[ 626 ] 
therein ; and let it, neverthelcfs, be able to ihovc 
readily along the canal ; and let each particle 
of fluid in the canal be attradted and repelled 
by the matter and fluid in the canal and 
in the bodies B and juft in the fame manner 
that it would be if it was not incompref- 
fible * j and let the bodies B and b be 
either over or undercharged. I fay that the 
force with which the whole quantity of fluid 
in the canal is impelled from A towards D, m 
the diredtion of the axis of the canal, by the 
united attradlions and repulfions of the two 
bodies, muft be nothing ; as otherwife the fluid 
in the canal could not be at reft : obferving that 
^ by the force with which the whole quantity of 
fluid is impelled in the diredtion of the axis of 
the canal, I mean the fum of the forces, with 
which the fluid in each part of the canal is 
impelled in the direaion of the axis of the canal 
in that place, from A towards D; and obferv- 
ing alfo, that an impulfe in the contrary di- 
' region from D towards A muft be looked upon 
as negative. 
For as the canal is exadly faturated with fluid, the 
fluid therein is attraded or repelled only by the re- 
dundant matter or fluid in the two bodies. Sup^fe 
now that the fluid in any fedtion of the canal, as E e, 
* This fuppofuicin of the: fluid in the canal being incom- 
nreflible, is not mentioneJ as a thing, which can ever take place 
in nature, brt is merely imaginary j the reafon lor making oi 
which will be given hereafter. 
IS 
