Engineering Wonders of the World
Volume III

THE LAYING OF SUBMARINE CABLES. 369 operations consisting mainly of grappling for and picking up cables, any short lengths subse- quently laid being performed from the same machine. The buoys used in cable work, together with their attachments, fixings, and moor- ings, are of various shapes, sizes, and de- scriptions, such as it would Cable Buoys impOgsibie f0 ({eaj with in and Cable r Buoying. detail here. Briefly it may be said that for shallow water, where the necessary moorings are no great weight, they need only be of small dimen- sions ; while for great depths they are of considerable size, and capable of supporting three or four tons of moorings. The shape of a buoy is of great importance. A badly shaped buoy in a heavy sea will be so un- steady that it will soon chafe its moorings, and may even give such violent jerks as to break the flagstaff and lamp supports sur- mounting it. A very ordinary type of buoy for deep-sea cable operations is that shown on p. 369 of the article on “ Early Atlantic Cables,” and also—in operation at sea—as a heading to the said article (vol. ii., p. 277). Let us now briefly consider the buoying of a cable. In buoying a cable which is hanging from the bows, the method of procedure is similar to that employed nautically when let- ting go a mark or “ watch ” buoy. When, however, the cable hangs over the stern, and it is necessary to pay the moorings out from forward, the matter becomes less simple. A side rope is taken round the picking-up drum, out over the bow sheave and along the ship’s side to the quarter. Here it is shackled to a length of chain which passes inboard over the stern sheave, and which has shackled on to it another length of chain—the “ stray chain.” This in turn is shackled to a heavy mushroom anchor weighing anything between 3 and 5 cwt., according to circumstances. The free end of (1,408) < 24 a the chain is now secured to the cable. In- board of this a rope is stoppered on to the cable and set taut round a large bollard. The cable is then slacked out so that the rope takes the entire weight. All being ready forward, as soon as the end of the cable has been eased out till the strain comes on the mushroom slip-rope, the rope holding it is cut, and the mushroom let go at the same moment. The ultimate result is shown in Fig. 22. In picking up a buoy, whether serving as simple mark buoy or as a buoy on the Fig. 22.—END OF CABLE BUOYED. end of a cable, it should, if possible, be ap- proached with the ship’s head to the current or wind, and certainly never with these forces on the broadside. By the time the ship is within a hundred fathoms or so from the buoy, a boat is lowered and sent off to unrig it. Fig. 23 shows a boat going off to the Great Eastern for the purpose, in connection with the repair of an early Atlantic cable. This unrigging is accomplished as quickly as possible ; and the ship having run up close to the buoy, the boat pulls to out a small line which is made buoy. her, paying fast to the Having described the various implements vol. in.