The Cook County herald. [volume] (Grand Marais, Minn.) 1893-1909, 1896-04-25
SCIENTIFIC MATTERS,
SOME NEW WRINKLES IN THE
USEFUL ARTS.
Tampa Lighted by Electric Fish
Improving the Mfcroscope-A Pop
aiar DeluEiOn-IncreasinE Utiliza-
ton of Wind Power.

.g s Il -55 ~
NJ. d'Arsonval, the well known cleo
trician, has been doing some extraor-
binary things in the way Of demon
strating the electric discharge Of the
torpedo fish. His experiments, which
were made before the French academy
Of sciences, were so astonishing as to
almost suggest that the central station
Of the future may be a huge and well
populated fish tank. Several special
instruments were used for recording
the phases of the discharge from the
fish. One was a modification Of a
movable circuit galvanometer, which
was wound the circuit traversed by
the fish current. The coil was at
cached to the center Of a rubber dia-
phragm, stretched on a Marcy air
drum, which was connected by rub
Der tube to second smaller drum, car
rying short recording needle, mov-
Ing on a smoked cylinder. Another
testing instrument Is composed Of a
silver wire tenth of a millimeter in
diameter and forty or fifty centime-
ters long. As it Is stretched horizont-
ally between two rigid supports, it's
center connects with a second wire,
feld by rubber spring, and carrying
a needle moving on the recording cyl
inder. The torpedo is placed on a
plate with metallic bottom, on which
Is left about one inch of sea water, to
enable the fish to breathe during the
experiments. Two pieces are cut out
of a sheet Of tin foil in the shape Of
the electric organs, and, Joined by a
band of tin foil five ceutimeters long.
Thus the lower metallic plate consti-
tutes the negative electrode and the
tin strips form the positive electrode
Of this living electro-mctor. The cleo
trodes are then united to the various
apparatus for measuring or rendering
visible the discharge Of the organs.
The demonstration is opened by pinch
ing the edges of the fins of the fish
with pair Of dissecting tweezers.
This usually provokes a single dis
charge; but the torpedo is not Of pa
tient disposition, and if he is pinched
hard he loses his temper, and plies his
electrical artillery vigorously and rap
idly. The discharge appears to be con-
tinuous, but in reality it is composed
Of six to ten successive discharges.
The back of the fish is always positive
and the belly always negative. It
seems difficult to believe that the cleo
trio current from one Of these fish will
not only light ordinary lamps but burn
them out; such, however, is the fact.
Torpedoes Of a foot In diameter, which
lave been kept in a tank for week,
had an electro-motive force Of from
eight to seventeen volts, and an In
tensity Of from one to seven amperes.
M. d'Arsonval took an incandescent
lamp, consuming four volts and one
ampere, and connected it to one Of the
electrical organs. AS the fish was
squeezed the lamp was brilliantly
lighted: D'Arsonval counsels the ex-
perimenter to press the fish very
lightly. In his experiments he used
unnecessary pressure, and the fish dis
chal ged such a current that his lamps
were all burnt out. Lamps placed on
each organ lighted at the same time,
with the same intensity, although on
different circuits. The organ, however,
soon eXhausts itself, and requires rest
before it is again available. NJ. OAR
sonval is now at work on experiments
for establishing a comparison Of the
respective electrical powers Of the tor
pedo, the gymnotus, or electric eel, and
the electric cat.