RELATION TO THE DISTRIBUTION OF BAROMETRIC PRESSURE. 
303 
Balasore . 
Miclnapore . 
Krishnagh av 
Jessore 
Faridpur . 
Dacca 
Mymensinglt 
Sylliefc 
Cherra Punji 
4 - 78 inclies 
5-08 
6'62 
7'56 
8- 33 
9- 26 
11-74 
21-64 
51-46 
99 
95 
99 
99 
5 9 
5 5 
9 9 
99 
The line joining these places coincides almost exactly with the axis of lowest 
pressure at 10,000 feet on the chart for May. 
In July the triangular area of high pressure in the Deccan has retreated to the 
extreme south-east of the Peninsula, and occupies those parts of the Carnatic where 
the rainfall at this time of the year is very light. 
Along the foot of the Himalayas there is a zone of relatively high pressure, 20‘80 
inches, or slightly less, which widens out in the west, so as to include the western 
Punjab and Afghanistan. Parallel to this, and south of it, from the head of the Bay 
of Bengal to Sindh, extends a region of lower pressure, below 20 '7 5 inches ; which is, 
however, interrupted along the line of the Aravalis by a belt of higher pressure, 
exceeding 20 - 80 inches in the vicinity of Ajmere. 
As regards the country south of the parallel of 24°, there can, therefore, be but 
little difference in direction between the winds prevailing at high and low levels, and, 
except for the diminution of frictional retardation on ascending, the upper currents 
have probably no greater velocity than those at the ground surface, since the 
gradients of 10,000 feet are no steeper than those at sea-level. In Bengal the winds 
at this elevation should be easterly or north-easterly, while those deduced from the 
distribution of pressure at sea-level by Buys Ballot’s Law would be southerly. The 
prevailing winds are south-easterly, or in Cachar north-easterly, the average angle 
between the wind and the isobars being about 60°, an effect which is possibly due in 
part to convective interchange ; though, as we have already seen, the activity of such 
interchange at this season is not great. The northerly winds at Multan, Jeypore, and 
Agra, to which attention was directed in the first part of this Paper, are evidently the 
effects of the high pressure in the upper strata over Afghanistan and the Aravali 
region respectively, these stations being all in the drier part of North-western India, 
where clear skies and a high temperature range, with their accompaniment of active 
convection currents, are not infrequent even in July. 
The extensive belt of low pressure, at high altitudes, stretching across the Central 
Provinces and the head of the Bay, is doubtless connected with the fact, brought 
prominently to notice in Mr. Eliot’s paper last referred to, that cyclonic storms 
formed during the prevalence of the S.W. monsoon usually pass inland across the 
Orissa coast, meeting with little obstruction from the ranges of low hills they have to 
3 A 2 
