are constantly used in repairing the bottom of
docks, landing-piers, and in the construction of
breakwater works, such as those which are at
present being raised at Dover Harbour.

Among other remarkable objects in the
museum of natural history we recognised,
swimming upon his shingly bed under a glass
case, our old friend the Gymnotus Electricus,
or Electrical Eel. Truly, he is a marvellous
fish. The power which animals of every
description possess in adapting themselves to
external and adventitious circumstances, is
here marvellously illustrated, for,
notwithstanding this creature is surrounded by the
greatest possible amount of artificial
circumstances, inasmuch as instead of sporting in his
own pellucid and sparkling waters of the
River Amazon, he is here confined in a glass
prison, in water artificially heated; instead
of his natural food, he is here supplied with
fish not indigenous to his native country,
and denied access to fresh air, with sunlight
sparkling upon the surface of the waves—he
is here surrounded by an impure and obscure
atmosphere, with crowds of people constantly
moving to and fro and gazing upon him;
—yet, notwithstanding all these disadvantageous
circumstances, he has continued to
thrive; nay, since we saw him, ten years
ago, he has increased in size and is apparently
very healthy, notwithstanding that he is
obviously quite blind.

This specimen of the Gymnotus Electricus
was caught in the River Amazon, and was
brought over to this country by Mr. Potter,
where it arrived on the 12th of August, 1838,
when he displayed it to the proprietors of the
Adelaide Gallery. In the first instance, there
was some difficulty in keeping him alive, for,
whether from sickness, or sulkiness, he refused
food of every description, and is said to have
eaten nothing from the day he was taken in
March, 1838, to the 19th of the following
October. He was confided upon his arrival to the
care of Mr. Bradley, who placed him in an
apartment the temperature of which could
be maintained at about seventy-five degrees
Fahrenheit, and acting upon the suggestions of
Baron Humboldt, he endeavoured to feed him
with bits of boiled meat, worms, frogs, fish, and
bread, which were all tried in succession. But
the animal would not touch these. The plan
adopted by the London fishmongers for
fattening the common Eel was then had recourse
to;—a quantity of bullock's blood was put
into the water, care being taken that it should
be changed daily, and this was attended with
some beneficial effects, as the animal gradually
improved in health. In the month of October
it occurred to Mr. Bradley to tempt him with
some small fish, and the first gudgeon thrown
into the water he darted at and swallowed
with avidity. From that period the same diet
has been continued, and he is now fed three
times a day, and upon each occasion is given
two or three carp, or perch, or gudgeon, each
weighing from two to three ounces. In
watching his movements we observed, that in
swimming about he seems to delight in
rubbing himself against the gravel which
forms the bed above which he floats, and the
water immediately becomes clouded with the
mucus from which he thus relieves the surface
of his body.

When this species of fish was first
discovered, marvellous accounts respecting them
were transmitted to the Royal Society: it
was even said that in the River Surinam, in
the western province of Guiana, some existed
twenty feet long. The present specimen is
forty inches in length; and measures eighteen
inches round the body; and his physiognomy
justifies the description given by one of the
early narrators, who remarked, that the
Gymnotus "resembles one of our common
eels, except that its head is flat, and its mouth
wide, like that of a cat-fish, without teeth."
It is certainly ugly enough. On its first
arrival in England, the proprietors offered
Professor Faraday (to whom this country may
possibly discover, within the next five hundred
years, that it owes something) the privilege
of experimenting upon him for scientific
purposes, and the result of a great number of
experiments, ingeniously devised, and executed with
great nicety, clearly proved the identity between
the electricity of the fish and the common
electricity. The shock, the circuit, the spark,
were distinctly obtained; the galvanometer
was sensibly affected; chemical decompositions
were obtained; an annealed steel
needle became magnetic, and the direction of
its polarity indicated a current from the
anterior to the posterior parts of the fish,
through the conductors used. The force
with which the electric discharge is made is
also very considerable, for this philosopher
tells us we may conclude that a single medium
discharge of the fish is at least equal to the
electricity of a Leyden Battery of fifteen jars,
containing three thousand five hundred square
inches of glass, coated upon both sides, charged
to its highest degree. But great as is the force
of a single discharge, the Gymnotus will
sometimes give a double, and even a triple shock,
with scarcely any interval. Nor is this all.
The instinctive action it has recourse to in
order to augment the force of the shock, is
very remarkable.

The Professor one day dropped a live fish,
five inches long, into the tub; upon which the
Gymnotus turned round in such a manner as
to form a coil enclosing the fish, the latter
representing a diameter across it, and the fish
was struck motionless, as if lightning had
passed through the water. The Gymnotus
then made a turn to look for his prey, which
having found, he bolted it, and then went
about seeking for more. A second smaller
fish was then given him, which being hurt,
showed little signs of life; and this he
swallowed apparently without "shocking it." We
are informed by Dr. Williamson, in a paper
he communicated some years ago to the Royal