Apr, 33,1917 
Flow through Submerged Rectangular Orifices 
103 
sion horizontal. If it is desirable to use an orifice with bottom contrac¬ 
tion, or with wood sides and top, or with gate guides and gate, the dis¬ 
charge tables may be corrected in 
accordance with the data given 
in Table I and the deductions 
from that table given on pages 106 
to 10S. 
The elevations of the water levels 
in the channels of approach and re¬ 
cession should be taken in separate 
stilling boxes, one connection being 
5 feet upstream and the other 1.5 
feet downstream from the plane of 
the orifice. The connections should 
be through the side of the orifice box about 0.5 foot above the floor line. 
The discharge tables were computed for a depth of 2.5 feet of water 
in the channel of approach. This depth was used in nearly all the stand¬ 
ard experiments, the exceptions 
being with some of the smaller 
orifices, where a depth of 2.75 
feet was used. This slight differ¬ 
ence was not sufficient to change 
the discharge appreciably, be¬ 
cause the velocity of approach 
was small in both cases. 
Table I contains a summary 
of the results of the 317 observa¬ 
tions with . 60 different combina¬ 
tions of sizes of orifices, sharp 
and thick edges, with and without gate guides, with and without small 
bottom contraction, with different depths of water in the channel of 
approach, and with different end contractions in the channel of approach 
and recession. The data inthe ta¬ 
ble and the figures referred to in 
the column to the right of the equa¬ 
tions indicate the conditions under 
which each set of observations was 
made, with the exception of No. 49 
and 50. No. 49 was with the sides 
of the channel of approach set at a 
width of 1 o feet and the sides of the 
channel of recession set at a width Fxo * xo “ Elevation and sections of broad-edged 
„ 1 orifice with wood gate slide and guides. 
of 3.0 feet, which gave end contrac¬ 
tions of 0.5 foot. No. 50 was with the sides of both the channels of 
approach and recession set at a width of 10 feet. In all other cases the 
sides of the channel of approach and recession were set at an equal width. 
Fig. 9.—Elevation and sections of broad-edged orifice 
with wood gate guides moved out 6 inches. 
Fig. 8.—Elevation and sections of broad-edged orifice 
with wood gate guides and wood backing. 
