620 
MR. H. F. STANFORD ON THE WINDS OP NORTHERN INDIA 
and the upward diffusion and condensation of their vapour, the heat also is diffused to 
higher levels. In May the rise of temperature at 7000 and 8000 feet proceeds as 
rapidly as on the plains, or even somewhat more so. By this diffusion of heat and the 
increasing temperature of the ground surface and the lower strata of the air under a 
nearly vertical sun, the pressure falls steadily, and the sea-winds are drawn from a greater 
distance south. At length, as seems probable, in June, the ridge of high pressure over 
the sea, which has steadily receded southwards since February, is obliterated, and the 
south-east trade, or perhaps only a portion of it, crossing the line, brings the monsoon 
rains to Bengal and the west coast of India*. The two principal divisions of the mon- 
soon, advancing, from opposite sides of the peninsula, appear to follow a course very 
similar to that of the anti-monsoon currents of the winter season, but of course more 
influenced by the irregularities of the land-surface. The Arabian-Sea branch blows 
right across India, and is felt as a westerly wind in Orissa, and even beyond to the east- 
ward, being probably influenced by the direction of the Satpooras and their virtual con- 
tinuation in the plateaux of Sirgoojah, Chutia Nagpore, and Hazareebagh ; while the 
Bengal current is restricted to Assam and Cachar, Bengal and the Gangetic plain. The 
moist south winds blow up to the Himalayan snows and even beyond into Tibet (but 
this is probably their limit in that direction), and westward up to the further limits of 
the Punjab plains. The greater part must form an ascending current over the plains, 
and return southwards at such a height that it is doubtful if any direct evidence of it is 
forthcoming. I am unable to agree with Hr. Muhry’s conclusions on this head ; but of 
these I will speak presently. That the mean movement of the air decreases from the 
coast-line inland is shown by the following Table 
Table showing the decreasing velocity of the South-east Current up the Gangetic valley 
during the South-west Monsoon. 
June. 
July. 
August. 
September. 
Saugor Island ... 
201 
255 
262 
242 
Miles per day. 
Calcutta 
198 
157 
139 
132 
„ 
Hazareebagh 
185 
152 
132 
129 
„ 
Patna 
90 
81 
81 
84 
„ 
Benares 
95 
73 
70 
58 
„ 
Roorkee 
73 
53 
38 
27 
” 
The accompanying chart shows the average course of the wind-currents during the 
height of the south-west monsoon. To what height they extend there is no evidence 
to show, but it is probably much greater than that of the north-east monsoon currents 
in Northern India. * 
* See ante, Part I., page 583. Also Maury’s Physical Geography, edit. 12th, page 367 ; and Meldruji, 
British Association Report, 1867, Trans, of Sect. p. 21. 
