170 THE MECHANICS OF THE EARTH'S ATMOSPHERE. 



horizontal luoveinent, aud at a greater distance from the center a ring- 

 shaped region of descending cnrrents. 



If we assume that the boundaries of the three regions consist of con- 

 <?entric circles, it would not be difticult to compute the wind system for 

 the whole region by the help of the potential theory as above employed. 

 In this case, where we have to do with an annular region with a 

 descending current of air, the use of the function / (r), even with a 

 negative sign before the /./, is allowable, and can be adopted in order 

 to produce the necessary continuity of motion at the boundary of the 

 two annular regions. If there are several regions of depression with 

 ascending currents of air, as at A, B, C, fig. 27, then each of them is 

 immediately surrounded by a zone of purely horizontal movement, which 

 is bordered by an outside annular zone of descending movement. I 

 have in the figure (27) distinguished the region of ascending and de- 

 scending current by double and single shading. In the region where 

 the different ring systems of ascending air currents merge into each 

 other there will lie a region of highest pressure with auticycloual 

 movement of the air somewhat as within the isobar M, N, P. How- 

 ever, the characteristic difference between ascentling and descending 

 currents of air always consists in this, that the former consist of defi- 

 nite, simply connected areas ; the latter, on the other hand, of a net- 

 work of several comi)lexly connected regions. 



Halle a. S.,June, 1882. 



/'. S. — After sending the above treatise to the editor of the Annahn, I foinid iu the 

 May miuiber of the Zeitschrift of the Austriau Association for Meteorology (vol. xvii, 

 pp. 101-17;')) a review by Dr. A. Spriiug of the second part of the collected memoirs 

 by VV. Ferrel, under the title of "Meteorological Researches." 



From this I perceive that the views expressed by me as to regions with high 

 pressure had been already expressed by Ferrel. Therefore, although my point of 

 view is no longer new. still I rejoice to see that it is shared by a prominent meteor- 

 ologist. 



