Light. 133 



wastes as it perfumes us; but the sun's light 

 is diffused in a wide sphere, and seems inex- 

 haustible. 



That the motion of light is inexpressibly rapid 

 you may easily convince yourselves, by only 

 giving attention to the firing of a cannon at a con- 

 siderable distance, and observing the time that 

 elapses between your seeing the flash and hearing 

 the sound. It has been calculated from some very 

 accurate experiments, that sound travels at the 

 rate of one thousand one hundred and forty-two 

 feet, or three hundred and eighty yards, in a 

 second of time ; and if you remark, as was before 

 observed, the time which intervenes between your 

 seeing the flash and hearing the noise of the 

 cannon, you will soon perceive how infinitely 

 more rapid light must be in its motions than 

 sound. 



II. It is a principle in mechanics, that the force 

 with which all moving bodies strike is conjointly 

 in proportion to the size of those bodies, or the 

 quantity of matter which they contain and the 

 velocity with which they move. Now if we con- 

 sider the amazing velocity of light, it is evident, 

 that if the separate particles of it were not in- 

 finitely smaller than we can conceive, they would 

 be destructive in the highest degree. To illus- 

 trate this by a plain examplej: A few grains of 

 shot, fired out of a musket or fowling-piece, will 

 deprive a large animal, or even a man, of life. 

 How is this? If the shot were thrown by the hand, 



