The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 378
Fig. 343 Fig. 344 case a girder clip, Figs. 343 and 344, is employed, made indifferent sizes for various girders. Tubes for these poles are made 4, 4J, and 5 inches diameter,the metal being J-inch thick, so that the smaller tubes fit intothe next size above. The usual lengths are 8, 10, 15, and…
Telephone
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