THE FLOW OF WATER IN lEEIGATIOISr CHANNELS. 33 



ated to capacity. The flume has been in use nine years, and the inside relined with 

 1-inch lumber meanwhile. Mr. Hai'ding suggested in designing a flume where such 

 waves are to be expected, that a liberal freeboard be allowed for or else that the crests 

 of the waves be considered the water surface. He has solved n for both assumptions 

 and finds n runs about 0.004 higher where crests are considered the water surface. 

 This difference was quite close thi-oughout the four tests. 



Xo. 70, Expt. H-39, Bitter Root Valley Inigation Co.'s flume No. 2, Montana. This 

 flume is built of 2^-inch finished tongued and grooved siding. The side boards are 

 12 inches wide, with the cracks battened with J by 2-inch strips. On each side of 

 the cracks in the bottom is laid a ^ by 1-inch strip, leaving a groove about one-half 

 inch wide over the crack. This groove is then poured with an asphaltic filler. The 

 reach chosen foUows a contoiu- with the following alignment: Station about 100 

 feet below upper end of flume; thence 100 feet of about 10° curve right; thence 200 

 feet tangent; thence 100 feet of about 5° curve right; thence 100 feet tangent; thence 

 50 feet of about 10° curve left; thence 100 feet tangent to a small bend; thence 50 

 feet tangent, to end of reach which is about 150 feet above outlet to flume. This 

 reach is verj- similar to that of No. 71. Coefficient n=0.0125. 



No. 71, Expt. H-37, Bitter Root Valley Irrigation Co.'s flume No. 1, Montana. The 

 reach tested is at the lower end of a flume about 1 mile long. The sides were formed 

 of 2^ by 12-inch finished, tongued and grooved lumber with cracks battened with -J by 

 1^-inch strips. There are no battens on the bottom. There was a thin coating of 

 sand and gravel in places. The alignment is about as follows: Station to 1 is about 

 20° curve right; thence 200 feet tangent; thence 300 feet of about 10° curve left; 

 thence 200 feet tangent; thence 50 feet of about 20° curve left; thence 150 feet tan- 

 gent. The value of n should be compared with those found in Nos. 58, 70, 73. It is 

 higher than for No. 58, because the latter is on a clean tangent. It is lower than for 

 No. 73, which is on a very crooked reach. Coefficient n=0.0127. 



No. 72, Expt. H-28, Hedge Canal, Bitter Root Stock Farm, Montana. This test is 

 on a new reach of flume built of 3 by 12-inch finished tongued and grooved lumber. 

 The canal is rough both above and below the flume, which is too short for the best 

 grade of results. Coefficient n=0.0129. 



No. 73, Expt. H-32, flume No. 7 of the Bitter Root Valley Irrigation Co.'s main 

 canal, Montana. This is a very crooked flume of the same construction as in No. 58. 

 There was no moss or gravel. The flume follows mountain contours, having sharp 

 curA-es right and left, with short tangents between. The higher value of n found in 

 this test is to be expected and gives comparative results between straight and very 

 crooked flumes, when compared with the three other tests on flumes of this canal. 

 Coefficient n=0.0135. 



No. 74, Expt. H-ll, lateral No. 4, Billings Land and Irrigation Co., Montana. This 

 is a small flume 2 feet wide and 2 feet deep. There are no battens and the butt joints 

 are calked with oakum. The inside of the flume is weathered, but appears to have 

 been originally of surfaced material. The flume is generally straight, there being 

 wavy places which slightly distort the true alignment. The ends of the reach are 

 far enough from entrance and exit to the flume to be uninfluenced. Coefficient 

 n=0.0KJ8. 



No. 75, Expt. S-Ifj, ''I'elluride flume, Utah Power & Jvight Co., near Logan, Utah. 

 ThiH te.st is on a straight reach of flume with an angle of about 20° left, located 35 

 feet below the end of the reach. See Plate VI, figure 3. The sides are of 1-inch 

 Oregon pine with all cracks battened with f by 3-inch strips, the vertical battens, 

 about 16 feet apart, being beveled on the upstream edge to reduce friction. The 

 bott<jm batten.H appear U) be about 6 inches wide, but examination was dil!i( nil . All 

 BUrfarcH of w(><A in c:orita^:t with water ai)iK'ar l/i have l>c'(;n surfaced, l)ut are so weath- 

 ered and waUfrworn that this point is indeterminate. Coefficient n=0.0i4i. 

 79250°— Bull. 194—15 3 



