4()9 
DEEP MINING. BY W. E. GARFORTH, F.G.S. 
The question of working coal at depths varying from two to 
four thousand feet below the surface was fully investigated in the 
years 1866-71, by the Royal Commission appointed to enquire into 
the probable duration of the coal-fields, and the several matters 
relating to coal in the United Kingdom. 
The evidence given before that Commission was most valuable 
and exhaustive, and the Report, which not only dealt with the state 
of affairs at that time, but foreshowed many of the circumstances 
which have since occurred, reflects the highest honour on the 
distinguished men who formed the several committees. The com- 
missioners estimated the available coal in the known British coal- 
fields (excluding all seams less than 12 inches thick, and after making 
the necessary deductions for loss in working, faults, &c.) to be 
90,297 millions of tons. In addition to such quantity coal is sup- 
posed to exist at workable depths under the Permian, New Red 
Sandstone, and other superincumbent strata, equal to 56,278 millions 
of tons. The aggTegate quantity, wliich in 1871 was reasonably 
expected to be available for use, was estimated at 146,480 millions 
of tons. 
Since that report was published an interval of 19 years has 
elapsed, during which time the (quantity of coal raised in the United 
Kingdom, including the years 1871 and 1889, has been 2,797,344,007 
tons. 
