322 



The Supply and Waste of Coal. 



a very large area, and there are others far larger than our own. 

 Beyond their recognized limits many of the British seams ap- 

 pear to thin out and cease altogether. They have been ac- 

 cumulated on or near small islands, and the circumstances of 

 deposit have not been in all cases the same, neither have they 

 been uniformly affected by the forces employed to depress 

 them in ancient times, and afterwards to elevate them. Some 

 seams are horizontal, some at a moderate dip, and some 

 actually vertical. 



The reader will now be in a position to advance one step 

 farther, and estimate the probable amount of the stores of coal 

 sealed up beneath the earth's surface, but accessible to human 

 labour. 



Let us see, in the first place, what quantity of coal is con- 

 tained in a given area. An acre of land contains 2840 square 

 yards, and a square mile 640 acres. Each square yard of coal 

 one foot thick is one-third of a cubic yard, and, as a cubic yard 

 of water weighs about three-quarters of a ton, and coal is 

 about one-fourth heavier than water, each square yard of coal 

 one foot thick must weigh 6x cwt. A square mile of coal one 

 foot thick will therefore weigh mo x «ff x 6 * == 568,000 tons. 

 If, then, we can obtain an idea of the average thickness of 

 workable coal, and the area under which it can be worked 

 within certain limits of depth, there is no difficulty in cal- 

 culating the supply. 



A careful measurement of the best geological maps, and 

 a reference to the best sources of information, gives the fol- 

 lowing result for the British Islands : — 



Name of Coal-field. 



Estimated 

 area in 

 Square 

 Miles. 



Possible ex- 

 tension 

 under newer 

 beds. 



Esti- 

 mated 

 total 

 thick- 

 ness of 

 seams of 



work- 

 able coal 



Newcastle and Durham . 



460 



225 



30 ft. 



Cumberland, Westmoreland, and 









West Riding of Yorkshire . 



40 



20 



15 „ 



Lancashire, Flintshire, and North 









Staffordshire .... 



380 



150 



50 „ 



Yorkshire, Nottinghamshire, and 

 Derbyshire ..... 



750 



400 



40 „ 



Shropshire and Worcestershire. 



28 



20 



27 „ 



South Staffordshire .... 



100 



— 



45 „ 



Warwickshire and Leicestershire 



45 



120 



30 „ 



Somersetshire and Gloucestershire . 



120 



100 



60 „ 



South Wale .... 



900 



— 



84 „ 



Scotland ...... 



1600 



500 



54 „ 



