MAN'S PLACE IN NATURE 



375 



the stone was ground to an edge for a cutting instrument 

 (Figures 333, 334). 



It is not possible to know just when a knowledge of 

 the mechanical principles was attained. It is quite 

 probable that such knowledge 

 developed slowly for centuries. 



The use of metal gave cer- 

 tain tribes a distinct advantage 

 over their adversaries. The 



f ,, 11 FIG. 333. A Rude Axe, Showing 



USe Of the wheel Was an- a Handle Attached to a Stone. 



other important discovery. 



And so we might enumerate hundreds of inven- 

 tions which we use to-day with little 

 thought of the ages that were consumed in 

 their development. 



This age in which we are living is dis- 

 tinctly the age of wonderful inventions and 

 achievements in all branches of science. 

 We no sooner see the completion of a won- 

 derful mechanical conception than another 

 more marvelous attracts our attention. 

 FIG 334 An The Home. --The animals inferior to 

 Indian Knife with man build their homes by instinct. They 

 have little ability to modify them to vary- 

 ing conditions of climate and environment. Man, how- 

 ever, has never been hampered by any such restrictions, 



FIG. 335. Pottery from Ancient Burial Mounds. 



