120 



CLIMATIC CYCLES AND TREE GROWTH 



It became very evident that improvement in method of cycle analysis 

 was urgently needed. This was accomplished, as related, by the multiple 

 plot and the first automatic periodogram. In 1914, the automatic cyclogram 

 was made. 



Sunspot cycle showing 

 inverted minimum. 

 (Dotted line) 



Hellmann's curve, 

 No. Germany rain. 



Flagstaff pines 



\ Flagstaff pines. 

 (True position) 



Springville sequoias. 



v So.California rain. 

 ( See note page 178) 



Grant Park sequoias. 



80 European trees, 

 Summation showing 

 frequency of maximum 

 growth. 



Bear Valley (San Bernardino) 

 pines. 



So. Sweden pines 

 Eberswalde pines 



57 European trees 

 Sunspot numbers 



Max. 



Mm. 



Fig. 51 — Integrations on 11.4 years of data mostly between 1850 and 1900; arranged 

 according to prominence of second maximum of Hellmann cycle. See footnote pp. 118, 

 119. 



Then for several years an obstacle seemed to stand in the way of progress; 

 there were too many cycles. The smoothed annual sunspot means had been 

 analyzed and, as we know, a clear, well-defined if somewhat variable cycle 

 was the most conspicuous character; but not so in climatic and tree-ring 



