FLUMES AND LOG SLUICES 
437 
from 30 to 32 inches. The boxes are supported on trestle work 
similar to that used for the V-flume, although the construction is 
stronger. 
The boxes of log sluices (Fig. 158E) are of larger size than those 
for lumber flumes and carry more water. They are used chiefly 
to supplement stream driving by transporting logs through rocky 
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Fig. 159. — A V-flume for transporting Mining Stulls. Montana. 
gorges where an excessive amount of water would otherwise be 
required or where boulders prevent the improvement of the 
stream for loose driving, and for transporting logs over stretches 
of streams whose banks are so low that the flood waters scatter 
the logs over the lowlands. They are also used in connection 
with log haul-ups to tranport logs from one watershed to another, 
and, in some cases, to transport logs directly from the forest 
to the mill. They have been used frequently in the Lake States 
and occasionally in the Northeast. 
