MR. H. F. BLANFORD ON THE WINDS OF NORTHERN INDIA. 
619 
Table showing the increasing mean movement of the North-west Current during the 
Cold Weather. 
November. 
December. 
January. 
February. 
Roorkee 
19-2 
25*4 
40-2 
47 
Miles per day. 
Benares 
55 
34-2 
55*6 
73-3 
Patna 
51-7 
34-4 
64-6 
72-8 
Hazareebagh 
91*1 
92-7 
98 
131-4 
Calcutta 
82-1 
9P2 
104-5 
114-8 
” 
Secondly, on the Himalaya, especially the north-west portion, southerly winds prevail 
throughout the cold weather; and at stations 7000 or 8000 feet above the sea the 
atmospheric pressure falls in December and January, while on the plains it rises in 
December, and does not begin to fall till the end of the latter month. Thirdly, in 
Upper India and the Punjab, easterly winds, bringing rain, are much more common than 
in Bengal, and the atmosphere is characteristically calm. Winter rains also occur in 
Central India, where the lower current is from east and north-east. Fourthly, there is 
a ridge of high mean pressure running from Roorkee through Benares to Cuttack, which 
I can account for only on the supposition that it coincides with a trough of low pressure 
in the upper atmosphere where the currents from north-east and south-west meet 
and descend. Fifthly, there is in Eastern Bengal a region of low pressure where the 
northerly wind is unsteady and much interrupted by calms. It is in the prolongation 
of the line of the Arakan coast where the southerly monsoon blows a month longer than 
on the Indian coast. This I suppose to indicate the course of a main stream of the 
anti-monsoon, which is here lower than over Western Bengal, but does not, at least in 
general, descend to the land-level*. Sixthly, the isothermal lines bend northward 
(indicating a relatively high temperature) opposite the Gulf of Cambay and in Eastern 
Bengal, and southwards between Western Bengal and Central India. The former I 
suppose to indicate the course of the two principal branches of the anti-monsoon flowing 
northwards, the latter the place of their meeting, descent, and return as the beginning 
of the northerly monsoon. 
The south-west monsoon is produced by the heating of the land-surface of the penin- 
sula and the superincumbent air to a temperature much above that of the sea to the 
southward. Six weeks before the vernal equinox, sea-winds begin to set in in the lowest 
stratum of the atmosphere, on the maritime belt of Lower Bengal and Orissa, and gradu- 
ally advance further and further inland. At the same time over the whole of Northern 
India the winds continue to blow from the westward, rising gradually in temperature, 
and at length* blowing only or chiefly in the daytime as the hot winds of April and May. 
This state of things depends probably on the high temperature being restricted to the 
stratum of air immediately over the ground. But with the advance of the sea-winds 
* When rain does occur, or the sky is cloudy, at Calcutta in the cold weather there is generally an easterly, 
south-easterly, or southerly current above and calm below. 
MDCCCLXXIV. 4 O 
