The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 513
d Hand-Micro-Telepkone Set.—Thedifficulty which has prevented the use of the generally favouritehand-micro-telephone set in connection with C.B. systems hasbeen that it did not allow of all persons using the instrument tospeak close into the mouthpiece owing to the great variation inthe lengths of… … Fig. 453.—Wood Case C.B. Radial-Arm Wall Instrument {British Insulated & Eelsby Cables)
Telephone
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