348 Limits of our Coal Supply. [July, 



the lifetime of many 'of the present generation. By such a 

 famine, I do not mean an actual exhaustion of our coal 

 seams (which will never be effected), but such a scarcity and 

 rise of prices as shall annihilate the most voracious of our 

 coal-consuming industries, those which depend upon 

 abundance of cheap coal, such as the manufacture of pig- 

 iron, &c. 



The action of increasing prices has been but lightly 

 considered hitherto, though its importance is paramount 

 in determining the limits of our coal supply ; I even 

 venture so far as to affirm that it is not the depth of the 

 coal seams, not the increasing temperature nor pressure as 

 we proceed downwards, nor even thinness of seam, that will 

 practically determine the limits of British coal-getting, but 

 simply the price per ton at the pit's mouth. 



In proof of this, I may appeal to actual practice. 

 Mr. Hull and others have estimated the working limit 

 of thinness at two feet, and agree in regarding thinner 

 seams than this as unattainable. This is unquestionably 

 correct so long as the getting is effected in the usual 

 manner. A collier cannot lie down and hew a much thinner 

 seam than this, if he works as colliers work at present. 

 But the lead and copper miners succeed in working far 

 thinner lodes, even down to the thickness of a few inches, 

 and the gold-digger crushes the hardest component of the 

 earth's crust to obtain barely visible grains of the precious 

 metal. This extension of effort is entirely determined by 

 market value. At a sufficiently high price the two feet 

 limit of coal-getting would vanish, and the collier would 

 work after the manner of the lead-miner. 



We may safely apply the same reasoning to the limits of 

 depth. The 4000 feet limit of the Royal Commissioners is 

 at present unattainable, simply because the immediately 

 prospective price of coal would not cover the cost of such 

 deep sinking and working : but as prices go up, pits will go 

 down, deeper and deeper still. 



The obstacles which are assumed to determine the 4000 

 feet limit are increasing density due to greater pressure, and 

 the elevation of temperature which proceeds as we go down- 

 wards. The first of these difficulties has, I suspect, been 

 very much overstated, if not altogether misunderstood ; 

 though it is but fair to add that Mr. Hull, who most promi- 

 nently dwells upon it, does so with all just and philosophic 

 caution. He says that " it is impossible to speak with cer- 

 tainty of the effect of the accumulative weight of 3000 or 

 4000 feet of strata on mining operations. In all probability 



