File:The practical telephone handbook and guide to the telephonic exchange (1906) (14569680157).jpg

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

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Text Appearing Before Image:
asped by the hand, ispressed inward, and so makes the necessary battery contact for the microphone. Instrument Plugsand Jacks.—The figurealso shows a 5-strandconnecting cord at-tached and fitted witha 5-point instrumentplug. The latter ismade up of five metalplugs fitted in anebonite block, and soarranged that theymay be all inserted atonce into a 5-pointinstrument jack. Aswill be seen, this is anebonite block fittedwith five springs, onthe free ends of whichare fitted metal studs.These studs projectinto holes drilled inthe ebonite block, inwhich the plugs areinserted. Contact isthus effected betweenplugs and springs. The 5-point plugs and jacks are onlyrequired when a connection has to be made to the centre ofthe receiver coils. In ordinary circumstances 4-point plugsand jacks, as shown in Figs. 97 and 98, suffice. Two-way switches are often required for the purpose ofbreaking a circuit or to change on to different apparatus.Figs. 99 and 100 show a good form. The handle is attached
Text Appearing After Image:
Fig. 96 SUB-STATION APPARATUS 103 to the centre of a brass spring a a, one end of which bearson the piece b, and the other end on one of the brass piecesc or d, according to the direction in which the handle is

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