18 
BULLETIN 194, U. S. DEPARTMENT OF AGRICULTURE. 
Water Surfa 
Column 10 shows the method of securing all depth determinations from which areas 
and perimeters were secured. 
ON refers to office notes. Taken in connection with elevations secured at time 
of test. 
SG refers to a special gauge of some form. Those noted were quite accurate. 
LR refers to a difference between level readings on a rod. This obviates all defects 
of water climbing up the rod, and is the best method, in the opinion of the writer. 
S refers to soundings with a graduated stick or rod and although quite accurate in 
low velocities is uncertain where water climbs up the rod . 
T refers to measurements by 
tape on the outside of a flume. 
Column 14 shows the method 
of securing the discharge meas- 
urement. 
M refers to a current meter. 
I signifies the integration 
method was used. Extensive 
tests showed that full weight may 
be accorded this method. 
VC signifies that the mean ve- 
locity was secured by means of 
the multiple-point method in- 
terpreted through vertical ve- 
locity curves. 
—2+8 signifies the mean of the 
velocities obtained at 0.2 and 0.8 
depths in each vertical was ac- 
cepted as the mean of the vertical. 
Extensive experiments showed 
this method may be given full 
weight. 
—6 signifies the velocity ob- 
tained at 0.6 of the depth below 
the surface was accepted as the mean for the vertical. Extensive experiments show 
that the results of this method as a rule are too high and for this reason tests made in 
this manner are not given full weight. 
RC signifies the discharge was taken from a rating curve. 
W refers to a weir measurement, under standard conditions. 
C after the W signifies that a trapezoidal or Cipolletti weir was used. 
Column 15 shows the typical shape of the vertical velocity curves, referred to in 
figure 3. 
Column 23 shows the various wind conditions: C signifies calm; U signifies upstream; 
D signifies downstream; and A signifies across. 
Where of sufficient importance to seriously affect results, additional 
information is given in the text. 
The other columns are considered self-explanatory. 
Fig. 3.— Typical vertical velocity curves and depths at 
■which meter was held. See column 15, Table 1. 
