VOL. LXI.] VHILOSOPHICAL TRANSACTIONS. 251 



pellecl 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. 



Corol. 2. 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 con- 

 trary direction. For the force with which the redundant fluid is impelled in the 

 direction Aa, by its own repulsion, is nothing ; for the repulsion of the particles 

 of any body on each other, have no tendency to make the whole body move in 

 any direction. 



Remarks. When Mr. C. first thought of the 20th and 22d propositions, he 

 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 di- 

 rection, would be equal to that of the other body on it, in the contrary direc- 

 tion, 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 con- 

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

 parts. But from the foregoing proposition it appears that he 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 at- 

 traction or repulsion of the redundant matter or fluid in the canal, has some 

 tendency to alter the disposition of the fluid in the 2 bodies; and in the 22d 

 proposition, the canal cg exerts also some attraction or repulsion on the c^nal 

 EM, on all which accounts the demonstration of those propositions is defective, 

 when the bodies are joined by real canals. He has good reason however to 

 think, that those propositions 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 

 he is by no means able to prove that they do : he 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 show whether they really hold good or not. 



What principally makes him think that this is the case, is, that as far as he 

 can judge from some experiments he has made, the quantity of fluid in difierent 

 bodies agrees very well with those propositions, on a supposition that the electric 



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