30 BULLETIN 852, U. S. DEPARTMENT OE AGRICULTURE. 
elevation of the water in a delivery box 7S5.1 feet from gauge Xo. 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 
o^auge 1. TVater 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 Xo, 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. 
Xo. 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 cmiet so that hook gauge 
readings could be taken directly, no stilling box being necessary. 
Gauge and piezometer Xo. 2 were like those described under Xo. 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 rim 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 
Xo. 1, p. 25). The line is well laid, in comparison with other 1SS3 
pipes, the value of C s being about 0.304. 
No. 11, Experiment S-25. — 16-inch jointed cement pipe, Irrigation 
Co. of Pomona, Calif. — Immediately upstream from the reach of pipe 
discussed as Xo. 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 practicable 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 Xo. 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 Xo. 2 of this reach was gauge Xo. 1 of reach Xo. 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 (Xo. 10), upon which 
several observations were possible. The value of C s is 0.306. 
