TWO TYPES OF MACHINES USED IN THE HOME 333 



pose of this chapter to point out a few of these machines, 

 and to try to explain the simple principles which underlie 

 their construction and regulation. 



Two types of machines used in the home. The lever 

 and the wheel and axle are two types of simple machines 

 which play an important part in the construction of many 

 household devices. 

 If we look at a pair 

 of shears, for ex- 

 ample, we find them 

 to be made of. two 

 pieces of metal, held 

 together at one point 

 by a rivet with the 

 inner edges sharp- 

 ened at an angle. 

 If we try to cut a 

 piece of thick cloth 

 with these shears, 

 we find it much 

 more difficult to cut 

 the cloth when it 

 is placed farther 

 away from the point 

 where the parts of 

 the shears are ro- 

 tating, while it cuts 

 much easier close to the point of rotation. The shears 

 illustrate the lever, the force we exert being called the 

 force, the resistance we overcome in the cutting of the 

 cloth the weight, since it is measured in units of weight, 

 and the point at which the shears revolve, or turn, is called 



In which of each of these three cases will the same re- 

 sistance be overcome by a smaller force ? P=force. 

 W=weight (resistance). F=fulcrum. 



