BOOK VIII.

309

it on each edge narrow strips, of no great thickness, and fix them to the beamswith nails. They agitate the metalliferous material with wooden scrubbersand wash it in a similar way. As soon as little or no mud remains on thecanvas, but only concentrates or fine tin-stone, they lift one beam so thatthe whole strake rests on the other, and dash it with water, which has beendrawn with buckets out of the small tank, and in this way all the sedimentwhich clings to the canvas falls into the trough placed underneath. Thistrough is hewn out of a tree and placed in a ditch dug in the ground ; theinterior of the trough is a foot wide at the top, but narrower in the bottom,because it is rounded out. In the middle of this trough they put a cross-board, in order that the fairly large particles of concentrates or fairly large-sized tin-stone may remain in the forepart into which they have fallen, andthe fine concentrates or fine tin-stone in the lower part, for the water flowsfrom one into the other, and at last flows down through an opening into thepit. As for the fairly large-sized concentrates or tin-stone which have beenremoved from the trough, they are washed again on the ordinary strake.

K

m

m

m

A Canvas strake. B—Man dashing water on the canvas. C—Bucket.D Bucket of another kind. E—Man removing concentrates or tin-stone

FROM THE TROUGH.