30 BULLETIN 852, TJ. S. DEPARTMENT OF AGRICULTURE. 



elevation of the water in a delivery box 785.1 feet from gauge No. 1. 

 For run 1, readings were taken by a plumb bob attached to a steel 

 tape and allowed to scratch the water surface in the riser pipe at 

 gauge 1. Water entered and left this riser pipe in the same straight 

 line, so insuring that there was practically no loss of head within the 

 riser (see No. 1). Examination of the inlet and outlet of this line 

 indicated that there was no deposit upon the surface of the pipe. 

 The mean time of two batches of fluorescein was accepted in computing 

 the mean velocity of the water. The capacity of this line is about as 

 indicated in Table 6. 



No. 10, Experiment S-22.— 16-inch jointed cement pipe, Irrigation 

 Co. of Pomona, Calif. — This reach of pipe, laid in 1883, comprises 

 part of a main trunk line conveying water from the pumping plant to 

 minor pipe laterals. A straight section between boxes 36 B and 37 

 was chosen for test. Box 36 B is a single piece of riser pipe set 

 directly over a rough hole in the trunk line about 8 inches square. 

 The surface of the water in the riser was quiet so that hook gauge 

 readings could be taken directly, no stilling box being necessary. 

 Gauge and piezometer No. 2 were like those described under No. 9, 

 the piezometer tube being held 3.2 feet up the pipe line against the 

 current. The water was clear and no sediment in the pipe was seen 

 through the hole at box 37 B mentioned above. The pipe is on an 

 even down grade, at no place under more than 3 feet of head. From 

 three to five batches of fluorescein were timed for each run of water 

 and the mean time was accepted in computing the mean velocity of 

 the water for that particular observation. In order to secure runs 

 at varied discharges it was necessary to return to this pipe from day 

 to day and take an observation at the discharge then carried. The 

 regimen of flow for each run was thus fully established. The nominal 

 diameter was accepted in computing area and quantity of water (see 

 No. 1, p. 25). The line is well laid, in comparison with other 1883 

 pipes, the value of G g being about 0.304. 



No. 11, Experiment 8-25. — 16-inch jointed cement pipe, Irrigation 

 Co. of Pomona, Calif. — Immediately upstream from the reach of pipe 

 discussed as No. 10, a section of the same 16-inch pipe, 1,897.6 feet 

 long, between a masonry division box and delivery box 36 B was 

 available for test. It was ]^racticable to secure but one observation on 

 this line, however, for the reason that the pipe was full at the intake 

 end only when the maxium amount of water then needed was flowing. 

 The nominal diameter was accepted in computing area and quantity 

 of water (see No. 1, p. 25). A hook gauge in a stilling box was used 

 at the upper end. The stilling box was attached by pressure tubing 

 to a piezometer tube of type A, thrust 8.4 feet down the pipe line. 

 Gauge No. 2 of this reach was gauge No. 1 of reach No. 10 (for 

 description of which see this page). This pipe is laid on a gentle 

 down grade with one S curve in horizontal alignment as it is carried 

 around a residence. At no point is it under more than 3 or 4 feet 

 of head. Examination at inlet and outlet showed this pipe to be 

 free from sand or deposits. The water is clear at all times, being 

 pumped from a subterranean bowlder reservoir (cienaga). A glance 

 at Plate VI shows that the loss of head in this reach is practically 

 identical with that in the adjoining reach (No. 10), upon which 

 several observations were possible. The value of C s is 0.306. 



