VOL. LXI.] PHILOSOPHICAL TRANSACTIONS. 259 



As far as I can jude;e, these corollaries seem conformable to experiment : thus 

 far is certain, that bodies at a distance from other electrified bodies receive elec- 

 tricity from the air, if negatively electrified, and part with some to it if positively 

 electrified : and a bcxly not electrified, and not insulated, receives electricity from 

 the air if brought near an overcharged body, and loses some when brought near 

 an undercharged bo<ly : and a body insulated and containing its natural quantity 

 of fluid, in some cases receives, and in others loses electricity, when brought 

 near an over or undercharged body. 



§ 4. The well-known effects of points in causing a quick, discharge of electri- 

 city seem to agree very well with this theory. ; 



It appears from the 20th proposition, that if two similar bodies of different 

 sizes are placed at a very great distance from each other, and connected by a 

 slender canal, and overcharged, the force with which a particle of fluid, placed 

 close to corresponding parts of their surface, is repelled from them, is inversely 

 as the corresponding diameters of the bodies. If the distance of the two bodies 

 is small, there is not so much difference in the force with which the particle is 

 repelled by the two bodies ; but still, if the diameters of the two bodies are very 

 different, the particle will be repelled with much more force from the smaller 

 body than from the larger. It is true indeed, that a particle placed at a certain 

 distance from the smaller body, will be repelled with less force than if it be 

 placed at the same distance from the greater body ; but this distance is, he be- 

 lieves, in most cases pretty considerable ; if the bodies are spherical, and the 

 repulsion inversely as the square of the distance, a particle placed at any distance 

 from the surface of the smaller body, less than a mean proportional between the 

 radii of the two bodies, will be repelled from it with more force, than if it be 

 placed at the same distance from the larger body. 



Mr. C. thinks therefore, that we may be well assured, that if two similar 

 bodies are connected together by a slender canal, and are overcharged, the fluid 

 must escape faster from a smaller body than from an equal surface of the larger ; 

 but as the snrface of the larger body is greatest, he does not know which body 

 ought to lose most electricity in the same time ; and indeed it seems impossible 

 to determine positively from this theory which should, as it depends in great 

 measure on the manner in which the air opposes the entrance of the electric 

 fluid into it. Perhaps in some degrees of electrification the smaller body may 

 lose most, and in others the larger. 



LetnowACB, fig. 18, be a conical point, standing on any body dab, c being 

 the vertex of the cone ; and let dab be overcharged : Mr. C. imagines that a 

 particle of fluid placed close to the surface of the cone, any where between b and 

 c, must be repelled with at least as much, if not more force, than it would, if 

 the part ao6b of the cone was taken away, and the part acb connected to dab by 



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