38 
BULLETIN" 835, U. S. DEPARTMENT OF AGRICULTURE. 
Table 26. — Water used per inch of advance. 
Flume. 
Number 
of days. 
39 
58 
76 
96 
206 
c. c. 
c. c. 
c. c. 
c. c. 
c. c. 
1 
406 
816 
272 
541 
297 
3 
530 
835 
245 
558 
278 
5 
543 
826 
266 
589 
290 
10 
531 
786 
302 
617 
325 
15 
556 
782 
327 
644 
301 
20 
573 
792 
366 
679 
348 
30 
40 
50 
548 
605 
686 
840 
891 
423 
487 
589 
676 
flume 76 at the end of the fiftieth day there was used twice as much 
water per inch as for the first day. In flume 39 there is shown after 
the third day somewhat of an increase in the use of water from day 
to day, but it is much less marked than in any of the other flumes. 
In flume 96 the use of water on the thirtieth day is about 25 per cent 
in excess of the use on the first day. The increase in the quantity of 
moisture required per 
inch with the lapse of 
time is probably due 
largely to the effect of 
evaporation. In flume 
58 the distribution of 
moisture was so uniform 
as compared with the 
other flumes that the 
quantity of water in the 
flume per inch through- 
out its length is almost 
the same, with the exception of the upper few inches. In the 
other flumes there is a marked decrease in the percentage of moisture 
from near the tank to the outer extremity of the flume. The relation 
of the figures in this table to each other corresponds very closely with 
the relation of the moisture equivalents for the soils represented. 
To show the amount of water removed from the tanks by the 
flumes expressed in depth in inches on an area equal to the cross 
section of the flumes, Table 27 is presented. 
At the end of the thir- Tablf 27.— Water removed from the tanks uij 
tieth day it was found capillarity expressed in depth on an area equal 
that the flumes had taken 
from the tanks sufficient 
water to cover the cross 
section of the flumes to a 
depth of from 16 to 40 
inches. That is, where the 
rate of loss is the same 
over the area of an acre 
as over the area repre- 
sented by the flumes, 
then in 20 days the acre 
of soil represented in flume 39 would have removed from the under- 
ground water 16.78 acre-inches of water, while the soil represented 
by flume 96 would have removed 39.65 acre-inches of water, or a 
little more than twice as much. These tables are valuable in that 
they give an indication of the quantity of water that may be removed 
to the 
cross section of 
the flume. 
Flume. 
Number 
of days. 
39 
58 
76 
96 
206 
1 
3 
5 
10 
15 
20 
30 
40 
50 
Inches. 
4.58 
7.93 
9.44 
11.59 
13.42 
14. 95 
16.78 
19.06 
21.35 
Inches. 
6.41 
9.15 
11.59 
14.03 
15. 56 
17.08 
19.83 
22.42 
25.01 
Inches. 
3.05 
4.88 
6.10 
8.54 
10.37 
12.51 
15.99 
20.13 
24.40 
Inches. 
6.71 
12.20 
16.47 
23.79 
29.28 
34.16 
39.65 
Inches. 
4.27 
5.49 
6.41 
8.24 
9.00 
9.61 
