[ 642 ] 
along it, by the joint aaion of the two plates, 
is the fame with which the whole quantity of 
fluid in the canal CG orc^ is impelled by them; 
fuppofing the canal N R S to be every where of 
the fame breadth andthicknefs as CG or eg. 
For fuppofe that the canal N R S, inftead of com- 
municating with the plate DF, is bent back juft before 
it touches it, and continued infinitely along the line 
S j; the force with which the two plates impel the 
fluid in Sr, is the fame with which they impel that 
in EL, fuppofing S r to be of the fame breadth and 
thicknefs as EL ; and is therefore nothing ; therefore 
the force with which they impel the fluid in NRS, 
is the fame with which they impel that in N R S r ; 
which is the fame with which they impel that m 
CG. 
PRO P. XXVL 
Let now x y z be a body of an infinite fize, con- 
taining juft fluid enough to faturate it ; and let a 
communication be made between h and xyz, 
by the canal hy of incompreffible fluid, of the 
fame breadth and thicknefs asgc or GC ; the 
fluid will flow through it from h to xy% ', and 
the force with which the fluid in that canal is 
impelled along it,, is equal to that with which 
the fluid in NRS is impelled by the two 
plates. 
If 
