HOPE IN IRRIGATION 371 



" disease " or " desert ulcer," by the blowing of the fatally 

 exposed sand and the gradual extension, owing to the 

 action of the sand itself, of the area of destroyed vegeta- 

 tion. Sand-deserts are not, as used to be supposed, sea- 

 bottoms from which the water has retreated, but areas ot 

 destruction of vegetation often (though not always), both 

 in Central Asia and in North Africa (Egypt, etc.), started 

 by the deliberate destruction of forest by man, who has 

 either by artificial drainage starved the forest, or by the 

 simple use of the axe and fire cleared it away. 



The great art of irrigation was studied and used with 

 splendid success by the ancient nations of the near East. 

 They converted deserts into gardens, and their work was 

 an act of compensation and restitution to be set off 

 against the destructive operations of more barbarous men. 

 But they, too, long ago were themselves destroyed by con- 

 quering hordes of more ignorant but more war-like men, 

 and their irrigation works and the whole art of irrigation 

 perished with them. One of the absolutely necessary works 

 to be carried out by civilised man, when he has ceased to 

 build engines of war and destruction, is the irrigation of the 

 great waterless territories of the globe. A little home-work 

 of the kind has been carried on in Italy regularly year by 

 year since the days of Leonardo da Vinci, and our Indian 

 Government is slowly copying the Italian example. In 

 Egypt we have built the great dam of Assouan, whilst 

 in Mesopotamia it is proposed to re-establish the irriga- 

 tion system by which it once was made rich and fertile. 

 But, as has lately been maintained by Mr. Rose Smith in 

 his book, ' The Growth of Nations,' the vast possibilities 

 of irrigation have not yet been realised by the business 

 men of the modern world. Millions of acres in the 

 warmer regions of the earth now unproductive can be 

 made to yield food to mankind and rich pecuniary profits 

 to the capitalists who shall introduce modern engineer- 



