164 FLORA INDICA. 



mously elevated snow-clad masses of the Himalaya, and the 

 suddenness with which they rise out of the plain. 



During the rainy season, T\hen the wind blows from the 

 south, and arrives saturated with moisture at the base of the 

 mountains, a sudden condensation at once takes place; and 

 the distance from the sea is so small^ that the effect of the 

 cooling is nearly uniform over the whole ai'ea, and does not 

 diminish rapidly as we recede from the mountains, as in the 

 upper provinces. During the remainder of the year, when 

 land winds prevail, the humidity of the atmosphere must be 

 mainly due, as has already been observed (at p. 80), to an 

 upper return current, which is stopped by the high wall of the 

 Himalaya, and, being cooled, sinks towards the earth, and is 

 caiTied back towards the sea along with the normal current, 

 which descends along the course of the Ganges and Brahma- 

 putra. In support of this explanation, it may be noticed that 

 a belt of equable climate, gradually narrowing as we advance 

 westward, skirts the base of the Himalaya, the summers of 

 the Terai and Himalayan valleys being less hot, and the win- 

 ters moister and less cold than those of the open plain. 



The rain-fall in Bengal varies from sixty to one hundred 

 inches. It is least in the north-western part of the province, 

 and greatest on the eastern sea-coast, near the mouth of the 

 Megna. The mean temperature of Calcutta is 78°, which may 

 be considered as that of the whole area. 



The province of Bengal is celebrated for its fertility, and 

 is for the most part under cultivation. The surface is peren- 

 nially green, and the villages are usually buried among lofty 

 trees ; Bamboos, Figs, Mangoes, and various Palms occupying 

 a conspicuous place. The Palms are chiefly Cocoa and Betel- 

 nut, Phmniv, Borassus, and, near the sea, Covypha. The 

 two first may be considered the most characteristic cultivated 

 plants, as they are intolerant of cold and do not extend into 

 the drier provinces. Two species of Rattan (Calamus Rox- 

 burghii and fascicularis) are common thi'oughout Bengal, and 

 a third [C. Mastcrsianus) , which is common in Silhet and 



