Ganges and Burrampooter Rivers . 103 
I come now to the particulars of the annual fwelling and 
overflowing of the Ganges 
It appears to owe its increafe as much to the rain water that 
falls in the mountains contiguous to its fource, and to the 
fources of the great northern rivers that fall into it, as to that 
which falls in the plains of Hindooftan ; for it rifes fifteen feet 
and a half out of thirty-two (the fum total of its rifing) by the 
latter end of June : and it is well known, that the rainy feafon 
does not begin in moft of the flat countries till about that time. 
In the mountains it begins early in + April ; and by the latter 
end of that month, when the rain-water has reached Bengal, 
the rivers begin to rife, but by very flow degrees ; for the in- 
creafe is only about an inch per day for the firft fortnight. It 
then gradually augments to two and three inches before any 
* An opinion has long prevailed,^ that the fwelling of the Ganges, previous to 
the commencement of the rainy feafon in the flat countries, is in a great meafure 
owing to the melting of the fnow in the mountains. I will not gofo far as totally 
to difallow the fa£t; but can by no means fuppofe, that the quantity of fnow 
water bears any proportion to the increafe of the river. 
f The vaft colle&ion of vapours, wafted from the fea by the foutherly or 
fouth-weft monfoon, are fuddenly flopped by the lofty ridge of mountains that runs 
from eaft to weft through Thibet. It is obvious, that the accumulation and con* 
denfation of thefe vapours, rnuft firft happen in the neighbourhood of the obftacie ; 
and fucceflively in places more remote, as frefti fupplies arrive to fill the atmo- 
fphere. Hence the priority of commencement of the rainy feafon in places thatr 
lie neareft the mountains. 
All the rivers that are fituated within the limits of the monfoons, or drifting 
trade winds, are fubjeft to overflowings at annually ftated periods, like the 
Ganges: and thefe periods return during the feafon of the foutherly wind, that 
being the only wind which brings vapours from the fea ; and this being periodical, . 
the falls of rain muft necefiarily be fo too. 
The northerly wind, which blows only over the land, is dry ; for no rain 
(except cafual fhowers) falls during the continuance of that" monfoon. 
quantity 
