serted.
The bottom and sides are spiked together generally with nails four
inches apart. It is not necessary to plane either the bottom or side
planks. In many cases the planks are simply fitted well and closely
nailed together.
The
sills are placed from 3 to 4 feet apart, depending upon the size of
the scantling used, which is regulated by the width of the sluice; thus
a 4-foot sluice would require a sill 7 feet long, of 4 by 6 or 4 by 4
inch stuff. The posts are halved into the sills and firmly spiked, and
every second or third post should be supported by an angle brace. The
bottom planks should be solidly secured to the sills by a liberal use
of heavy spikes. The bottom of a new sluice is liable to be raised by
the pressure of the water which collects under it and finds no
discharge. To avoid this the flume should be heavily weighted down by
loading the ends of the sills with stones. In tunnels the ends of the
sills can be held down by braces extending to the rock overhead.
North Bloomfield Tunnel Sluice.—The
annexed diagrams give the detailed construction of the tunnel sluice
box used at the North Bloomfield Mine. The box is 6 feet wide and 12
feet long, with sides 32 inches deep.
To each sluice box are used :
