A FEW WOEDS ABOUT COAL. 319 



thirty years they will be 218 millions and 314 millions. 

 The difference in the last two cases is no doubt con- 

 siderable ; yet it is seen that the consumption twenty 

 years hence on Mr. Jevons's hypothesis is the same as 

 the consumption thirty-three years hence on the other ; 

 and it can readily be calculated that the consumption 

 thirty years hence on Mr. Jevons's hypothesis is the 

 same as the consumption fifty years hence on the other. 

 The advance to that rate twenty years earlier or later 

 is a matter of very little importance compared with 

 the question whether Mr. Jevons's view will be justified 

 during after years. 



If, on the contrary, as I believe, the present in- 

 creasing rate of increase will be changed long before 

 even thirty years have passed into a decreasing rate of 

 increase if such a consumption as 250 millions of tons 

 is not reached until long after the time when even the 

 present rate of change, continued uniformly, would 

 have brought it we need not fear that the exhaustion 

 of our coal-fields is so near at hand as either Mr. Jevons 

 or Mr. Hull has supposed. And we may recognise this 

 further cause of hope in such a view, that, whereas the 

 prospect of the exhaustion of our coal within 150 or 

 200 or even 300 years would imply little less than the 

 prospect of approaching national bankruptcy, the con- 

 tinuance of our supply for 800 or 1,000 years would 

 suffice to put us on a secure and stable footing. During 

 all these years the power and wealth of the nation 

 would be increasing, so far as the cause in question is 

 concerned (since our assumptions imply a continual 



