| PHYSICAL ayp LITERARY. 39 
the fame time to a thoufand different degrees 
of force. To talk of the equality of action 
and reaction in fuch a,cafe, means really no- 
thing more than, thatthe hand has not forse 
enough to move the ftone, 
Acarn, if the obftacle be, moveable, it 
coincides with another infiance given, that 
of percuffion,.or the collifion of hard bo- 
dies. Here indeed. it is true, that there is as 
much force loft by the one body, as is gene- 
rated’ in the other. But.then. this is plainly 
the effec of the vw7s refiflenti@ as explained 
above; and therefore, itis unphilofophical to, 
introduce any other principle by which-to ac- 
count for this phoenomenon, , At the fame. 
time, I-cannot difcover any equality of adti- 
on and reaction in this cafe; on the contrary, 
it is eftablifhed by infallible experiments, that 
the impreffed force or action is always great- 
erin a determined proportion, than the re- 
‘fiftancelor reaction. And it is this very pro- 
_ portion which produces the effe& of an equa- 
lity of motion before and after impulfe; or, 
in.other words, the acquifition of as much 
_ force by the one, as is loft by the other. 
ANOTHER inftance is of a horfe drawing 
: a {tone by a rope; and it is faid, that the 
i: - {tone 
