[Illustration: SKETCH OF FLUME.]

The planking ordinarily used is of heart sugar pine, one and a half to
two inches thick, and 12 to 18 inches wide. Where the boards join, pine
battens three inches wide by one and a half thick cover the seam. Sills,
posts, and caps support and strengthen the flume every four feet. The
posts are mortised into the caps and sills. The sills extend about
20 inches beyond the posts, and to them side braces are nailed to
strengthen the structure. This extension of the sill timbers affords a
place for the accumulation of snow and ice, and in the mountains such
accumulations frequently break them off, and occasionally destroy a
flume.

To avoid damage from slides, snow, and wind storms, the flumes are set
in as close as possible to the bank, and rest, wholly or partially, on
a solid bed, as the general topography and costs will admit. Stringers
running the entire length of the flume are placed beneath the sills just
outside of the posts. They are not absolutely necessary, but in point of
economy are most valuable, as they preserve the timbers. As occasion
may demand, the flume is trestled, the main supports being placed every
eight feet. The scantling and struts used are in accordance with the
requirements of the work.--_Min. and Sci. Press_.

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CHUWAB'S ROLLING MILL FOR DRESSING AND ROUNDING BAR IRON.