Electric Fishes. 281 
subject of some interesting experiments by Faraday (Ex. 
Researches, 15th series, 1838). This fish was 40 inches long. 
It remained in a healthy and vigorous condition till March, 
1842, when it died from the effects of a rupture of a blood- 
vessel. 
1. The Shock.—This was very powerful when one hand 
was placed on the body near the head, and the other near 
Matta tt was like that of a larce Leyden ‘battery 
charged to a low degree; and great as was the force of a 
single discharge, the fish was able to give a double and 
even a triple shock with scarcely a sensible interval of time. 
From some comparative experiments, Faraday thought it 
may be concluded that a single medium discharge of the 
fish was at least equal to that of a Leyden battery of 
fifteen jars, containing 3,500 square inches of glass coated 
on both sides, and charged to the highest degree. 
2. The Spark.—Through the upper cap of a glass globe 
a copper wire was passed, a slip of gold leaf being attached 
to its extremity ; a similar wire terminating in a brass ball 
within the globe was passed through the lower cap. The 
gold leaf and brass ball were brought into all but actual 
contact, the fish being provoked to discharge through the 
wires, the gold leaf was attracted to the ball, and a spark 
passed. 
3. Chemical Decomposition. — Polar decomposition of 
iodine of potassium was obtained by moistening three or 
four foldsof paper in the solution, and placing them between 
a platinum plate and the end of a platinum wire, connected 
respectively with two saddle conductors grasping the body 
of the fish. The middle of the fish was found to be negative 
to the azzerzor parts, and fosztive to parts towards the tail. 
4. Magnetic L:ffects,—By causing the fish to send powerful 
discharges through an instrument of no great delicacy, a 
deflection of the needle amounting to 30° was produced ; 
the deflection was constantly in a given direction, the 
electric current being always from the anterior parts of the 
animal, through the galvanometer wire to the posterior 
patts. When a little helix, containing 22 feet of silked 
wire wound on a quill, was put into the circuit, and an an- 
nealed steel needle placed in the helix, the needle became 
a magnet. and the direction of its polarity in every case 
indicated a current from the anterior to the posterior parts 
of the Gymnotus through the conductors used. 
When a number of persons all dip their hands at the 
same time into the water in the vessel in which the Gym- 
