Identifier: practicaltelepho00pool (find matches)
Title: The practical telephone handbook and guide to the telephonic exchange
Year: 1906 (1900s)
Authors: Poole, Joseph
Subjects: Telephone
Publisher: New York, Macmillan Co.
Contributing Library: Northeastern University, Snell Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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conduits. (3) Glazed earthenware ducts. Cast-iron Ducts.—These are extensively used, and are ofthe shape shown on the right of Fig. 374, each pipe being 9feet 4 J inches in length (including the socket), 3 inches internaldiameter, and each weighing about 100 lbs. The interior sur-face must be smooth and regular, so as not to damage thecable when being drawn in, and for the same reason the insideedge of the spigot end is carefully rounded. Jointing.—The pipes are fitted and the joint partly 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, or duct as it is called, by meansof which, when completed, the hauling rope is pulled through,ready for drawing in the cable. To test if the pipes are correct, a mandril of iron covered , Yarn Pmckinq
Text Appearing After Image:
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 and joints are required to be made, or the direc-

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