Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 442
the private exchange will, afteranswering the call with an answering plug, of a regular cord cir-cuit, withdraw this plug and insert in its place the plug of a trunkline. The relay, A, is polarized and is kept normally in the positionshown by current flowing from the main exchange battery. As… … FIC. Sie.-PRIVATE-DRANCH EXCHANGE SWITCHBOARD. ate, and thus cause the line lamp at the main exchange to be dis-played. The main exchange operator will answer in the ordinaryway, and after finding out the number of the line with which con-nection is to be established, establish this connection in…
Telephone
Internet Archive · Cornell University Library · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Telephones and telegraphs: 1902 : [and Municipal electric fire alarm and police patrol systems] (1906)](https://img.insideoutlibrary.com/img/200/ia-cu31924022817674-82-33.webp)
