542 BIOLOGY AND HUMAN LIFE 



his cultivated animals from six to twenty fold. We can get some 

 idea of the great advance of productivity in a comparatively 

 short time by comparing the hours of labor necessary to produce 

 various commodities at the close of the Civil War with the num- 

 ber of hours it took at the close of the nineteenth century (see 

 table below). During the thirty years since these figures were 

 compiled by the United States Bureau of Labor the improve- 

 ments in most directions have been even greater. 



COST IN HUMAN HOURS OF PRODUCING BY MACHINERY 

 THE EQUIVALENT OF 1000 HOURS OF HAND WORK 



Units of Value Hours Units of Value Hours 



Barley, 47obu 42.4 Books (binding) , 2190 vols. . 263.4 



151.3 Shoes, 45 pr 135.0 



107.5 Newspapers, 1,750,000 pages . 4.8 



345.3 Envelopes, 230,000 . . ... 72.6 



46.0 Granite (dressing), 6150 sq.ft. 77.9 



Corn, 220 bu. . 

 Oats, 606 bu. 

 Potatoes, 2000 bu. 

 Wheat, 310 bu. . 



It is now possible for more people to live with a given amount 

 of work, providing leisure for the many things that human be- 

 ings value ; or it is possible for each worker to get more leisure ; 

 or it is possible for each person to get more time for education in 

 childhood or for travel and relaxation in later years ; or it is 

 possible for more people to be supported by each acre of cul- 

 tivated land. 



390. National food resources. Scientists are constantly en- 

 gaged in solving problems connected with (i) producing more 

 food on a given area, (2 ) utilizing materials to better and better 

 advantage, (3) finding new sources of food, and (4) preventing 

 food from being wasted ; and of course the same kinds of effort 

 are directed toward increasing and conserving our supplies of 

 other organic materials. 



Advances in chemical and biological knowledge have brought 

 us new methods for preserving food for long periods. This 

 makes possible a cheapening of food supplies in two ways : 

 (i) It is possible to send food a long distance, from regions in 

 which it is abundant to cities and countries where food is not 



