38 BULLETIN 852, II. S. DEPARTMENT OF AGRICULTURE. 



pump was lifting water to the outlet of the 24-inch pipe. On reach 

 No. 28b a water column was used as gauge 1 and a mercury manom- 

 eter as gauge 2. On reach No. 28 the water column was moved 

 667.6 feet nearer the inlet, but the mercury manometer remained 

 the same as before. Air troubles at gauge 1 were minimized by the 

 device shown in Plate V, figure 1. Piezometer tubes of type A were 

 used for both gauges, No. 1 being slipped into the pipe through a 

 one-eighth-inch wrought-iron nipple, while No. 2 was thrust down 

 an air valve. Velocities were determined by timing fluorescein from 

 its injection at gauge 1 to its appearance at gauge 2. For drawing 

 off the colored water a "gooseneck" of one-fourth-inch brass pipe 

 was inserted down the air valve and the color detected in a white- 

 lined pan. 



For some reason that the writer is not able to explain the friction 

 factors are erratic and inconsistent. 



No. 29, Experiment $-36. — 36-inch jointed reinforced concrete 

 pipe, Deer Flat Forest pipe line, Boise project, United States Reclama- 

 tion Service, Idaho. — Water for irrigation is conveyed across a wide 

 depression, just below the dam of Deer Flat Reservoir, in a concrete 

 siphon pipe 8,575 feet long and 36 inches inside diameter. 1 As 

 shown in Plate IV, figure 1, this line is straight in horizontal align- 

 ment and without vertical curves other than two gentle bends at the 

 bottom of the slopes near the inlet and outlet. The maximum head 

 is about 70 feet. 



The pipe units, 6 feet in length, were cast on the ground in steel 

 forms. A very wet mixture of 1 part cement to 2\ parts sand and 3 

 parts well-graded gravel resulted in a dense concrete. The shell is 

 3 inches thick, reinforced with five-sixteenth-inch wire. As shown 

 in the plate, the joints were made with reinforced collars, each 3 

 inches thick and 8 inches wide in addition to the usual bevel and 

 taper. The joints were calked on the inside with great care, the 

 mixture used being 1 part cement to 2 of sand and tempered with 

 hydrated lime in the proportion of 10 per cent of the cement by 

 volume. 



A reach of this pipe 7,282 feet long from the foot of the first slope 

 to the outlet was chosen for test. Gauge No. 1 was a mercury 

 manometer attached to the pipe at a small hole through a cast-iron 

 manhole cover. At the outlet a piezometer tube of type A was 

 thrust 2 feet into the pipe, and the pressure head conveyed by tubing 

 to a stilling box within the outlet chamber, the elevation of the 

 water in the box being determined by a hook gauge. 



Unfortunately, in 1915 it was not feasible to vary the discharge 

 through the pipe, so only one observation could be made. The 

 velocity of the water was determined by accepting the mean of five 

 batches of fluorescein, injected at gauge No. 1 and observed at the 

 outlet. Accepting the mean diameters of 6 units of pipe remaining 

 from construction, 2.999 feet, as the mean diameter of the pipe line, 

 then the discharge was 24.6 second-feet, while the mean discharge 

 over a weir below the outlet was 24.3 second-feet and the discharge 

 as measured by a Price current meter, using the integration method, 

 was 24.57 second-feet, and using the 0.2 and 0.8 depth method was 

 25.15 second-feet (see Table 2, p. 18). 



1 Engin. News, Aug. X, 1912, vol. us, p. 2 is. 



