34 CLIMATIC CYCLES AND TREE-GROWTH. 
All the sections so far in this group came from the west side of 
Norway near latitude 60°. The remaining two came from farther 
north and were first examined in the office of Dr. Jelstrup. No. N1 
was a small tree some 6 inches in diameter with its center in 1848. It 
grew in Mo i Ranen in latitude 66° 15’, a 2 days’ trip by boat from 
Trondjem. The rings show a rhythmic character, and a photograph 
of the thin section presented to me is given in plate 3,8. As in the 
other similar photographs, the years of sunspot maxima are marked 
with arrows. It was cut in 1907 and the outer incomplete ring was 
taken as of that year. The identification with trees from near Bergen 
is poor, as would be expected. 
No. N 2 was an interesting cross-shaped section from beyond the 
Arctic Circle, latitude 68° 45’. It had been damaged by forest fires at 
various times to such an extent that the injured parts of the trunk 
ceased growing while the rest kept on; hence it was of this extraordi- 
nary shape. It was cut in the winter of 1905-6, and the outer ring was 
taken as of 1905. As a rule the rings were very easy to follow until 
before the year 1600, and even then by carrying the ring to other arms 
the identification seemed practically certain. The rings reached a 
suspiciously small size between the center at 1497 and 1512. 
The measuring of this 400-year section was done on December 31, 
1912. By noting ring after ring with care, tracing all rings a short 
distance and following the one case of suspected double across into 
another arm, there seemed to be no errors, certainly none of doubling 
and none suspected of disappearance. Letters B, BB, indicating 
maximum growth, were placed at the center of groups of large rings as 
the measuring progressed, without knowledge of any relation between 
them. That same day, on looking over the measures, a Briickner 
period seemed indicated. The maxima were marked as the measuring 
progressed. See table 3, on page 35. 
This series of maxima, 270 years long, from 1561 to 1830, shown in 
figure 38, permits the application of a 34-year period with an average 
error of less than 3 years. If that case were alone, I would not include 
it here, but I believe I shall be able to show it in a number of very old 
trees in widely separated localities. 
From the above description it is evident that we have in this group 
some very interesting trees, even though they grew far apart. They 
are probably worth more as individuals than as a group, but until 
more trees can be added from their various localities the usual method 
of presenting them here is used. So the group means are tabulated in 
the appendix, using an extrapolated value of N 1 from its center in 
1848 back to 1821. These means will be found plotted in figure 8. 
They have been corrected for age and reduced to standard size in the 
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