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ELECTRIC ‘FISHES: 
-*HERE are some remarkable instances of the genera- 
tion of electricity in living animals, to whom the 
power seems principally to be given as a means of defence. 
Of these animals, the Zorfedo Raia appears to have been 
noticed at avery early period, since we find a description 
of its properties in the writings.of Pliny, Appian, and 
others. It inhabits the Mediterranean and North seas; its 
weight when fully grown, is about eighteen or twenty 
pounds. 
Each electrical organ is about 5 inches long and about 3 
inches broad at the anterior end, and 4 an inch at the pos- 
terior extremity. Each organ consists wholly of perpendi- 
cular columns reaching from the upper to the undersurface 
of the body, and varying in their lengths according to the 
thickness of the parts of the body where they are placed. 
The longest column is about 14 inch, the shortest about } 
of an inch, and their diameter about 2-10ths of aninch. The 
figures of the columns are irregular hexagons or pentagons, 
and sometimes have the appearance of being quadrangular 
or cylindrical. The number of columns in the fish exa- 
mined. by John Hunter, was 470 in each organ; but in a 
very large fish, 44 feet long and weighing 73 pounds, the 
number was 1,182 in each organ. The number of parti- 
tions in a column 1 inch long was 150. 
The Torpedo must be irritated to cause it to give a 
shock, in the delivery of which it moves its pectoral fins 
convulsively ; the shock is felt on touching the fish with a 
single finger,and it can give a long series of shocks with 
great rapidity. When the Torpedo is placed on a metallic 
plate, so that the plate touches the inferior surface of the 
organs, the hand that supports the plate never feels any 
shock ; though another insulated person may excite the 
animal, and the convulsive movement of the pectoral fins 
may denote the strongest and most reiterated discharges. 
Direct contact with the electrical organs of the fish is in- 
dispensably necessary for the reception of the shock, but 
the Torpedo has not the power of directing its electrical 
discharge through any particular object. 
By passing the discharge from a Torpedo through a 
spiral of copper wire enclosing a steel needle, the needle 
becomes magnetised in such a manner as to show the 
direction of the current to be from the back to the under 
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