This
washing machine was practically the same as the Australian gold placer
miner's cradle, or the American rocker, and it had been used for years
on the Brazilian diamond fields, though the screening of the Vaal was
probably more exact. But the Brazilian negroes had become far more
expert by long practice and training than the green workers on the line
of the Vaal, and the handling of the concentrate in their bateas was
extraordinarily deft. It has been demonstrated over and over again in
placer fields that inexperienced washers cannot compete with trained
hands in concentrating gold dust, and even expert gold placer workers
often failed to handle diamond-bearing gravel efficiently. So it is not
surprising that many of the awkward adventurers in the new fields lost
heart completely at their failure to extract any diamond from the
masses of gravel which they dug and washed so laboriously ; and it is
practically certain that the percentage of gems saved, at first, was
below the average winning from the Brazilian sands.
The
irregularity of the distribution of diamonds in the shore bed was
greatly perplexing and disappointing to the groping locaters. The
precious stones were strewed in the gravel in a scattering way that
defied any calculation. Here and there was a rich patch of ground,
while tracts all around it, precisely similar in a surface view, held
only a few small diamonds or were
