104 
Journal of Agricultural Research 
Vot. IX, No. 4 
The words “with” or “without” in the column headed “Bottom 
contraction” indicate whether the floor formed the bottom of the orifice, 
or an angle iron or wood strip ex¬ 
tended above the floor a distance 
of i $4 inches, such as would be 
used for a bottom gate stop. 
In the column headed “Devia¬ 
tion from 
given the 
discharge table” are 
Flo. ii.—Elevation and sections of standard orifice 
with iron gate guides and backing. 
percentages by which 
the discharges computed from the 
individual formulas fail to agree 
with the discharges given in Table 
III, which were computed from 
the general formula for the standard conditions of orifices. The discharges 
computed from the general formula were taken as the basis of compari¬ 
son, plus and minus signs rep¬ 
resenting greater and less dis¬ 
charges, respectively, by the in¬ 
dividual formula than by the 
general formula. This arrange¬ 
ment allows the effects of vari¬ 
ous alterations in the size and 
setting of the orifice and orifice 
box to be compared more easily 
than would be possible from a 
number of complete discharge 
tables, and indicates the correc¬ 
tion which should be applied to 
make thedischarge tables appli¬ 
cable for each condition given. 
The equations given in Table 
I were obtained from large-scale 
logarithmic plots of the experimental data for each arrangement of orifice 
and orifice box by the use of the discharges and differences in heads as the 
coordinates. The straight-line 
curves represented the data 
quite accurately for all condi¬ 
tions except those given under 
No. 12 and 46 in Table I. In 
these two cases the discharge 
data for heads of 0.8 foot were 
greater by about 2 per cent 
than those represented by the 
curves, but all other points fell 
on the lines. It will be noted 
that both exceptions were for high heads and for the same size of orifice, 
0.5 by 2.0 feet, with and without angle-iron contraction in the bottom 
Exponent 
Fig. 12.—Plots of exponent values of equations in Table II 
25 
Fig. i3. 
Constant of Equations 
-Plots of constants of equations riven in figure is. 
