Ceylon Literary Society. 387 
The following remarks and observations, made during q period: 
of several years in Ceylon, are offered, not with a view of esta- 
blishing any fixed priuciple with regard to the above instrument, 
and of the laws by which its movements are regulated, but more 
to serve as general hints in any future observations that may be 
ade, and to afford the opportunity of forming comparisons: 
therein with any observations made in other parts of India and 
between the tropics. 
At Colombo, which lies in latitude 6° 56’ North, and close on 
the sea shore, the Barometer appears decidedly to undergo four 
periodical changes or revolutions in the course of twenty-four 
hours, amounting in general to about one-tenth of an inch, being 
highest about nine o’clock in the morning, sinking towards three 
in the afternoon, rising again towards nine at night, and sinking 
again towards three in the morning —There does not appear to 
be any sensible difference between the position of the mercury 
in the tube in the morning and at night—the point at which it 
stands in the morning being generally the same as at night. 
Heavy rains do not affect the Barometer in an equal degree 
proportionally with that in bigh latitudes,:nor do hard squalls of 
a sudden nature’ or short duration affect it any more than in other 
parts of the world; but a smart gale ofwind of any strength and 
continuance will sink the mercury to the extent of about three 
tenths of an inch; and though that change may not take place 
so great a period of time previous to the gale commencing as in 
other latitudes, yet still, by a careful and attentive observation 
it will give a sufficient warning of the approach of a gale, so as 
to prove of very great utility to ships at anchor in the roads of 
Colombo, or off the coast. Inthe month of November 1819, 
previous to the commencement of a smart gale of wind from the 
north- west, the mercury, which had been at 29.9 inches, fell to 
29.7, with the Thermometer at 76° of Fahrenheit, and remained 
low during the continuance of the gale, and gradually continued 
rising previous to the gale abating, and in several similar instances 
it has never been known to fail. 
The variations in the rise and fall of the mercury do not appear 
to be affected in any remarkable manner, or inflaenced by heat 
or cold, or to undergo any changes with the Thermometer in si- 
milar cases, but it appears to stand highest in steady, fixed, 
settled weather. ‘The different monsoons do not appear to affect 
it, though at the changes thereof a variation takes place in its 
rise and fall. 
The average height of the mercury throughout the year may 
be considered as about 29.9 inches; the highest range 30.1 
nearly, and the lowest about 29.7, making the greatest range 
somewhat near half an inch; and this observation may be consi- 
3 C2 dered 
