144 
IOWA ACADEMY OF SCIENCE Voi,. XXVII, 1.920 
TABLE C. EVAPORATION IN C. C. FOR NORTH AND SOUTH 
SLOPES IN TIMBER AND BRUSHY SITES 
Site — Timbered Seope 
Site — Brushy Slope 
Direction 
oE Slope 
Direction oe Slope 
Date 
North 
South 
North 
South 
(Sta. Ill) 
(Sta. 1a) 
(Sta. VI) 
(Sta. IV) 
Tuly 13 
1.44 
2.88 
4.32 
4.32 
15 
7.20 
5.76 
10.80 
8.64 
17 
5.04 
9.36 
8.64 
11.52 
19 
4.68 
6.94 
5.40 
13.68 
21 
8.28 
5.40 
13.68 
12.24 
23 
7.20 
14.40 
15.48 
19.44 
25. 
7.20 
12.96 
13.68 
20.16 
27 
8.64 
12.24 
15.12 
21.60 
31 
2.88 
2.16 
4.32 
5.04 
August 2 
9.36 
9.36 
10.08 
14.40 
8 
5.04 
5.04 
9.36 
10.80 
10 
5.04 
7.92 
7.20 
12.96 
12 
3.60 
7.20 
5.76 
8.64 
14 
2.88 
3.96 
7.92 
9.52 
16 
7.20 
6.48 
12.96 
14.40 
19 
4.32 
6.84 
14.40 
21 
3.60 
5.04 
12.24 
12.% 
23 
2.52 
4.68 
6.48 
9.36 
25 
11.52 
7.92 
15.84 
18.00 
27 
9.36 
7.92 
13.68 
15.48 
29 
5.76 
5.04 
Total 
122.76 
149.50 
192.96 
257.56 
Aver, for season.... 
5.58 
6.79 
9.64 
12.26 
August 25th. The range from minimum to maximum for the 
various sites is shown in the following table, taken from the 
records of the stations at the tops of the respective slopes. 
Minimum 
Maximum 
Range 
Timber 
4.32 c. c. 
18.72 c. c. 
14.40 c. c. 
Brush 
5.76 c. c. 
28.08 c. c. 
22.32 c. c. 
Open 
8.50 c. c. 
34.68 c. c. 
26.18 c. c. 
It is interesting to compare the data in this connection with 
observations made by Shimek near Missouri Valley, Iowa, and 
by Weaver in the mountains of northern Idaho. Shimek found, 
with cup evaporimeters, an average evaporation of 21.07 c.c. for 
the prairie as against 10.07 c.c. for the groves. Furthermore, 
in a series of curves he shows a direct increase in evaporation 
with increase of wind velocity and temperature; also, in his dis- 
cussion, he presents facts bearing out the results obtained above 
relative to the evaporation on sites with north and south exposures, 
and relative to the effect of topography on evaporation. Weaver 
14 Shimek, B., The prairies: Tab. Nat. Hist., Univ. of Iowa, 6, 169-240, 1911-13. 
15 Weaver, J. E., Natural reforestation in the mountains of Northern Idaho: 
Plant World, 18 , 31-47, 1915. 
