THE FLOW OF WATER IN WOOD-STAVE PIPE. 79 
prevent the attachment of growths. The capacity of this pipe was about 11 per cent 
less than the discharge computed by the new formula, 
No. 43. 48f-inch Continuous-Stave Douglas Fir Siphon Pipe, Mabton 
Pressure Pipe, Sunnyside Project, U. S. Reclamation Service, Washington. — 
Under and adjacent to the Yakima River the Mabton pressure pipe is reduced in size 
from the 55f-inch pipe tested by Moritz and described as Nos. 45 and 46, page 79, to a 
48f-inch pipe of similar construction. At the time of the test the pipe had been in 
operation two and one-half irrigation seasons. During this time the mean velocity 
had been about 5.4 feet per second. The discharge was measured during the tests in 
the same way as that used for Nos. 45 and 46. Several diameters were measured at 
the time similar measurements were made on the 55 f -inch pipe. Mercury manometers 
were used for both gauges. The mean of these three observations indicates that the 
capacity of this pipe was about 20 per cent greater than the discharge computed by 
the new formula. This same excess of capacity is shown in the other portions of this 
siphon, discussed as Nos. 45 and 46. Subsequent to the tests described by Moritz, 
J. S. Moore experimented upon the portion of the Mabton pressure pipe below the point 
where the reduction from 55f inches to 48| inches in diameter was made. These tests 
are all described in the same publication. (See footnote under Nos. 2-3.) 
No. 44. 54^-inch Continuous-Stave Douglas Fir Pipe, Municipal Water 
Supply, Seattle, Wash. 1 — T. A. Noble conducted a series of tests for loss of head by 
friction in the reach of 54-inch pipe between the intake at the dam and the settling 
basin. As the line follows the sinuosities of Cedar River, it consists of gentle curves 
joined by short tangents. The minimum radius of curvature is 289 feet. From the 
appearance of the profile the pipe is laid on an even gradient, with the exception of 
one slight depression, where a blow-off is located. As a summit is reached after this 
depression, a 3-inch standpipe is carried above the hydraulic gradient. Holes for 
the attachment of the piezometers were made by boring with an ordinary wood bit 
until the tip of the bit pierced the inside of the pipe, making a hole about three-six- 
teenths inch in diameter. This method was afterwards adopted by Moritz for his 
experiments. The pipe had been in use about 10 months at the time of test. Gauge 
No. 1, a water column, was located 232 feet from the intake, while gauge No. 2 was a 
hook gauge in a well at the outlet of the pipe near the settling basin, 2,446.7 feet below 
gauge No. 1. The zero points of the various gauges were connected by lines of levels 
run by three different observers, the mean of the two nearest together being accepted 
as correct. Noble states that the probable error does not exceed 0.007 foot. The 
discharge was very carefully measured by an elaborate series of current-meter tests. 
For this purpose the area of the pipe was divided into four concentric zones, and each 
zone was covered with a sufficient number of meter readings to develop fully the mean 
velocity within that zone. In all, the meter was held at 50 points. The interior size 
of the pipe was carefully measured some two months after the tests. Vertical and 
horizontal diameters were taken every 100 feet. The resulting figures indicate that 
the pipe was badly distorted in several places. Growths of Spongilla in scattered 
bunches, each about one-fourth square inch in area and projecting about three-six- 
teenths inch, were distributed over the inside of the pipe, except along the bottom. 
The capacity of this pipe was about 2 per cent less than average, probably accounted 
for by the growth within the pipe; but the 44-inch pipe downstream from this one 
lacked an average capacity by 11 per cent, with no growth inside. 
Nos. 45 and 46. oo^-inch Continuous-Stave Douglas Fir Siphon Pipe, 
Mabton Pressure Pipe, Sunnyside Project, U. S. Reclamation Service, Wash- 
ington. — Irrigation water is conveyed across the valley of the Yakima River by a 
siphon pipe carried under the river. At the intake end water in an open channel 
passes over an 18-foot rectangular weir into a 54-inch reinforced-concrete pipe. At 
1 Trans. Amer. Soc. Civ. Engin., 49 (1902), p. 112. 
