87 
Ï possess a good many discs of wood from the North 
of Germany, near the Fms and the Weser. To my 
regret they are cut down at an earlier age, so that I 
could not procure specimens even fully 100 years old. 
One batch of these, however, show a very suggestive fact. 
The fact is that, whereas for the trees which we have 
been considering all along and which I will call our 
southern trees, the 12!/, years period dies out shortly 
before the beginning of the 19th Century, it reappears or 
continues to exist in North Germany. 
Not only is the length of the period exactly the same, 
but the years of maxima and minima occur just at those 
epochs at which the prolongation of the southern curve 
would place them. — So that finally, if we combined the 
results for this particular wood with those for our southern 
trees, we would have a curve showing a regular fluctuation 
in 12.4 years during the whole of the two centuries for 
which I have somewhat extensive materials !). Only one 
minimum, that of 1794 would be missing. 
VII. However I will not insist on the importance of 
this period. IT feel that it is still strongly in need of 
confirmation. 
But suppose that further materials confirm it. What 
would it mean? Would it mean a period of 12.4 years 
in the weather? 
For me there is no doubt about it. Would it mean 
such a period in the spring and summer rain? This 
seems much more doubtful, although certainly it is not 
impossible. We have not to forget that, though we have 
proof of a strong influence of rain on the growth of our 
trees near Treves, we certainly cannot maintain that there 
are not several further factors, which have their influence 
also. 
1) See Note III. 
