mine,
and early in 1885 the west end yellow ground caved in, and an enormous
mass of nearly five million cubic feet fell in one day to the bottom of
the mine, overlapping the fallen reef and burying the claims still open
for work. This disastrous fall forced the stoppage of mining for six
months until some part of the reef and yellow ground could be taken
out, and mining was then resumed in a partial and half-hearted way in
the open pit, though it was evident that further pit sinking in the
face of such
disasters was irrational mining.
The
only possible resource was the introduction of a system of underground
mining, and the first attempt in this direction was made in 1884 by the
opening of a large circular shaft at a point 1000 feet from the north
margin of the mine. This shaft was sunk vertically about 320 feet in
the reef and then abandoned as too costly. In its place an incline was
sunk, starting from a point about 150 feet from the west side of the
claims, and entering the mine at the edge of the amyg-daloidal trap
underlying the basalt and shale, so as to avoid the expense of cutting
through this hard rock. This work was begun none too soon, for before
the end of the year 1887 further open pit working was proved to be
utterly impracticable, and was wholly abandoned when the deepest open
digging had been carried in three years only fifty feet farther than
the depth of 350 feet reached in 1884.
Dutoitspan
mine opening was practically the same as the course followed in
Kimberley and De Beers. Owing to the comparative poorness of the
diamond-bearing ground, pit sinking was not pushed as rapidly as it was
at Kimberley, and, in 1874, most of the miners went over to Kimberley
and were glad of the
