The Ley den vial 77 



which the fluid from Ef can enter. By the above-mentioned proposition, 

 if be, the thickness of the glass, is very small in respect of bd, the diameter 

 of the plates, the quantity of redundant fluid forced into the space Bd, or 

 B8, (that is, into the plate Bd, if the fluid is unable to penetrate at all into 

 the glass, or into the plate Bd, and the space b8 together, if the fluid is 

 able to penetrate into the glass,) will be many times greater than what 

 would be forced into it by the same degree of electrification if it had been 

 placed by itself; and the quantity of fluid driven out of E<f> will be nearly 

 equal to the redundant fluid in B8. 



If a communication be now made between B8 and E<f>, by the canal 

 NRS, the redundant fluid will run from 58 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. 



130] It appears from the 26th proposition, that if a body of any size 

 was electrified in the same degree as the plate Bd, and a communication 

 was made between that body and the ground, by a canal of the same 

 length, breadth and thickness as NRS; that then the fluid in that canal 

 would be impelled with the same force as that in NRS, supposing the 

 fluid in both canals to be incompressible ; and consequently, as the quantity 

 of fluid to be moved, and the resistance to its motion is the same in both 

 canals, the fluid should move with the same rapidity in both: and I see 

 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 conductor and the ground, as between the two sides of the Leyden 

 vial, by canals of the same length and same kind, seems a necessary con- 

 sequence 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. I hope soon to be able to say whether this 

 agrees with experiment as well as theory. 



131] 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 the wire the greater 

 charge it requires to melt it. 



132] As the fluid in B8 is attracted with great force by the redundant 

 matter in $, it is plain that if the fluid is able to penetrate at all into 



