CHAPTER XVIII 

 MACHINES 



Early man once worked with his hands alone, unaided 

 by any tool. When, however, he found that an object, per- 

 haps a boulder, too heavy to move by hand, could be pried 

 from its bed by means of a long, tough stick, he made a 

 discovery that later gave us scissors and wheelbarrows, 

 claw hammers and knives and many common tools and 

 devices. 



He discovered, also, that objects too heavy to lift to a 

 new level could easily be rolled to that level up a smooth 

 incline. These discoveries marked the beginning of 

 machinery. 



Today, in home and office, we use hundreds of machines 

 and labor-saving devices. We depend on them every hour 

 of the day. Machines make possible our comforts, our 

 travels, and in many ways provide pleasures and protect 

 health. 



By the use of machines we harness, for our service, the 

 wind, water, steam and electricity. By a pull on a lever, 

 or a turn of a wheel, a single man controls and directs a 

 power equal to that of hundreds of horses. 



In such complicated modern machinery as great print- 

 ing machines, weaving machines, and express locomotives, 

 we find merely the early machines perfected and applied in 

 new ways. 



A machine is a device for transforming and applying energy 

 and for making work easier or less burdensome. In early times 

 man did nearly all work with his hands. Gradually he learned how 

 to make and use machines or tools to provide for his three greatest 

 needs, food, clothing and shelter. 



The lot of mankind has greatly improved through the ages 

 with the development of machines in the many different indus- 

 tries. The march of civilization may be traced by a study of the 



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