*44 MK smEx\ton’s Fundamental Experiments 
can happen in the collifion of bodies perfectly hard, the refult 
and confequence of fuch a broke mu ft b q different. 
The confequence of a broke of bodies perfectly hard, but 
void of elafticity, muft doubtiefs be different from that of bo- 
dies perfectly elajiic : for having no fpring tlie body at reft 
could not be driven oft with the velocity of the ftriking body, 
for that is the confequence of the action of the fpring or elaftic 
parts between them, as will be (hewn in the refult of the expe- 
riments ; the ftriking body will therefore not be bopped, and 
as the motion it lofes muft be communicated to the other, 
from the equality of adtion and re-a6tion, they will both pro- 
ceed together, with an equal velocity, as in the cafe of non-elaftic 
loft bodies : the queftion, therefore, that remains is, what that 
‘velocity mu ft be? — It muft be greater than that of the non- 
elaftic foft bodies, becaufe there is no mechanical power loft in 
the broke. It muft be lefs than that of the ftriking body, 
becaufe, if equal, inftead of a lofs of motion by the collifion, 
it will be doubled. If, therefore, non-elaftic foft bodies lofc 
half their motion, or mechanical power, by change of figure 
in collifion, and yet proceed together with half the velocity, 
and the non-elaftic hard bodies can lofe none in any manner 
whatever ; then, as they muft move together, their velocity 
muft be fuch as to preferve the equality of the mechanic power, 
unimpaired , after the broke the fame as it was before it. 
For example, let the velocity of the ftriking body before the 
broke be 20, and its mafs or quantity of matter 8 ; then, ac- 
cording to the rule deduced from the experiments in the tra<ft on 
Mechanic Power (fee exp. third and fourth) that power will be 
expreffed by 20 x 20 = 400, which x 8 = 3200 ; and if half of 
it is loft in the broke, in the cafe of non-elaftic loft bodies, it 
will be reduced to 1600 ; which -f- 16 the double quantity of 
matter, will give 100 for the fquare of their velocity; the 
4 fquare 
