XLIV. J. HAYDON CAHDEW. 



The specific gravity is 1-329. One pound of this coal will 

 convert 12 pounds of water into steam. 



Coke making was tried some years ago but with unsatisfactory 

 results, it requiring 3 tons of coal to make 1 ton of coke. The 

 seam is reached by a vertical shaft, 14 feet by 7 feet and 200 feet 

 deep, through which all coal is drawn, and there is a ventilating 

 shaft 8 feet diameter, about 375 yards distant from the hauling 

 shaft; the cages in the shaft are single deck and fitted to hold 

 two skips. At the bottom of the shaft there is a Blake pump 

 which is capable of lifting 40,000 gallons of water in 24 hours, 

 and it generally runs about 4 hours a day to keep the mine dry. 

 In the dip there is one of Evans' hydraulic pumps connected to 

 the Lithgow Water Supply, giving a head of 385 feet, or about 

 170 lbs. pressure; the diameter of the supply cylinder is 3 inches, 

 connected to a supply pipe 1J inch diameter, and the diameter of 

 the pump cylinder is 5 inches with a discharge pipe 4 inches 

 diameter and 418 yards long, the length of stroke is 12 inches, 

 and the number of strokes is 26 per minute ; the pump is estimated 

 to deliver 15,000 gallons a clay, but two or three hours pumping 

 a day is sufficient to keep the workings dry. It is a very handy 

 pump for a low lift, and has few working parts to get out of order, 

 it can be started at the surface or in the pit as convenient. The 

 ventilation of the colliery is effected by a furnace at the bottom of 

 the ventilating (or air) shaft, and the quantity of air circulating 

 through the workings is 33,000 cubic feet per minute. 



System of Working. — The system of working adopted in this 

 mine and generally through the Western District is that known 

 as the 'pillar' and 'stall.' In the greater part of the broken mine 

 the bords were driven 5 feet 8 inches high, or just the height of 

 the compact coal, and from 4 to 5 yards wide with pillars of the 

 same dimensions, later on the bords were widened first to 8 yards 

 and then to 12 yards, but the size of the pillars was not increased. 

 These dimensions for pillars are totally insufficient for the due 

 preservation of the broken mine and render it very susceptible to 

 'thrust' and 'creep': the pressure of the roof splits up the pillars 



