TELOCITY OP FALLING BODIES. 



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Fig. 11. 



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air-tight. Through this cap passes an air-tight wire, which, 

 by turning, opens a small pair of pincers. Within these 

 are placed a feather and a half dollar, and the air is then 

 thoroughly drawn from the receiver by means of an air- 

 pump. The Avire is turned, and the feather and coin both 

 drop at once, and strike the bottom at the same moment. 



There are many examples showing the accelerated 

 motion and increased force of falling 

 bodies. When a large stone rolls down 

 a mountain, it first moves sloAvly, but 

 afterwards bounds with rapidity, sweep-' 

 ing before it all smaller obstacles. Hail- 

 stones, although small, acquire such veloc- 

 i-ty as to break windows ; and but for 

 the resistance of the air, they w^ould be 

 much more destructive. The blow of a 

 sledge-hammer is more severe as it is lifted 

 to a greater height. Newton w^as first 

 led to the examination of the laws of 

 gravity by observing, Avhen sitting under 

 an apple-tree, that the fruit struck his 

 hand with greatest severity when it fell 

 from the top of the tree. 



It is not an unusual error to suppose 

 that a large body will fall more rapidly 

 than a small one. Some can scarcely be- 

 lieve that a fifty-six pound weight will Feather and coin failing 



not drop with a greater velocity than a ""^'^^ '" " vacuum. 

 small nail, not remembering that a proportionately 

 greater force is required to overcome the inertia and 

 set the larger body in motion. This error existed for 

 many centuries, from the time of Aristotle until Galileo 

 first questioned its correctness. The celebrated ex- 

 periment which established the truth on this subject, 

 and led to the discovery of the laws of falling bodies 

 just explained, and which fonncd an era in modern 

 2 



