GLOSSARY OF IRRIGATION TERMS. 487 



Fly-Off — Evaporation of water as compared with run-off 

 waters. 



Fore Bay — That part of a canal where the water enters the 

 headgate. 



Fountainhead — Original source; a spring from which water 

 flows. 



Grade — The degree of inclination in a canal. 



Grade Level — An instrument for determining the slope of a 

 watercourse. 



Gradient — Rate of variation in the grade of a ditch. 



Head — The measure of stored up or gathered force ready to 

 be used in irrigating; the hight of a body of water in 

 covering land, as by flooding. 



Head Bay— See Fore Bay. 



Head Ditch — A lateral running along the highest level of land 

 to be irrigated. 



Headgate — The up-stream gate of a canal; a water or flood- 

 gate. 



Hydraulic Engineer — One skilled in hydraulics and the con- 

 struction of waterways. 



Hydraulic Ram — An automatic device for raising water by its 

 own power. 



Hydraulics — The science of liquids, especially of water in 

 motion. 



Hydrometric Sluice — A certain kind of measuring box. 



Intake — The point in a stream where a canal is taken out. 



Inundation — Overflowing or covering land with water. 



Irrigant— An irrigating ditch. 



Irrigation — The process of watering agricultural lands by arti- 

 ficial means. 



Irrigator — A cart for watering crops; one who irrigates. 



Lateral— A side ditch; the small service line leading from a 

 supply ditch or canal. 



Levee — A border or embankment. 



Loess — A deposit of fine clay loam or very fine sand; the sedi- 

 ment found in canals. 



Measuring Box — A device set in ditches for apportioning 

 water to consumers. 



