34 BULLETIl^ 854, TJ. S. DEPARTMENT OF AGRICULTURE. 
Table 5. — Elements of experiments for clay tile poorly laid — Continued. 
12-INCH TILE— Continued. 
2 
Test No. 
2 
Depth 
of 
flow. 
id) 
3 
d 
D 
•! 
Area 
of 
flow. 
(a) 
5 
a 
A 
6 
Hy- 
draulic 
radius. 
{E) 
Dis- 
charge. 
(Q) 
S 
Ve- 
locity. 
(V) 
9 
Slope. 
(s) 
10 
Kutter 
coeffi- 
cieno. 
11 
Chezy 
coeflB- 
cient. 
iC) 
882 
Neet. 
0.756 
.636 
.549 
.450 
.356 
.929 
.849 
.709 
.700 
.638 
.519 
.428 
0.77 
.65 
.56 
.46 
.36 
.94 
.86 
.72 
.71 
.65 
.53 
.43 
Sq. ft. 
0. 6280 
.5207 
.4368 
.3394 
.2485 
.7455 
.6991 
.5877 
.5796 
.5225 
.4073 
.3178 
0.S2 
.68 
.57 
.45 
.33 
.98 
.92 
.77 
.76 
.69 
.53 
49. 
Feet. 
0. 2987 
.2830 
.2630 
.2320 
.1955 
.2847 
.2982 
.2941 
.2931 
.2834 
.2544 
.2240 
Cu.ft. 
per sec. 
1. 8025 
1. 2980 
.9820 
.5887 
.3231 
2. 8640 
2. 5800 
2. 1360 
2. 0380 
1. 7350 
1. 0260 
. 6265 
Feet 
per sec. 
2.870 
2.493 
2.248 
1.735 
1.300 
3.842 
3.691 
3.635 
3.516 
3.321 
2.519 
1.972 
0.0050 
.0050 
.0050 
.0050 
.0050 
.0075 
.0075 
.0075 
.0075 
.0075 
.0075 
.0075 
0. 0152 
. 0164 
.0170 
.0191 
.0137 
.0146 
.0147 
.0150 
.0154 
.0178 
.0198 
74.3 
883 
66 3 
884 
62;0 
885 
50.9 
886. . 
41.6 
887 
83.1 
888. 
78.0 
889 
77.4 
890 
75.0 
891 
72.0 
892. . . 
57.7 
893. 
4.8 1 
i 
Note: Nos. 825 to 832, inchisive, 841 to 848, inclusive, and 857 to 893, inclusive; grade of flume uniform. 
Nos. 833 to 840, inclusive, and 849 to 856, inclusive; grade of flume undulating. 
DISCUSSION OF COMPUTATIONS. 
AJl of the formulae derived herein are of the exponential type 
since this seems to be the only form capable of representing the data. 
It seemed most natural to determine first the relation of velocity to 
slope, other elements being unchanged. In using for this pmpose 
the same line of tile ^^'ithout disturbing the joints, the most uncertain 
element in tile observations was removed. The chief remaining diffi- 
culty lay in the observations of depth of flow, to secure a constant 
value for comparison at different slopes. When, for a given size of 
tile and constant depth of flow, slopes are plotted logarithmically as 
ordinates against their corresponding velocities as abscissse, the 
resulting points are approximately on a straight line. The equation 
of such a line is of the form, 
which in logarithmic terms may be written, 
log s = log m +2 log V 
(14) 
(15) 
where m is the intercept on the unity vertical axis, and z is the slope 
of the line, i. e., the tangent of the angle which it makes vdih the 
axis of V. 
For several different sizes of tile of the same material, the values 
of m follow the equation, 
m = eD^ (16) 
