Durinj? 1913 single-observation only has been applied, and during 

 the other years the same has been applied mostly for ascensions 

 between 6 a. m. and 9 a. m., during which hours the lower layers 

 are little or not disturbed by convection currents. 



The material of observation consisted of the direction and velocity 

 of the wind at various heights and at various hours, dei'ived from 

 series of consecutive balloon ascensions and the problem remained 

 to deduce therefrom the diurnal and semi-diurnal oscillations. 



To this end it was assumed in the first place that (hese oscilla- 

 tions are constant for each height. However, this is certainly not 

 the case with the diurnal oscillations in the lower layers, because 

 the latter are influenced by land and sea breezes, the intensity of 

 which varies from day to day ; but the departures from an average 

 might be classified among all non-periodical variations of the wind. 



However, the semidiurnal variation of the East- West-component 

 might be surmised to possess a great constancy and also the 

 North-South-component to retain the same sign during at least a 

 semester. 



In the second place the "difference method" was applied ; each 

 time two ascensions, succeeding each other at a short interval, were 

 joined and by doing so it might be expected that the non-periodical 

 variations would be eliminated for the greater part; moreover, ascen- 

 sions with intervals not disturbed by showers were mostly joined 

 and, as regards the lower layers, with intervals no longer than 24 

 hours. In case of the upper layers longer intervals were admitted. 



Therefore, each couple of ascensions yielded the value of the 

 following expression for each height and for each of the two com- 

 ponents (E. W. and N. S.) : 

 •x^{sin t^ — sin t^) -\- y-^{cos t^ — cos t^ -\~ w,{sin2t^ — sin2t^) -\- y^{cos 2<, — cos 2<,) 



and the values of ^t, y,, jk, and y, were calculated from the whole 

 for each height and for each of the two components according to 

 the method of least squares. 



When performing the ascensions, which took place by day and 

 night, and the enormous amount of calculations attending the 

 deduction of wind components and the making up and solving of 

 the normal-equations, we have been greatly assisted by the staff of 



