TUNNELS AND SLUICES. 223
stone riffles are used the bottom of the sluice is lined with rough plank.
top sluice on one side is for carrying sipage water when the blocks are
being set. It is 13 inches wide and 14 inches deep, and is made of
Bed-Rock Claim Sluice Boxes.—At
the Bed-Rock Claim, Nevada County, the tunnel sluice boxes are 14 feet
long, 5 feet wide, and 32 inches deep. The details of a box are as