164 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



of 65 to 701b. per square inch. Below, there are two intake- 

 roadways, one from the downcast shaft, the other from the 

 travelling roadway ; and there are two return roadways to the 

 upcast shaft. 



The skips, which hold 15cwt. of coal, are made of tallow 

 wood sides one inch thick, the boards being ll|in. wide. The 

 skips are 4ft. 4in. long, 3ft. Gin. wide, and 23in. high; the 

 boards are connected together by angle iron, and have a 

 wrought iron rim round the top. The bottom is of 3-16in. sheet 

 iron. The cast iron wheels, llfin. diameter, are fixed on to 

 1 Jin. axles. To prevent skips from being filled so full that the 

 coal is knocked off against the roof in low places, a gauge is 

 erected, which consists of a horizontal piece of timber protected 

 by iron, placed across a track under which the skips are obliged 

 to pass. In the bords, short lengths of bridge rails are used. 

 These are lighter than solid rails, and being in short lengths 

 are easier to handle and bring close up to the face of the coaL 



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Fig. 96. Track Arrangement at the Pit's Bottom. 



The air current is circulated by means of a 20ft. diameter 

 Walker fan, which is worked at a pressure of about 2.25 inches 

 water gauge, and supplies 60,000 to 80,000 cubic feet of air per 

 minute, the fan being given 80 revolutions per minute. It is 

 driven direct by a tandem compound engine, but only the high 

 pressure cylinder is used at present, the low pressure cylinder 

 being disconnected. 



Haulage underground is carried out by means of the end- 

 less rope system. At the bottom of the pit the empty skips are 

 pushed off the cage by the full skips which replace them. 

 Each empty skip then runs down a siding by gravity^ at the 

 bottom of which it strikes a wooden spring, consisting of a 

 plank fixed at one end only. This starts the skip down the 

 in-bye track to the place where it is attached to the endless 

 rope by clip (Fig. 96). The greaser for the skips is placed as 

 usual between the rails, but the pair of wheels that convey the 

 lubricating oil from the wooden trough to the skip axles have 

 a series of arcs of circles cut out of their periphery, into which 

 the skip axles fit and turn the greaser, so it does not require 

 any springs, as in the case of greasers that revolve by friction. 



The endless hauling ropes are Lang's lay, with an iron core. 

 The main rope is 3-J inches in circumference, and passes down 



