The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 410
y packedwith yarn, and then, with the assistance of a mould of softclay, melted lead is run into the joint, and, when cold, ham-mered or * caulked, so as to render the joint solid andwatertight. Draw Wire.—As the jointing progresses, a No. 8 iron wire UNDERGROUND WORK 38i is drawn through the tube,… … Fig. 374.—Joint in Cast-Iron Ducts (Scale \) with lead 2| inches diameter and 4 feet long must be drawnthrough the duct, and each is required to hold an air pressureof 5 lbs. per square inch for 30 minutes when closed at the ends.Split Pipes.—These are used when only one or two ductsare being laid…
Telephone
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