144 Strictures on Dove's Essay " On the Law of Storms." 



of their mean diameters. Of course if the zone nearest the area, 

 having a mean diameter of ten thousand five hundred feet, move 

 inwards with the velocity of one hundred miles per hour, the 

 velocity at four times that distance, or forty two thousand feet, 

 cannot be more than one sixteenth as great, or little more than 

 six miles per hour. Thus at only four miles from the centre, the 

 centrifugal velocity would scarcely be adequate to a breeze. 



122. This calculation, founded on the idea of the confluence 

 of the air equally from all points of the periphery, would seem 

 too much to contract the theatre of great storms ; but in point of 

 fact, it probably never happens that there is a confluence of the 

 wind from all quarters. In the storm, of which the phenomena 

 are so well recorded by Prof. Loomis, the wind blew principally 

 from two opposite quadrants. But in either case the influence of 

 the inward suction must diverge and diminish in force as the 

 distance from the focal area increases, so that the greatest vio- 

 lence will be in the vicinity of its border, where the wind is most 

 concentrated. For as soon as the confluent currents get within 

 the border, they must be deflected upwards ; and thus the cen- 

 tral space must escape their influence ; excepting the diminution 

 of pressure consequent to the upward motion. 



123. It is I hope thus rendered evident, that the facts adduced, 

 in the quotation above made from Prof. Dove's essay, are quite 

 consistent with the idea of winds rushing towards a focal area, 

 while they are utterly irreconcilable with that in support of which 

 they have been brought forward. 



124. I would recommend Prof. Loomis's* observations to the 

 candid attention of Prof. Dove, and would request him to show 

 in what manner the earth's motion cooperated to produce it ; or 

 how the enormous length of the focal area, or area of minimum 

 pressure, comparatively with its breadth, can be reconciled with 

 the idea of its having formed the centre of an extensive whirl- 

 wind. There is another fact which would seem to be literally an 

 unsurmountable obstacle to the rotation of a storm travelling from 

 the valley of the Mississippi to the Atlantic coast. I allude to the 

 interposition of the Alleghany mountains. Prof. Dove's imagin- 

 ary aerial cylinder would be cut nearly in twain when bestriding 



* See American Philosophical Transactions for account of the storm of Decem- 

 ber, 1836. 



