98 Journal of Agricultural Research voi. ix, No. 4 
there often being several kinds on a single canal system; but, as few of 
them have been calibrated, their value as measuring devices is not great. 
Of the few experiments made upon submerged orifices with modified 
contractions, only a small percentage are comparable to irrigation 
conditions. 
A series of experiments was made in the hydraulic laboratory at Fort 
Collins, Colo., during the summer of 1914, for the purpose of developing 
some form of submerged orifice that would meet practical conditions. 1 
It was practically impossible to make experiments upon all the different 
arrangements of structures used in the field, because of their infinite 
number and the further fact that many of them are essentially not adapted 
to the measurement of water with a reasonable accuracy. Obviously it 
was necessary to work toward a standardization of the dimensions and 
arrangement of the orifice and orifice box in order that it might meet 
as nearly as possible the many conditions under which it would have to 
be installed in the field and still give a discharge to conform to a general 
formula or table. Several series of experiments were made before a set 
of conditions was decided upon as the standard. 
The standard is a simple arrangement of orifice without bottom con¬ 
traction but with angle-iron sides and top, and with end contractions 
of 1 foot (fig. 1). In this form it is a measuring device exclusively, 
but it may be combined with a gate, as indicated in Table I and the 
1 For a description of the hydraulic laboratory, see the following: 
Cone, V. M. Hydraulic laboratory for irrigation investigations, Fort Collins, Colo. In Engin. News, 
v. 70, no. 14, p. 662-665, 5 fig- *9*3- 
— " ■ Flow through weir notches with thin edges and full contraction. In Jour. Agr. Research, v. s, 
no. 23, p. 1051-1113, 21 fig. 1916. 
