GLOSSARY OF IRRIGATION TERMS. 307 



Measuring Box A device set in ditches for apportioning. 



water to consumers. 



3Iiner's Inch A unit of water measurement. 

 Module A French device for measuring water. 

 M udsill The structure upon which rests the floor of a head- 

 gate. 

 Nilometer A gauge for measuring and recording the rise 



and fall of streams. 



Overfall The apron of a weir or dam. 

 Penstock A pipe for supplying water ; a sluice or conduit 



for controlling the discharge of water. 

 Percolation Filtration of water through the soil. 

 Phreatic Underground, as the sources of wells ; phreatic 



waters. 



Pipe-Line A system of pipe or conduit for conveying water. 

 Points Perforated pipes driven into the earth to secure 



water for pumps. 



Porosity Porous condition or possessing pores. 

 Puddle To line, as canal banks with clay to render water- 

 tight ; preparing plants for transplanting. 

 Reduction Box A device for decreasing the flow of a, 



canal. 

 Reservoir A basin for collecting and impounding water; 



a storage lake or pond. 

 Rill A small stream or delicate furrow. 

 Riparian Pertaining to the banks of a river. 

 Riprap Broken stone arranged in beds for protecting 



embankments. 

 Rim-Off Those waters which escape by natural courses on 



the earth's surface ; those waters which do not " fly-off." 

 Sakiyeh A rude water wheel used in Egypt. 

 Sand Gate An appliance for diverting sand from a canal. 

 Second Foot A unit of water measure ; the discharge of 



one cubic foot a second. 

 Seepage Oozing or percolation of water in soil ; also spelled 



seapage and sipage. 



Sewage The discharge from sewers ; waste water. 

 Shadoof An oriental device similar to a well-sweep. 



