The Laws of Motion. 217 



Band miles, we shall easily see that the small dif- 

 ference which this would produce is scarcely to 

 be estimated. 



Falling bodies, however, we know, acquire an 

 accelerated or increased force, according to the 

 height from which they are precipitated; but 

 this mast be accounted for from different prin- 

 ciples. Every man is sensible that the fall of a 

 stone is to be dreaded in proportion to the height 

 from which it descends. If it falls from only a 

 foot above his head, it is not likely to be so fatal 

 as if it fell from the parapet of a high house. 

 The falling body, therefore, must of necessity 

 acquire an increase of velocity in its descent ; and, 

 in fact, it is said that a leaden bullet let fall from 

 one of the steeples of Westminster Abbey ac- 

 quired velocity sufficient to pierce through a deal 

 board. 



This effect must therefore be referred to the 

 law of acceleration conjointly with the first law of 

 motion, as laid down by Sir Isaac Newton, which 

 is, that " all bodies are indifferent to motion and 

 rest : in other words, a body at rest will continue 

 in that state, unless put in motion by some exter- 

 nal impulse ; and a body in motion will continue 

 that motion for ever, unless stopped by some ex- 

 ternal obstruction." This property of matter is 

 termed, in the technical language of philosophy, 

 its vis intrtice. 



To apply this to the case immediately in point, 

 it is evident that the bullet which is dropped 



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