Mar. 6,1916 
Flow through Weir Notches 
1091 
Table XII. —Errors and percentage of error in computed discharges caused by o.oi-foot 
error in reading the heads —Continued 
CIPOLLETTI weirs 
Error. 
head. 
i-foot crest. 
zH-ioot crest. 
2-foot crest. 
3-foot crest. 
4-foot crest. 
Cu. ft. 
Cu. ft. 
Cu.ft. 
Cu. ft. 
Cu. ft. 
Feet . 
per sec. 
Per ct. 
per sec. 
Per ct. 
per sec. 
Per ct. 
per sec. 
Per ct. 
per sec. 
Per ct. 
0.20 
0.022 
7*3 
0.034 
7.6 
0.045 
7-5 
0 .068 
7.6 
0.09 
7 -S 
•30 
.028 
S-o 
.041 
5 -o 
•05s 
S-o 
.082 
5 *o 
. XI 
S-o 
.40 
•034 
3-9 
■05 
3-9 
.07 
4-1 
.09 
3-6 
. 12 
3-6 
• 5 ° 
.04 
3-3 
•os 
2. 8 
•07 
3 -o 
. 11 
3 -i 
.14 
3 -o 
. 60 
.04 
2 - 5 
. 06 
2-5 
.08 
2. 6 
. 12 
2. 6 
• 15 
2.4 
.70 
.05 
2.4 
.07 
2.3 
.09 
2.3 
• 13 
2. 2 
• 17 
2.2 
. 80 
*05 
2. 0 
.07 
1.9 
.09 
1.9 
• 14 
1.9 
. 18 
1.9 
.90 
•05 
1.6 
. 08 
1.8 
. 10 
I- 7 
• *5 
i *7 
.19 
1-7 
1.00 
. 06 
1 .6 
.08 
i *5 
. 11 
1.6 
•IS 
I- 5 
. 20 
i-S 
1. 5 
. 12 
1. 5 
. 17 
1. 5 
. 21 
1.4 
1. 20 
. 
.09 
. 12 
1.3 
• 17 
1.3 
. 22 
1. 3 
.18 
1. 2 
.24 
1. 2 
• 19 
f, 1 
. 24 
1.1 
1 40 
90® TRIANGULAR WEIRS 
O. 20 
•50 
.70 
I. OO 
1. 25 
S 8.2 S| 
13 . 04 
4.94 
3-9 
2.4 
2.1 
: I 
i 
i 
j 
EFFECTS OF DIFFERENT END AND BOTTOM CONTRACTIONS UPON 
DISCHARGES 
RECTANGULAR AND CIPOLLETTI NOTCHES 
To determine the effect of different end and bottom contractions 
upon the discharges through rectangular and Cipolletti notches, 120 
tests were made with i-foot rectangular notches, 72 with 3-foot rectan¬ 
gular notches, 205 with i-foot Cipolletti notches, and 89 with 3-foot 
Cipolletti notches. Heads of 0.2 foot, 0.6 foot, and 1 foot were used with 
each notch. The end contractions (the distances of the sides of the 
weir box from the ends of the crest) and the bottom contraction (the 
distance of the bottom of the weir box below the crest of the notch) 
for each notch were varied from 0.5 foot to 3 feet by increments of 0.5 
foot. The discharges under the different conditions were compared 
with those obtained with the standard weir box. The small error in the 
.experimental determinations of the discharges with a 0.2-foot head 
caused such large percentages of error in the discharges that they were 
unreliable and so were not included. 
Figures 14 and 15 and Tables XIII and XIV show the percentages of 
increase in discharges and the velocities of approach with heads of 0.6 
foot and 1 foot under the different conditions of contractions. The 
equations of the curve are all of the general form, e = a(V + b) n , in which e 
