FLUMES AND LOG SLUICES 451 
traordinary efforts had to l)e inatle to conserve it. Some canyons from which 
timber was to be transported liad no available water in them and it was 
necessary to build the flume from one watershed to another to get the timber out. 
The preliminary work consisted of a survey of the whole route and a very 
careful determination of the levels. The construction work was begun at the 
mill and carried forward each year as required to secure the requisite amount 
of timber. The first section of the flume was built nearly on a dead level, 
but as the work progressed a grade of 1 inch in 100 feet was given. 
The natural gradient greatly exceeded that given to the flume and it was 
necessary to build the latter in three imits, each ending in a V-shaped chute 
which led from the flume to a pond at a lower elevation. These ponds were 
about 75 by 100 feet in size and were located at points where the natural con- 
ditions favored their construction. They not only served as storage reser- 
voirs for water and points for the change in grade of the flume but also as 
places for logs to enter the flume. 
The grade line was kept as near the ground as possible in order to avoid 
expensive trestle work and cuts. However, some cuts could not be avoided 
and trestles had to be built when the flume crossed canyons or other depres- 
sions. 
The flume box was constructed of 2- by r2-inch planks and was 6 feet wide 
and 4 feet deep, except on sharp curves where it was wider. The normal 
depth of the water was 3? feet. Trestles were built of sawed timbers and braces 
of the same sized timbers were placed along the box at 3-foot intervals. A 
running board extended along one side of the box for the use of flume tenders. 
Lumber for building the flume was cut in a portable mill which was kept as 
near the actual construction point as was practicable. This reduced the charge 
for transport of flume material. Each flume unit was provided with three 
lift gates suspended from the center of a beam which was supported by two 
upright posts placed on either side of the flume. One gate was used for the 
control of the water and the other two for emergency purposes. Should an 
accident happen to the gate in use, or a log become jammed in it, one or both of 
the others could be closed and a waste of water prevented. The gates 
were opened by lifting them with a lever until they cleared a 2-inch cleat 
nailed across the bottom of the flume when the force of the water raised 
them to a horizontal position. They were then supported by 2- by 4-inch 
joists, which were placed across the flume. 
In the spring of the year an abundance of water was available and a slight 
current was created in the flume by keeping open a small extra gate. During 
this season the logs were floated loose and only an occasional man was needed 
to keep them moving and to prevent jams. In the summer and fall the water 
was at a low stage and the logs were dogged together in strings of from 50 to 
75 (10,000 to 15,000 board feet) and were towed along the flume by a man who 
traveled the running board. The opening of the large gates also created an 
artificial current which assisted in keeping the logs moving. The tow was 
kept as near the gate as possible and when the latter was opened the logs were 
rushed through to get the maximum benefit from the accumulated head. 
The flume was built at a cost of .S3, 000 per mile and it was estimated that 
with minor rej^airs, it would last for fifteen years. 
