with free access to the river bank; the gravel and
sand were washed in cradles provided with screens of perforated metal,
and the concentrates were sorted by hand on tables by means of an iron
scraper.

But towards the close of 1870 stones were found at Jagersfontein and
at Dutoitspan, far from the Vaal river, and led to a second great rush
of prospectors, especially to Dutoitspan, and in 1871 to what is now
the Kimberley mine in the neighbourhood of the latter. At each of
these spots the diamantiferous area was a roughly circular patch of
considerable size, and in some occupied the position of one of those
depressions or "pans" so frequent in S. Africa. These "dry diggings"
were therefore at first supposed to be alluvial in origin like the
river gravels; but it was soon discovered that, below the red surface
soil and the underlying calcareous deposit, diamonds were also found
in a layer of yellowish clay about 50 ft. thick known as "yellow
ground." Below this again was a hard bluish-green serpentinous rock
which was at first supposed to be barren bed-rock; but this also
contained the precious stone, and has become famous, under the name of
"blue ground," as the matrix of the S. African diamonds. The yellow
ground is merely decomposed blue ground. In the Kimberley district
five of these round patches of blue ground were found within an area
little more than 3 m. in diameter; that at Kimberley occupying 10
acres, that at Dutoitspan 23 acres. There were soon 50,000 workers on
this field, the canvas camp was replaced by a town of brick and iron
surrounded by the wooden huts of the natives, and Kimberley became an
important centre.

It was soon found that each mine was in reality a huge vertical funnel
or crater descending to an unknown depth, and filled with
diamantiferous blue ground. At first each claim was an independent pit
31 ft. square sunk into the blue ground; the diamantiferous rock was
hoisted by bucket and windlass, and roadways were left across the pit
to provide access to the claims. But the roadways soon fell in, and
ultimately haulage from the claims could only be provided by means of
a vast system of wire ropes extending from a triple staging of
windlasses erected round the entire edge of the mine, which had by
this time become a huge open pit; the ropes from the upper windlasses
extended to the centre, and those from the lower tier to