310 
LIEUT.-COLONEL SYKES’S DISCUSSION OF METEOROLOGICAL 
At Madras the mean daily oscillation would appear to have been least when the 
barometer was highest in November, December, or January; and the reverse of 
this was the case when the barometer was lowest in May, June and July. The mean 
of the four years, at Madras, in the months of highest pressure, December and 
January, is OTll, and the mean of the four years in the months of least pressure 
0*122. The mean daily oscillation therefore was greatest when the pressure of the 
atmosphere was least. The same was not observed to be the case in the observations 
made in the Dukhun in the years 182/, 1828, 1829 and 1830; the means for the 
two periods being 0*131 and 0*081 ; nor in Calcutta in the years 1829, 1830 and 
1831, the oscillations being respectively 0*118 and OJOO ; and in 1848 the difference 
was more marked, the means of the daily oscillation for the periods of greatest and 
least annual pressure being 0*135 and 0*106 : the same was the case at Bombay and 
at Dodabetta. This peculiar feature exhibited at Madras is not satisfactorily ex- 
plained by its not being subjected, like Calcutta and Bombay, to the south-west 
monsoon, because the general curve of pressure at Madras follows the order of pres- 
sure at Calcutta and Bombay, with the exception of the month of November in the 
years 1844 and 1845, when the mean monthly pressure was greater in that month 
than in December. The hourly observations at Madras were too systematically and 
apparently accurately taken to suppose there could have been inaccuracy in the 
records, and they are quite as trustworthy, if not more so, than any other meteoro- 
logical records in India. There appears a great discrepancy in the mean daily range 
at Madras and Bombay in the months from March to November, partieularly in the 
month of April, which does not belong to the monsoon of either place. In the other 
months, the small range at Bombay may be accounted for by the prevalence of the 
monsoon at Bombay and the absence of the monsoon at Madras, but the means of 
the daily range for the year indicate a greater oscillation at Madras than might 
have been expected. 
Times of ebb and flow of the Atmospheric Tides, or Turning-points. 
I have given separately the chief of the four daily tides, namely, the fall between 
9 — 10 a.m. to 4 — 5 P.M., to facilitate comparison of the movements of the same tide at 
dilferent places by simple inspection. The following Table gives the movements of 
the three other daily tides ; but I have confined it to the Madras records, as three 
daily movements for various places could not have been put conveniently into juxta- 
position. 
