f8 SIXTEENTH CENTURY. PT. III. 



served that a stone or any other body, dropped from a 

 height, falls more and more quickly from the time it 

 starts till it reaches the ground, and after many experi- 

 ments he succeeded in calculating at what rate its falling 

 increases. At the end of the first second it will be falling 

 at the rate of 32 feet per second, at the end of two seconds 

 it will be falling at the rate of 64 feet per second, at the 

 end of three seconds at the rate of 96 feet per second, and 

 so it will continue, falling 32 feet faster every second till it 

 reaches the ground. 



Galileo explained this increase of velocity, or quickness 

 of falling, in the following way : It is the weight of the stone, 

 he said, which drags it down ; and when it had been once 

 started downwards by its weight, it would go on moving at 

 the same rate for ever, without any more dragging. But 

 the weight still goes on pulling it down just as much at the 

 end of the first second as it did when it started, and so the 

 stone falls, first with the drag of its start, then with the 

 drag of the first second added, then of the next, and the 

 next all added together, until it reaches the ground. 



This was quite a true explanation, so far as it went, and 

 Galileo went on to prove another fact, which sounds very 

 strange at first, namely, that if you let two weights, one 

 light and the other heavy, drop from the same height, they 

 will both take exactly the same time in falling to the ground. 

 Galileo could not make the learned men of Pisa believe 

 this, because Aristotle had said that a ten-pound weight 

 would fall ten times as fast as a one-pound weight ; so to 

 convince them he carried different weights up to the top 

 of the Tower of Pisa, and let them fall before their eyes. 

 Still, though they saw them reach the ground at the same 

 moment, they would not believe, so obstinately were they 

 determined to think with Aristotle ; and they actually an- 



