Identifier: americantelepho00mill (find matches)
Title: American telephone practice
Year: 1905 (1900s)
Authors: Miller, Kempster B. (from old catalog)
Subjects:
Publisher:
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
e insula-tion of the sleeve side of the line with respect to the ground or a par-tial cross between the tip and sleeve sides of the line would lower thepotential of the test ring, and thus cause a false busy test. The general appearance of a modern common battery multipleswitch-board, equipped with lamp signals controlled by line andcut-off relays, is shown in Fig. 284, which is taken from a photo-graph of the switch-board installed by the Western Electric Com-pany for the Bell Telephone Company, of Missouri, in their St. Louisexchange. This board consists of 19 sections, with three operatorspositions at each section. It is finished in mahogany, and is aboutsix feet high, four feet wide, with an over-all length of nearly 115feet. It is at present wired for 4800 lines, and is capable of accom-modating an ultimate number of 5600 lines. 352 AMERICAN TELEPHONE PRACTICE. In addition to the 4000 multiple calling jacks shown on theupper panels of each section there are on the lower panels of
Text Appearing After Image:
the switch-board 260 answering jacks and lamps, representing theset of subscribers lines over which the three operators at that sec-tion receive their calls. Between the answering jacks and the mul- THE COMMON BATTERY MULTIPLE SWITCH-BOARD. 353 tiple jacks are placed the outgoing trunk jacks, forming the ter-minals of trunk lines leading to other offices in the exchange. On the horizontal keyboard, below the jacks, is a double row ofplugs, the rear set or answering plugs being those used for inser-tion in the answering jacks in answering a call, and the front setbeing used for testing and afterward connecting with the line of asubscriber called for, in the multiple jacks above. The listening andringing keys may be seen directly in front of the plugs. The details of the arrangement of apparatus and wiring in cen-tral office equipments will be more fully discussed in a succeedingchapter. In Fig. 285 is shown a front view of somewhat more than onesection of the great multiple switch-boar

Note About Images