1112 
Journal of Agricultural Research 
Vol. V, No. 23 
per second, and the discharges with medium to high heads do not agree 
more closely than approximately 1 per cent with the discharges com¬ 
puted by the formulas. 
(19) The average ratio of the cross-sectional area of the weir box (A) 
to the cross-sectional area of the notch (a) required to give discharges 
within 1 per cent of the values obtained with the formula is greater than 
7 and is probably near 15. 
(20) In order to make the results comparable with those for rectangu¬ 
lar notches, the end contractions for trapezoidal notches should be 
measured from about the middle point of the side of the notch, rather 
than from the end of the crest. 
(21) A notch which would give discharges proportional to the lengths 
of the notches would probably have curved sides, the slope decreasing 
with the head. 
(22) For all practical purposes, discharges through rectangular and 
Cipolletti notches are not affected until the notch is submerged to a 
depth equal to one-tenth the head upstream from the weir. Submergence 
equal to one-eighth the head upstream from the notch decreases the 
discharge approximately 2 per cent, that equal to one-fourth approxi¬ 
mately 6 per cent, and that equal to one-third approximately 9 per cent. 
LITERATURE CITED 
(1) Barr, James. 
[910. Experiments upon the flow of water over triangular notches. In Engi¬ 
neering [London], v. 89, no. 2310, p. 435 “ 437 > 4 fig; no. 2311, p. 473. 
(2) Carpenter, L. G. 
1911. On the measurement and division of water. Colo. Agr. Exp. Sta. Bui. 
150, 42 p., illus. 
(3) CipollETTi, Cesare. 
1886. Canale Villoresi. Milan. 
(4) Cone, V. M. 
1913. Hydraulic laboratory for irrigation investigations, Fort Collins, Colo. In 
Engin. News, v. 70, no. 14, p. 662-665, 5 fig. 
(5) Francis, J. B. 
1909. Lowell Hydraulic Experiments, ed. 5. 286 p„ 23 pi. 
( 6 ) Forschheimer, Phillipp. 
1914. Hydraulik. 566 p., tables and diagr. Leipzig; Berlin. 
(7) Horton, R. E. 
1907. Weir experiments, coefficients, and formulas. U. S. Geol. Survey, 
Water-Supply and Irrig. Paper 200 (Rev. of 150), 195 p., 17 fig., 38 pi. 
( 8 ) Merriman, Mansfield. 
1912. Treatise on Hydraulics, ed. 9, 565 p., 201 fig. New York, London. 
(9) Parker, P. & M. 
1913. The Control of Water as Applied to Irrigation Power and Town Water 
Supply Purposes. 1055 p., 273 fig., 7 tab., 10 diagr. New York. 
(10) Smith, Hamilton, jr. 
1886. Hydraulics . . . 362 p., illus., 17 pi. New York, London. 
(11) Strickland, T. P. 
1910. Mr. James Barr’s experiments upon the flow of water over triangular 
notches. In Engineering [London], v. 90, no. 2339, p. 598. 
