RELATION BETWEEN TERRESTRIAL AND SOLAR RECORDS 



121 



sequences. Here was a mixture in which, in some places, well-defined cycles 

 stood out, including the 11-year length, but there were many others in addi- 

 tion and apparently of similar importance. The two-crested 11-year cycle, 

 heretofore found by integration, was the gateway into this new forest of al- 

 most unknown tree-record cycles. 



One of the first uses of the new analyzing method was an attempt to see 

 the cycles in the Flagstaff ring record. A double-crested 11-plus-year cycle 

 was evident since about 1400 except for a considerable interval near 1700. 

 Mention of this was made in Climatic Cycles and Tree Growth (1919, vol. I, 



1420-1476 



1.0 



1853-1909 



2 4- 6 8 10 



Fig. 52 — Hellmann cycle in Flagstaff 

 pines, FLC-FLU, since 1420; averages of 

 five or six successive 11.4-year intervals. 

 Dotted lines show effect of subtracting two 

 interfering cycles, 19 and 13.5 years. 



p. 102). The history of the 11-year cycle is shown in figure 33 and in Plate 

 12f, of that volume, and in this volume in figure 52; the change and flattening 

 of the 11-year cycle between 1660 and 1725 is evident. As Maunder pointed 

 out in 1922, this coincides with the great dearth of sunspots described by him 

 as extending from 1645 to 1715. In the next few years until 1926, many 

 hundreds of cycle plots of tree-growth curves were made and analyzed without 

 bringing understanding of why so many cycles existed. In 1925, a collec- 

 tion of new ring specimens was made through New Mexico, Colorado, Wyo- 

 ming, Idaho, Oregon, Washington, and California. The 42 groups, collected 



