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 55|-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. Diu-ing 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 55f-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 55| 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.^ — 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 

 aa 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 ab.out 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. 553^-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. 



