SECTION OF IRRIGATION AND METEOROLOGY. 
15 
heating, the surface heats rapidly and the lower layers slowly. But 
in cooling, the whole mass of water cools. The mean of the maxi- 
mum and minimum temperatures is much closer to the true average 
temperature. 
TABLE V.— MEAN TEMPERATURE OP WATER IN EVAP- 
ORATION TANK. 
Surface temperatures. Average of 7 a. m. and 7 p. m. 
Note— T he means thus found are less than the true average by 3 or 4 degrees. 
Year. 
Jan. 
Feb. 
Mar. 
April ^ 
1 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
1887 
46.6 
49.5 
62.3 
69.8 
73.0 
71.5 
64.7 
59.0 
38.9 
1888 
1889 
66! 6 
7^.0 
70’.5 
6i!i 
1890 
5S’9 
68.4 
75 1 
69.9 
62.0 
49.0 
1891 
59.4 
68.5 
74.1 
70.5 
64.3 
50.8 
43! i* 
1892 
46.7 
54.4 
66.9 
71.8 
70.0 
63.2 
49.5 
1893 
47.0 
55.5 
68.9 
73.9 
70.3 
63.2 
49.0 
1894 
49.9 
59.8 
67.7 
73.0 
71.8 
63.1 
51.1 
42' 8t 
1895 
.50.4 
.59.4 
65 6 
69.4 
70.7 
62.8 
48.1 
1896 
51.1 
,58.9 
69.6 
74.1 
71.4 
63.3 
50.9 
1897 
48.2 
61.4 
66.6 
70.9 
71.4 
66.4 
51.5 
Average 
49.0 
58.9 
67.9 
72.7 
70.8 
63.4 
51.2 
41.6 
* First fifteen days . 
t First thirteen days. 
§ 20. Observations have also been made on the evaporation 
from reservoirs. Tanks one foot square and eighteen inches high 
were used and floated by pontoons, and filled with water to 3 or 4 
inches from the top. It was intended to maintain the water in the 
tank at the same level as the water on the outside. In order to break 
the waves the whole was surrounded by a triangular float of boards, 
which was anchored so that the angle would face the waves and 
prevent them washing into the tank. The device was not always 
completely successful in this respect. At times boys interfered with 
the tanks. Observations were carried on for several years in War- 
ren’s lake, but the interference was so great the observations at that 
place were abandoned. For the last two years tanks were placed in 
other lakes, convenient of access, and chosen because the lakes were 
partially closed to the public and the observations less likely to be 
interfered with. 
§ 21. The lakes used in 1896 and 1897 were Lee’s lake, Loomis 
lake and Claymore lake. 
The Lee lake is a small reservoir owned by Dr. E. A. Lee of 
Fort Collins, and situated about four miles from the College. The 
lake is shallow and exposed to the wind. Weeds grow freely in the 
lake, and late in summer form a mass which is difficult to pass 
through, and greatly hinders the formation of waves. The water 
has varied from about six to ten feet in depth during the season. 
Loomis or Sheldon lake is the same as previously mentioned 
in the observations on loss from seepage. It is a little over a mile 
