568 
ME. H. F. BLANFOED ON THE WINDS OF NOETHEEN INDIA. 
their ascendency, and veer by west towards the north in October. The annual rotation 
is therefore normal as at Rawul Pindee. 
It results from the above analysis that the winds of t the Punjab are far from uniform 
in different parts of the great plain. Except in the region that lies under the lee of 
the Sulaiman range, currents from the westward preponderate on the average of the 
year ; and this we shall see is a general rule throughout Northern India. On the plateau 
north of the Salt range, west winds and their opposites prevail almost to the exclusion 
of those from other quarters — the former coinciding with the cold and the hot dry 
seasons, the latter with the summer monsoon. To the south of this, northerly winds 
preponderate over southerly in the greater part of the Punjab, but at Mooltan the latter 
are somewhat in excess. In the winter months (December to February) the mean 
direction is west at Rawul Pindee, nearly north at Dera Ishmail Khan and Mooltan, and 
between north and north-west at Lahore — diverging, therefore, from the angle formed 
by the mountain-ranges that bound the plain on the north and west. With the rise of 
temperature in Northern and Central India in the months of March, April, and May, 
the wind-currents draw round to the north-east along the foot of the Sulaiman range, 
to west over the more exposed parts of the plain ; but in the latter month, or in June, 
when the rains are setting in over the greater part of India, reducing its temperature, 
and thus transferring to the Punjab the locus of greatest heat*, easterly winds begin to 
increase in frequency, and in July and August preponderate in the central and northern 
parts of this region. At Mooltan, however, as in Sindh, easterly winds never gain the 
upper hand, and during the height of the summer monsoon the prevailing winds come 
from the direction of the Arabian coast. The south-west wind is not, however, here a 
rain-bearing current. It probably comes as much from the desert as the sea, and passing 
in its course over the heated arid plains that surround the lower course of the Indus, 
the increase of its temperature counteracts any tendency to precipitation which may be 
induced by the upward diffusion of its vapour ; so that Mooltan receives on an average 
only 5 inches of rain during the five months from June to October. 
Thus it appears that during the south-west monsoon the winds perform a kind of 
cyclonic circulation in the Punjab, converging from the plains to the south and east ; 
and this region is the goal of the Indian portion of the monsoon. In Affghanistan, 
further to the westward, easterly winds are irregular and uncertain, even when the 
summer monsoon is at its height, and dry west winds predominate throughout this 
season. 
The Gangetic Plain, North-western Provinces, and Behar . — Of the four stations that 
I have selected for illustrating the winds of this region, the most northerly (Roorkee) 
is situated 15 miles from the foot of the Sivaliks or sub-Himalayan range, on the JDoab 
or fork between the Ganges and Jumna; its elevation is 880 feet above mean sea-level. 
The second (Agra) lies due south from Roorkee, at a distance of 190 miles, on the south 
bank of the Jumna, just at the point where a low spur of the great Malwa plateau abuts 
* S eejoost, Part II., page 588. 
