CHAPTER XIX 

 SIMPLE MACHINES 



116. Evolution of Machines. Primitive man, who 

 spent most of his time gathering food from the plants 

 that grew wild and by killing wild animals, did not know 

 much about even the simplest machines, and he had but 

 little use for them. The first tool that he learned to use 

 was the stone or club which he chanced to hurl at an 

 animal for self-protection or to secure the animal for 

 food. Later he learned how to make a sling of a piece of 

 hide, with which a stone could be thrown with greater 

 force, and by practice accuracy was developed. This 

 device was the first machine which man used to subdue 

 nature, and he has been busy conquering the forces of 

 nature ever since. Probably the next machine which 

 man used in the pursuit of game was the lever, by taking 

 a stick to pry open a log or to remove a stone from a 

 hole into which an animal had fled for protection. Next 

 came a cutting device made of a sharp bone or stone. 



After primitive man had learned to use these three 

 simple devices, the sling, lever, and crude knife, he 

 was well on the road toward civilization. They gave him 

 something to think about. The thinking led to wider 

 uses and modifications of the simple machines. He 

 could now build a place in which to live and protect 

 himself from his enemies. To live in one locality required 

 man to store food when it was plentiful in order to nour- 

 ish himself in time of scarcity. By combining the lever 



