Disintegrating auriferous gravels by powerful jets of water, and the sluice system described above; in the second case the vein stuff is prepared by crushing and the amalgamation is carried out in mills.
Broad; it has vertical shafts at intervals, and a sluice chamber at its egress from the lake.
At neap-tide; in the sluice of the dock the numbers are 291 and 231 respectively.
A small sluice placed in the side of the conductor opposite to the meadow, and at the upper end of it, will drain away the leakage that may have escaped from the head sluice.
It is first surrounded by an embankment, after which the water from the river is allowed to flow through a properly constructed sluice in its bank, along a drain or ditch to the land which is prepared for warping.
It then passes through screens and grizzlies to retain the coarse gravel, the finer material passing on to sluice boxes provided with riffles, supplied with mercury.
The incline of the sluice varies with the conformation of the ground and the tenacity of the stuff to be washed, from 1 in 16 to I in 8.