6 2 First published Paper on Electricity 



manner the body h impels the fluid in eg with the same force that H does 

 the fluid in CG ; and consequently h impels the fluid in eg one way in the 

 direction of the canal, with the same force that the two plates impel it 

 the contrary way; and therefore the fluid in eg has no tendency to flow 

 from one body to the other. 



87] COR. By the same method of reasoning, with the help of the 

 corollary to the 23rd proposition, it appears, that if AB and H each, 

 communicate with a third body by canals of incompressible fluid, and a 

 communication is made between AB and H by another canal of incom- 

 pressible fluid, the fluid will have no tendency to flow from one to the other 

 through this canal; supposing that the fluid was in equilibrio before this 

 communication was made. In like manner if AB and H communicate 

 with each other, or each communicate with a third body, by canals of 

 real fluid, instead of the imaginary canals of incompressible fluid used in 

 these propositions, and a communication is also made between them by 

 a canal of incompressible fluid, the fluid can have no tendency to flow 

 from one to the other. The truth of the latter part of this corollary will 

 appear by supposing an imaginary canal of incompressible fluid to be 

 continued through the whole length of the real one. 



88] PROP. XXV. Let now a communication be made between the 

 two plates AB and DF, by the canal NRS of incompressible fluid, of any 

 length; and let the body H and the plate AB be overcharged. It is plain 

 that the fluid will flow through that canal from AB to DF. Now the whole 

 force with which the fluid in the canal is impelled along it by the joint 

 action of the two plates is the same with which the whole quantity of 

 fluid in the canal CG or eg is impelled by them ; supposing the canal NRS 

 to be everywhere of the same breadth and thickness as CG or eg. 



For suppose that the canal NRS, instead of communicating with the 

 plate DF, is bent back just before it touches it, and continued infinitely 

 along the line Ss; the force with which the two plates impel the fluid 

 in Ss, is the same with which they impel that in EL, supposing Ss to be 

 of the same breadth and thickness as EL ; and is therefore nothing; there- 

 fore the force with which they impel the fluid in NRS, is the same with 

 which they impel that in A^RSs ; which is the same with which they impel 

 that in CG. 



89] PROP. XXVI. Let now xyz [Fig. 17] be a body of an infinite size, 

 containing just fluid enough to saturate it; and let a communication be 

 made between h and xyz, by the canal hy of incompressible fluid, of the 

 same breadth and thickness as gc or GC; the fluid will flow through it 

 from h to xyz; 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 the canal hy is of so great a length, that the repulsion of h thereon 



