352 THE DIAMOND MINES OF SOUTH AFRICA
it
shows itself in numerous " fonteins " or springs. Below the lime
coverlet the diamond-bearing yellow ground extended to a depth of sixty
feet, where it changed to blue ground. The work which had been done
proved the area of the mine, and it was found to contain about 1162
claims of diamond-bearing ground, equal to about 24 acres.
Under
Ward's administration the diamond-bearing ground was removed by means
of trucks drawn by an endless chain haulage, which delivered them at
the top of a large washing plant, where it was at once treated.
In
January, 1896, Ward's lease expired, and from that time work in this
mine has been constantly carried on by the De Beers Consolidated Mines.
An incline with a grade of one foot in five was constructed in 1896;
the drainage water from all parts of the mine was concentrated in a
sump, and a pumping plant erected capable of handling the great influx
of water, averaging 42,726 gallons an hour in 1896, or about 7,178,000
gallons a week. At the end of that year the new works were so far
advanced that 271,777 loads of blue ground had been raised. For the
economic working of this mine, a complete mining and washing plant,
with compounds, machine shops, stores, and other necessary buildings,
was installed soon after the mine was turned over to the Company by the
lessee.
The
incline mentioned above was made through the marginal reef, and down to
a depth of 185 feet. At present the diamond-bearing blue ground is
hauled from the mine by means of an endless wire rope haulage (see
illustration opposite) driven by an engine on the surface. The mine is
being worked in sections of 50 feet in depth. The ground is broken by
drilling deep holes (12 feet) with jumper drills and blasting with
dynamite. The average number of loads broken per case of dynamite (50
lbs. net) is 416, equal to 233 tons. The breaking of the ground
was formerly done by contract, and cost 5-1/2d. per load delivered upon
the " flat-sheets" near the mine end of the wire rope haulage. This
mining is now done by the Company. Loading is done in the mine upon the
contract system, by paying the
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