TREE RECORDS: GEOGRAPHICAL DISTRIBUTION 69 



fore were not corrected by cross-identification, which was applied 

 to the others in 1912. The 19 original sections have been retained and 

 two sets of radials have been cut from them; one is the set measured 

 in 1906 and cut in 1912 and the other was cut about 1925, so that 

 accidental loss of the fragmentary pieces of the original sections would 

 do no harm. The curve values as extended to 1910 are given in the 

 appendix of Volume I, to which volume reference is also made for the 

 curve itself (p. 25) and further details. Measures were by ruler. 

 There were so many in this group that for the present purpose it did 

 not seem necessary to standardize each tree-curve, as has been done 

 in nearly all of the western-pine groups. The smoothed curve shown 

 in figure 4 was made by a graphic Hann. The cycles are 6.9 (3), 13.6 

 (3), 20.6 (2), and 28.3 (-J-).* It still remains uncertain whether the 

 cycle 20.6 years is a real value or whether it is a combination of two, 

 of which one is under 20 years and the other about 21 years. 



FLAGSTAFF 500-YEAR GROUP (FLU) 



This group was collected September 10, 1919. Mr. J. F. Freeman 

 measured the specimens by the cathetometer method. Long records 

 were sought at that time and the two 500-year trees, Nos. 12 and 13 

 in the previous Flagstaff series, were completely remeasured and added 

 to the five similar trees in this group, Nos. 33, f 34, 35, 37, and 40, and 

 a table of seven (unstandardized) trees produced. It is a plot of their 

 averages, 1750 to 1917, of which a graphic Hann is shown herewith in 

 figure 4. The use of the same two trees in each of these Flagstaff 

 groups probably has no real effect on the similarity between the two 

 groups, which is very marked, for all these trees give very nearly the 

 same record. The cycles found in this group are 14.0 (2), 20.6 (3), 

 26.7 (|), 29.1 (|), and 40 (£). The 20.6 varies from 20.2 to 21.0. 

 The two near 28 are perhaps variants of one cycle. 



FORT VALLEY GROUP (FV) 



This group is made up of complete sections cut in Fort Valley, 12 

 miles northwest of Flagstaff, by Mr. G. A. Pearson, for the purpose of 

 studying group effects, or the effect on tree-rings of near neighbors. 

 But practically no effect was found unless the neighbor was within 

 5 or 10 feet. The trees grew one-quarter mile northeast of the experi- 

 ment station, elevation 7,300 feet. Mr. L. R. Patterson measured 

 these rings by the auto-plot method. Each tree was standardized. 

 The final table and plot were made by Mr. W. G. Austin and the cycle 

 plots by Mr. F. M. Douglass. The curve 1686 to 1920, shown from 

 1750 in figure 4, resembles FL and FLU and is equally typical of the 



*It will be noted that thia fraction means doubling and not weight. 



fNos. 26 to 32 were cut east of Lake Mary in 1911 and are often called the LM group. They 

 are given in the curve on page 27 of Volume I, and as they were only small pieces cut from the 

 edge of the stumps, they are not used in this study of western cycles. 



