INTRODUCTORY ESSAY. 171 



parts of India, an upper current of south-westerly wind 

 carries its moisture to the higher mountains, where it is con- 

 densed in the form of snow. Snow falls in the eastern parts, 

 in severe seasons, as low as 5000 feet, and in the north- 

 west occasionally as low as 2000 feet. The ordinary limit, 

 however, is several thousand feet higher. After the vernal 



iin 



usually 



To the eastward this rule is subject to frequent exceptions, 

 the same causes which make the climate of Bei 

 at all seasons operating more markedly on the Himalaya to 

 the northward of that province. As summer advances, the 

 wind becomes more humid, and occasional heavy thunder- 

 storms in the afternoons mark the approach of the rains, 

 which set in about midsummer ; considerably earlier, however, 

 in the eastern than in the north-western Himalaya. During 

 the rainy season, which continues almost till the autumnal 

 equinox, when the decreasing declination of the sun changes 

 the direction of the wind, the atmosphere is very humid, usu- 

 ally almost to saturation. There are, however, occasional in- 

 terruptions in the rains, during which the weather is superb. 

 The rain-fall is greatest to the eastward, and diminishes gra- 

 dually in advancing westward. 



Hima 



rily 



very distant, a great part of the moistur 



comes m 



saturation, 

 evated from 



greatest 



advance in considerable masses near to the plains, while 



as 



alleys of the great rivers, are evidently drier. As a consc- 

 ience of this, all the valleys of the interior which are sepa- 

 ated from the plains by continuous chains, attaining an ele- 

 ction of 10-12,000 feet, are to a great extent sheltered by 

 hese from the rains, which fall only as occasional showers j 



