36 CLIMATIC CYCLES AND TREE-GROWTH. 



from the interior. The logs came from the vicinity of Dalarne in 

 central Sweden, a large district. The bark is taken off as required by 

 law and the logs are floated down to the mill. I visited the mill on 

 Saturday, December 28, 1912. Twelve sections had been cut, but they 

 were too thick and the whole 12 were cut a second time. These logs 

 had been in the water a year and the last ring would therefore be of 

 1911 or possibly 1910. Of the 12, I think that all but 2 or 3 show the 

 1911 ring. Though these sections must have come from a considerable 

 area (unless in the water and mid-afternoon darkness they accidentally 

 secured original neighbors from thousands of logs), they identify 

 among themselves extremely well. Cycles or pulsations were noticed 

 and marked on all the sections of this group before identification. 

 No. S 8 seems the most regular; a photograph of it is reproduced in 

 plate 4, B. The cross-identification for the last 100 years hardly needs 

 review, as it is entirely reliable and practically nowhere are there 

 doubtful rings. 



The means of the years 1820 to 1910 are given in the appendix and 

 a plot of the same will be found in figure 8. The tree-growth in this 

 group and others before 1820 will be taken up separately. There seems 

 to be here no real change of growth with age, and the values were 

 changed to standard by dividing by 0.8 mm. These results were then 

 smoothed by Hann's formula and plotted in figure 23. 



SOUTH SWEDEN GROUP. 



This group of 6 sections was measured at Stockholm on December 

 27, 1912, in the office of Professor Gunnar Schotte, chief of the Swedish 

 Forest Service. In my lists they are numbered from S 13 upward. 

 They are all Pinus silvestris save S 14 and S 17, which are spruce, 

 Picea excelsa. No. S 14 is noted particularly because it showed as 

 perfect a sun-spot rhythm as G 8 from Eberswalde, whose photograph 

 is given in plate 8, A. An entirely satisfactory cross-identification was 

 made at the time of measurement. 



The individual trees came from different localities and are therefore 

 mentioned separately. No. S 13 was marked "4105-6" and was cut 

 in May 1909. It grew about 100 miles southwest of Stockholm, in 

 latitude 58 40'. About 1833 it has a doubtful ring which was settled 

 by comparison with other measures. Its center was in 1763. No. 

 S 14, a Picea excelsa, marked "4105-14," was cut in July 1910 on the 

 east side of Vetter Lake, less than 100 miles .south west of the preceding. 

 Its center was in 1816. No. S 15, marked "4105-2," was cut in August 

 1909, about latitude 64 30', near Lycksele, Lapland. It showed clear 

 and well-sized rings to its center in 1701. No. S 16, marked "4131-al, " 

 was cut in August 1910, in Elf dais, in latitude 61 24'. Its center was 

 about 1838, but its inner 10 rings were uncertain and therefore not 



