The practical telephone handbook and guide to the telephonic exchange (1906) (14776123743)

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:

ls, giving 24 volts, are employed. Thisincreased voltage is used in order to keep up the voice trans-mission to the proper standard, as it has been found that up toabout 300w resistance in the line circuit the transmission withthe Stone system is not so good as with the Hayes system.* The No. 9 sections are 6 ft. 3 in. high, 2 ft. 5 in. wide in front,and 2 ft. 9 in. in depth from front to back including key-board. Up to 15 pairs of cords may be fitted to one section,the corresponding number of pairs of supervisory signals beingfitted directly below the calling signals. The former signalsare said to be indirect or negative, as they are operated all thetime that speaking goes on and restore to normal position whenthe subscribers replace their receivers, and thus give an indirectsignal for clearing. Fig. 468 gives a general view of the East Ham London * See M. Ramsey in Post Office Electrical Engineers Journal,April 1908. 504 PR A CTICA L TELEPHONE if A NDDOOK £n?af £»Wa3 <#€=£(

Text Appearing After Image:

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

1906

Northeastern University, Snell Library

http://commons.wikimedia.org/

public domain