A Detailed Exposition of the Telephone System of the British post Office Herbert , Procter creator london Sir Isaac Pitman 1940 Vol II 749p; Introduction (Page-1), Elementary Principles of the Step-by-step System (Page-11), Subscribers Station Apparatus (Page-36), Relays and Mechanisms (Page-85), Power Plant and Common Apparatus (Page-170), Non – Director System (Page-202), Multi – Exchange Areas (page-280), Director System (Page-303), Miscellaneous Circuits (Page-443), Siemens no 16 System (Page-476), Relay System (page-519), Unit Automatic Exchanges (Page-547), Revertive Impulse Systems (Page-583), Recent Developments in Swathing Systems (Page-612), Trunking and Grading (Page-560), Maintence (Page-684). Procter Herbert , Telephony 621.385,HER 20221227122156.0