Strictures on Dove's Essay "On the Lata of Storms " 139 



fore, it may be demanded, should the upper current penetrate 

 through the lower current, and supposing it to do so, why should 

 it be productive of a hurricane ? 



105. The professor goes on to say — "It is evident, that if the 

 above deduction of these phenomena be the true one, a similar 

 whirlwind must be produced wherever, owing to any other me- 

 chanical cause, a current flowing towards a high northern lati- 

 tude is more southerly on its eastern side than on its western." A 



106. It seems as if Prof. Dove, no less than Mr. Redfield, falls 

 into the error of making the cause of gyration the only object of 

 inquiry. It is, according to them, sufficient to show that the 

 rotation of the earth, or the reaction of a mountain, may give a 

 curvilinear direction to the wind. To account for the wind itself 

 is not in the least necessary ! 



107. Can any thing be more inconceivable, than that a cur- 

 rent of air, not previously moving with the force of a hurricane, 

 should, by influence of the earth's motion, or a conflict with 

 one or more mountains, be excited into a tempestuous fury ? 

 Whence comes the alleged peculiar violence of the whirling por- 

 tion of the atmosphere noticed in such storms ? Evidently de- 

 flection could not cause any augmentation of force. The velo- 

 city of the whirl would be less instead of greater than that of 

 the generating gale, since the centrifugal force consequent to 

 rotary motion would be productive of a collision with the sur- 

 rounding atmosphere, tending to dissipate the momentum. This, 

 as I have already observed, could receive no reinforcement, while 

 the mass actuated by it would increase with the square of the 

 distance from the axis. (See additional objections to Redfield's 



theory, par. 65.) 



108. Prof. Dove has not considered the incompetency of a 



local cause of deflection, to beget permanency of rotation in a 

 travelling storm ; nor the impossibility of the endurance of a 

 momentum sufficient to cause the violence of hurricanes without 

 continuous exciting forces. 



109. In a passage which I shall in the next place quote, the 

 idea is advanced that the axis of a whirlwind may incline for- 

 ward so as to cause the higher portion to precede the lower, and 

 to make the lower stratum of the air forming the whirl exchange 

 places with the upper stratum. 



This view of the phenomena I 



prove 



