326 Progress of Storms due to Aérial Currents. 
reaching the S. W. border of the Gulf of Mexico at Vera Cruz, 
be found to afford little or no rain ;—and why these North Amer- 
ican storms should be distinguished for their almost iim peri- 
odicity of occurrence. 
Proeress or Storms DuE TO PREVAILING CupitenmeellPans 
the progression of these and other storms is caused by the pre- 
dominating current in which they are imbedded, appears nearly 
a self-evident proposition ; and there is much evidence of the 
prevalence of aérial currents which correspond to the courses 
pursued by the several storms. 
At the windward islands of the ‘Antilles, we have seen 1 that 
the course of the lowest trade winds is often from E. to 8. B.; 
although, from thence to the northern border of the ne it 
comes, most commonly, from the N. E. quarter. Mr. 
has shown us that at Barbadoes, during a part of the year, o“ 
predominating course of the neina both at the surface and in the 
region of clouds, is from east.to. aailedact; and this is also the 
prevailing course of the higher portion of these winds in other 
months.+ His observations, which are confirmed. by others, may 
be deemed to show the actual. course which is there pursued by 
the great body of the trade wind, and thus may fully account ~ 
for the west-northwesterly course which is commonly pursued by 
the hurricanes of the Antilles, while passing to the extra-tropical 
latitudes. In the United States and north of the tropic in the 
Atlantic, the predominating currents come. from the southwest 
quarter, which also corresponds to the courses here pursued by 
the great storms.—I have now to maintain that this prevailing 
southwest current exists far back in the intertropical latitudes, — 
where it is derived, not from the trade wind of the Atlantic, 
north of the equator, but, toa large extent, from the. aasiacinted 
winds of the Pacific ocean. 
_ In the lower latitudes a general current from the southwest 
equdtter has been noticed, as seen in the common course of the 
higher clouds, which pertain to the Lowen hnlées of the atmosphere; 
ae 
#7 ho:jntarial bébwecn the great Cuba gale and the next stormy weather Was 
the same at both Apt i ‘and New York. “I have long since referred to . 
a or approximation to weekly periods which is shown in the occurrence 
of our pence pa cael which is. wery wanerelly noticed when they occur on Sundays. 
wendy rom the natare oft the pease, t this pe 
i. 
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ey z 
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