Electric resistance of iron wire compared with water 195 



holding the wire in his hands; which shews, that part of the electricity 

 passes through his body, and part through the wire. Some electricians 

 indeed seem to have supposed that the electric fluid passes only along the 

 shortest and readiest circuit; but besides that such a supposition would 

 be quite contrary to what is observed in all other fluids, it does not agree 

 with experience. What seems to have led to this mistake is, that in dis- 

 charging a jar by a wire held in both hands, as in the above-mentioned 

 experiment, the person will feel no shock, unless either the wire is very 

 long and slender, or the jar is very large and highly charged. The reason 

 of which is, that metals conduct surprisingly better than the human body, 

 or any other substance I am acquainted with; and consequently, unless 

 the wire is very long and slender, the quantity of electricity which will pass 

 through the person's body will bear so small a proportion to the whole, as not 

 to give any sensible shock, unless the jar is very large and highly charged. 



398] It appears from some experiments*, of which I propose shortly 

 to lay an account before this Society, that iron wire conducts about 400 

 million times better than rain or distilled water; that is, the electricity 

 meets with no more resistance in passing through a piece of iron wire 

 400,000,000 inches long, than through a column of water of the same 

 diameter only one inch long. Sea water, or a solution of one part of salt 

 in 30 of water, conducts 100 times, and a saturated solution of sea salt 

 about 720 times, better than rain water. 



399] To apply what hath been here said to the torpedo; suppose the 

 fish by any means to convey in an instant a quantity of electricity through 

 its electric organs, from the lower surface to the upper, so as to make the 

 upper surface contain more than its natural quantity, and the lower less ; 

 this fluid will immediately flow back in all directions, part over the moist 

 surface, and part through the substance of its body, supposing it to conduct 

 electricity, as in all probability it does, till the equilibrium is restored: 

 and if any person hath at the time one hand on the lower surface of the 

 electric organs, and the other on the upper, part of the fluid will pass 

 through his body. Moreover, if he hath one hand on one surface of an 

 electric organ, and another on any other part of its body, for instance the 

 tail, still some part of the fluid will pass through him, though much less 

 than in the former case ; for as part of the fluid, in its way from the upper 

 surface of the organ to the lower, will go through the tail, some of. that 

 part will pass through the person's body. Some fluid also will pass through 

 him, even though he does not touch either electric organ, but hath his 

 hands on any two parts of the fishes body whatever, provided one of those 

 parts is nearer to the upper surface of the electric organs than the other. 



400] On the same principle, if the torpedo is immersed in water, the 

 fluid will pass through the water in all directions, and that even to great 

 distances from its body, as is represented in Fig. i, where the full lines 



* [Arts. 576, 577, 084, (.87.! 



13-2 



