ELECTRICITY. 
plication of metallic substances to ani- 
mats. 
Three fishes have hitherto been discovered 
to have, whilst living, the singular property 
of giving shacks analogous to those of artifi- 
cial electricity ; namely, the torpedo, the 
gymnotus electricus, and the silurus electri- 
cus. Those animals belong to three differ- 
ent orders of lish ; and the few particulars 
which they seem to have in common are 
the power of giving the shock ; an organ in 
their bodies, called the electric organ, which 
is in all probability employed by those ani- 
mals for the exertion of that power; a 
smooth skin without scales; and some spots 
here and there on the surface of their bo- 
dies. 
The torpedo, which belongs to the genus 
of rays (raja electrica), is a fiat fish, very 
seldom 20 inches long, weighing not above a 
few pounds when full-grown, and is pretty 
common in various parts of the sea-coast of 
Europe. The electric organs of this animal 
are two in number, and are placed on each side 
of the cranium and gills, reaching from that 
place as far as the semicircular cartilages of 
each great fin, and extending longitudinally 
from the anterior extremity of the animal to 
the transverse cartilage which divides the 
thorax from the abdomen. In those places 
they fill up the whole thickness of the ani- 
mal from the lower to the upper surface, 
and are covered by the common skin of the 
body, under which, however, are two thin 
membranes or fasciae. The length of each 
organ is less than one-third part of the whole 
length of the animal. Each organ consists 
of perpendicular columns, reaching from the 
under to the upper surface of the body, and 
varying in length according to the various 
thickness of the fish in various parts. The 
number of those columns is not constant, 
differing in different torpedos, and likewise 
in different ages of the animal. In a very 
large torpedo, one electric organ was found 
to consist of 1182 columns. The greatest 
number of those columns are either irregular 
hexagons, or irregular pentagons, but their 
figure is by no means constant. Their dia- 
meters are generally equal to one-fifth part 
of an inch. 
The above-mentioned electric organs seem 
to be the only parts employed to produce the 
shock; the rest of the animal appearing to 
be merely the conductor of that shock, as 
parts adjacent to the electric organs ; and, in 
fact, the animal has been found to be a con- 
ductor of artificial electricity. The two great 
lateral fins, which bound the electric organs 
laterally, are the best conductors. 
If the torpedo, while standing in water, or 
out of the water, but not insulated, is touch- 
ed with one hand, it generally communicates 
a trembling motion, or slight shock, to the 
hand ; but this sensation is felt in the fingers 
of that hand only. If the torpedo is touch- 
ed with both hands at the same time, one 
hand being applied to its under, and the 
other to its upper surface, a shock in that 
case will be received, which is exactly like 
that wliieh is occasioned by the Leyden phial. 
When the hand touches the fish on its oppo- 
site surfaces, and just over the electric or- 
gans, then the shock is the strongest ; bht if 
the hands are placed upon other parts of the 
opposite surfaces, the shocks are somewhat 
weaker ; aud no shock at all is ’felt when the 
VOL. I. 
hands are both placed upon the electric, or- 
gans of the same surface ; which shews that 
the upper and lower surfaces of the electric 
organs are in opposite states of electricity, 
answering to the plus and minus sides of a 
Leyden phial. When the fish is touched by 
both hands on the same surface, and the 
hands are not placed exactly on the electric 
organs, a shock, though weak, is still receiv- 
ed ; but in this case the opposite power of the 
other surface of the animal seems to be con- 
ducted over the skin. 
The shock which is given by the torpedo, 
when standing in air, is about four times as 
strong as when standing in water; and when 
the animal is touched on both surfaces by 
the same hand, the thumb being applied to 
one surface, and the middle finger to the 
opposite surface, the shock is lelt much 
stronger than when the circuit is formed by 
the application of both hands. Sometimes 
the torpedo gives the shocks so quickly one 
after the other, that scarcely two seconds 
elapse between them ; and when, instead of 
a strong determinate shock, it communicates 
only a torpor, that sensation is naturally at- 
tributed to the successive and quick dis- 
charge of a great many consecutive shocks. 
This power of the torpedo is conducted by 
the same substances which conduct artificial 
electricity, and is intercepted by the same 
substances which are non-conductors of elec- 
tricity ; hence, if the animal, instead of being 
touched immediately by the hands, is touched 
by non-electrics, as wires, wet cords, & c. 
held in the hands of the experimenter, the 
shock will be communicated through them. 
The circuit may also be formed by several 
persons joining hands, and the shock will be 
felt by them all at the same time. If, when 
the animal is in water, the hands are put in 
the same water, a shock will also be felt, 
which will be stronger if one of the hands 
touches the fish, whilst the other is kept in the 
water at a distance from it. In short, the 
shock of this animal is conducted by the same 
conductors as that of the Leyden phial ; thus 
it may pass through more than one circuit 
at the same time, or the circuit may be 
much extended, &c. but in those cases the 
shock is much weakened. 
The shock of the torpedo cannot pass 
through the least interruption of continuity ; 
thus it will not be conducted by a chain, nor 
will it pass through the air from one conductor 
to the other, when the distance is even less 
than the 200th part of an inch ; consequently 
no spark was ever observed to accompany 
it. 
No electric attraction or repulsion was 
ever observed to be produced by the tor- 
pedo, nor indeed by any of the electric 
fishes, though several experiments have 
been instituted expressly for that purpose. 
These shocks of the torpedo seem to de- 
pend on the will of the animal ; for each 
effort is accompanied with a depression of its 
eyes, by which even his attempts to give it 
to non-conductors may be observed. It is 
not known whether both electric organs must 
always act together, or one of them only 
may be occasionally put in action by the will 
of the animal. 
Almost all these effects of the torpedo may 
be imitated by means of a large electrical 
battery weakly charged. 
The gymnotus electricus has been fre- 
6og 
quently 'called electrical-eel, on account of 
its bearing some resemblance to the common 
eel. The gymnotus electricus is found pretty 
frequently in the great rivers of South Ame- 
rica'. Its usual length is about three feet, but 
some of them have been said to be so large as 
to be able to strike a man dead with their 
electric shock. A few' ot these animals, about 
three feet long, were brought alive to Eng- 
land thirty or forty years ago, and a great 
many experiments were made with them. 
A gymnotus of three feet in length gene- 
rally is between 10 and 14 inches in circum- 
ference at the thickest part of its body. The 
electric power of this animal being much 
greater than that of the torpedo, its electric 
organs are accordingly a great deal larger ; 
and indeed that part of its body which con- 
tains most of the animal parts that are com- 
mon to the same order of fishes, is consider- 
ably smaller than that w'hich is subservient 
to the electric pow'er, though the latter must 
naturally derive nourishment and action from, 
the former. The head of the animal is large, 
broad, flat, smooth, and impressed with vari- 
ous small holes. The mouth is rather large, 
but the jaws have no teeth, so that the ani- 
mal lives by suction, or by swallowing the 
food entire. The eyes are small, flattish, and 
of a bluish colour, placed a little way behind 
the nostrils. The body is large, thick, and 
roundish, for a considerable distance from the 
head, and then diminishes gradually. The 
whole body, from a few inches below the 
head, is distinguished into four longitudinal 
parts, clearly divided from each other by 
lines. The carina begins a few inches below 
the head, and widening as it proceeds, 
reaches as far as the tail, where it is thinnest. 
It has tw'o pectoral fins ; and the anus is situ- 
ated on the under part, more forward than 
those fins, and of course not far distant from 
the rostrum. 
This animal has two pairs of electric or- 
gans, one pair being larger than the other, 
and occupying most of the longitudinal parts 
of the body. They are divided from each 
other by peculiar membranes. 
The nerves which go to the electric or- 
gans of the gymnotus, as well as of the tor- 
pedo, are much larger than those which sup- 
ply any other part of the body. The electric 
organs of the gymnotus are supplied wdth 
nerves from the spinal marrow, and they 
come out in pairs between the vertebra of 
the spine. 
The gymnotus possesses all the electric 
properties of the torpedo, but in a superior 
degree. His shock is conducted by con- 
ductors of electricity; it is communicated 
through water, &c. The strongest shock is 
received when, the animal standing out of 
the water, you apply one hand towards the 
tail, and the other towards the head of the 
animal. In this manner shocks may be re- 
ceived from one of those animals, which are 
felt not only in the arms, but very fcfrcibly 
even in the chest. If the animal is touched 
with one hand only, then a kind of tremor is 
felt in that single hand ; which, though strong- 
er, is however perfectly analogous to that 
which is given by the torpedo when touched 
in the like manner. ‘ 
This power of the gymnotus is likewise 
depending on the will of the animal, so that 
sometimes he gives strong shocks, and at 
other times very weak ones. He gives the 
