1 68 The Drainage of Fens and Low Lands. 



The calculations are based on a quantity of water due to a quarter 

 of an inch rain in 24 hours, and allowing for the drains and sluices 

 to run the whole 24 hours* 



The larger sluices are calculated to discharge at about the same 

 velocity as the drains. In the smaller sluices a greater head has been 

 allowed. If a greater head can be given, the width of the sluices can 

 be reduced accordingly. 



As the velocity varies as the square root of the fall, four times the 

 fall per mile given in the table will double the discharge, or, one- 

 fourth of the fall will give one-half the discharge. 



