/ LECTURE XVI. 



EXPERIMENTAL PHILOSOPHY. 



THE MECHANIC POWERS. 



MAN, considered as to his bodily structure, is 

 but a feeble creature ; it is mind which gives 

 him a superiority over other animals. Con- 

 trivances to assist his natural powers we have rea- 

 son to believe took place at a very early period 

 of society, as we find few nations, even in the most 

 savage state, which are entirely without them. 

 It is philosophy, however, which explains their 

 theory and uses, and which extends their appli- 

 cation. 



When we survey the vast variety of complex 

 machines, which one of our great manufactories, 

 for instance, exhibits, we are struck with astonish- 

 ment, and the creative genius of man appears to 

 the greatest advantage ; but the surprise of the 

 unscientific person will be increased, when he 

 learns that this vast assemblage of mechanism is 

 reduced into six simple machines or powers, from 

 which, and their different combinations, the most 

 stupendous works of human art are produced. 

 These machines are ; 1. the lever ; 2. the wheel 

 and axle ; 3. the pulley ; 4. the inclined plane ; 

 5. the wedge ; and 6. the screw. 



1. The lever is, perhaps, the simplest of all 



