456 
Middle Java, 13 Madioen, Kediri, Blitar and Malang, 14 North coast 
of East Java, 15 the Lesser Sunda Islands and Timor, 16 West 
coast of South West Celebes, 17 East coast of South West Celebes, 
18 South coast of North Celebes, 19 North coast of North Celebes, 
20 Amahai, Banda, Ambon and Saparoea, 21 Wahai and Kajeli, 
22 Ternate. 
For our analysis the period 1883—1908 was chosen. 
For each group the deviations of the monthly means were calcu- 
lated from the monthly means of all the years of observation, 
including 1908. Since probably the oscillations in the rainfall have 
a retardation of about two months with respect to those of the atmos- 
pheric pressure *), the barometric deviation for January, February 
etc. was always compared with the rainfall for March, April ete. 
Being only a small fraction of the total period, this shifting is indeed 
of secondary importance, but still it has the advantage of eliminating 
the pressure variations of short duration, which as a rule last a 
month or less and probably are not without any influence on the 
formation of rain. 
In order to express mathematically the relation between rainfall 
and atmospheric pressure, the correlation factors between them were 
calculated for each group and for the twelve months. Denoting by 
“,@,2,...2, the deviations of the separate monthly averages from 
the general monthly mean for the rainfall and by y,y,y,.-.Yn for 
the atmospheric pressure, the correlation factors are represented by *): 
= vy 
a VS Sh 
The values of 7 have been collected in the following table. 
From these data the following conclusions may be drawn: 
An influence of the mountain ranges on the correlation cannot be 
proved with certainty. For the Preanger district bebaves in the same 
way as the coast stations of Java and the stations of group 13, 
lying between high volcanoes. Also the West and East coast of 
South-West Celebes (except in January, February, March, and 
May), the South and North coast of North Celebes (except in 
April) and the stations to the North (group 21) and to the South 
(group 20) of the mountains of Ceram and Buru (except in February 
and April) behave generally in a similar way; besides, during 
1) Cf. Natuurk. Tijdsch. voor Nederl. Indië, Vol. LXX, p. 110. 
*) Cf. R. H. Hooker: An elementary explanation of correlation..., Quarterly 
Journal Royal Met. Soc. Vol. 34, p. 277, 1908 and the extract by Feux M. Exner 
in Meteorol. Zeitschr. June 1910, p. 263. 
