614 REPORT— 1898. 



Of late years much progress has been made in new coal winnings, in 

 improvements in winding engines by compounding, balancing, and in some 

 cases condensing, and in the quality of the wire ropes ; and in the future 

 it is suggested that progress must be looked for in the application of 

 compound engines, working with a separate condenser, raising heavier 

 loads at a higher piston speed, but with somewhat smaller drums, with a 

 balance rope somewhat heavier than the winding rope, to assist in 

 starting the load from the bottom and arresting the load as it arrives 

 at the surface. The writer gives further details as to improvements 

 practicable. 



Experience has shown that except under special circumstances, such 

 as the workings approaching the Millstone Grit or Mountain Limestone, 

 porous rocks underlying the Coal Measures, feeders of water in the Coal 

 Measures proper at great depths are rare, and pumping water, although 

 very expensive, will not materially operate in increasing the cost of deep 

 coal mining. 



2. Ventilation. 



So far as the obtaining of a sufficient quantity of air for ventilating 

 deep mines is concerned, no difficulty exists. The higher temperature, 

 provided the shafts and air roads in the mines are large enough, will rather 

 facilitate the supply of air. Improvement in useful effects in the exhaust 

 fans which are now nearly universally employed for ventilating deep 

 mines is practicable. 



3. Increase of Temperature due to Depth. 



This is a most serious obstacle to deep mining. It is well known that 

 thfe temperature of the stratification increases with depth at the rate of 

 about one degree Fahrenheit in every 60 feet, and adopting this ratio 

 we reach a temperature of 9P at 2,.500 feet, 99° at 3,000 feet, and 

 according to Professor Hull the temperature at a depth of 4,000 feet 

 will be 116°. And manifestly, inasmuch as in deep mining it will be 

 necessary to take precautions against explosions by damping the dust and 

 otherwise creating a certain amount of moisture in the atmosphere, which 

 further increases the high temperature difficulties, it is difficult to see how 

 coal, even at from 3,000 to 4,000 feet, can be worked without great 

 increase in the cost due to the reduced amount of work which can, at a 

 high temperature, be performed by manual labour. 



Tt has been suggested that the difficulty may be overcome by artificially 

 cooling the air admitted to the mine, but the immense volume of air 

 necessary in a deep colliery, probably from 300,000 to 400,000 cubic feet 

 per minute, and the rapid rate at which after cooling, in passing along the 

 passages of the mine, the temperature increases, render any application 

 of the freezing process, as far as present appliances go, out of the question. 



This process may, however, be practicable for cooling the smaller 

 currents of air required in very deep metalliferous mines. 



It has, however, been observed that in longwall working, as compared 

 with pillar and stall working, the temperature of the air does not rise so 

 rapidly owing to the fact that the current in its progress through the mine 

 does not come into contact with so much of the strata, and in passing 

 tlirough long passages in a mine, the air has a tendency to cool the exposed 

 surface of the passages, and so reduce the heating effect of the sides of the 



