PART II 

 FARM DRAINAGE 



CHAPTER XII 



PRINCIPLES OF DRAINAGE 



IT has been pointed out that if all of the irri- 

 gated lands of the world were brought together in 

 a solid body, they would scarcely aggregate more than 

 an area 500 miles on a side, or 250,000 square miles. 

 But Professor Shaler estimates that in the United States 

 alone, east of the 100th meridian, there are more 

 than 100,000 square miles of swamp lands. Some of 

 these have been reclaimed by drainage, and the great 

 majority of them could be, if the expense of the 

 reclamation would be warranted by the returns which 

 would follow. In the Canadas, in Europe, and in 

 other portions of the world, also, there are vast areas 

 of land, when measured in the aggregate, which 

 must be drained before they can become agricul- 

 turally productive. Hence the principles of land drain- 

 age, like those of irrigation, must be clearly under- 

 stood by those who are concerning themselves with 



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