Frictional Resistance in Artificial Waterways 21 
of seven percent. At Mile Post No. 9 the chute has a bottom width 
of 13 feet, side slopes 1 to 2 and a grade of seven percent. The 
length of section tested on the former was 201 feet and on the lat¬ 
ter 142 feet. There was also a section 730 feet in length between 
stations 4 b 9 'T 45 an d 49 6 ~F 75 > which was tested. This has a bot¬ 
tom width of 13 feet, side slopes 1 to 2, and a grade of .15 percent. 
In Table 7 the sections are designated as (a), (b), and (c) 
respectively. 
Fortunately, near the upper and lower ends of the chutes, 
beams had been placed over the channel as a means of reinforcing 
the sides against earth pressure, and from these, cross-sectional 
and slope measurements were taken. (Plate VII.) For the other 
section the rodman used a fireman’s ladder placed against the side 
slope and held from above, as a means of getting the elevation of 
the bottom of the channel and the water surface. On chutes of 
heavy grade, depths in a section were measured perpendicularly to 
the bottom, rather than in a vertical direction. 
The results of these tests show an average value of (n) to 
be .0161 for this kind of lining, which, as would naturally be ex¬ 
pected, is somewhat higher than that of the cement, or mortar¬ 
faced lining. 
TABLE 7 
HYDRAULIC ELEMENTS OF CONCRETE-LINED CHANNELS AND CHUTES. 
Discharge sec-ft. 
Area of Wetted 
Section sq-ft. 
Velocity sec-ft. 
Wetted Perimeter 
lin. ft. 
Hydraulic Mean 
Radius 
Slope feet 
per foot 
[ 35.79 
2.78 
12.87 
5.68 j 
.489 
.02978) 
I 78.32. 
4.29 
18.26 
6.36 
.674 
.02968 
100.38 
5.61 
17.89 
6.96 
.806 
.02943) 
104.47 
£>.17 
20.21 
6.76 
.765 
.02990| 
122.94 
6.24 
19.70) 
7.24 
.862] 
.02971) 
1154.00 
9.76 
15.78) 
10.oo | 
.942 
.01459) 
89.80) 
5.78) 
15.52) 
11.28) 
.514) 
.07180) 
59.68) 
5.28) 
11.32 j 
13.92) 
.379) 
.07230 
111.30 
23.66 
4.71 
16.82 
1.406) 
.00151) 
Long- 
Long - 
Long 
Long 
Long 
Dry 
Name of 
Channel 
Pond 
Pond 
Pond 
Pond 
Pond 
Creek 
Chute 
Chute 
Chute 
Chute 
Chute 
G 
o 
•pH 
O 
0> 
in 
O 
he 2 
G w 
0 ) 0 ) 
E-* 
J 600 
1600 
.| 600 
.[600 
.[600 
Flume .1514.5 
South Canal (a).1201 
South Canal (b).[142 
South Canal (c).1730 
o 
G 
o> 
o 
O) 
o 
O 
c 
0> 
a> 
o 
U 
106.6 j 
128.9 | 
116.11 
133 . 5 ) 
122.91 
134.5 [ 
80 . 8 ) 
68.4 [ 
102.11 
.0125 
.0113 
0128 
.0111 
.0123 
.0115 
0158 
,0171 
0155 
EARTH CHANNELS 
These investigations were made chiefly upon some of the 
larger canals of the Arkansas, San Luis and Grand Valleys. The 
main object in view was to ascertain the amount of frictional re- 
