590 
ME. H. F. BLANFOED ON THE WINDS OF NOETHEEN INDIA. 
The average of the three Tables of the Bengal stations gives a mean increment of 343 
feet elevation for each temperature decrement of 1° Fahr. In the North-west Hima- 
laya the temperature decrease would appear to be on the whole more rapid, the average 
of the two Tables being 326 feet per 1°. But these are only the mean results of the 
year, and the Tables show a wide departure from this average in different months of the 
year, which is least at Darjeeling, greatest at Chuckrata. The difference of temperature 
between this latter station and Roorkee in October is more than twice as great as in 
December. 
At Darjeeling the decrease of temperature with elevation is most rapid in February. 
This is not, indeed, the coldest month at Darjeeling ; but in the first two months of the 
year the temperature rises less than at Goalpara. Between February and June, on the 
other hand, the rise is greater at the hill-station, especially in the month of May ; and 
about the time when the rains set in generally over Bengal, the difference of temperature 
between Darjeeling and Goalpara is less than at any other time of the year. The dif- 
ference increases during the rains, but only to the extent of 1°T. On their cessation 
in October a sudden increase of 2 0, 4 takes place, and the difference is further augmented 
by 2°-6 up to the month of February. 
At Chuckrata the difference from Roorkee is greatest in October and least in Decem- 
ber. From this month it increases rapidly till April, after which there is a slight fall 
till July, followed by a rise which is extremely rapid at the close of the rains up to the 
maximum in October. At Nynee Tal the variations are similar, except that the first 
and absolute maximum difference occurs in May, and the increase at the close of the 
rains is comparatively small in amount. 
It would lead me into a lengthy digression, unnecessary to my present purpose, to 
enter on a detailed discussion of the extremely complicated causes which give rise to 
these irregularities in the vertical distribution of temperature in the lower atmosphere ; 
and, indeed, I am doubtful whether with our present data a very satisfactory result could 
be looked for. An investigation of similar phenomena in the case of Hoch Obir com- 
pared with Klagenfurt and other stations in Carinthia by M. J. Hamt has led him to 
some general conclusions, which I quote below*, and which seem to help to an expla- 
* The problem which M. Haxn desired to solve in this inquiry was the relation of the temperature decrement 
with altitude to the wind-direction ; and he expresses his results in the following empirical laws : — 
1. “Die Temperaturabnahme nach oben ist bei siidlichen und siidwestlichen Winden langsamer als bei 
nordlichen und nordostlichen. 
2. “ Die Temperaturabnahme mit der Hohe zeigt eine grosse Abhangigkeit von der Windstarke — sie ist stets 
grosser bei Sturmen, aus welcher Eichtung sie auch kommen mogen ; aber auch der Fnterschied zwischen 
nordlichen und siidlichen Stromen spricht sich dann noch scharfer aus. Die Ursache davon liegt, wie noch 
gezeigt werden soil, zumeist in dem raschen gezwungenen Emporsteigen der Luft. 
3. “ Bei schwachen Winden und heiterer Witterung ist die Temperaturabnahme in den unteren Schichten 
sehr verzogert; sie wachst aber dann rascher in den hoheren Luftschichten. Die Temperatur-Verminderung 
mit der Hohe ist am langsamsten bei heiterer Witterung und schwachen westlichen Stromungen in die Hohe.” 
