cultivation, from cuttings imported from Australia, has been carried out in recent years in the Mysore State.
CHAPTER XXI
IRRIGATION
Irrigation has been defined as an artificial appli- cation of water to the land in order to promote cultivation. Where, as on the west coast, there is an abundant rainfall, there is no need for irrigation except of a simple kind. East of the western ghats, however, irrigation is extensively carried out by means of dams thrown across rivers, tanks, wells, etc. Of 671 square miles of land, which were irri- gated in the Coimbatore district in 1903-4, 502 square miles were watered by wells, 119 square miles by Government canals, and 35 square miles by tanks. In that district, there are said to be 100,000 wells, sunk, in many cases, through hard rock, to a depth of 80 to 90 feet. The name " tank " is applied to artificial ponds or lakes, made either by excavating or banking, which sometimes breach during the wet season, and dry up altogether in the hot weather. The number of tanks in the Madras Presidency and Mysore is said to be about 75,000. Some tanks are of immense size, and resemble great natural lakes. For example, the Viranam tank, which is a very ancient work, has an area of 35 square miles, and an embankment 12 miles long. The great tank at Cumbum in the Kurnool district, which is by tradition attributed to the sage Jamadagni, was formed by damming a gorge through which the Gundla- kamma river flows. It has a capacity of 3,696 million cubic feet, and a drainage area of 430 square miles. The Chembrambakam tank in the Chingleput district, which
