HISTORY AND PROGRESS. 165 



at one of their ends over the axis of the eccentric, and their 

 free ends entering corresponding holes in the grooved frame. 

 These three wires are not fixed to the axis of the eccentric, 

 but each of them rests against it by the upward pressure of 

 a spring, so that when a light pressure is exerted on the free 

 ends of either of them, it is capable of being separately 

 depressed. When the slip of paper is not inserted, and the 

 eccentric is in action, a pin attached to each of the external 

 wires touches, during the advancing and receding motion 

 of the frame, a different spring, and an arrangement is 

 adopted by means of insulation and contacts properly ap- 

 plied, by which, while one of the wires is elevated and the 

 other remains depressed, the current passes from the voltaic 

 battery to the telegraphic circuit in one direction, and passes 

 in the other direction when the wire before elevated is de- 

 pressed, and vice versa; but while both wires are simul- 

 taneously elevated or depressed, the passing of the current is 

 interrupted. When the prepared slip of paper is inserted in 

 the groove and moved forward, whenever the end of one 

 of the wires enters an aperture in its corresponding row, the 

 current passes in one direction, and when the end of the 

 other wire enters an aperture of the other row, it passes in 

 the other direction. By this means the currents are made to 

 succeed each other automatically, in their proper order and 

 direction, to give the requisite variety of signals. The 

 middle wire acts only as a guide during the operation of the 

 current. 



In the recording instrument a paper strip is drawn off a 

 paper drum by revolving rollers, which are turned by means 

 of a clockwork inside the case. The paper strip passes 

 underneath a shallow reservoir about an eighth of an inch 

 deep, containing ink. At the bottom of the reservoir are 

 two holes, so small as to prevent, by capillary attraction, 

 the escape of the ink through them. The ends of the print- 

 ing styles are placed immediately above these holes, and, 

 when deflected by means of the electro-magnet, they are 

 pushed down through the holes, and carry with them suffi- 

 cient ink to produce legible marks upon the paper. 



