lERIGATION IN INDIA. 437 



oration, partly absorbed by vegetation, and partly carried down 

 by infiltration to subjacent strata which gave it out in springs at 

 lower levels, and thus a fertility of soil and a condition of the 

 atmosphere were maintained sufficient to admit of the dense 

 population that once inhabited those now ai-id wastes. At pres- 

 ent, the rain-water runs hnmediately off from the surface and is 

 carried down to the sea, or is drunk up by the sands of the wadis, 

 and the hillsides which once teemed with plenty are bare of vege- 

 tation, and seared by the scorching winds of the desert. 



In fact, climatic conditions render irrigation a necessity in all 

 the oriental countries which have any importance in ancient or 

 in modern history, and there can be no doubt that this diffusion 

 of water over large sm'faces has a certain reaction on chmate. 

 Some idea of the extent of artificially watered soil in India may 

 be formed from the fact that in fourteen districts of the Presi- 

 dency of Madras, not less than 43,000 reservoirs, constructed by 

 the ancient native rulers for the purpose of irrigation, are now in 

 use, and that there are in those districts at least 10,000 more 

 which are in ruins and useless. These reservoirs are generally 

 formed by damming the outlets of natural vaUeys ; and the dams 

 average half a mile in length, though some of them are thirty 

 miles long and form ponds covering from 37,000 to 50,000 acres. 

 The areas of these reservoirs alone considerably increase the 

 water-surface, and each one of them irrigates an extent of culti- 

 vated ground much larger than itself. Hence there is a great 

 augmentation of humid surface from these constructions.* 



* The present government of India obtains the same result more econom- 

 ically and advantageously by constructing, in many provinces of that vast 

 empire, canals of great length and capacity, vrhlch not only furnish a greater 

 siipply of water than the old reservoirs, but so distribute it as to irrigate a 

 larger area than could be watered by any system of artificial basins. The 

 excavations for the Ganges Canal were nearly equal to those for the Suez 

 Canal, falling little short of 100,000,000 cubic yards, without counting feeders 

 and accessory lines amounting to a length of 3,000 miles. This canal, accord- 

 ing to an article in the London Times, waters a tract of land 320 miles long 

 by 50 broad. The Jumna Canal, 130 miles long, with 608 miles of distributing 

 branches, waters a territory 120 miles long with a breadth of 15 miles. 



Other statements estimate the amount of land actually under irrigation in 

 British India at 6,000,000 acres, and add that canals now in construction will 

 water as much more. The Indian irrigation canals are generally navigable. 



