thumb|220px|right|A sawmill with log flume, [[Cascade Range, USA]]
A log flume or lumber flume is a watertight flume constructed to transport lumber and logs down mountainous terrain using flowing water. Flumes replaced horse- or oxen-drawn carriages on dangerous mountain trails in the late 19th century. Logging operations preferred flumes whenever a reliable source of water was available. Flumes were cheaper to build and operate than logging railroads. They could span long distances across chasms with more lightweight trestles.
Flumes remained in widespread use through the early 20th century. The logging truck replaced both the logging railroad and the flume after WWII. Today, log flumes remain in the popular imagination as amusement park rides.
History
J. W. Haines built the first successful lumber flume in 1859. The v-shaped trough brought a half-million feet of lumber daily from the eastern Sierra Nevada to the Comstock Lode. The route was between Lake Tahoe and Reno, terminating at the Virginia and Truckee Railroad terminus in Washoe Valley. Soon, log flumes spread across the mountains of the western United States as artificial rivers that brought lumber to market.
Flume heads
Log flumes need a steady supply of water. Often, a log pond or artificial reservoir serves this purpose. The head directs the flow of water into the top of the flume. Flume boxes are built tight with lumber free of knots to prevent leaks. Feeder troughs resupply water on long routes.
Flume construction
thumb|The high trestle on the Sanger Flume was over tall.
Flume routes were surveyed by engineers using the same methods as a railroad survey. However, flumes had several advantages to logging railroads in steep terrain. They could span gulches using much lighter trestles and they took up less space, fitting inside narrower canyons where there wasn’t room for a railroad. The main disadvantage of the light construction was they were damaged more easily by fire, floods, wind, and falling timber. But they could be repaired more cheaply.
Box flumes were not made obsolete. They continued to be built when a large volume of water was desired for a secondary use, such as irrigation. Box flumes were also more capable of handling materials uneven in size and weight simultaneously. Lumber, pulpwood, shingle bolts, and whole logs move at different speeds and were prone to double-up in a V-flume’s low grades and curves. Finally, box flumes could move an unprecedented amount of material, up to a maximum capacity of , or three times as great as the maximum for a V-flume. On longer flumes, flume herders lived in permanent flume houses along the route. Light signals, and later telephone lines, enabled communication up and down the line.
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Flume Herder Picaroon.jpg|Flume herders used a metal-tipped wood handling tool called a pickaroon.
Flume Herder Madera Sugar Pine.jpg|Narrow catwalks provide maintenance access along the length of the flume.
Flume House Banjo.jpg|A flume house along the 54-mile route of the Hume-Bennett flume.
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Flume boats
On occasion, despite it being exceedingly dangerous, flume herders and others would ride down the flume in small craft or boats, either for inspection or for thrills. Such rides were the precursor of the modern log-ride amusement park attractions.
Every flume boat was one of a kind, but they shared common design characteristics. They were V-shaped to fit the flume trough. An open front allowed water in for stability in the curves. A closed back allowed water to push the craft forward. Flat boards across the top created a platform for passengers and cargo.
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Flume Boat and George Hume.jpg|A flume boat loaded with a rifle and supplies.
Flume Boat Boys.jpg|Flume boats shared a V-shaped design with an open front.
Workmen Riding a Flume Boat.jpg|Making repairs aboard a flume boat.
Flume Boat on High Trestle.jpg|Workers on the catwalk guide a boat over a high trestle.
Flume Boat Ride.jpg|A United States Forest Service employee "shoots the chute".
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Flume terminals
There are a variety of flume terminals. The kind of terminal depends on the materials the flume transports and its disposal at the end point of a flume.
An elephant terminal splits from a central trunk into many forked branches. From there, logs are diverted into open branches by closing branches not in use. Logs collect at the end of the terminal in a loose pile. Other terminals shoot logs onto rollers that move them onto loading platforms. The water from the flume drives a waterwheel that drives the rollers. This arrangement works well with heavy railroad crossties or mining timbers.
- In 1890, the Kings River Lumber Company completed the Kings River Flume from the upper Kings River area to Sanger.
See also
- Timber slide, similar to log flumes but used on rivers to bypass rapids and falls