THE TELEGRAPH 323 



that these are no longer a magnet, and hence the armature is 

 pulled back by the spring. Thus two sounds are made, one 

 when the armature is drawn down, and another when it is 

 released by the striking of the bar against the screw. 



Morse alphabet. When these two sounds come very close 

 together, so that they seem as one, the signal is called a dot. 

 Where they are separated by an appreciable time, so that 

 two distinct sounds are heard, the signal is called a dash. 

 The different letters are represented by various combina- 

 tions of dots and dashes. The American code of the Morse 



alphabet is as follows : A B C D E 



p. G- H---. ! J K L- 



M- -N o-.p Q R s T- 



U V W - X Y Z ... - 



These dots and dashes may be recorded on a strip of paper 

 run by clockwork, which passes under a point attached to 

 the sounder. When the key is held down for a dash, a 

 longer mark is made on the paper than when the key is held 

 down for a dot. The telegraph operator can learn by 

 practice to read the signals by ear and write them down 

 directly as fast as they come in. This method is commonly 

 used. 



If the two stations are only a short distance apart, the 

 sender, sounder, and batteries are all that are necessary for 

 sending messages. But when the stations are long distances 

 apart, the wire offers so much resistance that the sounder is 

 worked only very weakly or not at all, so that" no signals are 

 transmitted. 



Relay. To overcome this difficulty, a relay is used. The 

 method of connecting this is shown in figure 132. There are 

 two distinct circuits, first, the long distance circuit which 

 operates the relay, and second, the local circuit which 

 operates the sounder. In the long distance circuit only 

 one wire is needed as the ground serves as another conductor 

 through which the current returns. The ends of the main 



