1064 
Journal of Agricultural Research 
Vol. V, No. 33 
The offsets from each of the straight lines in figure 4 to the points rep¬ 
resenting the discharges with the head for which the line was drawn 
were tabulated, and an expression for the offsets was determined to be 
0.283 H 1 - 9 
1 + 2 L 1 - 8 * 
Substituting the values of a and b in the equation form Q=aL—b and 
making a correction for the offsets from the straight lines, the formula 
for the rectangular notches was found to be 
2=3.247 
Table II gives the discharge values for the rectangular notches of dif¬ 
ferent lengths computed by this formula. This formula gives discharge 
Fig. 6.—Curve showing the relation between b in the equation Q^aL—b and the heads on rectangular 
notches. 
values within a maximum of approximately 1.2 per cent of the values indi¬ 
cated on the curves plotted from the experimental data, but the aver¬ 
age variation is only 0.28 per cent. Table V compares the values indi¬ 
cated on the curves plotted from the experimental data and values com¬ 
puted with formulas. 
Table II .—Discharges {in cubic feet per second) through rectangular weir notches 1 
Head. 
i-foot crest. 
iK-foot crest. 
a-foot crest. 
3 -foot crest. 
4 -foot crest. 
Feet. 
0. 20 
Inches . 
2$/i 
0. 291 
0.439 
0.588 
0. 88 7 
1. IQ 
. 21 
• 3 12 
.472 
.632 
•954 
1. 28 
. 22 
2 % 
*335 
•505 
.677 
1. 02 
i -37 
•23 
2 % 
•358 
•539 
• 723 
1. 09 
1. 46 
.24 
2j4 
,380 
•574 
.769 
1.16 
i- 55 
Computed by the formula H 1 . 9 
