to draw through the socket than to break, and, unless the socket is well fastened on, the rope is very likely to draw out. When the wires of the rope-end are bent back, the part of the rope above is often not bound with wire, but the ends of the wires 3 FIG. 532.-Rope-clamp for FIG. 533. Round rope- are threaded into the rope, so that they are fast. Another method is to slip an iron cone over the rope-end; the wires are bent back over this cone, and then bound with wire; this is then placed in a conical socket, as in the case above described. Sometimes the ends of the wires are bent back forming a cone, which is drawn into a conical iron socket; melted white metal is then poured into the socket, which firmly fixes the wires. This plan is adopted by Professor Goodman when testing ropes at the Yorkshire College. It must be understood that the capping illustrated in Fig. 533 is only a diagram, and not a working drawing. For a load of say 10 tons of cage and contents, a very strong cap is required. If each wire is hooked at the end and secured in lead hardened with antimony, a short cap, sufficiently wide to hold all the wires and the lead, will suffice. If the lead mixture is not used, a long cap grasping the rope for a length of at least 3 feet is necessary, so as to avoid all risk of the wires being broken one by one; six collars should be driven over the split cap, of sufficient strength to withstand the wedge-like action of the load. The caps are generally cut off at intervals varying between six weeks and six months, and with them 6 to 12 feet of rope, if that length can be spared, and thus a fresh part of the rope is brought to bear on the pulley when the cage is at the top. In the following table are given the results of some tests made for the author at the Yorkshire College, on specimens supplied by him. FIG. 533a.-Tests of rope caps. These show the relative strengths of different kinds of rope capping. In the four cases given, the makers of the ropes capped them, and the breaking strength of the rope was the same in each case; a perfectly efficient cap should of course be as strong as the rope, but it will be seen that this is rarely the case. Quality of Ropes.-Fifty years ago hemp ropes were generally used; they were superseded by iron-wire ropes. About twenty-five years ago steel ropes were introduced; these are used almost universally (in England), to the exclusion of any other kind, and the strongest kind of steel, called in the trade "plough steel," is now frequently employed. The advantage of the best steel is that a light rope suffices, thus reducing the strain upon the engine and upon the brake; and steel endures much longer than iron, thus there is greater economy. The strength of steel ropes is given in the lists of various makers, from which the opposite table is extracted. The following rules give roughly approximate results, and will be easily remembered. (1) To find the weight of a round wire rope made in the ordinary way with twisted strands: The circumference in inches squared = weight per fathom in pounds. (2) To find the breaking strain: The weight per fathom in pounds multiplied by 2 = breaking strain in tons for Bessemer steel. Multiplied by 3 for "patent crucible steel," and by 4 for "improved plough steel." = Example.-Let the wire rope be 4 inches circumference: 42 16; therefore the weight of the rope is about 16 lbs. per fathom. In the table it is given as 15.87 lbs. per fathom. The breaking strain for Bessemer steel وو = 16 X 2 On referring to the table, it will be seen that the breaking strains are 27 25 tons, 49'50 tons, and 66 tons respectively. In winding-ropes there should be a large factor of safety, in order to avoid the danger of breakage; that is to say, the rope should be very much stronger than the supposed working strain. Thus if the load upon the top end of the rope, when the cage is fully loaded and the rope is all down the shaft to the bottom, is 10 tons, the rope should be capable of bearing a strain of 100 tons before it will break, the factor of safety being 10. Steel ropes, as now used, are generally made with a hemp core (see Fig. 534), and sometimes with a wire strand for the core. If an ordinary round rope is suspended over a pulley, and a weight hung at the end, the effect of the weight is to cause the rope to untwist. When this weight is a cage fastened to conductors, the rope is prevented from untwisting to any great extent, although as soon as the rope gets slack, as when the cage rests on the props, it curls, twisting the chains, which uncurl when the weight comes on. Ropes have been made that will not untwist with a loose weight, such as a sinking-hoppet ; this is achieved by twisting the strands in a different way. FIG. 534.-Wire rope. 1 There is a new kind of rope, called the "locked coil rope," patented by Messrs. Latch and Batchelor (see Fig. 535). This does not untwist when loaded, and can therefore be used for sinking pits. The following is a description of a rope made in 1880 for Harris's Navigation, described by Messrs. T. Forster Brown and G. F. Adams. The diameter was about 1'9 inch. It was made of the best selected steel; the gauge of the wire No. 11 B.W.G., 'Their names are not now associated with this rope, as the patent is worked by others. 19 wires to each strand; six strands formed the rope, or 114 wires in all. Each strand was made by plaiting six wires round one wire, and then other twelve wires were plaited round the first group in the reverse way. The six strands were plaited round a hempen core. The weight of the rope below the pulley-sheave (700 yards) was about 5 tons. The calculated breaking strain was about 104 tons. The load it had to lift was as follows: Two trams of coal, 3 tons; two trams, I ton; cage and bridle, 2 tons 5 cwt.; rope, 5 tons; total, 11 tons. It was intended at a future date to increase the weight of coal, trams, cage, and bridle to 10 tons, and it was then intended to use a rope of the same size FIG. 535.-Rope: Latch and as that above described, but to be made of the best plough steel. It was also intended to adopt a finer gauge of wire when the grooves of the drum were worn smooth. Cages. Cages have one, two, three, and four decks (and even perhaps more). Some examples of iron cages are shown in Figs. 536, 536a. Fig. 536 shows a single-decked iron cage, intended to hold two corves, each corf holding about 10 cwt. of coal. The cage is guided by four iron-wire conductors, and four cast-iron collars are bolted on to the top and bottom frames of the cage, making eight collars in all, the details of which are |