XCii PEOCEEDIKGS Or THE GEOLOGICAL SOCIETY. [June 1912^ 



in drafting their estimates, the most important is the allowance 

 for ' faults and other natural causes.' The arerage deduction 

 made on this account is 17 to 18 per cent, of the coal as it lies in 

 situ, and the amounts var}' from 30 per cent, in Xorth Wales and 

 Cumberland, and 27 per cent, in South Wales, South Staffordshire^ 

 and Scotland, to as little as 18 per cent, in Cheshire and 15 per 

 cent, in Shropshire. The losses under this head comprise ' wants ' 

 or destruction caused by folds and faults, the existence of masses 

 of older rocks protruding through the Coal-measures, the effects 

 due to crushing and to alteration by igneous rocks, the variations 

 in thickness and quality of the seams, and the ' wash-outs ' and 

 other results of contemporaneous or subsequent denudation. Pro-^ 

 bably also some allowance is made for the average effects of 

 accidents, fire, water, and creep. 



The second principal deduction is for the amount of coal which 

 it is necessary to leave underground in order to support the shafts, 

 plant, and buildings, and to hold up the surface where it and the- 

 structures upon it are of more value than the underlying coal-seams. 

 The average deduction under this head amounts to a little over 

 5 per cent. It varies from 12 per cent, in Durham and Scotland to- 

 2 per cent, in Cheshire, and 1 per cent, in Cumberland. A certain 

 amount of allowance is also made for the present practice of 

 leaving boundary barriers between adjoining properties ; but it is. 

 assumed that this practice will be reduced to a minimum, or even 

 abandoned under improved conditions of working. 



Thus the Commission assumes that coal-working will be carried 

 on in a much more efficient manner in the future than in the past ;. 

 that the old mistakes will not be made again ; but that the most 

 advanced knowledge and the most economic methods and machinery 

 will be made use of. Can we hope that their trust in these- 

 respects will be justified ? The answer to this question involves, 

 a consideration of the special conditions which will prevail in future 

 working. 



(g) Prospects of Improvement in the Future. 



We may perhaps presume that the work which still remains ta 

 be done in the exposed fields will justify the expectation of the 

 Commissioners. In the concealed but proved areas too there 

 has been acquired a certain amount of knowledge from workings 

 and borings, though this falls short of that pertaining to the exposed 

 fields. 



But when we come to the unproved areas, there will have to be 



