22 On the prevailing Storms of the Atlantic Coast. 



winds, which, owing to partial obstructions or other causes, frequent- 

 ly form into eddies or whirls, the rotative motion of which increases 

 with their progress as they are wafted along by the surrounding at- 

 mospheric current, raising clouds of dust and other light substances, 

 till they finally become broken or dissipated. The writer has seen 

 a whirlwind of this kind, operate with so much violence in passing 

 over a river, as to raise a white cloud of spray to the height of some 

 forty or fifty feet, which disappeared before reaching the opposite 

 shore. Whirlwinds of a still severer character sometimes occur, and 

 are, by seamen, denominated white squalls, from the white appear- 

 ance of the spray thus raised into the atmosphere. Doctor Frank- 

 lin, it is well known, maintained the identity of these smaller whirl- 

 winds with water spouts. 



Another class of whirlwinds, of more formidable character, are 

 those which sometimes attend the thunder storms, or gusts, of the 

 Atlantic states, and more frequently, ravage the fields and forests of 

 the regions west of the Alleghany mountains, carrying desolation and 

 death in their progress. Like the smaller class, they are carried 

 along by the attendant wind of whose mass they form an integral 

 portion. Their ravages are generally confined to a narrow track, of- 

 ten of but few yards in breadth. Rising at times, over objects in 

 their path, and leaving them untouched, they again descend to the 

 surface, and continue the work of destruction. The chief force of 

 these winds evidently consists in the almost inconceivable rapidity 

 with which the mass revolves about its own axis of rotation, a veloci- 

 ty which is, therefore, unopposed, except by the obstacles brushed 

 upon at the earth's surface, and which is maintained in full activity 

 by the concentric, or tangentical pressure, or action of the surround- 

 ing portions of the atmosphere. 



It is believed that no valid reason can be shown, why much larger 

 masses of the atmosphere may not acquire, and develope, rotative 

 movements, similar to those which are exhibited by whirlwinds, and 

 the demonstrated existence of the latter ought to free us from the 

 charge of maintaining a mere hypothesis, when we ascribe the same 

 character to such storms as that which we have already described, 

 if we can show that they are attended with corresponding phenom- 

 ena. 



It is demonstrably evident, that at any point over which the center 

 of a whirlwind may pass, the wind must, at the moment in which 

 this center passes, suddenly change to a direction almost exactly op- 



