452 IRRIGATION IN INDIA. 
which gave it out in springs at lower levels, and thus a fertility 
of soil and a condition of the atmosphere were maintained sufli- 
cient to admit of the dense population that once inhabited those 
now arid wastes. At present, the rain-water runs immediately 
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 vegetation, 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 surfaces has a certain reaction on 
climate. Some idea of the extent of artificially watered soil 
in India many be formed from the fact that in fourteen districts 
of the Presidency 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 valleys; and the dams average half a mile in length, 
though some of them are thirty miles long and form ponds 
covering from 87,000 to 50,000 acres. The areas of these reser- 
voirs alone considerably increase the water-surface, and each 
one of them irrigates an extent of cultivated 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 eco- 
nomically and advantageously by constructing in many provinces of that vast 
empire canals of great length and capacity, which not only furnish a greater 
supply 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 cubic yards, without counting feeders and 
accessory lines amounting to a length of 3,000 miles. This canal, according to 
a recent 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 
