THE FLOW OF WATER IN CONCRETE PIPE. 27 
outlet of the pipe to another division box. The mean velocity of 
four batches of color was taken as the velocity of the water for each 
of the two runs of water. Unfortunately it was not practicable to 
vary to a marked degree the quantity flowing in the pipe. The 
high velocities in this pipe and the clear water probably assure a 
pipe free from sediment. This is borne out by the value of C s = 0.287, 
the increase in this coefficient marking the improvement in the joints. 
No. 4, Experiment $-20. — 12-inch jointed cement pipe, Irrigation 
Co. of Pomona, Calif. — After passing through the reach of pipe 
described as No. 1, water may be delivered to the consumer or enter 
this reach of 12-inch pipe between boxes 89 and 90, on Franklin 
Street, Pomona. 
Water columns were used for both gauges, which were attached to 
peizometer tubes of type A, No. 1 being placed 10 feet down the line 
from the inlet and No. 2 being thrust 2 feet up from the outlet. 
Velocities were computed from the mean time of three batches of 
fluorescein, poured into the inlet and noted at the outlet. The color 
dragged out from 10 to 14 per cent of the total time spent in the 
pipe, indicating a very rough interior. 
Little is known of the condition of this pipe, as it was laid about 
1885. The nominal diameter was accepted in computing area and 
quantity of water (see No. 1, p. 25). So far as could be ascertained 
at the inlet and outlet, the line is free from silt. It has never been 
necessary to dig up the pipe on account of root troubles, although 
it is very close to a row of trees. The line is buried about 3 feet, is 
straight, and nearly level. The water is clear at all seasons of the 
year. The poor joints are indicated by the coefficient 0.250. 
No. 5, Experiment S-26. — 12-inch jointed cement pipe, Irrigation 
Co. of Pomona, Calif. — Water for this irrigation system is secured 
from wells located on a gravel and boulder subterranean reservoir, 
locally termed a "cienaga." Dikes of impervious material cut off 
the flow in the gravel, forming a natural reservoir. The water from 
several wells is piped to one circular collecting chamber, while two 
pipes from this chamber permit the water to be conveyed to either 
one or both of two portions of the main pumping plant. One of these 
latter pipes 193 feet in length was tested. With a constant draft, 
the discharge of either pipe could be varied by head gates at the upper 
end of each pipe. Thus it was possible to vary the velocity in the 
pipe under test from 1.50 to 3.63 feet per second. For each obser- 
vation the mean velocity of from 5 to 10 weighted floats was accepted 
as the velocity of the water between the intake chamber and a 
vertical riser pipe. These floats were made as follows: Small wire 
nails were thrust into an orange until it was of the same specific 
gravity as the water, showing little tendency to either float or sink. 
The pipe tested was under about a-4-foot head throughout its length, 
so that there was no tendency for the oranges to become heavier 
during passage through the pipe due to increasing water pressure, 
as is the case when a float of this nature is tried on a siphon pipe 
where the maximum head is much greater than the depth of the 
water in which the orange is tested while nails are being inserted. 
Of course, if a float in a pipe is too light it drags against the top of the 
pipe and if too heavy it drags along the bottom, in either case being 
impelled by velocities slower than the mean velocity in the pipe. It 
was thought that the round form of the orange would cause it to roll 
