Professor Hare on the Electric Fluid. 7 



other, accoi'ding to the premises. The appearance may be 

 explained by either doctrine, as resulting from intense attrac- 

 tion between the paper and the knobs transmitting the dis- 

 charge. 



It has been observed, in favour of the French theory, that, 

 when the hands are made the medium of a feeble discharge, a 

 shock is felt simultaneously in the fingers only of each hand ; 

 that, as the shock is made stronger, it affects the wrist, the 

 arm, and finally the chest. This is considered as proving the 

 operation of two distinct fluids ; for, were the shock the effect 

 of one current, it would be experienced equally, though feebly, 

 throughout the whole of the circuit. Admitting that such a 

 current were necessary to the discharge, agreeably to Frank- 

 lin's theory, it ought to be felt most in the fingers, where it is 

 most concentrated, as torrents flow with greater violence in 

 proportion as their channels are narrowed. A current passing 

 from one coating of a Leyden jar to another, is far from being 

 necessary to restore the equilibrium of its surfaces. As soon 

 as a circuit is established between them by the hands, the elec- 

 tricity in the hand which touches the negative surface, flows 

 into it to supply the deficiency ; while the hand which touches 

 the positive surface, receives from it a surcharge. It is a case 

 analogous to that of a syphon, in whicli a fluid, forcibly dis- 

 placed from the level, is suddenly relieved from restraint ; both 

 columns would move at the same time, and with a velocity 

 greater in any part, in proportion as the diameter should be 

 less. The deficit caused in the hand in contact with the ne- 

 gative coating, is supplied by electricity from the arm; and 

 this, again, from the body, where if the charge be inconsi- 

 derable, it is so much diffused as not to be perceived. In like 

 manner, a slight surcharge received by the hand in contact 

 with the positive coating, is diffused, as it proceeds up the arm 

 to the chest, so as to be too feeble to be felt there. 



A piece of tin foil, interposed between paper, has been found 

 not to be perforated by a charge, which had pierced the paper 

 on both sides of it. 



If there were but one current, it is alleged that tin foil, situ- 

 ated as above mentioned, would be pierced during its passage 

 from one coating to the other — a fortiori^ then, it should be 

 pierced, if two currents be necessary, passing each other. Be- 

 sides, the ex[)lanation afforded, in the case of a shock received 

 by the liands, ap))lies to this : owing to its great conducting 

 power, the tin foil difliiscs the attraction from each side so 

 much as not to be damaged by it. 



II. Dc- 



