'Transactions of the Bombay Geographical Society, from September 1850 to June 1852. Edited by the Secretary. Volume X.' [‎81] (102/458)

PROCEEDINGS OF THE SOCIETY.
Ixxxi
From these it will be seen that the barometer north of the line is invariably highest near tha
winter, and lowest near the summer, solstice,—and this without any reference whatever to the
occurrence of the wet season or fall of rain at all: it holds equally at Bombay when our
rains are at their height as at Madras in the middle of the dry season; at Aden and Kurra-
chee, almost rainless stations, as at Calcutta or Lucknow. As a general rule, the annual range
encreases, and the amount of daily tide decreases, as we recede from the equator ; Aden and
Toronto affording the most notable exceptions to this. At Trevandrum and Bombay in
Western India, the daily range, as well as the mean height of the mercury, is least in June.
At Kurrachee, the range seems nearly uniform throughout the year : at Madras, Aden, Lucknow,
and Futtyghur, the range is greatest when the mercurial column is lowest,—so we have some
thing besides latitude and longitude to deal with, though we cannot tell what it is. The
accuracy of all the observations here discussed may be fully depended on : alas I that we
should have so few on which reliance can be placed.
On receiving a collection of Mr. Pyle-’s observations through Dr. Spilsbury in May last, they
seemed so interesting that they were forwarded immediately to Colonel Sykes, who laid them
before the British Association at Ipswich, as having an important bearing on some of the
doctrines on hygrometry.
Some very valuable barometric observations, made by Mr. Pyle, at Fyttyghur, and by Captain
Barker, all the way from Bombay to Suez Roads and back, were exhibited. Captain Barker
gave all the four turning-points, but had made his morning barostice at 9 in place of 10 o’clock
his afternoon at 3 in place of 4 5 so that a rigid comparison with other observations could
not be made. The Futtyghur observations bore all the characteristics of perfect truthfulness.
Mean of 23 days in Suez Roads, from 20th September to 14th October, 1851, corrected for
temperature* Latitude, 29 ° 57'. Longitude, 32 ° 29'.
3 a. m. 9 a. m. 3 p. m. 9 p. m.
29. 95. 30. 02. 29. 93. 29. 98.
Range, +. 07. —.09. +. 05.
These were taken by one of the marine barometers first sent out by Mr. Adie, which, though
in other respects a very beautiful instrument, did not read lower than hundredths of an inch. The
range at Suez would appear to be little over half that at Futtyghur only two degrees further
south ; but then, when we find the mean altitude of the mercury in close accordance with that
of the Col aba Observatory, our faith in the whole concern was shaken by finding the range at
Aden, as well as at Bombay, little more than half what we know it actually to be from the
registers of the observations at these stations respectively. Sir Henry Lawrence had recently
expressed anxiety to assist in such researches, and it was hoped that through this means perfectly
accurate observations might speedily be had from Lahore, Mooltan, and Peshawur. The
observations expected from Mr. George, at Muscat and Zanzibar, had not yet been received,—*
a circumstance the more to be regretted inasmuch as the extraordinary anomalies at St. Helena
made it most desirable to have as many observations as nearly under the line as possible. St.
Helena is in Lat. 5° 40' 31" S., their midsummer being our midwinter. Here the great
law holds, and the barometer is lowest in December and highest in June.
Max.
28.352
28.268
St. Helena.
June and December.
Min.
Mean.
Daily
Tide.
Yearly
Range
Lat. S.
Long. w.
28.286
.198
28.319
28.233
.066
.070
.154
15°56'41 /f
5 o 40'31"5