36 First published Paper on Electricity 



redundant substance in B impels each particle of fluid and matter in A , 

 and consequently impels the whole body A , with the same force that the 

 whole body B impels it: for the same reason the redundant substance 

 in A impels the redundant substance in B, with the same force that the 

 whole body A impels it. It is shewn therefore, that the whole body B 

 impels the whole body A, with the same force that the redundant sub- 

 stance in B impels the whole body A, or with which the whole body A 

 impels the redundant substance in B; and that the whole body A impels 

 the redundant substance in B, with the same force that the redundant 

 substance in A impels the redundant substance in B ; therefore the whole 

 body B impels the whole body A, with the same force with which the 

 redundant substance in A impels the redundant substance in B, or with 

 which the redundant substance in B impels the redundant substance in A . 



15] COR. Let the matter in all the rest of space, except in two given 

 bodies, be saturated with immoveable fluid; and let the fluid in those 

 two bodies be also immoveable. Then, if one of the bodies is saturated, 

 and the other either over or undercharged, they will not at all attract or 

 repel each other. 



If the bodies are both overcharged, they will repel each other. 



If they are both undercharged, they will also repel each other. 



If one is overcharged and the other undercharged, they will attract 

 each other. 



N.B. In this corollary, when I call a body overcharged, I would be 

 understood to mean, that it is overcharged in all parts, or at least nowhere 

 undercharged: in like manner, when I call it undercharged, I mean that 

 it is undercharged in all parts, or at least nowhere overcharged. 



16] PROP. III. If all the bodies in the universe are saturated with 

 electric fluid, it is plain that no part of the fluid can have any tendency 

 to move. 



17] PROP. IV. If the quantity of electric fluid in the universe is 

 exactly sufficient to saturate the matter therein, but unequally dispersed, 

 so that some bodies are overcharged and others undercharged; then, if 

 the electric fluid is not confined, it will immediately move till all the bodies 

 in the universe are saturated. 



For supposing that any body is overcharged, and the bodies near it 

 are not, a particle at the surface of that body will be repelled from it by 

 the redundant fluid within; consequently some fluid will run out of that 

 body; but if the body is undercharged, a particle at its surface will be 

 attracted towards the body by the redundant matter within, so that some 

 fluid will run into the body. 



N.B. In Prob. IV, Case 3 {p. 42}, there will be shewn an exception to 

 this proposition ; there may perhaps be some other exceptions to it : but 



