AGRICULTURAL ENGINEERING. 



169 



8. The bottoms of open ditches should be at least three feet 

 wide, and the sides should be given slopes of at least one foot 

 horizontal to one vertical to avoid choking. Dirt should not 

 be piled near the edges of the bank. 



POINTS TO NOTE IN PLANNING A DItA.INAGE STSTE3I. 



1. Character of the land, as swampy, low, sloping, drv, etc. 

 also retentive or open, depth of surface soil, condition of sub- 

 soil, etc. 



2. Acreage of various kinds just described, their location 

 relative to drains, etc. 



3. The outlet, its character, capacity, depth, protection re- 

 quired for tile, etc. 



4. Fall or grade for mains, submains, and laterals, with depth 

 of cutting required. 



5. Various expedients, such as the use of cut-offs across necks 

 of land, to save distance and gain fall. 



6. Your drainage engineer should be competent to handle 

 these problems. 



SIZES OB' DRAIN-PIPE REQUIRED FOR CTILVERTS IN 

 PROPORTION TO CAPACITY AND FALL. (Eldridge.) 



