Electricity 253 

 Here is the Morse telegraph code in dots and dashes : 



LETTERS 



A B C D E F G 



m*mmm . mm^m 



H I J K L M X 



OP Q R S T I 



^m 



V W X Y Z & 



im^mm . 



NUMERALS 



1 345 



67890 



By using the Morse code, telegraph and cable mes- 

 sages are sent all over the world in a few seconds. The 

 ability to send messages in this way arose from the 

 simple discovery that when an electric current passes 

 around a piece of iron, it turns the iron into a magnet. 



How a telephone works. A telephone is much like a 

 delicate and complicated telegraph in which the vibra- 

 tions started by your voice press the "key," and in which 

 the sounder can vibrate swiftly in response to the elec- 

 tric currents passing through the wire. The " key " 

 in the telephone is a thin metal disk that vibrates easily. 

 back of the rubber mouthpiece. Each time an air 

 vibration from your voice presses against it, it increases 



