be seen that the movement of 

 this latter determines that of the receiving pen, both in amount 

 and direction, and that hence the two pens must move in exact ac- 



As written. As received. 



FIG. 15. SAMPLE WORK OF TELAUTOGRAPH. 



cordance with each other. The mechanism of the receiving instru- 

 ment is at present a little intricate, and some of the operations to 

 be performed, as the lifting the pen from the paper, shifting the 

 paper, and reversing the motion of the operating drums, require 

 in the present construction two additional line wires, but these, it 

 is expected, can by contemplated improvements be dispensed with, 

 leaving only two line wires for the performance of all the necessary 

 operations. The system has so far been operated over a distance 

 of only thirteen miles; but from the character of the currents 

 used distinct successive electric impulses there would seem to 

 be no reason why it should not be capable of operation over as 

 long distances as the ordinary telegraphic instruments. 



