424 The Origin of the Great Cyclones. (October, 
South America, comes in conflict with the lighter and 
feebler N.E. trade. I may further point out the equally 
striking coincidence, due to analogous causes, that it is in 
the very same region, the northern equatorial current of the 
North Atlantic and the southern equatorial respectively, 
under the propelling influence of the N.E. and S.E. trade- 
winds, rush together off the archipelago of the windward 
Antilles, and penetrating the meshes of this insular net- 
work move westward to form the Gulf Stream. 
(2). But striking and suggestive as are the coincidences be- 
tween the origin of cyclones, and the conflict of S.E. and 
N.E. trade with regard to place, they are equally or more 
striking with regard to the TIME at which cyclones occur. 
The West Indians occur most frequently from July to 
October. From Poey’s “‘ Chronological Table of 365 West 
Indian and North Atlantic Hurricanes, from 1493 to 1855,” 
it appears that 42 occurred in July, 96 in August, 80 in 
September, 69 in October. The most violent hurricanes 
occur between the 15th of August and the 15th of October ; 
but that of August ro, 1831, and that of October 29, 1867, 
may be mentioned, with others, as noted exceptions to the 
remark. But, as Professor Eastman well states, ‘‘ Storms 
of this class seldom, if ever, occur in the West Indies later 
than the 20th or 25th October; in fa¢t so well defined is 
this limit supposed to be by the residents in that portion of 
the world, that the end of the ‘‘hurricane season is 
believed to be more nicely determined* than even the 
change of seasons.” 
(3). In point of iutensity also the coincidence appears to 
be marked, not merely at the time when the irruption of 
the S.E. trade is most impetuous, but in August and October 
—the extremes of the “‘ hurricane season”’—which are the 
two months of the most violent cyclones, as we may easily 
see, the beginning and close of the battle of the trades are 
the periods of most desperate conflict in the West Indies. 
This conflict, it must be understood, is never settled, but 
the contest is fought on another line, or rather upon a line 
which ever sways backward and forward, at right angles to 
the meridian, and nearly under the vertical sun. 
(4.) The theory by which I have sought to explain the 
generation of cyclones is fully sustained by the laws of 
mechanics, as Professor Eastman, speaking of Dové’s 
theory, and has Dové himself has shown, ‘‘a mass of air 
* See an able discussion of this hurricane by Professor EASTMAN, of the 
U.S. Naval Observatory ; prepared by order of Admiral B. F. Sands. 
