[ 640 ] 
bodies remaining the fame as before ; and let us, for 
the fake of eafe in the demonflration, fuppofe the 
canal ^ c to be every where of the fame thicknefs as 
the canal G C ; though the propofftion will evidently 
hold good equally, whether it is or not : the fluid 
will flill be in equilibrio. For let us firfl; fuppofe the 
canal to be continued through the fubflance of the 
plate AB, to C, along the line crC ; the part crC 
being ot the fame thicknefs as the refl of the canal, 
and the fluid in it of 'the fame denfity : by the pre- 
ceding propofition, the repuUion or attradion of each 
particle of fluid or matter in the plates A B and D F, 
on the fluid in the whole canal C rcg, in the diredion 
of that canal, is equal to its repulfion or attradion on 
the fluid in the canal C G, in the diredion C G ; and 
therefore the whole repulflon or attradion of the two 
plates on the canal C r cgy is equal to their repulflon 
or attradion on C G : but as the fluid in the plate 
AB is in equilibrio, each particle of fluid in the part 
Cr^- of the canal, is impelled by the plates, with 
as much force in one diredion as the other; and 
conlequently the plates impel the fluid in the canal 
eg, with as much force as they do that in the whole 
canal Creg, that is, with the fame force that they 
inapel the fluid in C G. In like manner the body b 
impels the fluid in c gy with the fame force that H 
docs the fluid in CG ; and conlequently b impels the 
fluid in c gy one way in the diredion of the canal, 
with the lame force that the two plates impel it the 
contrary way ; and theiteforc the fluid in eg has no 
tendency to flow from one body to the other. 
2 
Co R 0 L- 
