DISPLACEMENT 



at all distances, but, rather, it acts like gravity, 

 after the inverse square. 



Again, let the circle B C F represent a disk of 

 iron. Let A be the centre around which it is re- 



volved toward B C. Let the dot B represent an 

 atom of the disk. Then the force which holds the 

 atoms together will cause the atom B to remain at 

 the same distance from the centre, while it crosses 

 the line A C D E. But the momentum acquired 

 by the atom B will strive to make it go at right 

 angles to the line A B; namely, in the direction 

 B E. 



Then, however strong the force of cohesion, if 

 the atom can move at all, relative to the centre, 

 the movement will be a compound between the 

 circular path B C and the tangent B E. Let 

 that resultant path be any line B D ; then, because 

 the line B D is between the circular line B C 

 and a line outside of the circle, the line B D must 

 be farther removed from the centre A than is the 

 atom at B. And because every atom in the disk is 

 subject to the same law of force and motion in a 

 degree, according to the distance from the centre, 



13 



