85 
town of Bürstadt to be partly flooded. I thus got to 
know that my trees grew only very little above the level 
of the Rhine and it seemed at once rather probable that 
the growth might be mainly dependent on the height of 
the subsoil water which in its turn would depend on the 
level of the Rhine. To test this idea [| hunted out some 
data about the level of the Rhine. — I did succeed only 
in finding the mean level of the Rhine 
for each year between 1840—'74 at Mainz 
AUS ñ je 1770—1835 at Emmerich. 
J had little hope that these would furnish a really 
definitive result because [ wanted: 
a. the mean levels for the different seasons and not 
for the whole of the year, and then 
b. at a place nearer to my forest than Mainz and 
especially than Emmerich, which is already on the border 
of Holland. 
To my surprise Ï found that notwithstanding this, the 
parallelism is quite evident. In years in which the mean 
level of the Rhine is one meter over the average level 
at Mainz, the growth in our forest is 32 percent above 
the average. Even with the Rhine-level at Emmerich, the 
parallelism is still clearly indicated. If the yearly mean 
level of the Rhine at Emmerich is one meter above the 
average, the average woodgrowth at Bürstadt is 12 percent 
above the average. I similarly find a strong parallelism 
between the tree-growth along the Weser and the height 
of the level of that river. 
There are other facts pointing to the same conclusion, 
but these may be deemed sufficient. 
V. In every year there was produced but one single 
growth-ring, at least this was the case in the last 70 
years. Îf, what seems improbable, the same thing does 
not hold in earlier years, then the anomaly must have 
occurred everywhere at the same time. 
