THE ELECTRIC RAY. 219 



a close cellular membrane, and also by short and 

 strong tendinous fibres, which pass directly across 

 from its outer edge to the semicircular cartilages. 

 They are covered above and below w T ith the com- 

 mon skin of the animal, under which are longitu- 

 dinal fibres spread entirely over them. Each organ 

 is about five inches in length, and at the anterior end 

 about three in breadth. They are composed of per- 

 pendicular columns, reaching from the upper to the 

 under surface, varying in length according to the 

 thickness of the parts of the body, from an inch and 

 a half to half an inch ; and their diameters are from 

 a fourth to a fifth of an inch. 



The coats of the columns are very thin, and al- 

 most transparent. The number of columns in each 

 organ varies considerably in different animals. That 

 of one that Mr. Hunter presented to the Royal So- 

 ciety was about 470 ; but in a very large Torpedo 

 jthe number of columns in one organ was 1182. 

 These columns were composed of films parallel to 

 the base of each, and the distance between each of 

 the columns was 150th part of an inch. If we 

 suppose these films to be charged with electricity, 

 and to be the 300th part of an inch thick, and a mid- 

 dling-sized Torpedo to contain in both organs, on 

 the whole, 1000 columns each an inch long, and 

 0.03 square inches area at the base, then 1000 X 

 150X0.3—4500 square inches. Now it has been 

 clearly proved that the capacity of stout glass is, 

 thirty-six times less than that of these organs ; 

 therefore both the organs of a middling-sized Tor^ 

 pedo will be equivalent to 4500X36 — 162,000 



