BOOK VIII. 



323 



particles or concentrates of gold, together with the sand, pass through the 

 holes into the trough which is placed under the frame, and after being 

 collected are washed in the bowl. 



A box which has a bottom made of a plate full of holes, is placed over 

 the upper end of a sluice, which is fairly long but of moderate width. The 

 gold material to be washed is thrown into this box, and a great quantity of 

 water is let in. The lumps, if ore is being washed, are mashed with an iron 

 shovel. 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 scraper 

 through an opening which is nearly in the middle of one side. Since a large 

 amount of water is necessarily let into the box, in order to prevent it from 

 sweeping away any particles of gold which have fallen into the sluice, the 

 sluice is divided off by ten, or if it is as long again, by fifteen riffles. These 

 riffles are placed equidistant from one another, and each is higher than the one 

 next toward the lower end of the sluice. The little compartments which are 

 thus made are filled with the material and the water which flows through 



A SLUICE. B Box. C BOTTOM OF INVERTED BOX. D OPEN PART OF IT. E IRON 



HOE. F RIFFLES. G SMALL LAUNDER. H BOWL WITH WHICH SETTLINGS ARE TAKEN 



AWAY. I BLACK BOWL IN WHICH THEY ARE WASHED. 



