248 CLIMATE OF HIMALAYA. 



Situated in the most southern part of tlie temperate zone, and 

 bounding' on the north a great peninsula, which extends far into 

 the torrid zone, the base of the Himalaya to the south possesses 

 an almost tropical climate, tempered however, when the sun is on 

 the tropic of Capricorn, by a moderately cool winter, and vari- 

 ously modified in different parts of tlie chain by the degree of 

 humidity, a most important matter to be taken into consideration 

 in every question connected with the phenomena of vegetable 

 life. 



The source of humidity in the Himalaya is almost entirely the 

 Bay of Bengal, which is situated about 5° to tlie south of the 

 eastern extremity of the chain ; and the wind which carries the 

 humid atmosphere along the chain, is that which is known to 

 nautical meteorologists as the south-west monsoon, a wind which 

 begins to blow in the open sea about the month of April, but 

 whose effects are not felt in tlie far interior before the month of 

 June. This wind, though constant in its direction at sea, is not 

 so in its inland course ; at the head of the Bay of Bengal it is 

 almost a south wind. It blows from the sea nearly due north 

 towards the Himalaya, striking in its course upon the low chain 

 of the Khasya hills, whose maximum elevation is scarcely 7000 

 feet. 



Upon this range the first force of the monsoon is expended, and 

 the annual fall of rain at Churra Poonjee, elevated 4000 feet on 

 its southern slope, amounts to about 500 inches. This range, 

 which has its origin among the mountain ranges of the south of 

 China and north of Burmah, lies to the south of the Burram- 

 pooter, and, following the course of that river, terminates in the 

 concavity of its great bend, where it turns dow)i toward the sea. 

 The Khasya mountains do not therefore entirely run across the 

 Bay of Bengal, so as to intercept the force of the monsoon from 

 the whole of the Himalaya, a part of which wind, laden to satu- 

 ration with moisture at a temperature of nearly 90' F., blows due 

 north from the Bay of Bengal upon the district of Sikkim, which 

 is on that account the most rainy part of tlie whole range of the 

 Himalaya, for, on the one hand, the more eastern parts of the 

 chain are protected by the Khasya range, and on the other, the 

 more westerly parts are more distant from the source of moisture, 

 and therefore receive a less share of it. The interception of tlie 

 moisture from the province of Bootan and the independent states 

 north of Assam, by the Khasya range, has this curious effect, 

 that the lower ranges of this portion of the Himalaya are dry and 

 arid, while above 7000 feet, to which elevation only the hills to 

 the south attain, the climate is very much more humid. 



The diminution in the amount of moisture in proceeding to 

 the westward along the Himalaya from Sikkim is extremely gra- 



