I 4H ] 
s’wjys tend to the Side where they are lefs prefTed; 
and it is by an aftual (^^Equilibrium alone that they 
are kept in their Places j which intirely overturns the 
Theory of thefe Gentlemen. 
Let us however grant to the Cartejians^ that the 
Sums of the Forces of the Two fpherical Surfaces arc 
equal ; I cannot fee, that they can thence infer, as 
they do, that the central Force diminifhes in a reci- 
procal Ratio of the Square of the Diftance from the 
Centre. Let us examine their Argument : 
F S —f s, fay they j therefore F-fi '.s.Sh but j, S 
mark the Sums of the Points contained in the 
Two Surfaces,' therefore they are as thefe Surfaces, 
which, being as the Squares of their Diftances, give, 
F.f::dd.T>F). 
But it mufl: be remarked, that the Surfaces of the 
Vortex are not Mathematical, they are Surfaces which 
have fome Thicknefs : They cannot then be propor- 
tional to the Squares of their Diftances from the 
Centre, except in the Cafe when their Thicknefs is 
equal. Now, according to the Cartefiansy the Points 
or Globules, which compofe the Vortex^ increafe in 
Bulk according as they recede from the Centre; and, 
befides, they are homogeneous, or of an equal fpe- 
cific Denfity, at leaft in their common Syftem. And 
confequently it is certain, that the different natural or 
real Strata of the Vortex are not of an equal Thick- 
nefs, and that the Matter contained therein is not 
proportionate to the Squares of the Radii of thefe 
Surfaces, but only to the Squares of thefe Radii mul- 
tiplied by the Thicknefs of the Strata. Therefore, 
^ E. E>. 
