The Venturi Flume 
23 
This formula is based on the results of the experiments made 
at the hydraulic laboratory at Fort Collins, Colorado, and the field 
laboratory at Bellvue, Colorado. To find the discharg-e from the 
diagram when the upper head, , and the difference in head, Ha, 
are given, find the point where the horizontal line, thru the given 
difference in head on the left of the diagram, intersects the upper 
head curve, and read the discharge in second feet at the bottom of 
the diagram directly beneath this point. 
PER CENT DEVI/A.TION 
FIGURE 12. — Plot Showing the Deviation of the Computed Data from the 
Experimental Data for the V-Notch Venturi Flume. 
The agreement of the results from the diagram with the ex- 
perimental data is shown in Figure 12 which is similar to Figure 2 
for the rectangular flumes. 
The installation of the V-notch Venturi flume should not 
offer any practical difficulties. Either concrete or timber may be 
used. For concrete structures, see description of method given for 
rectangular flumes on page 14. Ff built of timber, it is recom- 
mended that commercial 2-inch plank be used. These planks 
should be surfaced on one side and so placed that this smooth sur- 
face would form the inside of the flume. Care should be exercised 
in properly fitting the sides to the throat section so as to make the 
edge of the two surfaces or joint smooth and regular. The pipe 
connection to the throat gage well should be made as shown in 
drawing, and approximately 2 inches above the bottom point of the 
throat. The pipe connection for the upstream or upper gage well 
should be placed horizontally and at right angles to the edge of the 
plank, also approximately 2 inches above the floor. These pipes 
