364 CARNEGIE INSTITUTION OF WASHINGTON. 



of wind and charts of pressure of a much simpler description than 

 the original ones. But in spite of these simphfications, no satisfactory- 

 correspondence could be obtained between the calculated changes of 

 motion and those obtained from the observations, showing thus that 

 the irregularities of friction are not sufficiently smoothed out by this 

 averaging for short intervals of time and for small areas. 



These investigations are not yet finished. Especially will it be 

 important to take them up for Europe. Here the conmion meteoro- 

 logical observations are not so satisfactory. But we have the oppor- 

 tunity of choosing the days of the international meteorological ascents, 

 and thus to study the phenomena on the base of a tolerably complete 

 knowledge of the motion of the higher atmospheric strata. 



One of the possible explanations of the difficulties met with in 

 these investigations on friction may be motions of the type of waves 

 or of oscillations. The theory of atmospheric waves has therefore 

 been made the subject of further investigations. A first paper, 

 giving the fundamental equations of these waves, has been pubhshed 

 (see list of pubHcations, p. 30), and two further papers giving special 

 integrations are in preparation. 



In order to apply the laws of thermodynamics to atmospheric 

 processes, complete tables have been worked out for calculating 

 energy and entropy of moist air. Parallel with this practical ther- 

 modynamic work, our theoretical investigations have led to important 

 results concerning the atmosphere and the sea considered as heat 

 engines (see list of pubUcations, p. 30). 



A mixed dynamic and thermodynamic investigation concerning the 

 trade- winds has been taken up, based on observations collected in the 

 region of the north Atlantic trade-wind by Rotch, Teisserenc de Bort, 

 and Hergesell. Charts have been drawn representing average tempera- 

 ture, average pressure, and average horizontal motion in all levels up 

 to the height of 10 km. By use of the equation of continuity the corre- 

 sponding vertical motion has been derived. On the basis of these 

 data a thermodynamic discussion of the trade-wind will be attempted. 



In connection with the above special investigations on dynamics and 

 thermodynamics of the atmosphere, the preparation of volume III, 

 "Dynamics," of the work "Dynamical Meteorology and Hydrog- 

 raphy" has been continued. 



