The Express.
London, England, 1851-06-28 00:00:00

ILLUSTRATIONS OF MINING.

In resuming our notice of this subject, we shall
first mention the methods for removing the water from
mines, as far as they arc shown in the Exhibition. This is
one of the most troublesome and expensive of mining
I.
operations, and requires to be carried on continuously in
mines
which are below the surface, as the water is always
filtering through the fissures and crevices of the superior
strata, and depositing itself in the lowest part of the mine.
i During the last few years steam power has been applied to
this purpose, especially in Cornwall, where its use has
partially given rise to a very valuable improvement in
the construction of the steam-engine, which consists
in a combination of the high pressure and condensing
engines. By this means the quantity of water raised is so
great, that mineral veins have been worked by its aid in
situations where it would hitherto have been impossible.
Water power, when a sufficient supply is at hand, can be
advantageously made use of for this purpose. Among the
machinery in motion in the north-west side of the building,
close to the centrifugal pump, is a model of the pumping
machinery which is used at the copper mines of the Devon
Great Consolidated Mining Company. These mines arc
situated in the valley of the Tamar, near Tavistoek. It
consists of two largo overshot wheels, of4o feet diameter and
12 Let in the breast. The water by which they are turned
is obtained from the Tamer, at a point of suffi-
cient height about half a mile distant, from whence
it is led by an artificial canal to the wheels.
One of the pumps is an extraordinary sucking pump, the
other is constructed on the hydraulic principle, with a
plunger by means of which the water is pressed out. This
pump has only been working for about a month, but is
found to be very superior to the other ; it is capable of
raising 98 gallons of water at every stroke, while the suck-
ing pump raises only 65 gallons. They both work at 7,
feet stroke. The pumps are at a distance of three-quarters
of a mile from the water-wheels, and are connected with
them by means of lung jointed metal rods, supported
along their whole length by rollers fixed in the ground
at short distances. We were informed that, although the
first cost of this machinery was altogether 12,0001-,
its working is very economical ; it requires only the occa-
sional attention of one man, and it is estimated that the
company have effected a saving of 15,0001. by tho substitu-
tion of it fur steam power. It was constructed by Mr. Na-
' thaniel Smith, of Tavistock, and is exhibited by the com-
pany. The model is a working one, and is set in motion by
water from the water works. Plans and sections of the
position of the mineral lodes, shafts, river, &c., are to be
found with it.

An ingenious compound valve for large pumps is exhi-
bited by Mr. limiting, of Falmouth, by which the loss of
power from raising the water on the piston is obviated. In
this model the piston works air.tight, and raises the water
above a valve opening upwards during the upward stroke,
and in the downward stroke forcing it through another
valve at the side, which is opened by the pressure of
the water, and closes from its own weight when the I
pressure is removed, and thus preventing the return of the
water. Mr. Gowan, of Edinburgh, exhibits a model of a
steam crane, Sad a sectional drawing of a boring machine,
which is used in the Redhall quarries, and with which
holes may be bored to a depth of 40 or 50 feet, of from 3 to
6 inches in diameter. There is unfortunately no sufficient
description of the machine given. The safety fuse for
igniting the charge of powder in blasting is a very valuable
invention : it consists of a tube made of coarse canvas, and
covered on the outer surface with some kind of pitchy or
bituminous matter, which will render it impervious to
moisture ; the tube is filled with gunpowder in such a way
that the fusee burns with a uniform rapidity, and gives the
men sufficient time to get out of the way of danger. This,