THE FLOW OF WATER IN CONCRETE PIPE. . 85 



■with fine gravel not exceeding 1 inch in diameter. The sections were joined together 

 in the ordinary way with cement mortar mixed with 1 part cement to 2 parts fine 

 sand. The line has tangents ranging in length from about 100 feet to 500 or 600 feet, 

 and curves, none of which have a less radius than 15 feet. The slope was made uni- 

 form at the rate of 10.56 feet per mile. 



This pipe line delivered at its lower end, when filled to its full capacity, 9.2 second- 

 feet without any pressure at the intake, Which was provided with an enlarged section 

 for accelerating the flow of water in the pipe. It Was observed that the pipe did not 

 run full below the first 2,000 feet. Subsequently the upper 100 feet of the pipe were 

 raised to accelerate the water a little more, after which numerous tests Were made to 

 determine the greatest volume of water that could be passed through the pipe. From 

 this I found that the pipe Would carry the most Water when filled within 1 inch of 

 the top, or when carrying a depth of 21 inches of Water. Under this condition the pipe 

 delivered 9.8 second-feet of water. The discharge of the pipe was measured by means 

 of a rectangular, fully contracted Francis type of Weir in one-eighth inch steel plate, 

 and head taken with hook gauge. The depth of water in the pipe, from which the 

 velocity and hydraulic radius are computed , was measured by means of a straightedge 

 and hook gauge at the manholes, Which are located every 500 feet along the line. 

 Instead of using a trowel to make the joints, as is ordinarily done, I made a brass band 

 ring 10 inches wide, having spokes equipped with turnbuckles on the inside to vary 

 its diameters, the ring being flexible and lapped to permit reducing or enlarging 

 its circumference. 



In making the joints the pipes were carefully laid and evenly joined, and mortar 

 applied in the groove all around. Then the brass ring, reduced in diameter to slip into 

 place, was introduced and centered over the joint. By working the turnbuckles the 

 ring was then expanded to fit the diameter of the pipe and its inside circumference, 

 thus squeezing the mortar into the crack and the surplus out to the edges of the ring. 



Grasping the spokes, the ring was then turned around slowly about five times to 

 give the joint a smooth surface, after which it Was loosened and removed, and all 

 surplus mortar removed with a trowel, in such a manner as not t,o mar the surface left 

 by the ring. 



This method made the joint smoother than any other portion of the pipe, and, so far 

 as the eye could detect, made the pipe continuous on the inside. Had the same 

 method been used for the 31-inch pipe for Mill Creek No. 3 line (No. 51) and for the 

 36-inch pipe for Lytle Creek (No. 53) I have no doubt these would have given about 

 the same value for n in Kutter's formula. 



The nominal slope was used in computation. 



As shown in Table 11 the above test indicates the value of n to be 

 about 0.0116 for this pipe. If truly representing the inner surface of 

 the pipe, the joints were most carefully made and the pipe in excellent 

 condition. (See discussion No. 51 following.) 



No. 51, Experiment FF-2. — 31-inch jointed cement pipe of South- 

 ern California Edison Co. Mill Creek power plant, No. 3, Cali- 

 fornia. — The description of the experiment upon this line, as 

 taken from correspondence with Mr. Finkle, reads : 



The diameter of this pipe was 31 inches and it was given a slope of 10.56 feet per 

 mile. Its length was between 5 and 6 miles, with a few interruptions in the line, 

 where steel siphons were used to cross ravines. Having profited by my experience 

 regarding accelerations at the intake, showing that the pipe would be full at the upper 

 end and only partly filled at the lower end, I gave this line additional fall in its upper 

 part, calculated by a formula for that purpose. 



This pipe was manufactured in the same way as the 22-inch pipe (No. 50_, p. 84), 

 except that 1 part of cement was used and 4 parts of sand, containing considerable 

 gravel, the largest of which was 1| inches in diameter. It was made in 2-foot sections, 

 and laid in the same manner as the 22-inch pipe. The result was that the maximum 

 capacity of the pipe occurred when it was filled to within 1J inches of the top or 

 When it only carried a depth of water of 29^ inches. The carrying capacity of the pipe 

 under these conditions was 19.72 second-feet. 



This line was laid in 1901 and tested the same year. There are numerous curves 

 between the tangents of various lengths, but none of the curves has a radius of less than 

 20 feet. The discharge was determined by using a Francis type rectangular, fully 

 contracted Weir in three-sixteenths-inch steel plate, measuring head with a hook gauge. 

 (See PI. X, fig. 1.) 



The depths of water in the pipe, from which the velocity and hydraulic radius are 

 computed, were measured by placing straightedge along inside of upper invert on 



