326

BOOK VIII

O'E,

A —Head of the sluice. B—Riffles. C—Wooden scrubber. D—Pointed stick.E —Dish. F —Its cup-like depression. G —Grooved dish.

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The cup-like pockets and grooves are cut or burned at the same time intothe bottom of the sluice ; the bottom is composed of three planks ten feetlong, and is about four feet wide; but the lower end, through which the wateris discharged, is narrower. This sluice, which likewise has side-boards fixedto its edges, is full of rounded pockets and of grooves which lead to them,there being two grooves to one pocket, in order that the water mixed withsand may flow into each pocket through the upper groove, and that after thesand has partly settled, the water may again flow out through the lowergroove. The sluice is set in the river or stream or on the bank, and placedon two stools, of which the first is higher than the second in order that thegravel and small stones may roll down the sluice. The washer throws sandinto the head with a shovel, and opening the launder, lets in the water, whichcarries the particles of metal with a little sand down into the pockets, whilethe gravel and small stones with the rest of the sand falls into a tub placedbelow the sluice. As soon as the pockets are filled, he brushes out theconcentrates and washes them in a bowl. He washes again and againthrough this sluice.