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rizon and movable about its center O ; and then pro- 
pofes to determine the forces which thefe weights have 
to turn the wheel round its center. In order to do this, 
he fuppofes that it is indifferent from what points in 
the perpendicular lines M A and N P the weights 
are hung, for that they will ifill have the fame power 
to turn the wheel about its center. Plis words are : 
<{ Quoniam nil refert utrum filorum pundta K, L, D, 
<c affixa fint vel non affixa ad planum rotas ; pon- 
“ dera idem valebunt ac fi fufpenderentur a pundtis 
“ K et L, vel D et L”. Now whether the points 
of the threads K, L, D, are fixed or not to the plane 
of the wheel is certainly of importance, as it muff 
make a difference in the points of fufpenfion of the 
weights, and confequently in the degrees of obliquity 
with which the weights adt ; for the loweff point of 
the thread that is fixed to the plane muff be confidered 
as the point from which the weight hangs ; as the 
parts of the thread above that point are quite ufelefs 
not being at all adted upon. And from thence I fhall 
endeavour to fhew that to fuppofe the weight A will 
have the fame power to turn the wheel from what- 
ever point in the line M A it hangs, is in effedt pre- 
fuppofing what is intended to be proved. For it ap- 
pears, from what he fays immediately after, that, when 
the weight A hangs from the point D, if its whole 
force be exprefled by the line AD, and be relolved into 
two forces, D C and A C, the former only will have 
any effedt in turning the wheel, as it adts perpendi- 
cularly on the radius O D, while the latter is loft, its 
direction being parallel to O D. But it is evident, that, 
when the fame weight hangs from the point K, as it 
