UTAH ACADEMY OF SCIENCES 263 
of four to ten days preceded and followed by lighter 
showers. 
The previously mentioned work on the occurrence 
of western yellow pine in relation to the seasonal distri- 
bution of precipitation led the writer to believe that in 
northern Utah, central and southern Idaho a correlation 
of current height growth with rainfall might give results 
more nearly agreeing with the conclusions of Kirkwood 
than with those of Pearson, because the seasonal distribu- 
tion of precipitation resembles more closely that of Mon- 
tana and northern Idaho, where the maximum amount is 
received in the winter months and the minimum in the 
summer, than the Arizona type, where the maximum 
occurs during the middle of the summer and the minimum 
in late spring. 
For the purpose of throwing additional light on this 
subject, the writer in 1919 secured measurements on 143 
western yellow pine and 111 Douglas fir saplings from 5 
to 10 feet tall growing within a few hundred yards of 
the cooperative Weather Bureau station maintained at 
Grimes Pass, Idaho, at an elevation of 5,000 feet. The 
locality is toward the upper limit of the western yellow 
pine type and not far below the transition zone between 
the western yellow pine and Douglas fir types. No other 
convenient station within the western yellow pine type 
of the Intermountain region could be found having a 
continuous precipitation record for the period under 
study. The current annual height growth and precipita- 
tion for various periods of the year are shown graphically 
in Figure 1. The precipitation for other periods was also 
analyzed, but no correlation could be found. In general, 
a fairly close correlation is noted between the rate of 
growth and the rainfall during April and May of the same 
year, which in the main agrees with Pearson’s findings. 
Similar results were secured near Garden Valley, Idaho, 
which is near the lower limit of western yellow pine, 
but the data could not be used because of the incomplete 
precipitation records. 
A striking exception is seen in the case of Douglas fir 
in 1914. An analysis of temperature conditions for the 
spring of 1914 revealed the prevalence of high temper- 
