308 IRRIGATION FARMING. 



Sheet-Piling Thick planking driven as piles ; the sides of 



coffer-dams. 



Silt Detritus or floating matter in a ditch ; sediment. 

 Siplioii A bent pipe or tube, or even a box, for drawing 



water by atmospheric pressure ; also syphon. 

 Slope The grade of a ditch. 

 Sluice An artificial channel for carrying water, with gates 



or valves. 



Spillway A waste weir or overflow. 

 Staudpipe An elevated tap for draining water from a 



main ; a tower-like pipe at a reservoir into which water is 



pumped to give it a head. 

 Storm Water That which falls in catchments during 



freshets. 



Strut A compression brace in a framework, as a truss. 

 Subbing Water percolating near the surface and utilized in 



sub-irrigation. 

 Sub-Irrigation Watering land through pipes or channels 



below the surface. 



Subsidiary Canals Those that are secondary. 

 Subsoiling To break up ; to loosen the subsoil. 

 Tail-Race A wasteway from a canal. 

 Tamp To pack with earth or other materials. 

 Target An instrument used as a flag in directing 



surveyors. 



Terreplein The level fill or surface of earth made to con- 

 nect with flumes, etc. 

 Turiibeam A sort of treadmill device used in oriental 



lands for raising water. 

 Tympanum A large drum wheel for raising water from a 



running stream. 



Underflow Currents of water below the earth's surface. 

 Warping A method of retaining water by means of banks 



in overflows, as of tides along the ocean shore. 

 \Vaste Gate An outlet for discharging water from a canal 



<>r storage pond. 

 Water Register An instrument for measuring the flow of 



streams. 



