78 Irrigation and Drainage 



Mahanadi Eiver, and farther south, at various points in the Madras 

 Presidency. On the western side of the peninsula, too, back from 

 Bombay, both at Poona, in the valley of the Mutha River, and at 



Fig. 17. Ridged surface of a water-meadow, Salisbury, England. 



Bhutan, where there is a great dam 4,067 feet long and 130 feet 

 high, which forms a reservoir for the supply of the Nira canals, 

 are other extensive modern irrigation systems. The Vir weir, at 

 the head of the Nira canal, is 2,340 feet long, with a maximum 

 height above the river bed of 40 feet, and over this weir, at maxi- 

 mum flood, there pours 160,000 cubic feet of water per second, in 

 a sheet 8 feet deep over the crest. 



The number of wells used for irrigation in the Madras Presi- 

 dency has been estimated at not less than 400,000, while the area 

 they serve is placed at 2,000,000 acres. It is further estimated for 

 the whole Indian peninsula, British and native, that not less than 

 300,000 shallow wells are in use, while they serve certainly more 

 than 6,000,000 acres of land. 



Referring, now, more particularly to the extent of irrigation 

 enterprises in India, we learn from Richard J. Hinton's report to 

 the Senate that in the Madras Presidency, with a population of 



