THE FLOW OF WATER IN IREIGATION CHANNELS. 35 



of gravel, and the sides are slightly waterworn and have a slick deposit of silt. A 

 sharp ciir\^e occurs about 50 feet above station 0, but the reach tested is practically- 

 straight. Coefficient n=0.0167. 



No. 93, Expt. G-3, Roller flume, Louisiana. This flume was about 14 years old, 

 with the exception of a portion of the reach tested, about 75 feet long, which had been 

 repaired with new cj'press lumber. The original lumber was unsiu-faced, but at 

 .present is covered with a slimy growth. The lumber was parallel to the axis of the 

 canal, but the siirface was slightly irregular. Coefiicient n=0.0191. 



No. 94, Expt. S-76. Riverside Water Co.'s Lower Canal near Riverside, Cal. The 

 side boards of this flume were of vertical tongued and grooved lumber, making a very 

 rough interior. The bottom was painted with a tar or asphalt product, and the posts 

 were in such condition that the flume sagged and was out of line in numerous places. 

 The value of n as foiind for this flume may be taken as that of a flume in exceedingly 

 poor condition but without appreciable deposits of sand or gravel. It is understood 

 the company expects to replace this flume in the near future. The reach tested is 

 straight. Water enters from a cement-lined section about 50 feet above station 

 and leaves the flume into an earth ditch about 50 feet below station 7 plus 46. Co- 

 efiicient n=0.0196. 



No. 96, Expt. S-65j Fullerton Ditch of the Anaheim-Union Water Co., California. 

 This flume has the bottom so covered with soft sand that it classes more nearly with 

 an earth section. The lumber was imsurfaced, and a growth of moss retards velocity 

 for about 0.1 foot from each side. The reach tested was straight, but there is a sharp 

 cur\"e about 50 feet above station where the earth canal joins the flume section. 

 About 15 feet below station 6 plus 72 the water enters the earth section again. Coeffi- 

 cient n=0.0202. 



MASONRY-LINED CHANNELS. 



No. 113, Expt. S-29, Jacobs Ditch, Boise, Idaho. Tliis test is on a straight stretch 

 of ditch. As shown in Plate VIII, figure 2, the sides are of first-class rubble masonry 

 with all cracks smoothly plastered with cement. Tlie bottom is smooth cement 

 lining laid like a good grade of sidewalk. About 50 feet below the lower end of the 

 reach the ditch passed through a vertical trash grating, where there was a loss of head 

 of about 0.05 foot. This grating was kept clean of debris during the test. Coeffi- 

 cient 71=0.01.30. 



No. 115, Expt. S-27. This test was made on the same ditch as No. 113 above, but 

 this reach is lined on both sides and bottom with dry laid, unchinked rubble, as 

 shown in Plate VIII, figure 3. The bottom is quite irregular, with scattered loose 

 cobbles. A clean grating came a short distance below the reach, as in No. 113. Coeffi- 

 cient n=0.0235. 



No. 116, Expt. S-28. This test also is on the same ditch as No. 113 above. This 

 reach, one city squaie long, came between the reaches in No. 113 and No. 115 above, 

 It apf^eared to have been originally like No. 113, except that the bottom was not 

 Lined. There were several cobbles throughout the bottom of this reach, and this 

 probably accounts for the fact that the value of n is slightly higher than for No. 115, 

 while to all appearances it should liave been slightly lower. A grating similar to the 

 one.s noted above came below the lower end of the reach. Coefficient n=0.0250. 



No. 117, Expt. 8-45, Orr iJitcli, Rono, Nev. As shown in Plate IX, figure I, the 

 sidefl are quit/) nmoothly built rubljle, with most of the cracks well ])lantered, l)ut 

 the bottfim i.s covered witji shifting sand and hxwo cobbloH ho that, if lined, the lining 

 Ih complet/;ly concealed. The lined ser-tion ends Hhortly below tjio lovvcir «>nd of this 

 reach, j)a.H."ing int<; an earth channel. This test (sxoinpli/io.s tjio ntK-d of keo])ing 

 Hand and gravel from a lined section if tlie low value of n (hut might be expected is to 

 \)e realized. Coefiicient n=0.0298. 



