284 GENERAL SCIENCE 



Chicago, and the meat shipped to eastern towns for sale at 

 prices as low as the cost of production there. 



Any simple statement of changes in the life of the nation 

 due to these causes, and to an annual immigration, often 

 exceeding a million a year, is not broad enough. Any dis- 

 cussion of the economic conditions involved in these changes 

 in production, trade, and industry, and any discussion of the 

 geographical conditions that have directed and modified 

 these new currents of national life, is incomplete in itself. 

 Underlying it all, and interwoven with all this progress to- 

 ward more of the comforts and conveniences in life and less 

 of its hardships, is a degree of scientific achievement that is 

 marvelous. In its applied form, as translated into terms of 

 machinery, science has multiplied the working capacity of 

 individuals in many cases a thousand fold, and has shifted 

 the burden of large parts of the world's labor from man to 

 machines. Inventive genius, applying the results of scien- 

 tific discoveries, has perfected machines that demand workers 

 of the highest intelligence to operate and care for them. 

 Unskilled labor is ever put more and more at a disadvantage 

 in this scientific age. 



A striking illustration of development of natural resources 

 under stimulus of applied science and invention, and of a 

 revolution wrought in the social, agricultural, and industrial 

 life of the United States in connection with such development, 

 is seen in the widespread use of automobiles, motor trucks, 

 and gasoline-driven machinery of all kinds. Man's mastery 

 of the air waited upon the development of light but powerful 

 engines using petroleum oils for fuel. It was necessary that 

 these heavier-than-air machines be given a velocity not only 

 sufficient to sustain themselves, but to make long flights possi- 

 ble even when carrying passengers or other load. Marvelous 

 as was the rapidity in introduction and use of gasoline 

 machinery for factory, farm, and highway, the development 



