500 THE POPULAR SCIENCE MONTHLY 



commerce, and that it applies only within certain limited territories and 

 does not materially affect the problem if we consider the world at large. 

 Because several million people happen to make a living on Manhattan 

 Island by substituting capital for land, it does not follow that the whole 

 "world could do the same, nor would it follow even if two hundred mil- 

 lion people could make a living in a similar way within the present 

 boundaries of the United States. Our country would not then be truly 

 self-supporting, in any large and complete sense, any more than the 

 Island of Manhattan, or the Island of Great Britain, or Belgium now 

 is. All urbanized populations bring in the products of the soil from 

 regions where soil is abundant, work them over in industries which 

 require much labor and little land, and send them out again to exchange 

 for raw materials, living all the while on the profits of this class of 

 transactions. As these urbanized populations grow, it is necessary to 

 send farther and farther, to wider and wider fields for the products of 

 the soil. Why is this necessary ? Why should not England get all her 

 agricultural products from her own area? Merely because of the law 

 of diminishing returns. To double the produce of the English farms 

 would not double, but treble or quadruple, the cost of cultivation. That 

 is what the law of diminishing returns means, and it never meant any- 

 thing else. Because of this law England finds it cheaper to send to 

 distant countries for her wheat and beef, paying the cost of transporta- 

 tion, than to cultivate her own farms with a sufficiently high degree of 

 intensity to enable her to live off her own soil. 



To be sure, the available waste land of the world is not all in use 

 yet, and our increasing urban populations will be able, for many years 

 to come, to thrust their transportation systems out farther and farther 

 in order to secure these products which require land — space — superficial 

 area for their eflBcient production. Therefore we need not worry about 

 the food supply for a long time to come. It may, however, surprise 

 some of our urban economists to learn how little modern science has 

 enabled us to economize land, our inventions and machines having in 

 the main, increased the product per unit of labor rather than the 

 product per unit of land. So little has it increased the latter that, tak- 

 ing into account the rise in the standard of living, it is probable that it 

 takes as much land to support the average family in any part of the 

 civilized world to-day as it did when Malthus wrote his epoch-making 

 work on population. By support I mean support in a complete 

 economic sense. I mean that it probably takes as much land to supply 

 all the things actually consumed by the average family to-day as it did 

 then. 



We could, to be sure, if we chose to do so, consume more of those 

 crops which respond to intensive culture, such as corn, potatoes, 

 bananas, etc., and less of those which yield their best results under ex- 



