58 BELL SYSTEM TECHNICAL JOURNAL 



The method, ol which the above is a bare outline, is that used in 

 completing ordinary connections. Different arrangements and differ- 

 ent operating methods have to be provided for handling short haul 

 toll calls, long distance calls, calls from coin boxes, and calls of many 

 other kinds. 



In the simplest types of manual systems, the subscriber, in order 

 to signal the central office, turns a crank thus operating a magneto 

 generator. This throws a drop in front of an operator at the central 

 office. In the switchboards developed to meet the needs of the larger 

 areas, electric lamps are substituted for the drop, and relays auto- 

 matically controlled by the subscriber bring them into play at the 

 proper time. Electric lamps which serve as visual signals to the 

 operator to indicate the status of the connection are also associated 

 with the cords that the operator uses for connecting subscribers 

 together. The operation of these lamps is automatic and is under 

 the control of the switchhook at the subscriber's station. 



Many other arrangements of an automatic character have been 

 developed and are used as occasion requires — not merely because 

 they are automatic in character but only when it has been established 

 that they make for better service to the public or for efficiency and 

 economy of operation, or both. Among these may be mentioned 

 automatic ringing, automatic listening, and many forms of automatic 

 signaling. Many of these arrangements are highly ingenious and 

 contribute greatly to the efficiency and economy of operation. Thus, 

 the trend of switchboard development has been more and more in 

 the direction of automatic operation and automatic methods. 



In addition to all that has been done in developing and introducing 

 automatic operation with so-called manual switchboards, it has been 

 felt lor a long time that in large and complex telephone areas, such for 

 example as New York City, the time would ultimately come when it 

 would be desirable to go further in the direction of introducing auto- 

 matic operation in the telephone system. This whole matter has 

 been the subject of much thought on the part of engineers of the Bell 

 System and, as a lesult, there has been developed and recently put 

 into operation a system in which the work of establishing most of the 

 local connections is done entirely by machinery. 



The introduction of this system will eventually make a considerable 

 reduction in the telephone company's requirements for operators 

 which are becoming more difficult to fulfill year by year. Operators 

 will be required, however, to handle toll and many special classes of 

 local calls and for this reason, together with the constant growth of 

 the business and the considerable period of time that will be re- 



