THE SYDNEY HARBOUR COLLIERY. 



139 



sand to 1 of cement. The space between the brickwork and 

 the rock was filled up with concrete, made of sieved engine 

 ashes and cement. The walling was carried on from a cradle 

 (Fig. 72) suspended from the capstan ropes. This cradle or 

 platform was a double-decker, the decks being 6ft. apart. The 

 framework was built up of 9in. by 3in. Oregon pine, placed 2ft. 

 apart. The decks are provided with two hinged flaps, one on 

 either side, which can be raised to allow the cradle to pass be 

 tween the buntons ; when down, the flaps are supported by the 

 Oregon framework below, which projects a little beyond the 

 hinges. There is a hole left in the centre of each deck for the 

 bucket to pass through : that in the upper deck is 6ft. square, 

 and that in the lower deck 8ft. 6in. square, the tapered opening 

 between the two being lined with tongued and grooved boards. 

 There is a cover to the hatchway in the upper deck. This bricking 

 cradle was kept in the shaft all the time sinking 

 was going on. Its weight was about 4 tons 15 cwt.. 

 which was sufficient to keep the capstan ropes rigid 

 enough to serve as guides for the .buckets. The com- 

 bined breaking strain of these ropes was 86J tons, but 

 the maximum load on them, if the walling cradle was sus- 

 pended at a depth of 3000ft., and loaded with the customary 



Fig. 73. Cross-head. 



