72 BULLETIN 852, U. S. DEPARTMENT OE AGRICULTURE. 
puted,from which other similar chutes could be designed from a 
capacity standpoint without regard to the actual velocity attained. 
However, we do know, from experiments made on open-channel 
concrete chutes, that the value of n in the Kutter formula must be 
raised 0.002 to 0.004 when a chute is designed from a capacity 
standpoint - 1 In other words, the series of experiments on this 1 0-inch 
pipe chute indicates that a value of n of about 0.014 or 0.015 should 
be used in designing for capacity, instead of the values as shown in 
Table 11, namely, about 0.0119. 
A view of one of these pipe chutes, in course of construction, and 
showing the vertical curve mentioned above, is given on Plate 
XXVIII in Volume II of Prof. Etcheverry's work. The writer 
believes this view is of the 10-inch chute discussed above. 
No. 52, Experiment S-41. — 36-inch jointed concrete flow line, 
Colorado Power Co., near Nederland, Colo. — In 1909 a flow-line 
conduit 12 miles in length was laid down the canyon of Middle 
Boulder Creek from the dam at Barker Reservoir to a small reservoir 
about 4 miles from Boulder, Colo., and about 2,000 feet in elevation 
above the creek bottom, where one of the plants of the Colorado 
Power Co. is located. This conduit is laid on an even gradient of 5 feet 
per 1,000 feet of pipe, except where inverted siphons are required 
to cross gulches and draws leading into the canyon. An article 
describing this installation says: 2 
The 3-inch shell of the pipe that is laid on the hydraulic grade consists of one part 
Portland cement and three parts aggregate, graded from sand to stones having a 
maximum dimension of 1 inch. The pipe was cast in sections 2 feet long, with 
socket on one end and a bevel on the other end of each section to form the joints. 
Each section contains two hoops of No. 5 steel wire having a high tensile strength, 
one hoop being placed 6 inches from each end. These hoops are not considered to 
be of much value as reinforcing, but rather as an aid in preventing breakage before 
the concrete has set. The line of the conduit is very crooked, the longest tangent 
not exceeding 500 feet. Straight and beveled pipe were employed together to build 
the conduit on curves. The latter were located so their radii were as nearly uniform 
as possible, requiring only two kinds of beveled pipe. 
The mixture was placed hi rather dry layers 3 inches thick and 
carefully tamped. This allowed the forms to be pulled immediately 
after which the pipe section was kept thoroughly wet for 7 days, then 
the inner surface of the the sections was coated with a thick wash of neat cement to 
fill all irregularities. This surface was thus finished quite smooth, and, with the 
manner in which the joints were made, produced a conduit having a large carrying 
capacity. 
During the season of 1915 the writer conducted a series of experi- 
ments upon the carrying capacity of a portion of this conduit near 
the upper end. A reach 1,977 feet long was chosen. Open stand- 
pipes near each end of the reach and approximately each 500 feet 
between the ends gave opportunity for measurement of the pipe 
segment not occupied by the water at five evenly spaced stations on 
the reach. For each run the quantity of water flowing in the pipe 
was varied by regulation of the outlet gates of Barker Reservoir. 
The velocity of the water in the flow line was determined by accepting 
i The fact that the fundamental hydraulic equation Q=A Fdoes not hold for chute drops, where high 
velocities, wave action.and turbulence exist, was first called to the attention of the writer by Mr. W. G, 
Steward, of the United States Reclamation Service. The results of his experiments, which have been 
corroborated in essentials by those of the writer, are found in Irrigation Practice and Engineering, by 
B. A. Etcheverrv, Vol. Ill, p. 261. 
2 Engin. Rec, Nov. 6, 1909, vol. 60, p. 514. 
