ClipArt ETC
"The section of the flume is usually rectangular, but it may be of a V shape, and occasionally, as in California, it is semicircular, this latter form requiring least lumber, but necessitating the use of iron bands or brackets."—Government Printing Office, 1897

Combined Wood and Iron Flume

"The section of the flume is usually rectangular, but it may be of a V shape, and occasionally, as in…