The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 153
d all to be spoken through had avery detrimental effect upon the speaking currents. Intermediate Switches.—When three stations are to bejoined, and privacy is a desideratum, it is usual to employ someform of switch at the intermediate station which enablesthat station to speak to either one of the… … Fig. 144 SWITCHES AND EXTENSION INSTRUMENTS 131 munication between the end stations is not desired, an In-termediate Private Switch is used. When, on the other hand,in addition to the connections given by the last-named switchit is desired to give means of communication between thetwo end stations,…
Telephone
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