[ 625 ] 
any body, to be difpofed accurately in the fame 
manner, whatever fort of matter it confifted of. 
For fuppofe B to con fift of any fort of matter ; , 
and let the fluid in the canal and two bodies 
be in equilibrio : let now B be made to confifl: 
of fome other fort of matter, which requires a 
diflerent quantity of fluid to faturate it j but let 
the quantity and difpofition of the redundant or 
deficient fluid in it remain the fame as before’ 
it is plain that the fluid will flill be in equilibrio- 
as the attraction or repulfion of any body de- 
pends only on the quantity and difpofition of 
the redundant and deficient fluid in it. There- 
fore, by the preceeding propofition, the quantity 
of redundant or deficient fluid in B, will 
actually bear very nearly the fame proportion to 
that in h, whatever fort of matter B confifts of; 
provided the quantity of redundant or deficient 
fluid in it is very fmall in refpeCt of the whole. 
PROP. XIX. 
Fet two bodies B and b (fig. 1 1 •) be connected to- 
gether by a very flender canal h.V>da, either 
flraight or crooked let the canal be everywhere 
of the fame breadth and thicknefs.; fo that all 
feCtions of this canal made by planes perpendi- 
cular to the direction of the canal in that part, 
fhall be equal and fimilar : let the canal be com- 
pofed of uniform matter ; and let the eleCtric 
fluid therein be fuppofed incompreflible, and of 
fuch denfity as exaCtly to faturate the matter 
VoL. LXl. 4 L therein; 
