4 
24 ESSAYSanpOBSERVATIONS ~— 
are, the refiftance will be the lefs: and they 
may be made {moother and {moother, till the 
refiftance be quit infenfible. If the refiftance 
do not vanifh altogether, it may be owing 
to our want of art to make any furface 
abfolutely fmooth. There is no reafon, it 
may be thought, toafcribe the fmall remain- 
ing refiftance to a fuppofed vis inertia, when 
it can be accounted for by other caufes ; and 
that itis unphilofophical to fuppofe the exift- 
ence of a caufe, when we cannot point outa 
fingle effect that refults from it, and from no 
other caufe. : 
Burthere is another experiment of the 
very eafieft operation, and which is liable to 
noambiguity. Let a body of any determined 
weight be fufpended by a thread or rope fix’d 
toa hook in theceiling: the leaft conceive- 
able force will put this body in motion. If 
any refiftance at all be felt, it ought to be at- 
tributed to the denfity of the air, not to the 
body. And indeed thefe experiments infer, 
no more than what is admitted by every phi- 
lofopher, that the {malleft force is fufficient 
to move the greateft body. It is acknowled- 
ged, that, were the globe of the earth fuf- 
pended by a chain, there is net a force fo 
{mall 
