AGE OF MACHINERY 



497 



force is used to roll the barrel up the inclined plane. The longer 

 the inclined plane, the less force is needed at one time. 



The Wedge. A wedge is a type of machine which, in reality, 

 is an inclined plane. Such a machine is used for splitting logs, 

 separating objects, etc. 



Simple and Compound Machines. The lever, the wheel and 

 axle, the wedge and the screw are considered simple machines. 



FIG. 377. The milk separator, 

 compound machine. 



378. 'How many classes of 

 levers are represented in the wash- 

 ing machine? What other simple 

 machines do you find? 



Whenever a machine consists of two or more of these simple machines, 

 it is said to be a compound machine. 



QUESTIONS ON DIAGRAMS 



1. Where is the fulcrum of a pair of scissors? 



2. Where is the force applied? 



3. What is the weight? 



4. What class of lever is a pair of scissors? 



5. What class of lever is a pump? Why? 



6. What class of lever is a hammer? Why? 



7. What class of lever is a tack puller? Why? 





