44 BULLETIN 194^ U. S. DEPARTMENT OF AGRICULTURE. 



some grass on the lower water edge. Second third of distance much roughness, with 

 cobbles over most of bottom. Last third, in condition intermediate first and second 

 thirds. Coefficient 71=0.0262. 



No. 252, Expt. S-10, Upper Canal from Big Cottonwood Creek, Utah. This reach 

 of canal follows a gentle contour curve on a very gravelly hillside. The sides are 

 nearly vertical and lined with trees and willows whose rootlets extend into the water 

 prism. The bottom is completely covered with cobbles up to two-fist size. Like 

 nearly all ditches of this character the sides are irregular in outline, as the cobbles do 

 not break into an even bank. Coefficient w=0.0277. 



No. 253, Expt. S-15, Logan and Northern Canal, Utah. This is a fine example of 

 a ditch following a gravelly hillside contour near the mouth of a canyon, a condition 

 typical of many canals near the mountains. The sides are densely fringed with 

 willows and bushes whose rootlets hold silt and form nearly vertical banks. The 

 bottom is completely covered with well-packed gravel and cobbles up to two-fist 

 size. Coefficient n=0.0270. 



No. 254, Expt. S-51, Reno Ditch of the Reno Light & Power Co., Nevada. This 

 reach of canal was originally excavated in an old river bed containing innumerable 

 bowlders up to 5 cubic feet in size (PI. XVIII, fig. 3). About a year before this test 

 the sides and bottom of this channel had been paved with a hand-laid riprap of these 

 bowlders, the sides being laid about J to 1, and the bottom flat. Many of the 

 bowlders at the top of the walls have rolled into the canal, as no cement or other bond 

 was used, but the general condition of the walls appears to be good. The reach 

 tested was straight with the exception of a gentle curve in the last 200 feet. Coeffi- 

 cient w=0.0291. 



No. 255, Expt. S-43, Sullivan and Kelly Ditch, Nevada. This reach follows a gentle 

 contour on a rocky hillside (PI. XIX, fig. 1). The bowlders have been hand laid in 

 a nearly vertical wall on the lower side while the bottom and upper side are rough and 

 irregular with projecting large bowlders. A slime of mud from the Truckee River 

 water covers all rocks below the water Une. Vegetation is negligible. Coefficient 

 71=0.0324. 



No. 259, Expt. S-89, Beasley Ditch, Colorado. This canal on a straight reach with 

 a curve about 100 feet below the lower end. At the time of test it was carrying but 

 about one-fourth its capacity. The bottom and sides are a mass of unpacked gravel 

 and bowlders up to 2 cubic feet in size. Coefficient 71=0.0383. 



SIDEHILL CUTS, WITH RETAINING WALLS. 



No. 261, Expt. H-23, Hedge Canal, Montana. This test was made on a short reach 

 excavated in granite hillside, with the lower bank formed of a random rubble masonry 

 wall, well plastered with mortar on the nearly vertical water face. The reach is 

 straight except for a sUght curve in the last 50 feet. The bottom is covered with 

 granite gravel, most of which would pass a ^-inch screen, with occasional pieces one- 

 fist size. The excavation is quite true to line for a rock cut. Coefficient 7i=0.0185. 



No. 262, Expt. H-27, Hedge Canal, Montana. This reach is about 500 feet below 

 that in No. 261. The upper side is excavated quite true to line in earth and disin- 

 tegrated granite. The lower side is a vertical concrete wall laid against board forms. 

 The floor is concrete with from 1 to 2 inches of fine, sharp ravelings from the hilMde. 

 In scattered spots the floor shows. The reach is 450 feet long. Station 1 to 2 is about 

 a 20° curve, on 12-foot chords. At station 8-|-40 is a rather sharp bend. The rest is 

 fairly straight. Coefficient 71=0.0225. 



No. 263, Expt. H-9, Cove Ditch, Montana. This reach is cut from a sandstone 

 hillside (PI. XIX, fig. 2). The lower bank is a rubble masonry wall plastered with 

 concrete on the water side. The bottom is also overlaid with concrete. The align- 

 ment is wavy with some 20° curves. From stations to 2 there is some gravel ; from 

 stations 2 to 4, clean bottom, the rock on upper bank being smooth but the width 



