32 CLIMATIC CYCLES AND TREE-GROWTH. 
sections there is more than usual variation in different radii, an excess 
of growth starting in one direction and then slanting off in some other 
direction. Here it was found also that maxima were not always the 
same in different radii. It was suspected that some radii tried to follow 
a single cycle and others a double cycle. A photograph of one of these 
sections is shown in plate 4, a. 
The appendix presents a table of mean growth of this group from 
, 1845 to 1912. No. 2 had its center in 1865, and between that date and 
1845 extrapolated values have been used in forming the means. These 
extrapolated or artificial values preserve the average shown by the 
individual tree during its years of growth, but are made to vary from 
that average in accordance with the variation’s of the rest of the trees 
in the group. From 1828 to 1844 the mean of 3 sections only is given. 
The actual mean has in this latter case been multiplied by 1.25 to bring 
the average into accord with the group, for the mean of these 3 for the 
11 years from 1845 to 1855 inclusive is only 80 per cent of the mean 
of the group. In this group one center was in 1865, three in 1844, one 
in 1842, one in 1840, one in 1836, one in 1827, one in 1800, and one in 
1693. 
These means are plotted in figure 8. The same corrected to a 
standard mean and smoothed by Hann’s formula will be found in 
figure 23. No real correction for age has been made in this case, for 
there seems little change in rate of growth that can certainly be 
identified as such. The whole, therefore, has been simply reduced to 
scale for comparison with other groups by dividing every year by 1.25, 
which is very nearly the average growth in millimeters. 
INNER COAST OF NORWAY GROUP. 
It is a great help to visit the exact locality in which the trees grew, 
or to get very near it, as in the groups already described, and especially 
to obtain personal information in a mountainous country like Norway, 
where meteorological conditions may vary enormously within a few 
miles. But it was impossible in the present group, whose sections had 
mostly been collected some years before for use in the forest service 
and schools. By courtesy of various officials I was permitted to 
examine and measure these sections in their offices, and whenever it 
was possible thin sections were cut off for me to add to my collection. 
In measuring sections of which samples were not retained, for example 
B 15, B16, and N 2, there was no opportunity of cross-identifying 
rings, and hence unusual precautions were observed in numbering the 
rings. If at any spot they seemed to be very close together with any 
chance whatever of mistake by omission or doubling, the numbering 
was carried to as many other radii as were necessary for a check, and 
worked over very carefully until the best possible result was obtained 
