« On the Law of Storms:* 101 



126. 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 

 phaenomena 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 di- 

 minish in force as the distance from the focal area increases, 

 so that the greatest violence will be in the vicinity of its border, 

 where the wind is most concentrated. For as soon as the con- 

 fluent currents get within the border, they must be deflected 

 upwards ; and thus the central space must escape their influ- 

 ence; excepting the diminution of pressure consequent to the 

 upward motion. 



127. It is I hope thus rendered evident, that the facts ad- 

 duced, 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. 



128. 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 pro- 

 duce 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 whirlwind. There is another fact which would 

 seem to be an insurmountable obstacle to the rotation of a 

 storm travelling from the valley of the Mississippi to the At- 

 lantic coast. I allude to the interposition of the Alleghany 

 mountains. Prof. Dove's imaginary aerial cylinder would be 

 cut nearly in twain when bestriding that range. Obviously 

 more than one half of the air in such a cylindrical mass would 

 be below the average level of the summits of those mountains. 

 Under such circumstances could it be conceived to rotate 

 about a vertical axis? 



129. I am aware that various writers have referred to the 

 little transient whirls which are occasionally seen to take place 

 in a windy time, carrying up dust, leaves, and other light bo- 

 dies, as a support for the idea of whirlwind storms; and Mr. 

 Redfield has alleged, " that no valid reason can be given why 

 larger masses of air may not acquire and develope similar ro- 

 tative movements." 



130. It appears to me that there are several valid reasons 

 for not adopting the view of the subject which he has taken. 



* See American Philosophical Transactions for account of the storm of 

 December 1836. 



