274 POWER AND RESISTANCE. 



that whilst a ship in a calm is motionless bf 

 the pressure of the wind upon the sails, it is 

 enabled to overcome the resistance of the water, 

 It is owing to the resistance of the thing to 

 be moved, that is aseribable the impossibility 

 of finding out perpetual motion. The resist- 

 ance which is constantly exerted, by the fric- 

 tion of the moving body, against the medium, or 

 sides of the matter in which it is placed, has an 

 unceasing and everlasting tendency, not only to 

 obstruct, and to weaken, but finally to destroy the 

 force of the moving power. Various machines,, 

 which are invented by the ingenuity of man, can 

 only diminish, they cannot annihilate resistance. 

 Whether the thing moved, is moved by the mus- 

 cular power of the hand by the momentum of 

 a rapid stream by the expansibility o'f air, or 

 the elasticity of fire, or any other mechanical 

 force whatever ; it ought to be considered as an 

 universal and undeniable truth, that the cause 

 of motion is separate and distinct, from the 

 thing moved, the one is the agent, the other 

 the patient ; the former is vis sine inertia, the 

 other inertia sine vi, a force without power, a 

 forceless force. 



A vis inertiae such as this, is altogether sepa^ 

 rate and different from the vis inertiae ascribed 

 by Sir ISAAC NEWTON, to matter in general,, 

 both dead and common ; the attribute to which 



