The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 114
the shape shown in plan byFig. 81, and in end view by Fig. 82. Thiscore is a cylinder of iron, out of which hasbeen cut two deep and wide slots, one on eachside, leaving only a comparatively thin weband a shaft in the centre, on which it maybe made to revolve. As shown in Fig. 81,the web is cut… … Fig. 81
Telephone
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