that
some extraordinary rich yields reported in the early days, covered
additions by purchase of stones from undisclosed sources. It is
generally acknowledged that the volume of illicit trading was very
large, and it is equally certain that the most successful traders
escaped detection. As such transactions could be concealed in no other
way so readily, nor the purchases be disposed of so easily, the
presumption is that among so many, some of the claim owners took
advantage of the situation. There has been an apparent decrease in the
yield per load of most of the mines as they have been carried deeper.
The De Beers and Kimberley have steadily declined from over one carat
per load in 1888 to .80 of a carat in 1898 and 0.37 in 1908. The
Du-toitspan, which from the beginning gave a small average yield, has
nevertheless held very steady, dropping by one hundredth of a carat
only in the yearly average from .26 in 1905 to .23 in 1908. When first
reopened in 1904 the yield was only .12. The yield of the Wesselton
also has been very uniform, being the same in 1908 as it was in 1898,
i. e., .27 of a carat per load. In the interim it has never been less
than .28, and in 1907 it was .32. The Bultfontein shows an increase
from 1902, when the yield was .21 of a carat, to .41 in 1905, since
which it dropped again to .32 for 1908. The increase of the first four
years after the consolidation began to operate it, is accounted for by
the fact that there was an accumulation of poor material which was
first cleaned up. The Koffyfontein runs even: .473 in 1906 and .476 in
1907.
Of the open-cut mines, the Premier of the Transvaal shows the greatest decline in average yield. In the be-
