PAPER BY PROF. OBERBECK. 



169 



ing currents of air and the cyclones arising therefrom. It would be 

 easy in an entirely similar way to develop the theory of descending 

 currents of air and the anti-cyclones resulting therefrom, and here 

 also, as an example, to assume an inner region bounded circularly. 

 Before the actual execution of the exact computation I had believed 

 that this was simply a case of the change of the sign of the constant c. 

 But in this operation we stumble upon a peculiar difficulty. The 



function f (r) = l— -( -j-,) ( wherein /<=— ) which enters into the 



expression for the component velocities in the inner region becomes in- 

 finitely great for negative values of c and ju and for r = o. The same is 

 true of the function F (r) entering into the expression for the pressure. 

 Hence it follows that the formula just given can not be applied to anti- 

 cyclones with a reversed sign of c. 



Therefore minima and maxima of pressure show a characteristic dif- 

 ference in their theoretical treatment. But this, as I believe, corre- 

 sponds also to the real conditions of the true phenomena. Depressions 

 are ordinarily confined to limited areas, but are of considerable inten- 

 sity, while on the other hand the maxima of pressure extend with slight 

 intensity over broad areas. 



Fig 27. 



Moreover, both phenomena stand in close connection, such that one 

 can consider the ascending currents of air as the cause of the descend- 

 ing currents. Hence to a complete cyclone there belong an inner 

 region with ascending air current, a zone surrounding it of purely 



