Factors Influencing Plant-Life on Sandy Sea-shores. 41 
The sand used for these samples was almost pure quartz sand, 
completely dried before placed in the tubes. The results show that 
in finer sand, water rises much more rapidly than in coarser, and to 
a considerably greater height. A tube filled with clay was employed 
to ascertain the rate of capillary action in that soil, for comparison, 
but through an accident this tube was broken during the third week 
of the period. Enough was seen, however, to make it clear that 
while the rise in all the sand-samples was comparatively rapid during 
the first ten minutes after submersion in water, it was nearly four 
times slower in the clay. After a week’s time the rate of rise in the 
clay increased in comparison with that of sand, and continued to 
do so. 
The above results, which support those of Klenze, so often 
referred to by writers on the physical properties of dune sand, 
indicate that the rise of water by mere capillary action is slow, and, 
moreover, does not reach any considerable height. 
In order to investigate this question still further, I had a well 
dug at the foot of a sand-dune near Perth, in Western Australia, for 
the purpose of establishing the level of the ground-water. The site 
of the well was 97 meters from the high-water mark of the ocean, 
and the water in the well stood at average low tide 23 cm. above the 
level of the sea. Minute observations were made of the fluctuations 
of the ground-water-level, which was found to be influenced by 
atmospheric conditions and by tidal oscillations. 
Simultaneously measurements were taken of the rate of 
evaporation from the surface of the dune. This latter was 8'72 
meters high above the water-level in the well, and thus 8'95 meters 
above sea-level. The well was 4-3 meters distant from the middle 
of the base of the dune. 
The amount of rainfall during the five months covering the 
period of observation was 247 cm. It was found that a perceptible 
amount of moisture existed at 5 - 8 m. above the ground-water-level 
in the interior of the dune, but above this height, up to 7-4 m., the 
amount of soil-moisture was very small. The moisture then 
increased gradually, until it reached a maximum at 68 cm. from the 
surface. Again it decreased towards the surface of the dune. 
In trying to explain this condition of the moisture-content in 
the sandy soil of the coastal dune, it should first be borne in mind 
that there is a general tendency of the ground-water to stand at the 
highest level under the highest ground. The second point is the 
capillarity, which considerably assists in raising the water, as the 
above mentioned experiments show. 
