1321 



Batavia and Port Daiwin (N. Australia) and between Batavia and 

 Koepang. Tliej have been calculated applying for P. Darwin and 

 Koepang the same vertical gradients as were found for Batavia. 



The heights at which the differences given above change sign, 

 viz. 3 — 4 km. and 8 km., do not agree, however their average 

 5 — 6 km. coincides with the observed vertical extension of the 

 westmonsoon. 



Eventually the direction of the monsoon deviates with increasing 

 height in the same spiral manner which elsewhere has been observed 

 in aircurrents, moving to the right in the northern and to the left 

 in the southern hemisphere. Accordingly, at the bottom the wind is 

 WNW turning through WSW and S to SE gradually proceeding 

 upwards. 



Trade and AntitroAle-tuind. Disregarding the northerly components 

 in the bottomlayer, which originate from local disturbance, the lower 

 easterly winds have a southern component throughout the year; 

 accordingly the aircurrent is called by me tradewind, as flowing 

 towards the equator. 



Its ESE-direction tallies with Braak's isobars as drawn for the 

 months of July/Sept. Computing for these three months the pressure- 

 differences between Batavia and Koepang in the same manner as 

 was done for Jan./Febr. the following values were found : 



Pressure-difference for July/Sept. 



According to these figures the pressure difference disappears between 

 3— 4 km. and higher up changes sign ; nevertheless the ESE-wind 

 not disappearing as does the Westmonsoon at its upper limit, turns 

 to the E with decreasing force and going on turning, it gains force 

 and reaches an ENE-direction. 



In behaving so it renders it impossible to bring it in direct com- 

 pliance with any isobaric chart to be derived from given data for 

 surface-isobars and isotherms. For the trade which blows above the 

 layers of the westmonsoon in the southern summer, it is utterly 

 impossible owing to its high level to calculate a gradient with any 



