Septembbk 25j 1914] 



SCIENCE 



437 



of South Africa." If the settlers come, he 

 holds that the agency of man, tree-plant- 

 ing, ploughing and harrowing the soil, will 

 drive back and kill out the desert. The ef- 

 fect of tree-planting in arresting the sand 

 dunes and reclaiming desert has been very 

 marked in the Landes of Gascony. Here, 

 I gather from Mr. Perkins's report, are 

 some 3,600 square miles of sandy waste, 

 more than half of which had, as far back 

 as 1882, been converted into forest land, 

 planted mainly with maritime pines. 



What, again, will irrigation have to say 

 to the deserts? Irrigation, whether from 

 ^^nderground or from overground waters, 

 has already changed the face of the earth, 

 and as the years go on, as knowledge grows 

 and wisdom, must inevitably change it 

 more and more. I read of underground 

 waters in the Kalahari. I read of them too 

 in the Libyan Desert. In the Geograph- 

 ical Journal for 1902 it is stated that at 

 that date nearly 22,000 square miles in the 

 Algerian Sahara had been reclaimed with 

 water from artesian wells. What artesian 

 and sub-artesian water has done for Aus- 

 tralia you all know. If it is not so much 

 available for agricultural purposes, it has 

 enabled flocks and herds to live and thrive 

 in what would be otherwise arid areas. 

 Professor Gregory, Mr. Gibbons Cox, and 

 others have written on this subject with ex- 

 pert knowledge ; evidence has been collected 

 and published by the Dominions Royal 

 Commission, but I must leave to more 

 learned and more controversial men than I 

 am to discuss whether the supplies are 

 plutonic or meteoric, and how far in this 

 matter you are living on your capital. 



If we turn to irrigation from overground 

 waters, I hesitate to take illustrations from 

 Australia, because my theme is the blotting 

 out of the desert, and most of the Austral- 

 ian lands which are being irrigated from 

 rivers, and made scenes of closer settlement, 



would be libeled if classed as desert. Mr. 

 Elwood Mead told the Royal Commission 

 that the state irrigation works in Victoria, 

 already completed or in process of construc- 

 tion, can irrigate over 600 square miles, 

 and that, if the whole water supply of the 

 state were utilized, more like 6,000 square 

 miles might be irrigated. The Burrinjuek 

 scheme in New South Wales will irrigate, 

 in the first instance, not far short of 500 

 square miles, but may eventually be made 

 available for six times that area. If we 

 turn to irrigation works in India, it appears 

 from the second edition of Mr. Buckley's 

 work on the subject, published in 1905, that 

 one canal system alone, that of the Chenab 

 in the Punjab, had, to quote his words, 

 turned "some two million acres of wilder- 

 ness (over 3,000 square miles) into sheets 

 of luxuriant crops." "Before the con- 

 struction of the canal," he writes, "it was 

 almost entirely waste, with an extremely 

 small population, which was mostly nomad. 

 Some portion of the country was wooded 

 with jungle trees, some was covered with 

 small scrub camel thorn, and large tracts 

 were absolutely bare, producing only on 

 occasions a brilliant mirage of unbounded 

 sheets of fictitious water." The Chenab 

 irrigation works have provided for more 

 than a million of human beings; and, ta- 

 king the whole of India, the Irrigation 

 Commission of 1901-03 estimated that the 

 amount of irrigated land at that date was 

 68,750 square miles ; in other words, a con- 

 siderably larger area than England and 

 Wales. Sir William Willcocks is now re- 

 claiming the delta of the Euphrates and 

 Tigris. The area is given as nearly 19,000 

 square miles, and it is described as about 

 two thirds desert and one third fresh- 

 water swamp. Over 4,000 square miles 

 of the Gezireh Plain, between the Blue 

 and the White Nile, are about to be re- 

 claimed, mainly for cotton cultivation, 



