SHORT MEMOIRS ON METEOROLOGICAL SUBJECTS. 427 



which iu itself may be correct. One of the best examples of this is 

 found in the history of the geological views current in Germany in the 

 course of the nineteenth century ; but I believe that also the develop- 

 ment of the theory of storms can be considered as a similar example. I 

 will not here give a history of storm theories, but only briefly sketch, so 

 far as it seems important for my purpose, the two opposed views; 

 the older, which is still found almost exclusively in our German text- 

 books of meteorology, and the newer, which, proceeding iu the begin- 

 ning from America, and recently from the most northern states of 

 Europe, has also already found influential supporters in Southern 

 Europe. 



The older theory considers the storm-whirl, if I may so express it, as 

 purely mechanical, arising from the meeting of different currents of air. 

 The centrifugal force arising in consequence of the rotatory movement 

 of the air was held to be the cause of the low barometric pressure iu the 

 center of the whirls. We have lately heard this theory more fully 

 expounded by Dr. Wittwer iu this journal [vol. x, pp. 1-^]. The new 

 theory, which I would designate as the physical theory, finds in the 

 formation of some local diminution of pressure the first cause of an 

 inflow of air from all sides and the attendant formation of a whirl in 

 consequence of the influence of the earth's daily rotation. The baro- 

 metric depression itself is viewed as a consequence of the condensation of 

 the aqueous vapor over an extensive portion of the earth's surface [see 

 this journal, vol. vi, pp. 209, 240, and vol. viii, pp. 109, 177]. 



As we perceive, the diflerence between these views consists, besides 

 the diverse explanation of the origin of the whirl, also in this, that the 

 older theory explains the differences of pressure as due to the wind ; 

 the new theory, on the other hand, deduces the direction and strength 

 of the wind as phenomena resulting from the previously existing differ- 

 ences of pressure. 



Both theories cannot stand together. It is, however, not therefore 

 necessary that the one should be absolutely false and the other thor- 

 oughly correct. There may be in each correct and incorrect views min- 

 gled together. Wherefore we will examine them in reference to this. 



No one can deny that whirls can arise by the conjunction of currents at 

 an angle with each other. But how in this manner the invariable rota- 

 tion from right to left in the northern and inversely in the southern 

 hemisphere should arise, it would be difficult, indeed impossible, to 

 explain. Still more difficult is it to explain, according to this theory, 

 the fact that the whirl, once formed, pursues a path of hundreds of 

 miles through the atmosphere, iu the course of which it continually 

 draws new masses of air into motion, overcomes a great amount of fric- 

 tional resistance along its entire path, and exerts powerful mechanical 

 effects. This would be physically impossible, and surpasses even the 

 " perpetual motion " without a coustant accession of force. It must, on 

 the other hand, appear to every one as a pure play of the imagination to 



