34 BULLETIN 194, U. S. DEPARTMENT OE AGRICULTURE. 
Nos. 77, 78, 79, 80, Expts. S-35, a, b, c, Arnold flume, Central Oregon Irrigation 
Co., near Bend, Oreg. Tests were made on various sections of this flume, covering 
curves and tangent and both. The flume shown in Plate VII, figures 1 and 2, is 
about 3 years old and was constructed of green pine lumber, with cracks battened 
with 1 by 4-inch strips in the first 400 feet of the total reach and with 1 by 6-inch 
strips in the lower part. 
Test S-35 covers the whole reach 2,200 feet long, embracing 437 feet of 15° curve, 
then 1,147 feet of tangent shown in figure 2; then 616 feet of 20° curve with a short 
tangent at the lower end. Test lettered "a" covers the same 15° curve, "b" covers 
the long tangent, and test "c" covers the 20° curve and the short tangent. The 
value of n should have been lowest on the long tangent when judged by the appearance 
of the channel. 
No. 82, Expt. H-22, Hedge Canal, Bitter Root Stock Farm, Montana. The portion 
of this flume tested is about 14 years old. The lining is 3-inch tongued and grooved 
lumber, surfaced on the water side. There is no moss and only an occasional piece 
of gravel. The flume follows a mountain contour with heavy curvature, brought 
about with chords 16 feet in length. This accounts for the rather high value of n. 
Coefhcient ?i=0.0153. 
No. 83, Expt. H-24, Hedge Canal, Bitter Root Stock Farm, Montana. This flume 
is of the same age and general description as that tested in No. 82. It is clean of 
gravel except on the inside of curves. Coefficient n=0.0155. . 
Nos. 84, 85, 86, 87, Expt. S-33, Swalley Ditch near Bend, Oreg. This flume (shown 
in PI. VIII, fig. 1) is of rough pine lumber with £ by 4-inch battens on all cracks. 
It is weathered, but not made as smooth as if originally surfaced. There is a small 
amount of slime present. Reach (a) is on the first tangent in the view. Coefficient 
n=0.0157. Reach (b) covers the last 35 feet of the tangent in the view then around 
the curve to the left. Coefficient n =0.0149. Reach (c) covers the second tangent 
and the sharp curve, of about 75 feet radius, to the right. Coefficient n=0.0157. 
Reach (d) covers all of the above reaches. Coefficient n =0.156. 
No. 88, Expt. S-61, Golden Rock Lower Ditch, Yosemite Power Co., California. 
This test was made on a reach of flume made of unplaned pine lumber 1| by 15 inches. 
There were three battens in the bottom, each \ by 4 inches. There were no battens 
on the side within the water section. The water was clear. There was no percep- 
tible growth or slime on the wood. No structures were within a reasonable distance 
of the reach chosen, although a gentle curve ended about 30 feet above station 0. 
Coefficient n=0.0159. 
No. 89 , Expt. S-58, Modesto Irrigation District main canal, California. This wooden 
flume, built of 2 by 12-inch lumber, is battened with 1 by 4-inch ship-lap with the 
groove on top. The latter is then poured with asphalt. There are no battens on the 
bottom, which was covered with about one-half inch of sand. The dripping asphalt 
had rendered the sides quite rough, and the value of n found is about what might be 
expected. The flume is straight, with water in the lower end falling over check 
boards. For this reason and since the water raised in the canal about 0.2 foot during 
the measurement, the writer has classed this test B. There was no growth or slime 
noticeable. Coefficient n=0.0163. 
No. 90, Expt. S-6, lateral of Jordan and Salt Lake City Canal near Salt Lake City. 
This covers a straight stretch of old flume of rough lumber. There are no battens in 
the bottom, but the first batten up on the sides was sometimes in and sometimes out 
of the water through the reach tested. There was no slime, gravel, or moss present, 
but the flume was wavy, and the bottom on a wavy gradient. There was a sharp turn 
without curvature about 150 feet below station 4. Coefficient n=0.0167. 
No. 91, Expt. S-48, Wheeler Ditch near Reno, Nev. This flume is made of 2 by 
14 inch rough pine lumber with 1 by 6 inch battens. There are occasional deposits 
