64 First published Paper on Electricity 



whole or any given part of the fluid in the canal, has no tendency to impel 

 it cither way in the direction of the axis; then the force with which that 

 whole or given part is impelled by the two bodies must be nothing; or 

 the force with which it is impelled one way in the direction of the axis, 

 by the body B, must be equal to that with which it is impelled in the 

 contrary direction by the other body; but not if the fluid in the canal is 

 disposed in a different manner. 



93] COR. II. If the bodies, and consequently the canal, is overcharged; 

 then, in whatever manner the fluid in the canal is disposed, the force with 

 which the whole quantity of redundant fluid in the canal is repelled by 

 the body B in the direction Aa, must be equal to that with which it is 

 repelled by b in the contrary direction. For the force with which the 

 redundant fluid is impelled in the direction A a by its own repulsion, is 

 nothing; for the repulsions of the particles of any body on each other 

 have no tendency to make the whole body move in any direction. 



94] REMARKS. When I first thought of the aoth and 22nd proposi- 

 tions, I imagined that when two bodies were connected by a cylindric 

 canal of real fluid, the repulsion of one body on the whole quantity of 

 fluid in the canal, in one direction, would be equal to that of the other 

 body on it in the contrary direction, in whatever manner the fluid was 

 disposed in the canal; and that therefore those propositions would have 

 held good very nearly, though the bodies were joined by cylindric canals 

 of real fluid ; provided the bodies were so little over or undercharged, that 

 the quantity of redundant or deficient fluid in the canal should be very 

 small in respect of the quantity required to saturate it ; and consequently 

 that the fluid therein should be very nearly of the same density in all 

 parts. But from the foregoing proposition it appears that I was mistaken, 

 and that the repulsion of one body on the fluid in the canal is not equal 

 to that of the other body on it, unless the fluid in the canal is disposed 

 in a particular manner: besides that, when two bodies are both joined 

 by a real canal, the attraction or repulsion of the redundant matter or 

 fluid in the canal has some tendency to alter the disposition of the fluid 

 in the two bodies; and in the 22nd proposition, the canal CG exerts also 

 some attraction or repulsion on the canal EM: on all which accounts the 

 demonstration of those propositions is defective, when the bodies are joined 

 by real canals. I have good reason however to think, that those proposi- 

 tions actually hold good very nearly when the bodies are joined by real 

 canals ; and that, whether the canals are straight or crooked, or in whatever 

 direction the bodies are situated in respect of each other : though I am by 

 no means able to prove that they do : I therefore chose still to retain those 

 propositions, but to demonstrate them on this ideal supposition, in which 

 they are certainly true, in hopes that some more skilful mathematician 

 may be able to shew whether they really hold good or not. [See Note 3.] 



