( 675 ) 
found, with maxima about 1855—56 and 1882—1883 and a mini- 
mum about 1869—70. 
In his “Hyetography of the Netherlands” Mr. ENGELENBURG *) inquires 
if there exists any relation between sunspots and rainfall. He finds 
that we can admit that such a relation, if it exists at all, does not 
appear very distinctly. 
It is the merit of Dr. LAaurENs Vuyck, in his elaborate treatise on the 
vegetation of the dunes,’*) to have submitted the problem of the 
change of height of the ground-water in the dunes, as it also appears 
from older writings, to a close investigation. He however thinks of 
a progressive drying up of the low places in the dunes, having 
slowly taken place from as long ago as the end of the eighteenth 
century. From a careful consideration of the problem he arrives at 
the conclusion that the cause can only be found in a continuous and 
imperceptibly ‘slow filling up of those low places with eolian sand. 
The earliest intimation of the dunes drying out, which ought once 
more to be quoted, is from the end of the 18 century. In the 
report of a committee from that time to the Government, the reporter, 
JAN Kops*) makes mention of the fact, that at the time of his 
inquiry, in 1797, the obstacle to the culture of the dunes arising 
from an excess of ground-water has been removed for a great 
deal. “In all our inspections, in the North as well as in the South, 
the most experienced people told us unanimously that during the last ten 
years, from year to year, less and less water than before is found 
in the plains amidst the dunes. They showed us places which for- 
merly stood two or three feet under water and became extensive 
icefields for winter-sport, but now were only somewhat muddy in 
winter. In other plains, only four years ago, there stood still water 
in spring, from which nothing now is to be seen, and so it is with 
almost all the dunes. This particularity has raised our highest atten- 
tion and surprise, as on account of the well known and alarming 
rising of the level of our rivers and inland water, we should expect 
the sinking down of the water of the dunes to be checked and 
prevented by it. Nobody was able to explicate to what cause this 
decrease of the dune-water should be imputed and we too could not 
trace out the true cause of it. But where it is to be sought for, this 
circumstance is most favourable for all following undertakings in the 
dunes.” (p. 114 and 115). 
1) Physical Transactions of the Kon. Akad. v. Wet. Amsterdam 1891. 
2) Laurens Vuycx, De plantengroei der duinen, Leiden, 1898. 
3) Rapport van de Commissie van Superintendentie over het onderzoek der 
Duinen van het voormaalig Hollandsch Gewest. Leiden 1798/99. 
