454 
Corresponding in order of magnitude with my figures. 
There seems to exist no relation with the density of the solid. 
But it seems that substances with many atoms in the molecule have 
a larger radius. 
Although the results found may still need correction from the fact, 
that the boundary of the waterlayer and the vapour is not so sharply 
defined as has been supposed, and because the compressibility of 
liquid water has been neglected, the results seem interesting enough 
to call attention to them. Perhaps then some one more competent on 
this subject, will deduce a less approximate theory. This theory will 
also have to answer the question, what is the relation between the 
maximum and the minimum in Trovuton’s curves with the maximum 
and the minimum in the isotherm of vaN DER Waats, and if the 
supposition is right, that it is possible to calculate the maximum 
and the minimum of the equation of state from the minimum and 
maximum in TrouTon’s curves. 
The importance of these investigations for the problem of swelling 
(imbibition) will be treated later. 
Meteorology. — “The Correlation between Atmospheric Pressure and 
rainfall in the Kast-Indian Archipelago in connection with 
the 3,5 yearly barometric period’. By Dr. C. BRAAK. (Com- 
municated by Dr. VAN DER STOK). 
(Communicated in the meeting of June 29, 1912). 
The regularity of the East-Indian climate renders it eminently fit 
for clearly revealing weather variations of longer period. There the 
interest in the weather of next day is quite subordinate to the question 
whether the coming season will bring much or little rain and since 
predictions for the immediate future are not wanted, full attention 
can be paid to those for a more distant future. And this the more 
so as the circumstances there promise a much better chance of 
success for a prognosis of the seasons than elsewhere. 
That the variations from one year to another are very considerable 
and an investigation of their character and origin is important, may, 
perhaps superfluously, be proved by the following summary : (p. 455) 
One naturally looks for a relation between the oscillations in the 
rainfall and the barometric changes of long period. 
These variations of the atmospheric pressure are of the same 
character over an area extending from British India over the Indian 
