io6 
Journal of Agricultural Research 
Vol. LX, No. 4 
Table' I . —Summary of results of experiments , showing the influence of various changes 
in the size of the box and the arrangement of the orifice —Continued 
z 
1 
Size of 
orifice. 
N 
•8 8 
Depth of water in 
channel of ap¬ 
proach. 
£ 
i 
tion. 
Equation of discharge 
curve. 
£ 
a 
«a 
Deviation from discharge 
table. 
1 
Depth. 
Length. 
. +* 
r 
Bottom c 
+J 
& 
Head. 
Percent. 
Head. 
Per cent. 
51 
Ft. 
i. 0 
Ft. 
2.0 
Ft. 
4.0 
Ft. 
2.500 
With. 
j2=o. 665 a 2g i? 0 - 5019 . 
4 
Ft. 
0.03 
+ 8.6 
Ft. 
0. 75 
+ 8.1 
52 
1.0 
2.0 
4-0 
2.500 
. ..do, 
. 
(2= .637 aVwH * 4974 . 
5 
•03 
+ 5 - 6 
• 75 
+ 3-6 
S 3 
x. 0 
2.0 
4.0 
2.500 
.. .do, 
. 
(2= . 694 a }/2g H * 4949 . 
6 
*03 
+ 16.0 
•75 
+ 13-0 
54 
1.0 
2.0 
4.0 
2.500 
.. .do, 
. 
(2= . 694 a^zgFL * 4953 ... v* * 
7 
•03 
+ 15 * 7 
•75 
+ 12.8 
55 
1.0 
2.0 
4.0 
2.500 
.. .do 
. 
( 2 = .64 3 a ]/*g H * 4977 . 
8 
•03 
+ 6.3 
•75 
+ 4-4 
56 
1.0 
2.0 
4.0 
2.500 
.. .do, 
. 
Qr* . 669 a ^2 g H • B025 . 
9 
•03 
+ 8.9 
•75 
+ 8.6 
57 
i -5 
4.0 
6.0 
2.500 
. ..do 
(2= . 674 a ^2g H * 4339 . 
4 
.03 
+ 4-4 
.40 
+ 5-3 
58 
t -5 
4.0 
6.0 
2.500 
.. .do, 
. 
< 2 = . 669 a r^g H - 4800 . 
IO 
•03 
+ 5 -o 
.40 
+ 4-8 
59 
1-5 
4.0 
6.0 
2. 500 
.. .do, 
(2=* • 659 a \'2g H * 4788 . 
5 
•03 
+ 3-9 
.40 
+ 3-3 
60 
1-5 
4.0 
6.0 
2.500 
.. .do, 
. 
Q=> . 722 a ^2g H * 489a . 
6 
.03 
+ 9-6 
.40 
+xi. 9 
Although constant care was used in making, setting, and calibrating 
the orifices, placing the sides and bottom of the orifice box, and observ¬ 
ing precautions to eliminate all known sources of error, still there are a 
few inconsistencies, or what appear to be inconsistencies, in the data, 
though a more complete understanding of the flow through orifices of 
this type may show them to be due to more or less similar influences. 
Since the experimental data made straight-line logarithmic plots, only a 
few points were necessary to define those lines within a comparatively small 
percentage of error. Most of the curves for comparable conditions are 
practically parallel, but in two cases the curves cross. No. 8 in Table I 
crosses No. 17, and No. 5 crosses No. 14, these lines representing the 
data very faithfully. 
The experimental conditions for the greater differences of head and 
for the longer orifices were less reliable than for the smaller discharges, 
but the general agreement of the data indicates that the accuracy was 
within practical demands at least. The arrangement of the control gate 
at the end of the channel of recession very probably produced a back¬ 
lash, which influenced the discharge, especially when the velocity of the 
water was great. The velocity of the water and cross currents also may 
have affected the hook-gage readings, but Table IV proves the average 
accuracy to be satisfactory. (See additional information given on p. 114.) 
DEDUCTIONS FROM TABLE I 
From an inspection of the coefficient and exponent values of the equa¬ 
tions in Table I, the following general statements may be made: 
The exponent decreases as the length of the orifice L increases so 
long as the depth of the orifice d and the cross-sectional area of the 
water in the channel of approach A remain constant. Although no 
two sets of experiments were made with exactly the same A, some are 
sufficiently close for purposes of comparison. 
