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. 88 seems the most regular; a photograph of it is reproduced in 
plate 4,8. 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 § 13 upward. 
They are all Pinus silvestris save 8 14 and $17, which are spruce, 
Picea excelsa. No. 814 is noted particularly because it showed as 
perfect a sun-spot rhythm as G 8 from Eberswalde, whose photograph 
is given in plate 8, a. An entirely satisfactory cross-identification was 
made at the time of measurement. _ 
The individual trees came from different localities and are therefore 
mentioned separately. No. S 13 was marked “4105-6” and was cut 
in May 1909. It grew about 100 miles southwest of Stockholm, in 
latitude 58° 40’. About 1833 it has a doubtful ring which was settled 
by comparison with other measures. Its center was in 1763. No. 
S$ 14, a Picea excelsa, marked ‘‘4105-14,” was cut in July 1910 on the 
east side of Vetter Lake, less than 100 miles southwest 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 Elfdals, in latitude 61°24’. Its center was 
about 1838, but its inner 10 rings were uncertain and therefore not 
