The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1902-01-09
ELECTRIC OWNING Rolls
APPARATUS THAT INDICATES
COPPER,

Iron aud Gold-Mapping Out Invisi-
bic Veins of Metal From the Sur
face of the Earth.
One of the most ingenious as well as
modern applications of electricity te
practical use is in the finding of hidden
metals in the earth. A number of per-
sons, perhaps, have dreamed of this
possibility But Fred Fl. Brown, of OAK
Park, a suburb of Chicago, seems te
have worked out the idea more effeo-
lively than any one else.
The principle employed is a simple
one The working of the system de-
ponds on the fact that metal will con-
duct electricity better than ordinary
dirt or rock. This Is frequently Illus
trated by the return currents Of troll
ley road. If the route originally pro-
vided for them, a properly connected set
of rails, fails to serve satisfactorily, the
electricity will leak away into the earth
and take the shortest possible course
to reach the gas and water pipes there.
Nothing at all novel in the way of in
struments is required in this work. 1t
is necessary only to supply small por-
table battery, device like galvano-
meter. for measuring the resistance Of
fered to the flow of the current, and
two wires terminating in pointed metal
rods which can be thrust into the
ground. These are inserted into the
earth, with an interval of several hum
bred feet between them, and the re-
sistance carefully observed and record
ed. The positions may be marked with
surveyors stakes, for subsequent refer
ence, then both metal rods are pulled
up, carried along in the same general
direction-say to the southward-and
again thrust into the soil, the distance
between them being the same as be-
fore. After number of repetitionS of
this performance, 1t may be discovered
that the recorded readings show con-
siderable differences. If So the lowest
one will indicate the proximity of metal
in the ground
At the outset the operator may have
no idea either of the vein or the direc
ton in which 1t runs The former hay
ing been revealed, the latter is next in
vestigated. One terminal is inserted at
a spot giving a low reading, and the
other. carried about IN the hand, Is
swung to and fro slowly, while sharp
watch of the measuring instrument is
kept When minimum of resistance is
observed, the free terminal is stuck into
the earth, and the same tactics pursued
with the other one 1t is asserted that
the metal rods are finally found to be
standing directly above the vein, And
with proper care 1t Is possible to map
out irregularities and ramificatlons, as
well as the principal deposit.
Two trials Of this apparatus are men-
toned by THE Western Electrician"
One was in Montana. On either side of
the metallic streak the resistance was
$4,000 ohms. Immediately over rich
vein of copper it dropped to IS ohms.
The other test was in Michigan, in a
place where the percentage of native
copper in the rock was only from 21a
to 3ts per cent. Here the resistance OF
the adjacent soil was $1,000 or 10000
ohms, while over Til eveineit dropped to
1000. The latter exploration was con-
Quoted in crude and imperfect fash
ion. Had it been carried further, per-
haps the readings would have fallen to
200 or 300
Dampness in the earth improves Its
conductivity, but not to so great an ex-
tent as metal. Moisture will percepti-
bly, affect the figures obtained with the /
electric divining rod. but the expert
cannot be deceived. He learns in time to
recognize other influences which affect
the readings and to distinguish between
them and the object in view. Copper
and iron, of course, have the highest
electrical conductivity and consequent
ly show very low resistance. But 1t Is
possible to find gold, also, by the
method here described.
Some notion of the depths at which a
deposit lies may be derived
from the interval between the two ter
minals at which the best results are OBJ
tanned. Thus, If vein of copper did
not come within 200 feet of the surface.
and the two pointed rods We're placed
only 50 feet apart, the current might
travel almost straight from one to the
other. at a depth of only few feet. 1t
would encounter less resistance In do
ng so than in diving 100 feet. traversing
the copper for 50 more, and then COM
Ing up again. Consequently, the rods
are so planted that the distance be-
tween them IS Twice as great as CIldL
1t which the metal is supposed to be
rom the surface.
The inventor has succeeded in inter
asting in this apparatus James ]. Hill,
PRESIDENT of the Great Northern Rail-
way, Mr. oliver, the head of the Oliver
ron and Steel company, and a number
# other men prominently Unidentified
With the mineral interests of the North
vest. They will put it to use in loca-
ng unknown deposits in that part of
he country.-From the New York {
tribune.