kECHANICS. 119 



ef the lever will be the greatest possible, when 



If the bodies A and B are equal, 



EULER, cfe Machinarum usu maxime lucroso, Com. Pe- 

 trop. (1758) p. 67. Prop. & Also BLAKE, /%#. 

 Trans. 1751, p. 1., &c. 



We have abstracted here from the inertia and weight 

 of the lever, that the investigation might be the 

 more elementary. EULER has extended his inqui- 

 ry to the wheel and axle, and other machines im- 

 pelled by gravity. 



188. A state of uniform motion is sometimes 

 produced in machines where gravity is the mo- 

 ving power, by means of a resistance, so consti- 

 tuted, as to increase with the velocity : when the 

 velocity has reached a certain quantity, the re- 

 tarding force becomes equal to the accelerating, 

 and the velocity of the machine remains uni- 

 form. 



This is exemplified in the motion of a jack ; the re- 

 sistance that the fly makes, increases with its velo- 

 city, and after a certain time, prevents all farther 

 acceleration. 



