CABLE, a large, strong rope or iron chain used as a mooring tie. The term is most frequently used in its nautical sense to desig nate the means by which a ship is connected with her anchor. The large ropes used for towing, or for making a vessel fast to a buoy or pier, are commonly known as hawsers. In more recent times the term cable has been ex panded to include also the large suspensory ropes (usually of twisted or parallel wires) from which suspension bridges are hung; the endless ropes used to operate the kind of street cars commonly called cable cars or grip cars; the suspended wire ropes known as cableways, for the transport of goods, building materials, etc.; the groups of telephone wires placed in underground conduits or strung overhead in leaden casings; the wires for high voltage elec tric transmission; the undersea telegraph con ductors, and, in fact, any very strong flexible tension connection. Rope cables are made of hemp, manila or other fibre, or of wire, twisted into a line of great compactness and strength. The circumference of hemp rope varies from 3 to 26 inches. A certain number of yarns are laid up left-handed to form a strand; three strands laid up right-handed make a hawser; and three hawsers laid up left-handed make a cable. The strength of a hemp cable of 18 inches circumference is about 60 tons, and for other dimensions the strength is taken to vary according to the cube of the diameter. Wire rope has within recent years largely taken the place of hemp for towlines and hawsers on board ship. These usually consist of six strands, laid or spun around a hempen core, each strand consisting of six wires laid the contrary way around a smaller hempen core. The wires are galvanized or coated with a preservative composition. Wire ropes are usually housed on board ship by winding them round a special reel or drum. Hemp cables, moreover, have for long been almost wholly superseded by chain cables; the introduction of steam on board ship having brought in its train the powerful steam windlass wherewith to manipulate the heaviest chains and anchors required.
Chain cables are made in links, the length of each being generally about six diameters of the iron of which it is made, and the breadth about three and one-half diameters. They are generally of eight lengths of 15 fathoms each connected by swivels to prevent twisting. There are two distinct kinds of chain cables — the stud-like chain, which has a tie or stud welded from side to side of the long link, and the short-link or unstudded chain. The cables for use in the mercantile service are made in 15 fathom lengths, but in government contracts chain cables are required to be made in 12% fathom lengths, with one swivel in the middle of every alternate length, and one joining shackle in each length. Besides the ordinary links and joining-shackles,. there are end-links, splicing-tails, mooring-swivels and bending swivels. The sizes of chain cables are denoted by the thickness of rod iron employed in forging the links. The following table gives certain ascertained data concerning the cables in ordinary use: Compared with the strength of hempen cable, a chain cable of one inch diameter of rod is equivalent to a hemp cable 10% inches in circumference; PA inches, to 13% inches; PA inches, to 16 inches; IX inches, to 18 inches; and 2 inches, to 24 inches. In navigation a cable's length is a nautical measure of distance equaling 120 fathoms, or 720 feet, by which the distances of ships in a fleet are frequently esti mated. This term is often misunderstood. In all marine charts a cable is deemed 607.56 feet, or one-tenth of a sea mile. In rope-making the cable varies from 101 to 115 fathoms; tablet, 120 fathoms; hawser-laid, 130 fathoms, as de termined by the British Admiralty. According to Ure a cable's length is 100 to 140 fathoms in the merchant service. The wire rope used for submarine telegraphy is also called a cable. See CABLES, SUBMARINE.