CHAPTER II. 



INDUCTIVE EPOCH OF GALILEO. DISCOVERY OF THE 

 LAWS OF MOTION IN SIMPLE CASES. 



Sect. 1. Establishment of the First Lam of Motion. 



AFTER mathematicians had begun to doubt or 

 reject the authority of Aristotle, they were still 

 some time in coming to the conclusion, that the 

 distinction of Natural and Violent Motions was alto- 

 gether untenable ; that the velocity of a body in 

 motion increased or diminished in consequence of 

 the action of extrinsic causes, not of any property 

 of the motion itself; and that the apparently uni- 

 versal fact, of bodies going slower and slower, as if 

 by their own disposition, till they finally stopped, 

 from which Motions had been called Violent, arose 

 from the action of external obstacles not imme- 

 diately obvious, as the friction and the resistance of 

 the air, when a ball runs on the ground, and the 

 action of gravity, when it is thrown upwards. But 

 the truth to which they were at last led, was, that 

 such causes would account for all the diminution of 

 velocity which bodies experience when apparently 

 left to themselves; and that without such causes, 

 the motion of all bodies would go on for ever, in a 

 straight line and with a uniform velocity. 



