190 



president's address. — SECTION G. 



5. Rate of Exploitation of Natural Resources. — A survey of 

 the world conditions as a whole reveals the fact that all popula- 

 tions, human or other, necessarily live in a relatively limited 

 ■' ttoiid ;" that the limits are, however, not absolutely fixed hut 

 can, within a considerable range, be varied; that is, they can 

 b© enlarged or diminished ; that they may be greatly extended by 

 knowledge and by the conservation of natural products (e.r/.. 



Graph No. 2. 



1800 40 80 1920. 



1800 20 40 SO 1890 1900 l9IO 



Coal and Cereals. 



water), by exploitation {e.g., nitrogen from the air, energy from 

 the sun's rays, &c.), and by management (as in the development 

 of artesian water, irrigation, &c.) ; that howsoever the limits be 

 extended, population will soon accommcdate itself thereto, be- 

 cause potential fertility always exceeds the possibilities of reali- 

 zation. 



Reference has already been made to the ^ rate of exploitation 

 of metals, &c. Supplies are by no means unlimited and the rate 

 of use is growing apace. We can show this best by some simple 

 tables. The relative world production of iron, copper, tin, zinc, 



