174 TREUBIA VOL. II, 2—4. 
rain-observations at Tandjong Priok that in the Spring of 1918 after 
March 4th no rain-showers of importance have fallen in the littoral 
zone near Batavia. 
This circulation continuing within the borsten the salinity in all the 
ponds approaches more and more to the average salinity of the whole system, 
towards June 15th, It was only in the small fry-ponds C that I met with a 
higher salinity on June 15th, namely 30.20,,,. In connexion with the observa- 
tions of June 27th, when there were observed in these fry-ponds salinities 
considerably higher than that of sea-water, it is clear that in this salinity of 
30.2 0/, the influence of another factor, viz. evaporation of the pond-water, 
finds itself noticeably expressed for the first time. That the salinity in the 
fry-ponds C amounting to 30.204, on June 15th 1918, cannot be explained 
from the admission of sea-water alone, is put beyond a doubt by the fact 
that, at the same date, in the more seaward ponds, and SP in pond, 
E at point 5, the salinity was below 30.2 °/o. 
After the end of June the influence of evaporation of the pond-water on 
its salinity becomes increasingly clear. These observations tally with the data 
supplied by the Royal Magnetical and Meteorological Observatory according 
to which in 1918 the East-monsoon wind actually began to prevail with 
force and regularity in the latter half of June. 
Consequently, except in the most seaward ponds, F at point 6, an Gat 
point 7, the salinity in all the ponds, already on the 16th of July, exceeds 
that of the sea-water that can be admitted from the coast. The salinity 
of this sea-water was on October 21st 1918, towards the end of the 
dry monsoon: 32.59/,,; on February 19th 1919, in the wet monsoon, in two 
different places 26,8 »/,, and 27.2 0}, respectively. The samples I used for 
determining these salinities were collected shortly before or after high-tide, at 
any rate not at a time when water was flowing from the ponds, quite near the 
coast, at the mouths of the canals used for renewing the water of the fish-ponds. 
Now when we consider that, in connection with the evaporation of 
the pond-water, we see the salinity in all the ponds increase continually 
after June 1918, until, in September, October and November, the ponds 
A, B, C, C’ and D show salinities of 76.6 %/,,, 73.6 0/,,; 64.9 %0; 77.607, and 
75,1%, respectively, and the more seaward ponds E, F, and G at point 
7, salinities of 50.20/,; 38.40/,, and 48.3 /,,, the question arises whether the 
fish-pond owner is pleased to see these high salinities, and if not, why he 
does not replace the pond-water by sea-water, which itself had a 
salinity of 32.50/, only a few days before the maximum salinity of over 
76.60, was reached in pond A, 
The truth is that the fish-pond owner is anything but pleased to see 
the salinity in his ponds rise so high, but that, at any rate in Mr. Görs’s 
pond-system, it is often not possible to replace a sufficient quantity of 
pond-water by sea-water. 
In Diagram I I have traced the maxima and minima for 1918 of the 
