Engineering Wonders of the World
Volume III

THE LAYING OF SUBMARINE CABLES. 367 this apparatus have already been described somewhat fully in the article on “ Early Atlantic Cables.” * Fig. 17 shows a combined paying-out drum and brake of recent type, consisting of a large but light iron drum about six feet in diameter. Close against the rim of this drum, at the point where the cable arrives at and quits the machine, are pieces of hard steel (see Fig. 18) fitting to its circumference. These are Fig. 18.—FLEETING KNIVES. called “ fleeting knives.” As already men- tioned in the earlier article, with a view to retaining a firm hold on the line whilst being paid out, this drum is made to take * Vol. ii., pp. 291, 292. four or five turns of the cable, and the object of these knives is to prevent (by accurate guidance, or “ fleeting ”) the incoming turn riding over the last turn, or off the drum. To the drum shaft is geared a revolution- counter, indicating the length of cable laid. For the purposes of recovering on board a comparatively short length of line whilst in the act of laying—in the case of a fault or some untoward accident—it is usual for the paying-out machine to be fitted with steam gear. The same, also, is often required for paying out in a case where the cable out- board, in very shallow water, is not suffi- ciently heavy for it to run out freely of itself. The general principles of the brake which forms part of this apparatus have, as already stated, been described (vol. ii., p. 292) ; and the same applies to the dynamometer gear, through which the cable passes on its way outboard from the brake to the ship’s stern sheave. By means of the dynamometer we obtain a ready indication of the amount of longitudinal strain to which the cable has been subjected. The stress on the cable can, indeed, be actu- ally read off on a scale. The hand-wheel— shown in the previous article—for adjusting the brake-power is operated by a mechanic in accordance with the indicated strain. This winch controls a steel rope, the farther end of which is fastened on to the levers of the brake drum and weight platform. Fig. 19 presents a good general idea of the paying-out apparatus on a modern telegraph ship, showing the mechanic at the dyna- mometer wheel (on the farther side), by means of which he is able, as stated in the previous article, to release all the weights on the brake levers at a moment’s notice, as well as to reduce or increase the strain as required. To meet any emergency such as might involve additional brake-power—especially if the drum apparatus failed—additional hold-