376 
LIEUT.-COLONEL SYKES’S DISCUSSION OF METEOROLOGICAL 
the greatest height observed, 8640 feet at Dodabetta, from a mean annual and mean 
daily range at Madras of 0735 and 0*122 to 0’410 and 0*060 at Dodabetta; — the 
annual range would appear to increase, about and beyond the northern tropic, as the 
annual range at Calcutta (not by hourly observations) is 0*911 : but the diurnal range 
is somewhat less (0*115) than at Madras. At no one of the places of observation, 
even taking the maximum pressure of one year with the minimum pressure of an- 
other year, does there appear to have been a range of pressure equivalent to an inch 
of mercury; nevertheless in the Cyclones, or rotatory storms, there occurs at times 
a range of pressure of nearly 2 inches of mercury within forty-eight hours ; but it is 
shown from a comparison of the simultaneous records on board ship, where these 
great depressions were noted, with the records at the observatories on shore, that the 
great depressions occurred within very limited areas. 
I had formerly shown that the times or turning-points of ebb and flow (if the terms 
be permitted) of the aerial ocean were occasionally retarded or accelerated, although 
the means fixed the turning-points within certain limit hours; but 1 was not aware 
that in the ebb or flow of the four daily tides, they ever retrograded or halted in their 
onward or retiring course. The hourly observations now satisfy us that abnormal 
conditions are of no infrequent occurrence, — that the tides at times flow or ebb for 
four, five, six or even seven and eight hours*, — that frequent instances occur of re- 
trograde movements for short periods of time, as if the tide had met with a check 
and been turned back; and at the turning-points there are numerous instances of 
the atmosphere being stationary for a couple of hours. 
The maximum pressure of the atmosphere is in the coldest months, December or 
January, but the minimum pressure is not in the hottest months, but in June or 
July. The barometric readings, when protracted -i-, show a gradual curve from De- 
cember or January descending to June or July, and then ascending again to Decem- 
ber or January, there being an occasional interruption in October or November ; and 
as the curves at Madras, Bombay and Calcutta correspond, and as Madras has no 
S.W. monsoon, while Bombay has a S.W. monsoon, and as Bombay is destitute of 
the N.E. monsoon of Madras, it would appear that the general movements of the 
mass of the atmosphere are little influenced by any conditions of its lower strata; 
but the curve of pressure would seem to have some relation to the sun’s place in the 
ecliptic. 
The normal conditions of daily temperature are, that it is coldest in India at sun- 
rise, and hottest between the hours of 1 and 3 p.m.; but the preceding tables show 
many aberrations from this rule. The regular increment or decrement of mean 
monthly heat from the maximum or minimum period is somewhat remarkable, as the 
curve is independent of the S.W. monsoon at Bombay and the N.E. monsoon at Ma- 
* One instance at Aden of nine hours ! 
t To that very able and zealous meteorologist, Dr. Buist, LL.D. of Bombay, I am indebted for the pro- 
tracted curves of pressure of the barometer appended to this paper. Plates XVII. XVIII. XIX. XX. 
