COAL-MEASURES. 



351 



Of the 190,000 square miles' coal-area of this age in the United 

 States, 120,000 square miles is estimated as workable. 



Extra-Carboniferous Coal. — All the fields mentioned above belong 

 to the Carboniferous age. But, besides these, the United States is very 

 rich in coal of other periods. Probably 50,000 square miles might be 

 added from strata of later times, making in all 170,000 square miles of 

 workable coal. But of these latter fields we will speak in their proper 

 places. 



Coal-Areas of Different Countries compared. — The following table, 

 taken principally from Dana, exhibits the comparative coal-areas of the 

 principal coal-producing countries of the world : 



United States 120,000 to 150,000 square miles. 



British America 18,000 " 



Great Britain 12,000 " 



Spain 4,000 



• France 2,000 " 



Germany 1,800 " 



Belgium 518 " 



Europe, estimated 100,000 " 



Eecently enormous areas of coal have been found in China, much 

 of which belongs to this age. 



Relative Production of Coal. — But if the extent of coal-area repre- 

 sents approximately the amount of wealth of this kind present in the 

 strata, the production of coal represents how much of this wealth is 

 active capital ; it represents the development of those industries de- 

 pendent on coal. The following table is compiled from the best sources 

 at hand : 



ANNUAL COAL-PEODTTCTTON IN 

 MILLIONS OF TONS. 



1845. 



1864. 



1874. 



1884. 



Great Britain 



31*5 

 4-5 



*4-l 

 4-9 



90 

 22 



10 

 10 



125 



50 

 46 

 17 

 15 



160 



106 



70 



20 



18 



406 



United States 



Germany 



France 



Belgium 



World 





Inspection of the table shows that in the principal coal-producing 

 countries there is a rapid increase of production. It is believed that, if 

 the same rate of increase continues, the annual production of Great 

 Britain will be in thirty years 250,000,000 tons, and the whole work- 

 able coal will be exhausted in 110 years.* As might be expected, 

 therefore, British statesmen and scientists are casting about with much 

 anxiety for means by which to promote the more economic use of coal. 





* Armstrong, Nature, vol. vii, p. 291. 



