Page:Climatic Cycles and Tree-Growth - 1919.djvu/50

From Wikisource
Jump to: navigation, search
This page has been validated.
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

Climatic Cycles and Tree-Growth Fig 9.jpg

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