SYSTEMATIC MINING
UST
acknowledgment has been made in a former chapter of the essential
service rendered to the diamond mine owners by the device of Mr. Edward
Jones for underground work beneath the fallen reef covering the bottom
of the open pits. This was, however, confessedly only a temporary
makeshift, enabling the claim-holders to defray the heavy costs of
sinking shafts through the hard rock outside the craters, and pursuing
some systematic plan for the extraction of the diamond-bearing breccia
by underground workings. Deep-shaft sinking was undertaken with renewed
heart by several companies owning claims in Kimberley and De Beers
mines, but for some years there was an obvious lack of essential
cooperation and unity of method. Eight shafts were sunk, or were under
way, in 1885, within and without the craters, for opening De Beers and
Kimberley mines, and through these shafts the blue ground was extracted
by four different methods of stoping, none of which was satisfactory.
The system instituted by the Central Company, the largest operator in
Kimberley mine, illustrates sufficiently the inherent defects in all.
Here galleries fifteen feet wide were driven to the right and left of a
main tunnel, with pillars fifteen feet thick between them. Passages or
winzes for broken ground were sunk at short intervals to a tunnel
below. The ground was stoped to the height of fifteen feet above the
main tunnel, and then below it until the stope reached the next level.
The passes became filled frequently with large pieces of ground, and
had to be cleared. Under this system the mine was assuming the shape
