"معاملات الجمعية الجغرافية في بومباي، من يناير ١٨٤٧ حتى مايو ١٨٤٩. تحرير السكرتير. المجلد VIII." [‎٢‎٩] (٤٩٦/١٣٢)

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seriously trespassing on the indulgence of our readers, to offer a few
observations on the primary causes of storms. In the Indian ocean
South of the Equator, the great hurricanes which annually sweep over
its waters, are formed between, and in connexion with, two great oppo
sing currents of atmosphere, and we think the same will be dis
covered to be the case with those of the coasts of India. As the
principles and references necessary to illustrate this cannot now be
brought forward with any degree of fullness, a glance at them can
alone be given.
Primary Forces of a Rotatory Gale. —The two great trade-winds
of the opposite hemispheres having an easterly direction and inclina
tion towards the equator, are separated at the equator by the Line-
westerly monsoon blowing in an exactly opposite direction, and un
like the former, its direction is obliquely from the equator. This
great westerly current, like the trade winds, varies its position with
the season, being north of the equator, under a northerly declination
of the sun, and south, under a southerly,—blowing N. Westerly in
the latter position and S. Westerly in the former; but it rarely extends
beyond 10° or 12° degrees on either side of the Line. The vicinity
of Islands or Continents derange these otherwise regular winds of
the open ocean.
State of the Trade Winds, §c., in the Hurricane Month. It seems
to be a general law that the hurricane season of both hemispheres is
that in which the sun is over it, and the trade wind is pushed farther
from the equator, and its place temporarily occupied by the westerly
monsoon just referred to. At the outer margin of the latter, or in
the space of variables between it and the nearest or equatorial border
of the trade wind, the vortices of great storms, revolving in accord
ance with the two great opposite currents at their reversed sides, are
formed, and drift “ en masse” to the westward, gradually turning
toward their respective pole. Thus the N.E. trade deflecting from
East to North, and the S.W. Monsoon of the equator turning back
against it from West to South, give the specific mode of rotation,
E.N.W.S. at the Northern hemisphere ; and everything exactly re
versed on the Southern side of the line. With such a palpable con
nexion between these regular currents and their stormy movements,
we cannot refrain from placing them in the position of cause and
effect; even without resorting to the additional arguments which
niight be adduced.