324 



MODERN ELECTRICAL INVENTIONS 



The telegraphic alphabet consists of dots and dashes and 

 their various combinations, and hence an interpretation of 

 the dot and dash symbols recorded on the tape is all that is 

 necessary for the receiving of a telegraphic message. 



The Morse telegraphic code, consisting of dots, dashes, and 

 spaces, is given in Figure 218. 



A.. 



B_.. 



C.. 



]-) 



E. 



F... 



G 



H.... 

 I.. 

 J _____ 

 "K_._ 

 L _ 

 M__ 



O 

 P 



Q 



lv 

 S 

 T 



U 

 V 

 W 

 X 

 Y 

 Z 



FIG. 218. The Morse telegraphic code. 



The telegraph is now such a universal means of communi- 

 cation between distant points that one wonders how business 

 was conducted before its invention in 1832 by S. F. B. Morse. 

 301. Improvements. The Sounder. Shortly after the in- 

 vention of telegraphy, operators learned that they could read 

 the message by the click of the marker against a metal rod 



which took the place of the 

 tape. In practically all tele- 

 graph offices of the present 

 day the old-fashioned tape 

 is replaced by the sounder, 

 shown in Figure 2 ig. When 

 current flows, a lever, L, is 

 drawn down by the electro- 

 magnet and strikes against 

 a solid metal piece with a click ; when the current is broken, 

 the lever springs upward, strikes another metal piece and 

 makes a different click. It is clear that the working of the 

 key which starts and stops the current in this line will be imi- 



FlG. 219. The sounder. 



