00994    a2200157   4500003000500000005001700005040000900022082001600031100002200047245011300069250001100182260003600193300001000229505058300239650001400822Nust20221227122156.0  cNust  a621.385,HER  aHerbert , Procter  aTelephony :bA Detailed Exposition of the Telephone System of the British post Office  /cProcter Herbert ,   aVol II  alondon bSir Isaac Pitmanc1940  a749p;  aIntroduction (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).   aTelephony