The practical telephone handbook and guide to the telephonic exchange (1906) (14733164436)

Identifier: practicaltelepho00pool (find matches)

Title: The practical telephone handbook and guide to the telephonic exchange

Year: 1906 (1900s)

Authors: Poole, Joseph

Subjects: Telephone

Publisher: New York, Macmillan Co.

Contributing Library: Northeastern University, Snell Library

Digitizing Sponsor: Boston Library Consortium Member Libraries

Text Appearing Before Image:

thirty, or more, connected to as many exchanges and to asmany listening operators. Order-Wire Ringing Keys.—During very slack hours theorder-wire or B operators may cease listening, and connecttheir order wires to signalling apparatus, so that at such timesa ringing key is needed to call them. One such key is fittedon each operators position throughout the switch-board. Generator Reversing Key.—This is another extra key foruse with party fines on which two or more subscribers areconnected to the same line. In such party lines some ofthe magneto bells are connected only to the A wire, thesebeing for what are termed the X subscribers. Others areconnected to the B wire of the loop for the Y subscribers,the other ends of the magneto bells being earthed. Thereversing key is only needed when a Y subscriber has to berung, as all the ordinary lines are rung through the A wire. A 660-ohm resistance lamp is inserted in the generatorcircuit of each operators position. This lamp glows when an

Text Appearing After Image:

Fig. 244.—Testing Connections simplifiedP 224 PRACTICAL TELEPHONE HANDBOOK

the practical telephone handbook and guide to the telephonic exchange 1906 book illustrations telephone electric generators magneto images from internet archive

1906

Northeastern University, Snell Library

http://commons.wikimedia.org/

public domain