WESTERN IRRIGATION. 261 



leaf was withered and utterly dead before the end of 

 August, though the tree still lived, and would renew 

 its foliage next Spring. 



Most of this broad area is usually spoken of as des- 

 ert, because treeless, except on the slopes of its moun- 

 tains, where certain evergreens would seem to dis- 

 pense with moisture, and on the brink of infrequent 

 and scanty streams, where the all but worthless Cot- 

 ton-wood is often found growing luxuriantly. A very 

 little low Gamma Grass on the Plains, some strag- 

 gling Bunch-grass on the mountains, with an endless 

 profusion of two poor shrubs, popularly known as 

 Sage-brush and Grease-wood, compose the vegetation 

 of nearly or quite a million square miles. 



I will confine myself in this essay to the readiest 

 means of irrigating the Plains, by which I mean the 

 all but treeless plateau that stretches from the base 

 of the Rocky Mountains, 300 to 400 miles eastward, 

 sloping imperceptibly toward the Missouri, and 

 drained by the affluents of the Platte, the Kansas, 

 and the Arkansas rivers. 



The North Platte has its sources in the western, as 

 the South Platte has in the eastern, slopes of the 

 Rocky Mountains. Each of them pursues a gener- 

 ally north-east course for some 300 miles, and then 

 turns sharply to the eastward, uniting some 300 miles 

 eastward of the mountains, where the Plains melt 

 into the Prairies. Between these two rivers and the 

 eastern base of the mountains lies an irregular delta 

 or triangle, which seems susceptible of irrigation at 



