82 BULLETIN 376, TJ. S. DEPARTMENT OF AGRICULTURE. 
No. 15 and No. 21. 10.12-inch and 16.12-inch Jointed Pipe, Bonito Pipe 
Line. — The tests on this line were mentioned in the original publication of this 
bulletin (see pp. 11 and 75). Since then Mr. Campbell has supplied the data 
for computing the mean velocities as from time of injection of color or bran to 
the mean between first and last appearances. The results are given in Table 9. 
Like nearly all of the data on pipe capacities, there is a lack of consistency in the 
results. The tests were made with two years' interval between the first set and 
the second set and a similar interval between the second and third sets. If the 
tests are indicative of true conditions, then the capacity of both pipes increased 
during the first two years and then decreased again. At their face value the 
capacity of the 10-inch line appears near 5 per cent in excess of our formula 
capacity and the 16-inch line above 15 per cent. 
No. 55. 30-inch Continuous-Stave Redwood Pipe. Norfolk, Va., Supply 
Main. 3 — In 1922 the city of Norfolk finished a new supply main some 98,000 
feet long. This main employs three kinds of pipe — concrete, cast-iron, and red- 
wood staves. Five sections, comprising 73,750 feet in aggregate length, were 
tested for friction losses. Two of these sections, composed of the redwood 
staves, offer additional data for this bulletin. (See No. 56 below.) 
The reach of 30-inch pipe, tested when 2 years old under the direction of W. H. 
Taylor and N. Z. Ball, was 4,706 feet in length, relatively straight in both hori- 
zontal and vertical alignment. The discharge was determined by a Venturi 
meter which was checked before and after each test. The pressures at the ends 
of the reach were determined by mercury manometers, read simultaneously. 
These manometers were of the pot-and-column type, the column consisting of a 
rubber tube terminating in a gauge glass. The gauge readings, taken at five- 
minute intervals, were based on accurate levels over the pipe line. 
This single observation on a relatively new line indicates a capacity some 12 
per cent in excess of our formula. It will be interesting to watch the performance 
of this pipe line, as it is contemplated that these tests be repeated each year. Red- 
wood has a very smooth surface when first milled, as these tests indicate. 
No. 56. 36-inch Continuous-Stave Redwood Pipe. Norfolk, Va., Supply 
Main. — At the time of the test described under No. 55 above a similar test was 
made of a reach of 36-inch pipe of identical construction, but carrying a larger 
quantity of water. This reach, being 39,580 feet long, should yield the more 
reliable results as its great length causes such a gross loss of head as to completely 
overshadow experimental errors. The loss of head in this section indicates a 
capacity 12 per cent above our formula, which is reasonable for a new redwood pipe. 
No. 42. Expt. S-9 Continued. (See No. 42, p. 44.) — After a period of nine years 
the writer again visited the Cowiche siphon and set up gauges on exactly the 
same reach of pipe as before. The only difference of conditions was that the pipe 
was now 9.5 years old instead of 6 months. The velocity of 5.1 feet per second 
exceeded the highest velocity in 1914 of 4.84 feet per second and the gauge differ- 
ence indicated a deterioration in capacity of 5.4 per cent, if the loss of the two 
velocities nearest alike are compared. This might easily be accounted for by 
any slight accumulation of rock ravelings as the flume leading to the siphon un- 
doubtedly does catch some debris, being covered in the worst places but open in 
others such as a rock tunnel. 
No. 57. 67%-inch Continuous-Stave Douglas Fir Power Penstock. Munici- 
pal Light and Power Plant, Seattle, Wash.— In 1912 J. D. Ross offered the 
results of a series of tests on the penstocks made in connection with general 
tests of plant efficiency. 2 The loss of head was computed from the record of 
i Tests of Leakage, Friction, and Discharge in Norfolk Supply Main, by W. H. Taylor and Norman Z. 
Ball. Engin. News, Mar. 12, 1925, p. 446. 
2 Plant Efficiency, by J. D. Boss. Pro. Am. Inst. Elcc. Engineers, May, 1912, p. 467, Abstracted in 
Western Engineering, November, 1912. 
