- 2 3 ¥ - 
‘On Storms and a lias ae 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- 
eal 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 my own 
paper, and on this one point the whole question may be safely rested. 
_ 8’. 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 
S$ not seem safe to assign to phenomena of common occurrence, 
¢auses 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 2 
too much neglected in this country since Franklin’s time,) of ar- 
riving at valuitite and accurate results in meteorology. It is by tra- 
cing the progress of particular storms and noticing the succession n of 
changes over a wide district of country, that we must ascertain 
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 
