THE PLOW OS WATER IF CONCRETE PIPE. 20 



locity as above determined with that found by dividing the discharge 

 by this mean area, shows agreement with the mean of the two meas- 

 urements of 1.2 per cent. The discharge was measured over a 2-foot 

 contracted, rectangular sheet-iron-crested weir, with end contractions 

 greater than 2A, bottom contraction about 5 feet, and Ji less than one- 

 sixth of the length of the weir. The water welled Up from the bottom, 

 so that velocity of approach was negligible. This pipe was laid in 

 1900. A comparison of the zone occupied by points representing 

 this pipe with that of pipes 1, 2, 3, 4, 5, 9, 10, and 11 shows the 

 progress made since the early eighties in the matter of smoother pipe 

 pipe interiors and better joints, the value of € s for this line being 0.345, 

 an exceptionally high value for "dry-mix" pipe. 



No, 8, Experiment S-SS.— 12-inch jointed concrete pipe, J. W. 

 Crane private lateral near Oakdale, Calif. — From one of the laterals 

 of the Oakdale irrigation district water is conveyed down a gentle 

 hillside to the fields by means of a concrete pipe line. A reach 1 ,850.8 

 feet long was chosen for test, between the intake and an outlet 

 hydrant in a riser pipe. The reach has one gentle curve in horizontal 

 alignment and a slight sag near the far end. Water columns were 

 used for both gauges, which were attached to piezometer tubes of 

 type A. Ho. 1 was placed 4.4 feet down the pipe from the intake 

 chamber, while No. 2 was thrust up into the line 6.4 feet from the 

 riser pipe. Gauge No. 2 was a glass tube, while gauge No. 1 was a 

 hook gauge noting the surface of the water in a stilling box. Thus 

 a correction for capillarity was necessary in computing the elevation 

 of the water column for gauge No. 2. Between the inlet and the 

 second gauge are 21 riser pipes each 1 foot high, capped with a hydrant. 

 The interior of the pipe was examined through several of these hy- 

 drants and found to be clean of silt, but with rough joints between the 

 2-foot units of pipe. The line was constructed by a man rather new 

 in the business and the value of smooth joints was not appreciated 

 as it now is in southern California. This is shown by the fact that C s 

 ia but 0.245. Measurements of the pipe interior through these hy- 

 drants showed the average diameter to be 0.985 foot or that the area 

 of the pipe was about 97 per cent of the area of a 1-foot pipe. The 

 measured area was used in computations. Velocities were deter- 

 mined by injecting saturate solution of potassium permanganate 

 into the upper end of the line and observing the first and last appear- 

 ance of the color at an open hydrant 55 feet beyond the hydrant at 

 fauge No. 2. A few small leaks were evidenced by moist ground, 

 ut the use of color in determining velocities automatically takes care 

 of any correction for such leaks, the velocity of the color dropping in 

 proper proportion and at the proper time as each leak is reached. 



No. 9, Experiment S-24. — 1 6-inch jointed cement pipe, Irrigation 

 Co. of Pomona, Calif. — A second reach of the same main pipe line dis- 

 cussed as No. 10 was tested between boxes 91 and 92. This part of the 

 line runs diagonally under an orange grove, but, although it was laid in 

 1883, roots have never interfered with the flow of water. It is straight, 

 on a gentle down grade, and buried about 2 feet. There was one 

 riser pipe in the reach tested. The nominal diameter was accepted in 

 computing area and quantity of water (see No. 1, p. 25). Except for 

 run 1, both gauges consisted of hook gauges in stilling boxes, No. 1 

 being attached by pressure tubing to a brass piezometer of type A, 

 located 16.2 feet down the pipe line, while gauge No. 2 records the 



