INTRODUCTORY ESSAY. 163 



province of Bengal, differs so strikingly in climate and vege- 

 tation from the upper, that it must necessarily be regarded as 

 a separate province. Along the sea-coast Bengal includes the 

 whole of the delta of the Ganges, extending from Balasor to 

 the mouth of the Penny. It is bounded on the west by the 

 hilly districts of Orissa and Bahar, and on the east by the 

 Assam valley, and the Khasia, Tippera, and Chittagong hills. 

 To the north it extends to the base of the Himalaya, but to the 

 north-west the boundary between Bengal and the upper Gan- 

 getic plain must be an arbitrary one, the transition of climate 

 and vegetation being gradual ; it may, however, conveniently 

 be drawn at the river Cosi. Further west the plains are 

 screened by the Bahar hills from the direct influence of the 

 moist air from the Bay of Bengal, and are therefore drier. 



The surface of Bengal is perfectly flat, and so little ele- 

 vated above the level of the river that a great part of it is 

 under water during the rainy season. Close to the base of 

 the Himalaya the surface is a little more elevated, but else- 

 where it is everywhere intersected by watercourses, which are 

 formed by the branching of the two great rivers, the Ganges 

 and Brahmaputra, and of their tributaries. 



The climate of Bengal is much more equable than that of 

 the upper Gangetic plain. The rains are heavier and of lon- 

 ger duration ; the heat of summer never rises to so excessive a 

 temperature as in the north-west provinces of Hindostan, and 

 the winter is much less cold. North of the Ganges, hot 

 winds blowing from the westward towards the funuel-shaped 

 valley of Assam occasionally traverse the plain, but they are 

 rarely of sufficiently long continuance to afifect the vegeta- 

 tion. South of the Ganges the delta is sheltered by the hills 

 of Bahar, so that no hot winds blow, and the atmosphere 

 always remains more or less humid. This humidity is no 

 doubt primarily due to the proximity of the sea, though we 

 learn from the dryness of Sindh, on the opposite side of the 

 peninsula, that that alone is not suflScient to induce it; the 

 main cause would appear to be the proximity of the cuor- 



