264 Proximate Causes of certain Winds and Storms. 



distance was greater, and in Maine would hardly be felt at all. The 

 storm would cease when the cause by which it was produced had 

 ceased to act, and at nearly the same time throughout the whole 

 tract of country swept by it. The simplest doctrines of equilibrium, 

 as applied to elastic fluids, force these conclusions upon us. But the 

 storm is found in feet to be as violent at the north as at the south. 

 It proceeds, and is over. in Georgia, and the sun is perhaps shining 

 there at the time when it is exerting its utmost fury in Maine. 



I can account for all the phenomena, only by supposing that a vor- 

 tex or horizontal whirlwind, or rather a succession of them, is estab- 

 lished in Georgia, and passes gradually over the United Slates. 

 The existence of such a vortex, creating a wind from the north-east 

 at the surface of the earth, is obviously not incompatible with an ac- 

 tual transfer of the whole body of the atmosphere, incumbent upon 

 the United States /row the south-ivest. It is probable, however, that 

 the transfer is from the north-east. The warm air of the ocean, sat- 

 urated with moisture, is in this way brought over the land ; it is lifted 

 by the vertiginous motion that has been created and propagated along 

 the coast, into the upper regions of the atmosphere, and the intensely 

 cold air of those regions brought down to the surface. It is believed 

 that in this way, and in no other, we can account for the phenomena 

 pf our north-east storms. 



A ^ D B 



During a nine days' passage from New York to the Capes of Vir- 

 ginia, in the summer of 1821), I had ample opportunity of observin 

 the movements of the air during the prevalence of those light bafflin- 

 breezes by which the ocean is occasionally swept in calm weather. 

 The water is seen roughened by the wind in the direction from which 

 it is afterwards found to blow as at C, every other part of the ocean, 

 probably, except the tract immediately about C, being perfectly 

 smooth. It is calm at A, beyond the place of the breeze, at B, the 

 place of the vessel, and in the intermediate space at D. The rough- 

 ness gradually approaches the vessel, reaches it, fills the sails for a 

 moment, and passes by. How are these appearances to be account- 

 ed for ? It is not a vacuum at B that urges the breeze forward, for 

 that would set the air overhanging the whole intermediate space, 

 that at D for instance, in motion, before there would be any move- 

 ment at C. The effect is not produced by a portion of condensed 



