123 



tion of the trees and the rate of evaporation from the soil. The 

 season of 1909 was marked by ample rainfall in June and July, 

 and by temperatures, during the earlier part of the season, lower 



Table II 



Me.-vsurements on the Same Basis as Shown in Table I, but of Trees on 



A Different Area 



No. 



1909 



1910 



1911 



1912 



1913 



I 



10 



10 



9 



II 



— 



2 



8 



10 



7 



9 



12 



3 



10 



6 



4 



5 



7 



4 



7 



8 



6 



9 



9 



5 



6 



7 



6 



8 



II 



6 



7 



8 



7 



II 



10 



7 



7 



7 



4 



8 



8 



8 



7 



7 



5 



8 



8 



Total 



62 



63 1 



48 



69 



65 



Average 



7-75 



7-75 



6 



8.37 



9.28 



than those of any of the other years here recorded. Precipita- 

 tion was least in 19 10, and of the rain of this season over 40 per 

 cent, fell in September, too late to be of much influence in the 

 formative work of the year. The months of June and July were 

 marked by only four fifths of an inch of rain, and by temperature 

 higher than usual, which served to intensify the drouth during 



Table III 



Weather Data for Missoula, 1909 to 1913 Inclusive, April to September 

 T. = temperature, F. 



Mo. 



1909 



1910 



1911 



1912 



19 13 



Rain 



T. 



Rain 



T. 



Rain 



T. 



Rain T. 



Rain 



T. 



Apr. . . . 

 May. . . 

 June. . . 

 July... 



Aug 



Sept. . . 



1. 19 

 0.99 

 2.6s 



3-52 

 0.34 

 2.38 



40 

 50 

 60 

 65 

 66 

 57 



0.66 

 1.92 

 0.67 

 0.13 

 0.57 

 2.76 



51 

 56 

 63 

 71 

 62 

 56 



0.72 

 1. 00 

 3-38 



0.21 

 0.43 



I-3I 



43 

 51 

 62 

 66 

 64 

 54 



2.02 

 3-09 

 1.78 

 1.94 



1.88 

 1.58 



46 

 52 

 62 

 63 

 63 

 50 



1.46 

 1.44 



2-39 

 1.52 

 1.52 



0.74 



45 

 52 

 62 

 67 

 67 

 57 



Total . 



11.07 



6.71 



7-05 



12.29 



8.58 



the very period in which most of the new tissues were taking form. 

 This period was followed by another month of dry weather, in 

 which the slight amount of rain which fell could have had no 



