270 



COMMUNICATION 



receive messages much more rapidly. 



In one type of sending instrument the operator has 

 a keyboard before her similar to the one on a type- 

 writer. Messages are 

 sent by pressing the 

 keys. A receiving instru- 

 ment in a distant city 

 is connected with this 

 sender and the message 

 is typed automatically. 

 Figure 435 shows an in- 

 strument of this type. In 

 another modern instru- 

 ment the depression of 

 keys cuts perforations in 

 a tape which is later fed 

 through an automatic 

 sending instrument. Fig- 

 ure 436 shows the cut- 

 ting of this tape. 



Modern telegraphy is 

 of great importance to all of us. There are more than 

 6,500,000 miles of land and ocean telegraph lines in the 

 world. Not only is it possible to send messages but 

 money, photographs, and letters in handwriting. 

 Stock quotations are telegraphed to and from air parts 

 of the world, while the modern newspapers could 

 hardly be produced without the aid of the telegraph. 

 Great ocean cables now join all of the continents of 

 the world and make possible rapid telegraph com- 

 munication between them. Figure 437 is a map show- 



Bell Telephone Laboratories 



FIG. 435. TELETYPEWRITER 



Courtesy Western Union 

 FIG. 436. CUTTING TAPE FOR AUTOMATIC SENDING INSTRUMENT 



ing the principal cables of the world and Figure 438 

 shows a section of the newest type of ocean cable. 



FIG. 437. OCEAN CABLES 



