346

BOOK VIII.

plates, because it remains intact, while the rods, when worn by rubbing, caneasily be replaced by others.

Miners use the seventh method of washing when there is no stream ofwater in the part of the mountain which contains the black tin, or particles ofgold, or of other metals. In this case they frequently dig more than fiftyditches on the slope below, or make the same number of pits, six feet long,three feet wide, and three-quarters of a foot deep, not any great distancefrom each other. At the season when a torrent rises from storms ofgreat violence or long duration, and rushes down the mountain, some ofthe miners dig the metalliferous material in the woods with broad hoes and

A—Pits. B —Torrent. C —Seven-pronged fork. D—Shovel.

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drag it to the torrent. Other miners divert the torrent into the ditches orpits, and others throw the roots of trees, shrubs, and grass out of the ditchesor pits with seven-pronged wooden forks. When the torrent has run down,they remove with shovels the uncleansed tin-stone or particles of metal whichhave settled in the ditches or pits, and cleanse it.

The eighth method is also employed in the regions which the Lusitanianshold in their power and sway, and is not dissimilar to the last. They drive