4.6 First published Paper on Electricity 



The reason why I suppose the fluid in B to be immoveable is, that 

 otherwise a question might arise, whether the attraction or repulsion of 

 the body A might not cause such an alteration in the disposition of the 

 fluid in B, as to cause some parts of it to be undercharged; which might 

 make it doubtful, whether B did on the whole repel the fluid in A. It is 

 evident, however, that this proposition would hold good, though some 

 parts of B were undercharged, provided it did on the whole repel the 

 fluid in A. 



45] COR. If B had been made undercharged, instead of overcharged, 

 it is plain that some fluid would have flowed from the further part RS to 

 the nearer part MN, instead of from MN to RS. 



46] PROP. XII. Let us now suppose that the body A communicates 

 by the canal EF, with another body D, placed on the contrary side of it 

 from B, as in Fig. 5 ; and let these two bodies be either saturated, or over 

 or undercharged ; and let the fluid within them be in equilibrio. Let now 

 the body B be overcharged : it is plain that some fluid will be driven from 

 the nearer part MN to the further part RS, as in the former proposition ; 

 and also some fluid will be driven from RS, through the canal, to the body 

 D; so that the quantity of fluid in D will be increased thereby, and the 

 quantity in A, taking the whole body together, will be diminished; the 

 quantity in the part near MN will also be diminished; but whether the 

 quantity in the part near RS will be diminished or not, does not appear 

 for certain ; but I should imagine it would be not much altered. 



47] COR. In like manner, if B is made undercharged, some fluid will 

 flow from D to A, and also from that part of A near RS, to the part near 

 MN. 



48] PROP. XIII. Suppose now that the bodies A and D communicate 

 by the bent canal MPNnpm (Fig. 7) instead of the straight one EF: let 

 the bodies be either saturated or over or undercharged as before ; and let 



Fig. 7- 



the fluid be at rest; then if the body B is made overcharged, some fluid 

 will still run out of A into D; provided the repulsion of B on the fluid 

 in the canal is not too great. 



The repulsion of B on the fluid in the canal will at first drive some 

 fluid out of the leg MPpm into A, and out of NPpn into D, till the 



