(1235 ) 
R cos (t — 312.°8) 
the kappanumber ought to be: 
North of Batavia 122.°9 
South 3 302.°9. 
Now the tidal constants according to VAN DER STOK!) are: 
Kappanumber Amplitude 
in cm. 
M,-tide S. of Batavia 225° 49.6 *) 
fe ee aes eee " 304° 3.6 *) 
Cares nd Ai 268° EEG) 
ents Le Ah En 129° Fa. *) 
If, as is reasonable, the principal disturbance of the M, tide is 
ascribed to the Indian Ocean, where semidiurnal tides are paramount, 
and, on the contrary, the disturbance of the O-tide is ascribed to 
the Java sea, where diurnal tides are prevalent, the agreement 
between the kappaïumbers, as calulated from the disturbances and 
as observed, is very satisfactory. 
A closer inquiry into the influence of the K, and P tides would 
be useless; the period of these tides being but slightly different from 
that of mean solar time, meteorological influences probably cause 
considerable disturbances; the results for different hours therefore 
show large discrepancies : . 
K, tide for 10 and 115 0.167 cos (t—315.°6) 
for 12 and 15 0.532 cos (t—224.°8) 
P tide for 10 and 115 0.187 cos (t—349.°7) 
for 12 and 15 0.538 cos (¢—145.°3) 
Probably annual variations in the diurnal heat wave, and the 
intensity of land- and seawinds have an important disturbing influence °). 
On the assumption that the disturbances acting upon the M, tide 
are wholly due to the watertide, the disturbance of the /-JV com- 
ponent of this tide can be eliminated, as tbe disturbing force, acting 
on the £-W pendulum, in this case, has a difference of phase of 
about 90° and, consequently its influence on the amplitude is small. 
If we look at Van per Srox’s chart of homocumenes 5), it appears 
that, south of Sumatra from Padang to Vlakkehoek, the kappanumber 
1) Kon. Nederl. Meteor. Instituut. Mededeelingen en Verhandelingen n°. 8. 
Elementaire theorie der getijden. Getijconstanten in den Indischen Archipel, 1910. 
2) Amplitude at Tjilatjap, kappanumber according to chart of homocumenes. 
3) A and kappanumber for Edam, Tandjong Priok and Duizendeilanden. 
') %9 29 in for Tjilatjap. 
) ” ” ” for Edam, Tandjong Priok and Duizendeilanden. 
6) With sudden increase of the wind and the beginning of rainshowers, the 
direction of the wind can easily be traced on the seismograms; the deflections 
caused by these agencies amount to 1 à 2 mm. in maximo. 
7) loc. cit. 
81* 
