IOO 
Journal of Agricultural Research 
Vol. IX, No. 4 
was used first. Pieces of angle iron having a width of i $4 inches and a 
thickness of ^ inch, with an edge planed square, or strips of wood i $4 
inches square, were inserted in the opening to be flush with the upstream 
face of the bulkhead. These strips were screwed to the bulkhead to 
make the orifice opening true, of the desired size, and to prevent leakage. 
The condition of orifice taken as the standard had angle-iron sides and 
^ top, but no bottom 
Lower Hook Gage 
"FtI vStifi Boxes 
El 
.1 15 -Tm 
o 
-20 
Orifice Box Sides 
-► 
^--Bypasses 
Connection with 1 ~ 
Upper hook Gage 5tiil-Box 
Orifice Box Floor, 
Fig. a.—Plan, elevation, and section of orifice box in concrete channel. 
contraction (fig. 3), 
though other experi¬ 
ments were made with 
a similar arrangement 
of wood strips and with 
a bottom contraction 
of 1 inches formed by 
the width of the angle 
iron or wood strip. 
There were also sev¬ 
eral arrangements of 
metal and wood gate 
guides (see fig. 3 to 
11, inclusive). 
A bulkhead placed 
across the channel, 6 
feet downstream from the orifice bulkhead, contained a 20-inch square 
steel head gate the bottom of which was at the floor line. This gate was 
operated by a screw lift, which permitted a fair regulation of the water 
leveLdownstream from the orifice; but the finer regulation was obtained 
by a 2-inch valve placed in the side of the channel. 
Sections, 3 feet high and 10 feet long, made of matched lumber were 
used for the sides of the orifice box 
or channel of approach to the orifice. 
They could be moved to any posi¬ 
tion desired and fastened firmly to 
the floor. At the upstream end of 
the side sections, wings were at¬ 
tached at an angle of 90°, while the *===^2* 
other end of the side sections butted Piq, 3.—Elevation and sections of standard orifice 
against the orifice bulkhead. Al- without bottom contraction. 
though this box was practically water-tight, the question of leakage was 
of little importance because the box was entirely surrounded by water. 
Similar adjustable sides were placed downstream from the orifice and 
unless otherwise stated the widths of the channels of approach and 
recession were equal. In all the experiments the sides were set parallel 
and vertical and at an equal distance from the center line of the orifice. 
