BOOK VIII.

323

particles or concentrates of gold, together with the sand, pass through theholes into the trough which is placed under the frame, and after beingcollected are washed in the bowl.

A box which has a bottom made of a plate full of holes, is placed overthe upper end of a sluice, which is fairly long but of moderate width. Thegold material to be washed is thrown into this box, and a great quantity ofwater is let in. The lumps, if ore is being washed, are mashed with an ironshovel. The fine portions fall through the bottom of the box into the sluice,but the coarse pieces remain in the box, and these are removed with a scraperthrough an opening which is nearly in the middle of one side. Since a largeamount of water is necessarily let into the box, in order to prevent it fromsweeping away any particles of gold which have fallen into the sluice, thesluice is divided off by ten, or if it is as long again, by fifteen riffles. Theseriffles are placed equidistant from one another, and each is higher than the onenext toward the lower end of the sluice. The little compartments which arethus made are filled with the material and the water which flows through

Sluice. B — Box. C —Bottom of inverted box. D —Open part of it. E —Ironhoe. F —Riffles. G —Small launder. H —Bowl with which settlings are takenaway. I—Black bowl in which they are washed.

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