LAND DRAINAGE 



idea sufficiently definite for all practical purposes 

 may be gathered from experience. 



In tolerably porous soils, forty, or even fifty 

 feet apart is generally conceded to be sufficiently 

 near for four-foot drains. But for the more 

 retentive clays, all distances from eighteen feet 

 to fifty have been recommended. The feeling 

 grows more in favour of the greater width, from 

 continued observation of the successful working 

 of drains so placed. Still the author's opinion, 

 formed from over twenty years of personal experi- 

 ence and observation of such works, and with 

 due consideration of views published by others, is 

 that we should hardly ever, where a soil needs 

 draining at all, leave widths exceeding forty 

 feet. 



He further says that, in the lighter loams, there 

 has been good success in following Professor 

 Mapes's rule: that "three-foot drains should be 

 placed twenty feet apart, and for each additional 

 foot in depth the distance may be doubled. For 

 instance, four-foot drains may be forty feet apart, 

 and five-foot drains eighty feet apart." But with 

 reference to this greater distance eighty feet 

 it is not to be recommended in stiff clays for any 



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