THE TELEPHONE AND TELEGRAPH 



221 



either of these two and a great deal cheaper, is now commonly 

 employed. To send a message a long distance a stronger 

 battery is needed than to send one a short distance. A battery 

 can be made stronger by adding more cups or cells to it. 



269. Steps in Telegraphing. To telegraph from one 

 place to another it is necessary to stretch between the two 

 places a wire, over which the electric current may flow. Iron 

 wire is generally used, Because it is stronger and cheaper 



FIG. 97. A Telegraph System. 



than copper wire. In the United States, wires are usually 

 stretched upon high poles. As the electricity would run down 

 the poles to the earth if the wire touched them, the wire is 

 fastened to a glass knob. Glass being a non-conductor, the 

 electricity is thus insulated and flows freely between the 

 places connected by the wire. 



Figure 97 shows the actual arrangements of. a telegraphic 

 system. If the operator at one end of the line desires to send 

 a message he opens the switch connected to his key, which is 

 always kept closed except when sending a message. He then 

 begins to operate his key. Every time he touches his key he 

 closes the circuit and the electricity flows through the line 



