'Transactions of the Bombay Geographical Society, from January 1847 to May 1849. Edited by the Secretary. Volume VIII.' [‎27] (130/496)

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Distance
in miles
from the
Baron*
focus,
800
it
300
M
300
M
120
29'Ii
100
291
90
29'J
60
291
847.
Distance
in miles
from the
Barcn*
focus.
-
27
ments to a common standard ; yet it is satisfactory to see how nearly
the altitude of the Barometers at a given distance on one day corres
ponds with that of another ; and all agree in pointing to a gradual
lessening of the weight of the atmosphere from the periphery towards
the centre,—or more correctly speaking, the descent is in something
of a geometrical degree of progression.
We must consider the pressure of thirty inches, as observed on
board of the Zewfiindav within 800 miles of the storm’s centre, in
Lat. 6° and 7° North, as being somewhat above the ordinary standard
in the neighbourhood of the equator about the equinox. The daily
positions of the vortex were first deduced, and from these the dis
tances of the ship and places were computed, in order to ascertain
the relative level of the mercurial column ; and the general accordance
of the whole tends to show that our previous calculations of the path
and diurnal stages of progression were nearer the truth than was
suspected. The apparent, but really trifling, discrepancies between
the fall of the Barometer at the same distance on different days, or
between different places equally remote, are perhaps due partly to
errors in calculation or imperfections in the instruments. On the
whole, however, the results coincide with all that is yet known on
this head.
Influence on the Tides. —A moment’s reflection will show that a re
volving gale sweeping along the shores of a narrow sea, must have
great influence on the currents and tides of the ocean ; and the
facts quite agree with such a supposition. Captain Singleton says
“ The tides must have risen three or four feet above the highest
“ spring tides, and overflowed the paddy-fields in different directions
a within about 100 yards of the barracks.” At Bombay there
appears to have been “ enormously high tides” during the passage of
the storm. It is more than probable that the state of the Tide-
gauge at Colab a may be obtained before this goes to press.
A removal of the weight of the atmosphere equal to two inches of
the Barometer would be followed by an elevation of the sea beneath
to the extent of 27 inches. Hence a storm wave of the circular
form, having its apex under the focus, was carried along with the
hurricane, followed by a current in its wake. In addition to this,
the circular current, caused by the winds, round the vortex, must be
taken into account as also tending to heap up the sea near the centre.