129' 



fairly well with the results for July — September obtained at Noord- 

 wachter, viz. 176°. 



The principal results of the investigation as regards the East 

 component therefore are : 



From up to 4 km. the amplitude inci-eases and the phase 

 decreases from about J 80° — 144°, higher up to 7 km. both return 

 to the bottom values. 



On higher level until 10 the phase seems to increase greatly and 

 the amplitude to increase again. 



When calculating the air displacement (velocity X density) we find: 



The foregoing points to a slight increase up to 4 km and a 

 decrease from here upwards. The values above 7 km are too 

 uncertain to warrant a fresh increase; a gradual decrease is 

 more likely. 



The original decrease of phase for the semi-diurnal oscillation of 

 the East component in the lower parts of the atmosphere up to an 

 altitude of 4 km corresponds with that for the semi-diurnal variation 

 of the air pressure resulting from a comparison of the phases for 

 Batavia and for the neighbouring Pangerango top. 



Proceedings Royal Acad. Araslerdain. Vol. XX. 



