336 MR. S. A. HILL OH THE WINDS OF NORTHERN INDIA, AND THEIR 
been discussed from time to time, both in their normal aspects for each month or 
season and in their abnormal or disturbed conditions during the passage of storms. 
The latter conditions in particular have been very fully described by Mr. Eliot in his 
numerous reports on cyclones in the Bay of Bengal, while the former have been 
noticed in the annual reports on the meteorology of India, in occasional papers 
appearing in the ‘ Indian Meteorological Memoirs,’ * and latterly in a broad and 
general review in Mr. Blanford’s great monograph on the .Rainfall of India.! 
There still remain several points, however, in connection with the winds of 
Northern and Central India, with regard to which our knowledge is very far from 
complete,—points in which the relation of wind direction and intensity to the 
distribution of pressure, as given by observation, is more or less directly opposed to 
what we should expect from theory ; and the object of this paper is to try to find a 
key to the solution of such anomalies. 
The chief anomalies to which I refer are the following :— 
(1) The direction of the wind in the hot season, on the plains of Northern India, 
has often no relation to the baric gradient; instances not infrequently occurring in 
which the wind appears to blow directly in opposition to the gradient, i.e., from a 
place of low pressure to one where the barometer stands higher. 
(2) Over the plains of Northern India, the average velocity of the wind has little 
or no apparent relation to the pressure gradient, but a very obvious one to the 
temperature ; being, on the whole, greatest when the temperature is highest; while, at 
this season, the local pressure gradients are extremely small. 
(3) Mr. Blanford has shown j that it is highly probable there is some connection 
of the nature of cause and effect between copious and late snowfall (producing low 
temperature) on the Himalayan ranges and the subsequent prevalence of dry winds 
from the north-west over northern and western India. On the strength of this 
relation he has for several years based forecasts of the character of the coming rainy 
monsoon, which have on the whole been amply verified. The anomaly here is that 
a low temperature to the north of India, producing high pressure, at sea-level, under 
the sub-IIimalayan stations, gives rise to unusually strong westerly winds, whereas, 
according to the law usually quoted as “Buys Ballot’s,” which has been clearly deduced 
from the hydrodynamical principles by Ferrel, Colding, and others, such high 
pressure should give rise to easterly winds ; the rule being that the highest pressure 
lies in the northern hemisphere to the right of a person travelling with the wind. 
These three anomalous relations will be here discussed in the order mentioned. 
* “ On the Winds of Calcutta,” by H. F. Blanforp, ‘ Indian Meteorological Memoirs,’ vol. 1, 
page 1; “The Winds of Kurrachee,” by Fred. Chambers, ibid., page 249; “The Meteorology of the 
North-West Himalaya,” by S. A. Hill, ibid., page 377. 
f ‘ Indian Meteorological Memoirs,’ vol. 3. 
J ‘ Indian Meteorological Memoirs,’ vol. 3, Part II., and ‘ Proceedings of the Royal Society,’ vol. 3/, 
1884. 
