596 
ME. H. E. STANFORD ON THE WINDS OE NORTHERN INDIA. 
As regards the decrease of vapour-tension with elevation above sea-level, a comparison 
of its mean values at Hazareebagh, Shillong, and Darjeeling with those of neighbouring 
stations near the sea-level affords additional confirmation of the conclusions drawn by 
General Stra.chey # from the observations of Dr. Hooker in Sikkim and those of 
Mr. Welsh in England. Comparing, in the first place, the Darjeeling values with those 
of Goalpara, it appears that in most months the former are rather more than half as 
great as the latter, and that the proportions are relatively greater in the months of the 
rains than in those of the cold or hot seasons. The total atmospheric pressure, however, 
at the former station is at all seasons more than three fourths of that at the latter, so 
that the diminution of atmospheric density over Bengal from January to June, in so far 
as it is due to the admixture of water- vapour, chiefly affects the lower fourth of the 
atmosphere. Of this additional proofs will appear presently. At Shillong the propor- 
tion is somewhat higher, but more constant as compared with the means of Goalpara 
and.Silchar, the same reference-stations that have been selected for a comparison of tem- 
peratures. But at Hazareebagh, while the mean proportion is higher than either of the 
above, nearly three fourths of that on the plains, the range is also greater than either, 
varying from 59 to 90 per cent, of that at the lower stations. For this station I have 
taken as a standard of reference the means of Patna and Calcutta conjointly, these 
stations being alternately to windward and leeward of Hazareebagh at opposite seasons 
of the year. The results of these several comparisons are shown in the following Table : — 
Table of comparative vapour-tensions at stations at different elevations, showing 
the ratios of decrement in each month. 
Darjeeling, 
6941 ft. 
Goalpara, 
386 ft. 
Ratio, 
D:G. 
Shillong, 
4792 ft. 
Mean of 
Goalpara 
and 
Ratio, 
S:-+- S . 
Hazaree- 
bagh, 
Mean of 
Calcutta 
Ratio, 
H-°+ P 
Silchar. 
2014 ft. 
and Patna. 
January 
inch. 
0-212 
inch. 
0-439 
0-48 : 1 
inch. 
0-265 
inch. 
0-459 
0-58 : 1 
inch. 
0-280 
inch. 
0-407 
0-68 : 1 
February ... 
0-238 
0-435 
0-55 : 1 
0-273 
0-486 
0-56 : I 
0-264 
0-447 
0-59: 1 
March 
0-252 
0-487 
0-52:1 
0-321 
0-562 
0-57 : 1 
0-330 
0-548 
0-60 : 1 
April 
0-338 
0-632 
0-53: 1 
0-394 
0-690 
0-57 : 1 
0-423 
0-644 
0-65 : 1 
May 
0-427 
0-790 
0-54 : 1 
0-534 
0-851 
0-63 : 1 
0-557 
0-776 
0-72: 1 
June 
0-529 
0-897 
0-59 : 1 
0-598 
0-923 
0-64: 1 
0-796 
0-899 
0-88 : 1 
July 
0-546 
0-919 
0-59 : 1 
0-629 
0-946 
0-66 : 1 
0-867 
0-961 
0-90 : 1 
August 
0-548 
0-916 
0-60 : 1 
0-627 
0-942 
0-66 : 1 
0-812 
0-949 
0-85 : 1 
September ... 
0-501 
0-900 
0-55 : 1 
0-588 
0-926 
0-63:1 
0-786 
0-932 
0-84 : 1 
October 
0-381 
0-782 
0-49 : 1 
0-503 
0-828 
0-63 : 1 
0-563 
0-778 
0-72 : 1 
November ... 
0-276 
0-593 
0-48 : 1 
0-341 
0-623 
0-55 : 1 
0-360 
0-539 
0-66 : 1 
December ... 
0-213 
0-459 
0-46 : 1 
0-271 
0-480 
0-56 : 1 
0-279 
0-415 
0-67 : 1 
Year 
0-388 
0-687 
0-56 : 1 
0-445 
0-726 
0-61 : 1 
0-526 
0-691 
0-76 : 1 
Range 
0-336 
0-484 

0-364 
0-487 
0-603 
0-554 
Turning now to the Table of relative humidity, we find that while stations on the 
coast-line have at all times of the year a higher degree of humidity than those on the 
* Proceedings of the Roy al Society, vol. xi. p. 182. 
