MACHINE SWITCHING TELEPHONE SYSTEM 



75 



Detailed Plan of Operation 



The following will give in some detail the plan of operation for 

 handling typical calls between various types of offices in a large 

 metropolitan area such as New r York City. 



Calls Originating in Machine Switching Offices. Fig. 18 shows 

 schematically the path of a call originating in a machine switching 

 office. The pair of wires of a subscriber's line is attached to one of 

 the sets of fixed terminals in a panel bank appearing before a group of 

 selectors of the type which has been described. By putting fewer 



Fig. 17 — 165 H. P. Gas Engine Generating Set for Emergency Use 



lines in these panels and increasing the number of selector brushes, 

 we attain the speed necessary at this stage of the connection. These 

 selectors are called "line finders," since their function is to find calling 

 lines. The terminals correspond to the answering jacks and the 

 selectors to the "A" operators' answering cords of the manual 

 system. 



