220 
Journal of Agricultural Research 
Voi. V, No. 6 
Table II .—Comparisons of variations in percentage of discharge by two-point, single¬ 
point, and integration methods from discharge by multiple-point methods for different 
velocities, depths, and values of n 
COMPARISONS FOR DIFFERENT VELOCITIES 
Two-point method. 
Single-point method (cor¬ 
rected by—5 per cent). 
Integration method. 
Observation. 
Num¬ 
ber of 
experi¬ 
ments. 
Mean 
differ¬ 
ence 
from 
multi¬ 
ple- 
point. 
Aver¬ 
age va¬ 
riation 
of a 
single 
experi¬ 
ment. 
Num¬ 
ber of 
experi¬ 
ments. 
Mean 
differ¬ 
ence 
from 
multi¬ 
ple- 
point. 
Aver¬ 
age va¬ 
riation 
of a 
single 
obser¬ 
vation. 
Num¬ 
ber of 
experi¬ 
ments. 
Mean 
differ¬ 
ence 
from 
multi¬ 
ple- 
point. 
Aver¬ 
age va¬ 
riation 
of a 
single 
obser¬ 
vation. 
Velocities in feet per 
second: 
. 
Less than i .00. 
5 
+ 1. 02 
2. 56 
5 
+ 1. 64 
3-68 
3 
+ 2. 60 
3. 16 
1.00 to 1.50. 
18 
+ -63 
59 
18 
+ -43 
2. 90 
II 
-j-l. 62 
i -75 
1.50 to 2.00. 
12 
- -38 
I. 60 
13 
+ • 24 
2. 67 
IO 
+ 1-43 
2. 80 
2.00 to 2.50. 
20 
+ . 89 
i- 54 
19 
— . 01 
2. 66 
IO 
— . 02 
2. 51 
2.50 to 3.00. 
14 
+ 1. 67 
1. 68 
13 
- -25 
1. 67 
10 
- . 18 
1. 41 
3.00 to 4.00. 
15 
+ I.II 
1. 41 
*5 
- • 14 
1. 91 
9 
+ . 5 ° 
1. 81 
Over 4.00. 
12 
+ • 02 
* 73 
12 
-2. 66 
2.83 
2 
- -43 
. 72 
Mean. 
96 
+ ■ 73 
i- 5 1 
95 
— . 20 
2. 54 
' 55 
+ .76 
2.07 
COMPARISpNS FOR DIFFERENT DEPTHS 
Mean depth of canal 
section in feet: 
Less than 1.00. 
14 
0. 65 
2. 06 
14 
+ 1. 02 
3. 66 
10 
+ 1. 98 
2. 65 
1.00 to 1.50. 
18 
+ .21 
1. 23 
*7 
+ • S 3 
1. 90 
8 
+ 1. 46 
1. 65 
1.50 to 2.00. 
15 
+ i- 32 
73 
15 
- • °3 
2. 51 
7 
-*j-* . 86 
1. 49 
2.00 to 2.50. 
22 
+1. 29 
1. 58 
22 
— . IO 
2. 82 
12 
+ 1. 08 
2. 81 
2.50 to 3.00. 
16 
+ *97 
1-25 
16 
- • 77 
95 
12 
— . 60 
1. 84 
Over 3.00. 
11 
+ 1.09 
1. 19 
11 
- .79 
2.44 
6 
— . 26 
i -33 
Mean. 
96 
+ • 73 
5 i 
95 
— . 20 
2. 54 
55 
+ .76 
2. 07 
COMPARISONS FOR DIFFERENT VALUES OF n 
Value of n in Kutter’s 
formula: 
Less than 0.013... . 
13 
+0. 40 
0. 76 
13 
— I. 70 
2. 27 
5 
+0. 90 
0. 90 
0.013 to 0.017. 
18 
+ • 52 
1. 42 
18 
- -32 
2. 73 
11 
+ • 23 
2. 25 
0.017 to 0.021. 
20 
+ • 7 2 
1.45 
20 
- .85 
2. 16 
13 
- • 52 
1. 52 
0.021 to 0.02 c;. 
13 
-j- • 80 
2. 17 
13 
+1.81 
2. 52 
6 
+ 1. 87 
2. 91 
0.025 to 0.029. 
11 
+ • 53 
.88 
11 
- .41 
2. 56 
5 
— 1. 30 
i- 55 
Over 0.029. 
11 
4- .66 
1. 72 
10 
- .41 
3. 00 
5 
+ 4 - 35 
4-35 
Mean. 
86 
+ .61 
1. 41 
8S 
- -35 
2. 50 
45 
+ • 59 
2.14 
The two-point method appears to give results equally accurate for all 
velocities, depths, and values of n, the variations which occur not being 
seemingly dependent on any of these three factors. The probable error 
of a single observation is generally less for the large velocities and 
