Moving Force. 213 
overcoming the cohesion of pitch,* for exam- 
ple, can never be seriously compared with 
any supposed change of force in the case un- 
der consideration.—Yet, according to Mr. 
Bernoulli's acceptation, Sir Isaac Newton 
must have meant that there was in both cases 
the same kind of variation of force. 
If D be a non-elastic body, we shall then 
indeed have a variation of the force similar to 
that which takes place in the motion of the 
pitch.—A portion of the force will be expend- 
ed in producing change of figure, and the 
results after collision will exhibit four distinct 
effects of moving force, namely, a change in 
the progressive motion of D, a change of 
figure in D, a progressive motion in G, and a 
rotatory motion in A and B. For, D will 
move on with the velocity a and its figure 
will be changed, G will move on with the 
= v e. 
velocity =» and A and B will revolve around 
G with the velocity a That is, one fourth 
of the original force of D will remain 
with it after collisionx—one half will have 
been expended in changing the figure of jieo 
one eighth will have produced the progressive 
motion of G,—and one eighth, the rotatory 
motion of Aand B. But if these effects must 
* See Horsley’s Newton, vol. 4, p. 259, 
