94 



ENGINEERING FOR LAND DRAINAGE. 



Preliminary Estimate, 



The following will be useful in making preliminary 

 estimates of the number of feet of drains which will be 

 required per acre when laid in parallel lines at the dis- 

 tances apart indicated : 



20 feet apart 2205 feet 



25 



30 



40 



50 

 100 

 150 

 200 



1760 

 1470 

 1 102 

 880 

 440 

 270 

 220 



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The number of feet of drains per acre as shown 

 above does not include any intercepting main which 

 may be necessary to make the work complete. For 

 instance, should it be necessary to locate a main 

 through the centre of a field, its length must be divided 

 by the number of acres in the field, and the result 

 added to the number which is found in the table above, 

 opposite the number in the column indicating the dis- 

 tance apart which it is proposed to lay the drains. 



