2l6 



GENERAL SCIENCE 



of coal now required in the United States at prices which on 

 the one hand shall not affect disastrously the varied indus- 

 tries of the country dependent upon steam power, and* on 

 the other the comfort of the people in their home life, con- 

 stitutes a "fuel problem" likely to continue till the natural 

 resources of the country in its coal deposits shall have become 

 exhausted. 



nil lion Tons 



500 



JOO 



00 



IOO 



\l\l\\\\\ 



FIG. 70. Production of coal in the United States 1830 to 1910. 



Without coal as a fuel, and without any available substi- 

 tute for it in ample quantity, practically all the machinery 

 of modern life must come to a standstill. Factories, shops, 

 mills, furnaces, together with railway and steamship lines, 

 cannot be operated on the same scale as now. Commerce, 

 transportation, and manufactures will return to the lower 

 volume of an earlier age, and present-day standards of living 

 will likewise be lowered. That this may not come to pass 

 other motive power than steam more and more must come 

 into use. 



Coal as dug from the earth is carbon in varying per cent of 

 purity. Its structure gives ample evidence of its being the 



