118 



CLIMATIC CYCLES AND TREE GROWTH 



cott was used for special comparison with Prescott rainfall since 1867 and 

 strong correlation was obtained upon allowing a small conservation. 



But other developments occurred in the next few years. Late in 1912 

 an 11-year cycle had been found in German and Swedish trees, figure 51 

 (2, 9, 10, 11), similar in form to Hellmann's north German curve of rainfall 

 in relation to sunspots. Two of the original sections are shown in Plate 21. 

 North German and Swedish trees showed a single crest, paralleling the 

 smoothed annual sunspot numbers; other curves showed the beginning of a 

 second maximum in growth at sunspot minimum; still others showed this 

 second maximum well developed. The crest at sunspot maximum was evi- 



Anzona 



tree growth 



492 years 



California 



coast temp. 



1863-1912 



Calif, coast 

 rainfall, 60 yrs. 

 1863-1912 



50 Inverted 



sunspot nos. 

 , 00 125 years 



1 1. 4 yea ps 



Fig. 49 — Western correlations, 1914 in "The Climatic Factor," by E. Huntington. 



dent through a long period of years (1830 to 1911) and thus gave a high 

 correlation with the extended annual sunspot numbers. 



In the spring of 1913 the Flagstaff trees, numbers 7 to 25, still in hand, 

 were reviewed and corrected as to yearly identity and a new integration 

 made on an 11.4-year cycle, this time with far better success, for the dating 

 was correct. The resulting integration diagram is shown in figures 49 

 and 50. Hellmann's rainfall curve is included and matches that in California 

 rainfall. 1 



1 List of references to extended curves from which the summated curves in figure 51, 

 page 120, were made. 



2 (a) Hellmann's curve — Proc. Nat. Acad. Sci., Mar. 1933, vol. 19, p. 354, 



fig. 6. 



3 (j) Flagstaff Hellman— I, p. 102, fig. 32; Proc. Nat. Acad. Sci., vol. 19, 354, 



fig. 8. 



4 (h) Springville Sequoias; not published. 



5 (f) So. Calif, rain— Proc. Nat. Acad. Sci., vol. 19, 354, fig. 7; fig. 5. 



6 (g) Grant Park Seq— II, p. 100, fig. 10; measures— I, 122-3. 



7 (b) 80 Europ. Trees— I, 78, fig. 26. 



