[ 6i4 ] 
moveable fluid ; and there is great reafon to think 
that it will be fo, though the fluid in that matter is 
moveable. 
PROP. XVI. 
Let A E F B ( fig. 9 . ) be a long cylindric 
body, and D an undercharged body ; and let 
the quantity of fluid in AEFB be fuch, that 
the part near E F fliall be fatu rated. It appears 
from what has been faid before, that the part 
near AB will be overcharged j and moreover 
there will be a certain fpace, as A^z3 B, adjoin- 
ing to the plane A B, in which the fluid will be 
prefled clofe together ; and the fluid in that 
fpace will prefs againfl: the plane A B, and will 
endeavour to efcape from it ; and by Prop. II. 
the two bodies-will attrad: each other : now I 
fay that the force with which the fluid prefles 
againfl: the plane AB, is very nearly the fame 
with which the two bodies attrad each other in 
the diredion E A ; provided that no part of 
AEFB is undercharged. 
Suppofe fo much of the fluid in each part of the 
cylinder as is fufficient to faturate the matter in that 
part, to become folid ; the remainder, or the redun- 
dant fluid remaining fluid as before. In this cafe the 
preflhre againfl: the plane A B mufl: be exadly equal 
to that with which the two bodies attrad each other, 
in the diredion EA: for the force with which D 
attrads that part of the fluid which we fuppofed to 
become folid, is exadly equal to that, with which it 
repels 
