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BOOK VIII 



A — Head of the sluice. B — Riffles. C — Wooden scrubber. D — Pointed stick. 

 E — Dish. F — Its cup-like depression. G — Grooved dish. 



The cup-like pockets and grooves are cut or burned at the same time into 

 the bottom of the sluice ; the bottom is composed of three planks ten feet 

 long, and is about four feet wide ; but the lower end, through which the water 

 is discharged, is narrower. This sluice, which likewise has side-boards fixed 

 to its edges, is full of rounded pockets and of grooves which lead to them, 

 there being two grooves to one pocket, in order that the water mixed with 

 sand may flow into each pocket through the upper groove, and that after the 

 sand has partly settled, the water may again flow out through the lower 

 groove. The sluice is set in the river or stream or on the bank, and placed 

 on two stools, of which the first is higher than the second in order that the 

 gravel and small stones may roll down the sluice. The washer throws sand 

 into the head with a shovel, and opening the launder, lets in the water, which 

 carries the particles of metal with a httle sand down into the pockets, while 

 the gravel and small stones with the rest of the sand falls into a tub placed 

 below the sluice. As soon as the pockets are filled, he brushes out the 

 concentrates and washes them in a bowl. He washes again and again 

 through this sluice. 



