On Storms and Meteorological Observations. 363 



does, nevertheless, in very many cases accompany it — is not touched 

 at all by Mr. Redfield's theory. The problem to be solved in this 

 part of meteorology, is the bringing of large masses of air of very 

 different temperatures suddenly into a state of intimate mixture. 

 But no such effects could be produced by a whirlwind with a verti- 

 cal axis, which might continue to spin for ages without producing a 

 single drop of rain. It was with reference to this difficulty especially, 

 that an horizontal axis of gyration was ascribed to storms in ray own 

 paper, and on this one point the whole question may be safely rested. 

 3'. Though condensation and rarefaction may not in every in- 

 stance produce a wind, there are no other known agents by which 

 any considerable movements in the great aerial ocean can be gener- 

 ated ; and nothing is more certain than that the only motion they 

 have a direct tendency to produce is gyratory, and about an horizon- 

 tal axis. This is matter of demonstration. If they ever produce 

 whirlwinds with vertical axes it must be by an indirect action, and it 

 does not seem safe to assign to phenomena of common occurrence, 

 causes which act indirectly, and of which there is no full and positive 

 evidence that they have ever generated such a whirlwind half a 

 dozen miles in diameter. Nor must it be claimed that there are pe- 

 culiarities in the form and positions of the mountains, seas, and islands 

 of the western continent, which will determine the formation of 

 whirlwinds of a peculiar character, with us, rather than in other 

 parts of the globe. Storms are of common occurrence the world 

 over, their characteristics are every where much the same, nor is 

 there room for doubt that they are every where regulated by the 

 same general laws and to be referred to the same general causes. 



OF METEOROLOGICAL OBSERVATIONS. 



Mr. Redfield has unquestionably fallen upon the proper method 

 (too much neglected in this country since Franklin's time,) of ar- 

 riving at valuable and accurate results in meteorology. It is by tra- 

 cing the progress of particular storms and noticing the succession of 

 changes over a wide district of country, that we must ascertain the 

 laws that regulate the atmospherical phenomena. The collections 

 of meteorological tables, registers, and observations, under which 

 the shelves of our libraries have long groaned, are almost worthless; 

 partly by reason of the imperfections of the instruments employed, 

 partly because the objects aimed at may be gained by shorter meth- 

 ods, and partly because they are directed to the acquisition of mean 



