INTRODUCTORY. 1 1 



quirements is not entirely established. With the 

 land it is rather the fertility of the soil that makes 

 it a resource, except so far as it serves for building 

 purposes. With the water, except for the absolute 

 necessity of life, it is its desirable distribution — 

 terrestrial and atmospheric — which constitutes it a 

 resource in the sense of satisfying human wants. 



Of such resources as are in time exhaustible 

 without the possibility of reproduction, we may 

 mention the mines. The supply of coal, "the 

 bread of industries," in Europe is calculated to 

 last not more than three or four centuries, although 

 scarcity is expected long before that time ; and in 

 our own country we are told that anthracite coal 

 mines do not promise more than seventy-five to 

 one hundred years of supply under present methods 

 of working.^ The silver and gold mines, upon the 

 basis of which Nevada became a state, are said to 

 show signs of exhaustion. Oil-fields and natural 

 gas wells of very recent discovery belong to this 

 class of exhaustible resources. With their con- 

 sumption in satisfying our wants, they are de- 

 stroyed forever. 



The timber of the virgin forest and its game, 

 the water-power of the streams, largely dependent 

 on the conditions of the forest, the , fisheries, and 

 to some extent the local climatic conditions, are 



1 The present output of the anthracite mines is 50,000,000 

 tons, and the visible supply of the field is estimated at a little over 

 5,000,000,000 tons. 



