THE FLOW OF WATER IF CONCRETE PIPE. 33 



rough to the, touch in the usual washed-cement pipe way. The 

 discharge was measured over the rectangular, contracted weir shown 

 in the plate (fig. 1). The crest is 3.02 feet long, the end contractions 

 each 1 foot, and the bottom contraction more than 3 feet. For two 

 observations the end contractions were very slightly less than twice 

 the depth on the weir crest; for the others the end contractions 

 exceeded twice the depth. Elevations of the water surface above 

 the weir crest were determined with the hook gauge shown in the 

 stilling box. The mean inside area of the pipe line was taken as the 

 average area of 10 samples of the pipe remaining from construction. 

 This area was 2.106 square feet, while the area of a true 20-inch pipe 

 is 2.182 square feet. Thus this pipe is 3.5 per cent under size. The 

 velocity of the water in the pipe was found by dividing the discharge 

 in second-feet by the area of the pipe in square feet. This line was 

 laid in 1911, thus being in its fifth year of operation at time of test. 

 The coefficient tf, = 0.313. 



No. 18, Experiment $-60. — 20-inch jointed reinforced concrete pipe, 

 Temescal Water Co. , Corona, Calif .—Water for irrigation and domestic 

 use is conveyed through 27,000 feet of plain concrete pipe flow line 22 

 inches in diameter and over 15 depressions which require inverted 

 siphons. 1 Of these, 13 are of reinforced concrete, 20 inches in diameter. 

 One of the longest of the siphons, about 4 miles from Corona, was 

 chosen for experiment. Open standpipes occurred near both inlet 

 and outlet of the siphon. Water columns attached to piezometer 

 tubes of type A were used at both ends of the reaches chosen. For 

 observations 1, 2, and 3, piezometer tube No. 1 was thrust 9.8 feet 

 down the line from the standpipe at the inlet. For observations 4 

 and 5 a hole was tapped in the top of the concrete pipe 101.7 feet 

 from the intake manhole and the piezometer tube thrust 6 feet 

 farther down the pipe. For all observations piezometer No. 2 was 

 set in the pipe 0.8 foot upstream from a hole tapped in the concrete 

 pipe 98.7 feet upstream from the manhole at the outlet. Velocities 

 were ascertained by the use of solutions of potassium permanganate 

 and of fluorescein. For observations 1, 2, and 3 the color was 

 injected in the manhole at the inlet, while for observations 4 and 5 it 

 was injected at the tap in the concrete pipe 101.7 feet from the man- 

 hole. For all observations the color was observed at the manhole 

 near the outlet. This pipe was cast on the ground in units 3 feet 

 long. For moderate heads a 1 : 2 : 4 mixture of cement, sand, and 

 gravel was used and for higher heads the mixture was changed to a 

 ration of 1 : 2 : 3. All units were "washed " with cement grout before 

 being laid. This siphon is straight in horizontal alignment but is on 

 practically one long double-reverse vertical curve, the maximum head 

 being about 80 feet, while the total length from manhole to manhole 

 is 2,273 feet. The water is very clear and this siphon is undoubtedly 

 absolutely free from debris, as all sand must pass more than 15 other 

 siphons before reaching this one, the flow line between this siphon 

 and the next one upstream being but 300 or 400 feet long. One 

 blow-off valve is located at the low point of the siphon. The pipe 

 was laid early in the year 1911 and was thus about 5 § years old at the 

 time of the experiment. So far as could be determined from the low 

 standpipes, the joints were well smoothed and this pipe is probably 



1 Engin. Rec, vol. 64, Nov. 4, 1911, p. 526. 

 164725°— 20— Bull. 852 3 



