SECTION OF IRRIGATION AND METEOROLOGY. 
27 
TABLE XV. -EVAPORATION PROM THE ARROWHEAD RESERVOIR. 
Little Bear Valley, California. Latitade, 34® 16' ; longitude, 117 ® 11' ; elevation, 5,160 
feet. By H. B. Hedges, C. E. 
Jan. 
Feb. 
Mar. 
April 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Year. 
1895 
1.12 
1.84 
5.30 
6.60 
6.30 
6.20 
5.05 
2.80 
1.20 
.34' 
1896 
"09 
.94 
3.39 
2.86 
6.50 
5.04 
5.50 
4.01 
4.05 
1.28 
1.23 
35.70 
1897 
.57' 
.24 
3.01 
4.75 
6.17 
7.62 
5.17 
5.00 
4.01 
1.24 
1.21 
Average. . . 
.33 
..53 
1.03 
4.12 
4.30 
6.42 
6.32 
5.62 
4.69 
3.62 
1 24 
.93 
39.15 
§ 34. The following are records of the average evaporation 
from floating tanks made at Rochester, New York, and at Boston 
Mass. The former were made under the direction of Emil Kuich- 
ling, chief engineer of the water works, and were made in small indu- 
rated fiber tubs, about 10 inches in diameter and six inches deep. 
At Boston the observations were made under the direction of Des- 
mond Fitz-Gerald on the Chestnut Hill reservoir. Those at Roches- 
ter are dependent on records from one to five years of the different 
months, at Boston upon a much longer period. Those at Boston 
are not the actual means of observation, lout the smoothed values 
determined by the application of BesselFs formula to reduce periodic 
series : 
Jan. 
Feb. 
Mar. 
April 
May 
June 
July 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
Year. 
Rochester. 
.45 
.45 
.91 
2 67 
4.05 
4.93 
5.65 
5.28 
4.07 
3.13 
1.50 
1.22 
34.31 
Boston 
1.12 
1 20 
1.81 
3.01 
4.48 
5.55 
5.98 
5.. 50 
4 20 
3.14 
2.22 
1.50 
39.71 
THE EFFECT OF ELEVATION ON LOSSES. 
§ 35. Are the losses more or less at high elevations ? Is it more 
economical to store water at low or high elevations ? 
For increase of elevation the evaporation, if the wind conditions 
are the same, is greatly diminished. Practically the opportunities 
for storage are confined to basins not over 10,000 feet in elevation, 
and the question of the evaporation is of most importance for eleva- 
tions below that height. Observational data are almost entirely 
lacking. Such observations as have been made are not under the 
same methods and not strictly comparable. 
As far back as 1890, I made attempts to obtain such data and 
furnished evaporation tanks to several places, distributing some tanks 
coming from the U. S. Irrigation Survey of 1889-90 and also some 
new tanks. The highest point was at the U. S. Fish Hatchery near 
Leadville, at an elevation of nearly 10,000 feet. Few results were 
obtained except from the sub-stations connected with the College in 
the San Luis valley and on the Divide, at elevations of 7,600 and 
7,200 feet respectively. The other observers were voluntary, and as 
there were no funds to replace the broken instruments or repair the 
damaged tanks, the observations were abandoned. In the absence 
of observations, we may consider the probable effects. 
