I 



VOL. LXI.] PHILOSOPHICAL TRANSACTIONS. 263 



the glass, will be many times greater than what would be forced into it by the 

 same degree of electrilication if it had been placed by itself; and the quantity of 

 fluid driven out of e^, will be nearly equal to the redundant fluid in bS. 



If a communication l;e now made between si and e^, by the canal nrs, the 

 redundant fluid will run from Bi^ to e^ ;. and if in its way it passes through the 

 body of any animal, it will, by the rapidity of its motion, produce in it that 

 sensation called a shock. 



It appears from the 26th proposition, that if a body of any size was electrified 

 in the same degree as the plate hd, and a communication was made between that 

 body and the ground, by a canal of the same length, breadth, and thickness, 

 as NKs; that then the fluid in that canal would be impelled with the same force 

 as that in nks, supposing the fluid in both canals to be incompressible; and con- 

 sequently, as the quantity of fluid to be moved, and the resistance to its mo- 

 tion, are the same in both canals, the fluid should move with the same rapidity 

 in both : and he sees no reason to think that the case will be different, if the 

 communication is made by canals of real fluid. 



Therefore what was said in the beginning of this section, namely, that as 

 great a shock would be produced by making a communication between the con- 

 ductor and the ground, as between the two sides of the Leyden vial, by canals 

 of the same length and same kind, seems a necessary consequence of this theory; 

 as the quantity of fluid which passes through the canal is, by the supposition, 

 the same in both; and there is the greatest reason to think, that the rapidity 

 with which it passes will be nearly, if not quite the same, in both. Mr. C. 

 hopes soon to be able to say whether this agrees with experiment as well as 

 theory. 



It may be worth observing, that the longer the canal nrs is, by which the 

 communication is made, the less will be the rapidity with which the fluid moves 

 along it; for the longer the canal is, the greater is the resistance to the motion 

 of the fluid in it; whereas the force with which the whole quantity of fluid in 

 it is impelled, is the same, whatever be the length of the canal. Accordingly, 

 it is found in melting small wires, by directing a shock, through them, that the 

 longer tiie wire the greater charge it requires to melt it. 



As the fluid in si is attracted with great force by the redundant matter in Etp, 

 it is plain that if the fluid is able to penetrate at all into the glass, great part of 

 the redundant fluid will be lodged in bS; and in like manner there will be a great 

 deficience of fluid in e^. But in order to form some estimate of the proportion 

 of the redundant fluid, which will be lodged in bi, let the communication be- 

 tween Ey and the ground be taken away, as well as that by which Bd is electrified; 

 and let so much fluid be taken from bS, as to make the redundant fluid in it 

 equal to the deficient fluid in Ef. If we suppose that all the redundant fluid is 



