THE WORLD'S NEED OF COAL 191 



ance of a certain amount of coal for their own uses at a cer- 

 tain privileged price. 



The impetus given to the mining of coal by the growth 

 of railroads, as was mentioned before, was twofold in its 

 nature. It was partially due to the improved facilities for 

 movement, and consequently its greater cheapness, and sec- 

 ondly to the demand for iron and steel. The growth of the 

 iron and steel industry, however, has acted in many other 

 ways in stimulating a demand for coal. In many depart- 

 ments of industrial activity a revolution has taken place by 

 the substitution of iron and steel for wood and other articles. 

 Thus, in shipbuilding, v/ooden vessels are rapidly becoming 

 of smaller and smaller importance, while steel and iron vessels 

 are taking their place. In the constructions of buildings a 

 similar development has taken place, and steel and iron have 

 taken the place of other structural materials. The immense 

 strides in the structural steel industry have rendered this form 

 of building material cheaper, especially in view of its durabil- 

 ity, than other material for the construction of large buildings. 



The number of articles for which iron and steel are now 

 being used is too great to permit of individual instances, but 

 the importance of the entire movement, especially in its effect 

 upon an increased demand for coal, is apparent. Even on 

 the railroads the same development which has taken place 

 from wood to iron and iron to steel in the evolution of the 

 rail is now taking place in the evolution of the car, and iron 

 and steel are completely displacing the wood of the old cars. 

 At present the steel cars, which now average 50 tons capacity, 

 are found to be not only cheaper, in view of their greater 

 durability, but are also far cheaper in operation, owing to 

 the fact that in proportion to their capacity their weight is 

 considerably less than that of the old cars which they super- 

 seded. 



This development, however, has led not only to a large 

 increase in the demand for coal, but also to a dispropor- 

 tionately large increase in the demand for bituminous coal. 

 In a certain sense, anthracite may be said to have been super- 

 seded as completely in the manufacture of iron as has charcoal. 

 Thus, as late as 1880, the amount of iron manufactured from 



