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BOOK VIII.

task he suspends the box from a beam by two ropes. This box may rightlybe called a quadrangular sieve, as may also that kind which follows.

Some employ a sieve shaped like a wooden bucket, bound with two ironhoops ; its bottom, like that of the box, is made of iron wire netting.They place this on two small cross-planks fixed upon a post set in the ground.Some do not fix the post in the ground, but stand it on the ground untilthere arises a heap of the material which has passed through the sieve, andin this the post is fixed. With an iron shovel the workman throws into thissieve broken rock, small stones, coarse and fine sand raked out of the dump;holding the handles of the sieve in his hands, he agitates it up and down in

A —Sieve. B —Small planks. C—Post. D —Bottom of sieve. E —Open box.

F —Small cross-beam. G —Upright posts.

I

order that by this movement the dust, fine and coarse sand, small stones, andfine broken rock may fall through the bottom. Others do not use a sieve, butan open box, whose bottom is likewise covered with wire netting ; this theyfix on a small cross-beam fastened to two upright beams and tilt it backwardand forward.

Some use a sieve made of copper, having square copper handles on bothsides, and through these handles runs a pole, of which one end projects three-quarters of a foot beyond one handle ; the workman then places that end ina rope which is suspended from a beam, and rapidly shakes the pole alter-