IBBIGATION AND DBT-FARMING 685 



588. Extent of irrigated land. — In 1905, Mead ^ 

 estimated the total area of land irrigated at 100,000^000 

 acres. Since that date the practice of irrigation has 

 been extended rapidly in all parts of the world, and it is 

 probable that at the present time the total area of land 

 irrigated is at least 200,000,000 acres. In Egypt, in 

 Australia, and in India, as well as in the United States, 

 large projects for irrigation developments have recently 

 been undertaken. In the United States, according to 

 the Thirteenth Census, the area of land irrigated increased 

 7,500,000 acres between 1899 and 1909. At the latter 

 date enterprises for the provision of water were under 

 way to cover a total of 31,000,000 acres. 



589. History of irrigation. — The practice of irriga- 

 tion is very ancient. The very earliest records of the 

 peoples in the valleys of the Nile and Euphrates rivers, 

 in Africa and Asia, mention large irrigation works. 

 In China and India also the practice is very old. The 

 remains of ancient works for irrigation often amaze 

 the modern engineer by their size and excellence of con- 

 struction, considering the facilities that were available. 

 As early as 2084 B.C. an artificial lake fifty miles in cir- 

 cumference was constructed in Egypt, communicating 

 with the Nile through a canal. The Great Imperial 

 Canal in China, connecting the Hoangho River with the 

 Yangtze, was 650 miles long and had several lakes in its 

 course. In Peru, Mexico, and the southwestern United 

 States, there exist remains of very extensive irrigation 

 works of great antiquity. In Argentina large irrigation 

 canals may still be traced for from four to five l^undred 



1 Mead, B. Irrigation Engineering: and Practice. Ametioan 

 Cyclopedia of Agriculture, p. 420. New York. 1907. 



