THE HISTORY OF IRRIGATION 449 



260. The Christian era, to 1800. Clearly, a valuable 

 practice so ancient and so widespread, as is irrigation, 

 could not vanish from the earth. Therefore, in spite of 

 the changing fortunes of the race which has covered but 

 a small part of the earth, irrigation has remained a con- 

 tinuous practice. In some places, as in Babylon, with the 

 decline in civilization and the diminution of population, 

 irrigation disappeared wholly or in part; while in other 

 places, as in Egypt, China and Persia, it has continued 

 and often increased. New countries have adopted it; and 

 most of the older ones have maintained it. The most 

 enlightened peoples have always practised and do now 

 practice irrigation, if the climatic conditions make it 

 desirable. It is difficult for an unintelligent or shiftless 

 people to become good irrigators. 



During the Christian era, the practice of irrigation 

 has moved westward, with the general western movement 

 of civilization. During the days of the Roman Empire, 

 irrigation was fostered in all the Mediterranean countries, 

 although relatively few remains of the Roman structures 

 are known. That it was of high importance in Roman 

 days is well shown by the attention given irrigation in 

 the famous codes of law formulated in the fifth and sixth 

 centuries after Christ. As another trifling but interesting 

 evidence, Carpenter gives the word "rivals," derived from 

 "rivus," an artificial water channel, or ditch. The users 

 from a "rivus" were rivals the usual contests over water 

 are clearly implied. 



The invasion of southern Europe by the Moors, hi the 

 ninth and tenth centuries after Christ, became a great 

 stimulus to irrigation. The Moorish conquerors had a 

 good traditional and practical knowledge of irrigation, 

 and sensed quickly the value, to southern Europe, of more 

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