INTRODUCTORY ESSAY. 79 



directions at sea. At the commencement of the vernal equi- 

 nox, the south-west monsoon is very local in its character, 

 the heat being greatest over a small region in southern India. 

 At the same time Arabia and the countries east of Persia are 

 much heated, and cause a southerly wind to blow from the 

 ocean west of India, towards Persia and Afghanistan, while 

 an east wind blows up the valley of the Ganges. After April 

 the northern parts of India become miich hotter, and the di- 

 rection of the southerly monsoon is remarkably influenced, 

 as has been well pointed out by Dove, by the great heat of 

 Tibet, Siberia, and Tartary, which, in consequence of their 

 cloudless climate, acquire an almost tropical temperature dur- 

 ing the summer months, and attract the currents northwards. 

 I. The south-west or summer monsoon. This, in almost all 

 parts of India, is a sea wind, and is therefore loaded with va- 

 pour. On the west coast of the Madras Peninsula it comes 

 in contact with the range of mountains called the Western 

 Ghats, upon which it deposits a great part of its moisture ; 

 in its further course it meets with no greater elevation in 

 southern India, the eastern parts of which are comparatively 

 dry. On the coasts of Orissa and Bengal the direction of this 

 wind is more to the north, from the heating of the continent 

 to the north and north-west, and much moisture is deposited 

 on the mountains of these provinces. In northern India the 

 rainy season commences later than in the Peninsula, because 

 it is not till June that the sun acts sufficiently energetically 

 on the Tibetan mountains and the plains of temperate Asia 

 to attract in that direction the full force of the monsoon. 

 This wind, after passing over the plains of Bengal, comes in 

 contact with the Khasia mountains, upon which, and upon 

 the whole chain of the Himalaya, it discharges itself in 

 heavy rains diminishing in amount as we advance westward, 

 with the increasing distance from the sea. At Calcutta the 

 wind, during the whole of the monsoon, from April onwards, 

 blows from the east of south, but after the beginning of Au- 

 gust, when the great rain-fall in eastern Bengal has con- 



