150 A NEW METHOD OF ESTIMATING STREAM-FLOW 
It should be emphasized here that the above are not the final values of C, F 
and M derived in this investigation. The final (best) values will be presented later. 1 
The values in equation (62) are used in the illustration to be given because time 
will not permit remaking the computations with the best values. 
f^ = 2.3 (63) 
Substituting equation (62) in equation (36) there is obtained 
f- (28° -00.453 ) 
Net melting = + 6.40+ \ or I in units of 0.01 inch of depth per day on the 
[+(«-28°)8.39 J 
watershed (64) 
Substituting equation (63) in equation (34) there is obtained 
E, =| 0.319 e+1.49e(j^ -2.6) M2.3 in units of 0.01 inch of depth per day 
on the watershed (65) 
For definitions of e and w, see pages 136 and 137. 
The use of equations (64) and (65), together with the observed rainfall on the 
watershed, and the observed stream-flow (converted to 0.01 inch of depth per day) 
enabled one to compute r x , r t , r„ . . . r t . Having computed these, the next step 
is to use equations (59), (60) and finally (61). 
The mean rainfall as used in the computation of r it r,, r,, . . . ri„ was the 
arithmetic mean of the observed rainfall as made by the Weather Bureau at 
Stations A h A t , C, and D on and near Watershed A. The exact locations of 
these meteorological stations is shown on Plate 7. 
The mean air temperature, t, used in equations (64) and (65) was the arith- 
metic mean of that observed at Stations A i, A 2 , C and D on and near Watershed A. 
The mean vapor-pressure corresponding to the temperature of the dew point 
was taken as the mean of that obtained from wet and dry bulb observations at 
Stations A t and C, on and near Watershed A. 
The saturation vapor-pressure corresponding to t was obtained from Psychro- 
metric Tables for Obtaining the Vapor Pressure, Relative Humidity, and Temperature 
of the Dew Point, by Professor C. F. Marvin. 
The observed run-off, D', was the observed run-off from Watershed A as taken 
by the Weather Bureau. On account of the small flow of these streams the run-off 
was measurable by a v-notch weir, and was computed to 0.001 cubic foot per second 
from the well-known formula Q = CH &/2 , in which H is the vertical height in feet of 
the still water in the pond above the vertex of the weir, Q is the flow in cubic feet 
per second and C had a mean value of about 2.6 and was determined for the particu- 
lar weir. 
The conversion factor for converting the discharge of Stream A in c.f.s. to 
units of 0.01 inch of depth on Watershed A per day is 10.7. The area of the water- 
shed, from which this may be verified, is shown in Table 40. 
1 See page 192. 
