" On the Law of Storms." 99 



120. One of the grounds taken by Prof. Dove, appears to 

 me strikingly untenable. His language, vol. iii. p. 21 4, last 

 paragraph, is as follows: — "The dead calm, suddenly inter- 

 rupting the fiercest raging of the storm from opposite direc- 

 tions, which is shown in the register of observations at St. 

 Thomas, — that dreadful pause which fills the heart of the 

 bravest sailor with awe and fearful expectation, — receives a 

 simple explanation on the rotatory theory, which requires that 

 at the centre of the whirlwind the air should be in repose ; but 

 appears irreconcilable with the supposition of a centripetal in- 

 blowing, because two winds blowing towards each other from 

 opposite directions must gradually neutralize each other, and 

 thus their intensity must diminish more and more in approach- 

 ing their place of meeting. This takes place on the great 

 scale in the trade winds, and if the centripetal view of hurri- 

 canes were the just one, the same effect would necessarily be 

 seen as the centre of the storm passed over the station of ob- 

 servation. But the phaenomena shown by observation are 

 widely different. At St. Thomas the violence of the tempest 

 was constantly increasing up to 1^ 30™ a.m., when a dead 

 calm succeeded, and at 8*^ 10™ the hurricane recommenced as 

 suddenly as it had intermitted. How can this be reconciled 

 with the meeting of two winds?" 



121. I have made the preceding quotation from Prof. Dove's 

 essay, conceiving it to contain evidence which must be fatal to 

 the hypothesis which it is intended to prop. It establishes 

 that in hurricanes the wind is liable sudde7ily to subside from 

 its extreme violence to a calm, and then as suddenly to re- 

 commence blowing with as great violence as ever in an oppo- 

 site direction. I am very much mistaken if I have not in my 

 Additional Objections to Redfield's Theory (79 to 84-) demon- 

 strated that, in extensive whirlwinds, the ^^Jiercest raging" 

 cannot be suddenly interrupted so as to leave a dead calm du- 

 ring the interval which takes place between two opposite winds; 

 since in such storms, where they have a diameter not less than 

 three hundred miles, for the same station to be exposed suc- 

 cessively on opposite sides of the zone, where the wind is most 

 violent, the storm must move at least one hundred miles, which 

 would require from three to four hours. 



122. Referring the reader to the essay above mentioned, I 

 will urge, in reply to the query already quoted, that Prof. 

 Dove's allegation that " winds blowing from opposite quarters 

 will neutralize each other" arises from his forgetting that agree- 

 ably to the hypothesis which he is striving to confute, they are 

 caused by a deficiency of pressure at the axis of the storm 

 producing an upward current for the supply of which they are 



H2 



