38 



CLIMATIC CYCLES AND TREE-GROWTH. 



On page 114 will be found the Eberswalde means from 1830 to 1912. 

 Only one center occurs later than that date of beginning, namely, 

 1833. The others were mostly between 1821 and 1827. The means 

 of this group are plotted in figure 8 and also shown more in detail in 

 figure 9. These means have been corrected for age and reduced to 



1820 30 40 1850 60 70 80 90 190& 1910 



Mms. 



Nos. 1-6 



Nos 7-13 



Nos. 1-13 



Nos. 1-13 



corrected 



for age 



Nos. 1-13 

 smoothed 



Sun spot 

 curve 



100 



. 



A 





\ 



FIG. 9. Sunspots and growth of trees at Eberswalde, Germany. 



percentages of a mean line reading 2.57 mm. in 1830 and 0.54 mm. in 

 1910. These in turn have been smoothed and plotted in figure 23. 



In considering the significance of the agreement above noted, one 

 should, in my opinion, keep in mind first the unusually homogeneous 

 environment of these particular trees and the great care they have 

 received, and second, the suggestion they contain of eventually defining 

 distinct meteorological districts in which homogeneous effects are noted. 

 A small pine of 60 rings from the Hartz Mountains was examined in the 



