This
puddling trough would concentrate from twenty-five to thirty-five
cartloads in a working day and cost at first, about ,£250, while the
simpler cradle could be bought for £ 15,
or less. There were other more elaborate devices, but their cost put
them out of the reach of the ordinary digger. All were based on one
adaptation or another of the puddling principle, and the fall and
separation of minerals of different specific gravities.
The sorting of the concentrate from the
puddling troughs was done by the same
method employed after the dry sifting,
but there was some improvement in the
