CH. XXXVI. 



THE TELEPHONE. 



3*7 



telegraphic writing machine, in which the words written at 

 one end are reproduced in facsimile by a pen at the other 

 cud of the wire. IJut all these are only improvements of 

 the same principle by which an electric current going first 

 one way and then another acts on a magnetic needle. 



The Telephone, 1S37-1872. Wonderful as the elec- 

 tric telegraph is in its power to send messages almost in- 

 stantaneously across the world, yet within the last few years 

 an instrument still more wonderful, and at the same time 

 even more simple, has been invented. This is the telephone, 

 a small instrument which, when fastened to one end of a 



i. Bell's Telephone. 



FIG. 7 i. 



2. Section of the same. 



a, Iron plate, b, Soft iron core, c c, Coil of silk-covered wire wound round b. 

 d, Permanent magnet, c, e, Connecting wires. 



wire while a similar instrument is fixed at the other end, 

 enables us to talk with a person miles distant from us, so 

 that he can not only hear the words we say but even recognise 

 the tones of our voice, 



As usual many men have helped to bring this instru- 

 27 



