The Encyclopedia britannica; a dictionary of arts, sciences, and general literatureWith new maps, and original American articles by eminent writersWith American revisions and additions, bringing each volume up to date . form of cable is easilylaid,land if properly manu-factured is likely to be very durable. Submwrine Cables.—A submarine cable (figs. 2-4), asusually manu-factured atpresent, con-sists of a corea in the centreof which is astrand of cop-per wires vary-ing in weightfor differentcables between70 and 400 lbto the -strandedform was sug-gested by Thomsonat
The Encyclopedia britannica; a dictionary of arts, sciences, and general literatureWith new maps, and original American articles by eminent writersWith American revisions and additions, bringing each volume up to date . form of cable is easilylaid,land if properly manu-factured is likely to be very durable. Submwrine Cables.—A submarine cable (figs. 2-4), asusually manu-factured atpresent, con-sists of a corea in the centreof which is astrand of cop-per wires vary-ing in weightfor differentcables between70 and 400 lbto the -strandedform was sug-gested by Thomsonat a meetingof the Philo-sophical So-ciety of Glas-gow in 1854,because ? itsgreater flexi-bility rendersit less likelyto damage theinsulating en- . .^ , ^ ,, 1 J ? Fios. 2-4.—Sections of Ihrco tyjios of subraanno cables, vclope durmg f„n Ilg. 2.—Type or sliore end. Kig. 3.—Inter-the manipula- medjat^pe. Fig. sea type. tion of the cable. T* central conductor is covered vrithseveral continuous coatings of gutta percha, the totalweight of which also varies betwepn 70 and 400 ft) tothe mile. With a light core the weight of the guttai)crcha generally exceeds that of the copper, while in some. Fi^. 8. heavy cores the copper is heavier. The different coatmgsof gutta percha and of the conductor are usually separatedby a thin coating of Chattertons compound (a mixture ofgutta percha, resin, and Stockholm tar), in order to makethem adhere firmly together. This practice has recentlybeen departed from by Messrs Siemens Brothers, who havesucceeded by an improved process of manufacture in gettingperfect adhesion \rithout the use of the compound. Thecore is served vs-ith a thick coating of wet jute, yarn,-orhemp (h), forming a theisheath, which consistsof soft iron, or of homogeneous iron, \vire3 of the bestquality. The sheathing wires are usually covered withone or two servings of tarred canv^a tape lt),.or of tarredhemp, laid on alternately with coatings of
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Keywords: ., bookcentury1800, bookdecade1890, bookidencyclopedia, bookyear1892
