6 PROGRESSIVE MOTION OF MATTER. 



Bodies put in motion in free space continue to 

 move ; and in limited space they move until they 

 transfer the action they receive to other matter. 

 For this reason the axiom is adopted, that " action 

 and reaction are equal, and in opposite directions," 

 representing simply the transfer of an impulse. 



The ever onward and straight progressive 

 motion of matter, in transmitting mechanical 

 action in free space, is manifested by light from 

 the remotest visible stars ; which travels continu- 

 ously in a straight line during a thousand years 

 or more, before reaching the earth. The con- 

 tinuous progression of impulses imparted to pas- 

 sive matter is sportively verified by children, in 

 setting on end a row of bricks, or blocks, to fall 

 successively one on another. After thus testing, 

 on a small scale, the incapability of matter put 

 in motion to stop itself, the youthful experimenter 

 is impressed with the conviction that an impulse 

 imparted by a touch of the finger would continue 

 travelling around the world and come back to his 

 finger, were it practicable to extend the row of 

 bricks sufficiently. 



A tidal wave, raised by an earthquake on the 

 coast of Japan, as stated by Professor Bache, 

 continued steadily progressing across the broad 

 Pacific Ocean, and finally dashed against the 

 coast of America. 



The regular diffusion of an impulse of mechan- 

 ical force is also practically learned by casting 



