44 BULLETIN 852, U. S. DEPARTMENT OE AGRICULTURE. 
capacity is greater than a value of n of 0.012 would indicate. Air 
troubles in gauge No. 1 caused inconsistent results for this series, and 
for this reason full weight should not be assigned to the tests. The 
values of C s range from 0.380 to 0.434, and the corresponding values 
of n from 0.0116 down to 0.0101. During the season of 1917 the 
writer again visited this pipe while it was carrying far more water 
than for any of the observations made in 1915, but the air troubles 
were even greater than before, so experimentation was considered 
out of the question. This pipe shows the need of "air chimneys" 
near the intake if maximum efficiency is to be reached. 
No. 37, Experiment S-59. — 120-inch monolithic concrete pipe, 
Whitney siphon, Los Angeles Aqueduct, California. 1 — The Whitney 
siphon, on the Saugus division, is 955 feet long, 10 feet inside diameter, 
with a shell 9 inches thick, and is subject to a head of about 75 feet. It 
conveys water for municipal and irrigation purposes across a narrow 
canyon, between two flow-line tunnels. The sides of the canyon have 
a slope of about 3 feet horizontal to 1 foot vertical. 
The pipe was constructed in place, smooth wood forms being used 
for both inside and outside surfaces. 
The interior of the pipe was treated with a finish coat of rich cement 
mortar. The grit of the sand in this coat was very noticeable to 
the touch at the time of experiments in 1916. 
A reach of the siphon pipe below the level of the floor of the flow- 
line at both inlet and outlet was chosen for test. Holes were drilled 
through the top of the shell and one-eighth-inch iron-pipe nipples, 
each 18 inches long, were cemented into the shell. (The hole lor a 
one-eighth-inch pipe is nearly one-fourth inch in diameter.) Two 
piezometer tubes of type A, exactly alike in construction, were 
thrust into the pipe through the nipples. The tapering end of these 
tubes was made flexible by a small rubber-hose joint with the main 
tube, so that the current might hold each piezometer in the direction 
of flow by means of the flattened taper, like a vane. 
The flow-line channel is tapered into the round section of the 
siphon pipe by means of transition sections at each end of the siphon. 
Between the transition sections and the flow-line sections manholes 
are placed at both inlet and outlet. 
The tap for gauge No. 1 piezometer was 59.2 feet downstream 
from the manhole at the inlet, while the tap at gauge No. 2 was 61.1 
feet upstream from the manhole at the outlet. The holes in each 
piezometer tube were 3.6 feet downstream from the taps in the pipe. 
This made the reach between piezometers 857.4 feet long. Water 
columns were used at both gauges. 
The nominal size of the pipe was accepted in the computations. 
The velocities were determined by timing the passage of solutions of 
fluorescein, injected at gauge No. 1 and observed at the manhole 
beyond gauge No. 2, correction being made for the fact that the 
channel is not full for part of the distance between gauge No. 2 and 
the manhole. 
Experience with this pipe showed that satisfactory tests can not 
be made on a reach of pipe that is relatively short, compared with the 
size of the pipe, especially for low velocities. The loss of head for 
i Construction of the Los Angeles Aqueduct, Final Report, Los Angeles, Calif., 1916, pp. 210,214. 
Engin. Con. July 3, 1912, p. 20. 
