IN THE ANIMAL ORGANISM. 201 



According as the stone is allowed to fall during a 

 longer or shorter time, it acquires properties which 

 it had not while at rest ; it acquires, for example, 

 the power of overcoming more feeble or more pow- 

 erful obstacles, or that of communicating motion to 

 bodies in a state of rest. 



If it fall from a certain height it makes a per- 

 manent impression on the spot on which it falls ; if 

 it fall from a still greater height (during a longer 

 time) it perforates the table; its own motion is 

 communicated to a certain number of the particles 

 of the wood which now fall along with the stone 

 itself. The stone, while at rest, possessed none of 

 these properties. 



The velocity of the falling body is always the 

 effect of the moving force, and is, ceteris paribus, 

 proportional to the force of gravitation. 



A body, falling freely, acquires at the end of one 

 second a velocity of 30 feet. The same body, if 

 falling on the moon, would acquire in one second 

 only a velocity of ^ths of a foot=l inch, because, 

 in the moon, the intensity of gravitation (the pressure 

 acting on the body, the moving power) is 360 times 

 smaller. 



If the pressure continue uniform, the velocity is 

 directly proportional to it ; so that, for example, 

 the body falling 360 times slower, will, after 360 

 seconds, have the same velocity as the other body 

 after one second. 



Consequently, the effect is proportional, not to 



