142 ON MR. EWART’S PAPER ON THE 
assumptions to which he is not accustomed. For 
instance, in computing the effects of collisions 
between non-elastic bodies, Mr. Ewart adopted 
the language of Smeaton, (Phil. Trans. 1776, 
&c.) assuming that a large portion of the moving 
force of bodies (which he designated by bv’, in- 
stead of bv, as usual, b being the mass and v the 
velocity) was lost by changing the figure of the 
bodies. 
Thus, if a non-elastic ball whose mass is A, 
moving with the velocity v, strike another non- 
elastic ball whose mass is B, at rest, they will, 
after collision, move on together with a velocity 
—— But the moving force before collision, 
according to Mr. Ewart’s definition, is 4v*; and 
after collison it is (4+B) Faas = ne’ But 
Av’ S v?::1: 745. The fractional part of 
the moving force (according to this definition), 
which is found in the bodies after collision, is 
therefore = as hence the part of it which is 
spent in producing change of figure is — 
If the two bodies were equal, A=B, and the 
part of the moving force lost in changing the 
figure of the bodies would, according to this rea- 
soning, be one half. 
