The Irrigation Problem in Montana. 
221 
dryness of the atmosphere and the absence of very high winds in 
The more exposed plains to the north 
are subject to the frequent and agreeable visits of the famous 
‘Chinook ” winds, which blow from the west, and under whose in- 
fluence heavy falls of snow disappear in a single day. 
The following table shows the mean annual rain-fall at various . 
Signal Service stations in Montana, and from these it will be seen 
that during a period of ten years the maximum rain-fall for the 
entire State has only been 20.33 inches in 1880, while the minimum 
the mountain valleys. 
has occurred during 1886 and was but 12.52 inches ; 
the average 
precipitation for this period was 15.25 inches. 
Mean Precipitation in Montana during Growing Season. 
B | 5 e : ena = s s 
Ja )a) ae )oju|s| 2) s/ 8) a] é 
(ele) S/S) ek) ele |e pe | ela 
Growing season of '80 7.38 12.82 9.77 8.87 2.68 Nasa wewilce a seees 
© 81 7.05 5.81 3.90 5.67 7.15 3.70  5.7815.58 
« «46 989, 4.47129 5.01 3.64 1.96 2.78 4.233.00 
cc ‘6&6 998) 2,634.95 8.94 2.27 1.65 4.173.16 
« “© «© °84/17.29'5.69 3.466.31 8.09 2.90 5.80 4.306.72 
“ 66 66 QR 9.5710.336,07 6.29 5.98  7.146.4917.41 
« ‘66 986) 2.52'9.94' 2.655.183 1.91 3.56  2.672.87'3.03 
z 66 997/19.13 8,002.96 5.88 9.47 8.67 (7.85 
“ «9981 7.10 «10.16 8.22,7.28.4.8710.54 8.16 17.98 
z e« 789) 5.08) 3,48). 90)2.27/2.00 7.47 1.74 2.23 1.91 3.28 
7.21/5.45 6.57|5.6615.55/4.48) 6.03 9.74.5.19 4.25 5.23 
Growing season, May 15 to August 15. 
Annual Rainfall in Montana, 1880-1888. 
"1880. 
—— 
| | | 
| 1881. | 1882. 1883. 
1884. | 1885. | 1886. | 1887. “1888. 
Ft. Assinaboine 
Ft. Benton 
Ft. Buford, N. D. 
Ft. Custer 
Ft. Maginnis 
Bemveissoula 222-22. =~ | 
Opt RIVersse eel.) 2. | 
Ft. Shaw 
Ft. Ellis 
(28.25 13.90 12.73 10.82) 
30.16 17.55 19.28 15.72 
17.29 
12, 76 15. 10 
16. 00 16.81 10.18 18.01 
19.6511.88 
15.64 11.44 10.13 
19.9410.32 | 
| 18.29) 
20.56 13.24 | 
14.77 14.21 
25.67) (11.48 18. 94 13.99 
18.13 14.94, 14.00 
1.37 15.56 10.24 15.48 14.70 
| 
| | 
| 
| 
| 
16.60 9.34 13.25 12.18 14.00 
19.18 10.99 12.63 14.05'10.14 
9.00 13.96 15.44 26.00 25.70 
10.25 11.98 7.41/15.51 
12.64 13.64 12.56 | 
22.02 82.63 | 
20.30 16.01 12.93 13.69 
15.73 15.41 12.79 15.67 15.45 
