, THE METROPOLITAN COLLIERY. 151 



in first cost; they offer no resistance to ventilation, as 

 they require no intermediate supports, and take up little 

 space ; unless fixed at the bottom, they are free to expand and 

 contract ; if properly oiled they last longer than wooden guides, 

 require less repairs, and are easily fitted up and secured. 



The winding rope, which is 4J inches in circumference, is 

 capped with one of Becker's caps. The ordinary way of cap- 

 ping by separating the wires and doubling them back over 

 some underlying metal or other material, so as to form a cone- 

 shaped knot at the end, destroys the unity of the wires which 

 is essential so that the rope shall yield a tensile strength pro- 

 portionate to its metallic area, and as the strain is exerted on 

 this tapered knot, which is naturally the weakest part, the 

 factor of safety, which is right enough for the main body of 

 the rope, may be inadequate for that portion of it inside the 

 cap, where the wires break one after the other, and cannot be 

 detected. W. H. Becker designed a cap with sliding interlock- 

 ing wedges hollowed out in the centre, which clamps the whole 

 of the rope within it, and does not depend 011 a swelling at the 

 end, though in practice the end is turned over, as shown in Fig. 

 86. A rope can be capped in 15 minutes, so, if required, the 

 end of it can be examined daily. 



Of the three endless rope systems for hauling, two ropes, 

 each 3 Jin. in circumference cross the gully, and pass down 

 the upcast shaft direct to their work. A band rope, 

 l-Jin. diameter, passes down the main shaft and 

 drives several drums at the bottom, which are put 

 in and out of gear by Walker's friction clutches. This 

 clutch consists of three segments fixed to the drum : each seg- 

 ment is connected to those on either side by a left and right 

 : hand screw with large threads, so t^hat a slight turn will cause 

 them to come closer together or to go further apart, according 

 to the direction in which they are turned. A boss is fixed to 

 the drum shafting, so when the segments clutch this boss it 

 causes the drum and shafting to rotate : it is found that when 

 the "friction" is copper-lined it gives a better grip than other- 

 wise. The clutch is worked by means of a hand wheel at the 

 top of a fine threaded screw, and the motion is transmitted to 

 the segments by a system of levers. By having a fine thread, 

 the endless rope is started or stopped slowly, thus avoiding 

 shock. Of the drums in this underground chamber, one is for 

 a collecting rope that runs for about three hundred yards from 

 the pit's bottom, it being unsuitable to have a gravity system 

 for such a distance, besides the collecting rope controls the 

 traffic better; another is for the main haulage, and like the 

 other main haulage ropes is of the best plough steel SJ-mch 

 circumference : while a third is a driving rope for working two 

 secondary haulages in two headings, the ropes of which are 



