The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 504
charge and discharge are measured together when thebattery connections are reversed. Fault Clerics Test Keys.—Fig. 448 shows the arrangementsof the key switches (which are of the lever pattern) fittedon the test clerks desk for the purpose of readily making thedesired connections to any line. When… … 47<5 PRACTICAL TELEPHONE HANDBOOK Cohens Galvanometer Set.—This is an instrument designed tomeasure the very weak telephonic speech currents. The chief partof it is a barretter or bolometer, in the shape of a smallelectric lamp having a very fine carbon filament (-6 mil in diameterand -| inch…
Telephone
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