main
supports being placed every eight to twelve feet. The lumber,
scantling, and struts for bents are used in accordance with the demands
of the work. The foundations must be made secure to hold the
superstructure, and no mortises used, heavy spikes and strong timber
and braces being sufficient. Guy ropes are employed when necessary to
prevent any vibration or movement of the flume caused by severe wind
storms.
It
is the usual practice to distribute along the line of a ditch and flume
a certain amount of lumber, to be ready, in case of accident, for
repairing any breaks. Breaks on ditch lines, especially during the
winter, are repaired more easily with pieces of flume than with dirt. A
supply of ten per cent, of lumber is not an excessive amount to have on
hand. The life of a flume, under the best of circumstances and care,
will not exceed twenty years, and generally not over half that time.
Lumber.—The
following tables show the amount of lumber required in the construction
of twelve-foot flume-boxes of different widths and depths :
