40 Proceedings of the Asiatic Society. [ FE. — 
vantages which India offers for meteorological observation and re- 
search. The great peninsula covering as it does scarcely less than 
twenty-eight degrees of latitude is in various respects so special in 
its character, that the periodic shiftings of the equatorial wind belts 
of which I have spoken, have a greater range above its surface or 
in its neighbourhood than any where else probably in the whole 
circuit of the globe. Not only does the southern trade belt come 
up to and over it in the period of the southwest Monsoon, but in 
the other half of the year the polar edge of the northern trades 
lies far to the south of the Himalayas, thus bringing some of the 
principal phenomena of the extra-tropical region well within the 
observation of the Indian Meteorologist. Solow as Calcutta we 
not unfrequently get warm equatorial breezes and showers of rain 
about Christmas time. Also neither of the trade winds preserves 
its normal character in our region. The belt of highest tempera- 
ture does not, where it transverses this part of Asia in the summer 
months, mark the locus of minimum atmospheric pressure : obser- 
vation appears to have shown that this minimum prevails at that 
time over an extensive area in Central Asia, while there are com- 
paratively small spots of relative minimum within the peninsula 
itself. On the other hand in the winter months there seems common- 
ly to exist in the northern part of the peninsula a locus of relative 
maximum pressure. The consequence of these conditions is, that 
instead of a trade-wind in the ordinary sense of the term, 7. ¢. an 
atmospheric movement effected in approximately parallel currents 
towards an annulus which is coincident with the diurnal locus of 
maximum surface temperature, we have as long as the sun is on 
the north of the equator a monsoon converging towards a loca] 
focus of low pressure which lies outside that annulus; and at the 
opposite period of the year we perceive that the wind constantly 
inclines away, and often apparently blows directly, from a centre in 
the upper part of India. These recurring phenomena appear to pre- 
sent such a particular case of a general law as is especially valuable 
for the purposes of scientific inquiry. 
Again a consideration of the possible causes which give rise 
to a separation between the simultaneous positions of places 
of minimum pressure and of maximum heat respectively, leads 
us to see another reason for rating highly the importance of 
