580 



THE APPLICATIONS OF PHYSICAL FORCES. [BOOK v. 



give its general arrangement as well as the essential details. We 

 will follow the details of Fig. 376. 



K is a long roll which furnishes the band of paper p pp destined 

 to receive the message and which is turned by the clockwork of the 

 indicator. The same clockwork turns the c} 7 linder H against the ink 

 pad L which is charged with thickened ink. BB' is the lever which 

 is set in action by the passage of the current and whose point I 

 presses the paper against the inked cylinder. The dot or 'dash 

 which in the ordinary Morse system was marked on the paper itself 



FIG. 377. Telegraphic station on ilie Murse-Digney systen 



is now simply traced with ink ; it leaves a more visible impression, 

 while it requires, as we have said, less force to produce it. 



The Digney apparatus can do without relays if the line is of no 

 great length. When, however, the line is long, they may be used, as 

 also for sounding the alarum, an instrument which is common, as may 

 be easily supposed, to all telegraphic systems. Fig. 377 represents 

 the interior of a telegraphic station on the Morse-Digney system. To 

 the right is seen the manipulator, which communicates with the 

 galvanometer and the lightning conductor. In the centre is the 



