44 BULLETIN 376, U. S. DEPARTMENT OF AGEICULTUEE. 



straight. There is one summit, as shown by the view. The maximum head is 74 

 feet. Water columns were used for both gauges. Gauge No. 1 was located 88.8 feet 

 from the inlet. Gauge No. 2 was located 5,965.9 feet from gauge No. 1 and 115.7 feet 

 from the outlet. Velocity within the pipe was determined by fluorescein tests, the 

 mean time of travel of five batches of color being accepted. Levels were determined 

 by static head ; that is, on one visit to the pipe it happened that no water was running, 

 so simultaneous readings at both gauges, taken 10 seconds apart for 1 minute, gave a 

 true water level. The extremely slow fall of the water surface throughout these 

 readings indicated that the leakage was negligible, which fact was also apparent to 

 the eye. As well as an examination of the pipe outlet would disclose, the pipe was 

 clean and smooth on the interior, though an examination of the long, low stretch 

 across the marshy bottom of the swale might have shown deposits. The writer does 

 not believe this likely, however, for the reason that the water flows for about 6 miles 

 in open channels at comparatively low velocities before reaching the intake, and in 

 these channels the heavier sand would have precipitated, leaving the water little 

 more than clouded. The one observation at the commercial velocity indicates the 

 capacity of this pipe to be about 10 per cent greater than that computed by the new 

 formula. 



No. 40, Expt. S-6, 4:0-inch Continuous-Stave Douglas Fir Siphon Pipe, 

 Burbank Co., Washington. — Irrigation water is conveyed across a depression 

 between two sections of open channel by a cotitinuous-stave siphon, built in Decem- 

 ber, 1912, along the west side of section 6, township 8 north, range 31 east. This pipe 

 was constructed on the surface of the ground and supported on cradles. At the time 

 of these experiments, therefore, it was in its second irrigation season. As shown by 

 the profile in Plate III, figure 1, there is one summit on the reach tested, but as this 

 is protected by a standpipe, there was probably no air accumulation at the summit 

 at the time of this test. Although the pipe is about 2,900 feet long, a reach 927.4 feet 

 long was chosen near the outlet end for the reason that there is a diversion from the 

 lowest point of the pipe. Gauge No. 1, a mercury manometer, was located 1,049.6 

 feet above the outlet and gauge No. 2, a water column, was located 122.2 feet above 

 the outlet. The water divided in the outlet structure, flowing in two directions, one 

 stream continuing in an earth channel and the other in a concrete-Uned channel. 

 The discharge in the pipe was determined by the sum of the flows in these two chan- 

 nels, as measured by current meter. The nominal area of the pipe was accepted as 

 correct. At velocities exceeding 2 feet per second, it was noticeable that sections of 

 the pipe immediately following the sharpest vertical curves vibrate about 1 inch, 

 vertically, upon the cradles. This emphasizes the necessity for securing anchorage 

 at bends. The two observations taken at commercial velocities indicate the capacity 

 of this pipe to be about 3 per cent greater than that computed by the new formula. 



No. 42, Expt. S-9, 48-inch Continuous-Stave Redwood Siphon Pipe, 

 Cowiche Siphon, Yakima Valley Canal Co., Washington. — Water for irrigation 

 is conveyed across Cowiche Canyon, about 4 miles from North Yakima, Wash., in a 

 redwood siphon built in January, 1914. (PI. IV, fig. 1.) Gauge No. 1, a mercury 

 manometer, was located 67.3 feet from the inlet (PL III, fig. 2), while gauge No. 2, a 

 wat«r column, was located but 7.6 feet from the outlet. The inlet to the pipe is at 

 the bottom of a concrete well about 10 feet deep. Subsequent tests to determine entry 

 losses showed that much air was entrained and carried into the pipe, but no influence 

 of air was apparent at gauge No. 1, which was attached to the pipe at the mid-point 

 of its left side. From the intake to gauge No. 1 the pipe is straight. This is likewise 

 true of the pipe for about 100 feet before gauge No. 2 is reached. For the balance of 

 the distance between gauges the pipe is virtually one long vertical curve, as it is under 

 a maximum head of about 100 feet and the total length is but 962.3 feet. The pipe 

 has but one gentle bend in horizontal alignment. For each of the several runs made 

 with different velocities in this pipe fluorescein was timed from inlet to outlet, the 



