'Transactions of the Bombay Geographical Society, from January 1847 to May 1849. Edited by the Secretary. Volume VIII.' [‎34] (137/496)

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illustrating this part of the subject. A body of water in circular mo-
tion, as an eddy for example, exhibits the effects of centripetal ac
tion at the bottom and of centrifugal at the surface, where a concavi
ty is formed in a degree corresponding to the rate of the motion. If
the case is so in a fluid of equable density, how much more must these
effects extend to a mass of atmosphere, under similar circumstances
but with its specific gravity rapidly decreasing in a geometrical ratio
upwards.
^ Continuous causes. —The continuous causes of the rotatory action
are due to the momentum imparted at reverse sides of the circle by two
great currents of air moving in opposite directions, and pressing on
the exterior of the stormy mass. As already alluded to, this seems
to have been effected in the Malabar hurricane of April, by the
westerly winds of the equator on one side, and the easterly monsoon
near its recession on the other ; the former deflecting by S.W. to
South, and the latter by veering from East by N.E. to North; the
permanency, strength, and direction, of the storm being dependant on
the equipotence and combined action of the two, and its decadence, or
irregularity, on ordinary disturbances to which both were liable, from
circumstances sufficiently appreciable, but too numerous to be re
ferred to in this paper. To one of these accidental causes of dis
turbance, peculiar to the season and natural configuration of the land,
—viz. the vast extent of low sandy deserts of Northern India, Scinde,
and Beloochistan, being heated at that period of the year to a much
higher degree than the more southern parts of the peninsula, and
giving rise to new currents at variance with the N.E. monsoon,—we
are disposed to attribute the due northerly track of the vortex, and
its less steady, strong, and well defined, movements after it passed
Bombay than when on the Malabar Coast. Had the N.E. monsoon
been setting in, or in its full strength, its impulse, applied to that
side of the storm, would in all probability not only have augmented
the violence of its gyration near the tropic but have pushed the whole
mass more to the N.W., and given it the line of progression usually
followed. Hence, as both the season and surface of the land combined
to weaken the Easterly wind, the S.W. monsoon in its superior strength
appears to have carried the vortex along the coast, and even over
the western part of Scinde and Guzerat. This may also have been
the case with the severe storm of 20th April 1782, which travelled up
the Gulph of Cambay, and in all probability was influenced by the
causes to which reference has just been made.