SYMPOSIUM ON CONSERVATIOX 



6i 



coal, together with doubt as to future demands at home and 

 abroad, reduce the estimates to guesses. Nevertheless, in con- 

 sidering the lives of nations and the habitation of the globe, an 



Plate V. Average Yearh- Production of COAL in decades for Illinois. 



error of one or two hundred years is negligible. It therefore 

 behooves Illinois, as rapidly as possible, to take careful stock of 

 our coal and to minimize wastes in mining and utilization. 



WASTE OF COAL IX ILLINOIS. 



General Statement. 



Waste of coal in Illinois takes place chiefly in its mining and 

 utilization. To a lesser degree the coal is wasted through non- 

 use of cheaper substitutes. 



Mining the coal is simple from the engineering viewpoint. The 

 beds are unusually regular in distribution and thickness; and 

 they lie practically horizontal. Nevertheless, the variations in 

 recovery range from about 95 per cent to less than 50 per cent. 

 Additional loss assumes importance locally, where subsidence due 

 to mining may break overlying coals, and render easy recovery 

 of the higher bed impossible. The chief reasons for the loss are 



