* 
136 Additional Objections to Redfield’s Theory of Storms. 
per hour. There appears to have been within the sphere of ‘its 
violence an area, throughout which the barometric column stood 
at a minimum, and towards which the wind blew violently on 
the one side only from between east and south, and on the other 
only between north and west. ‘This area extended from south- 
west to northeast more than two thousand miles. Its great length 
in proportion to its breadth seems irreconcilable with its having 
formed the axis of a whirlwind. 'The course of this storm, as 
above stated, was‘at right angles to that attributed by Redfield to 
storms of this kind. (Trans. of the American Philos. Society, 
Vol. 7.) . 
79. Having said so much against the whirlwind theory of 
storms, it may be expected that I should, on this occasion, say 
— ing respecting the opinions which I entertain of their ori- 
- Toa certain extent this will be found in my communica- 
tions published in this Journal, Vol. xxxm, p. 153, Vol. xx, p. 137, 
also in my essay on the gales of the tials Gtetes I still be- 
lieve our northeastern gales were correctly represented in the last 
mentioned essay as arising from an exchange of position made 
between the air of the Gulf of Mexico and that of the:territory 
of the United States. which lies to the northeast of that great 
estuary; and that the heat given out during the conversion of 
aqueous vapor into rain, by imparting to the atmosphere as 
much caloric as could be yielded by twice its weight of red 
hot sand, is a great instrument in the production of the phenom- 
ena; also, that the cold resulting from rarefaction is a cause of 
the condensation of that vapor, and of course of clouds. On this 
last idea, derived from Dalton, Mr. Espy has founded his ingen- 
jous theory of storms ; alleging, erroneously, as I think; the buoey- 
ancy, resulting from the heat thus evolved, to be the grand cause 
of rain, also of tornadoes, hurricanes, and other electrical storms. 
In the essay above mentioned, I erred in ascribing too much 
to variations of density arising from changes of elevation, and 
twenty years’ additional experience as an experimenter in electri- 
city, has taught me to ascribe vastly more to this agent than I 
did formerly. To pursue this subject fully, would give this pa- 
per an undue length; yet I will subjoin a series of suggestions 
iam in September last were submitted to the Royal Academy 
nces at Paris. These will serve’ to.give a general:idew-of 
vS which I entertain of the electrical causes of storms. 
