78 Book of Engineering 



is not feasible, at the moment, for more 

 than local working. 



The day may come when everybody will 

 be their own operator, using wireless tele- 

 phony for communication. It is, of course, 

 a dream, but, in this age of wonders, so 

 many dreams have come true that it is 

 never safe to say: ' That is quite impos- 

 sible." 



The automatic telephone and its working 

 is too complex for description here. But 

 here is something of the simpler side of 

 automatic working. The usual telephone re- 

 ceiver is fitted with a dial with numbers i to 

 o. All the numbers on the automatic ex- 

 change must consist of a group of four 

 figures, that is why, at the moment, in antici- 

 pation of the change-over to automatic work- 

 ing, the numbers in the London area are 

 being altered to four figures. When a call is 

 wanted, the receiver is lifted off its hook 

 in the usual way, and if a low hum is 

 heard, then you know that you have your 

 connection with the exchange. The dial 

 is then operated by placing a finger in the 



