AGRICULTURAL EifGIN"EERIKG. 



167 



NU3IBER OF ACRES DRAINED BY OPEX DITCHES- 



(Continued). 



Depth of Water, 7 feet. 



Depth of Ditch, at least 9 feet. 



Depth of Water, 9 feet. 



Depth of Ditch, at least ii^ feet. 



The above tables are calculated by Kutter's formula, using 

 a "coefficient of roughness" equal to 0.03, as recommended for 

 channels in moderately good condition, having stones and weeds 

 occasionally. For ditches in first-class condition, the number 

 of acres may be increased about 25 per cent. The tables have 



