FARM IMPLEMENTS OF IRRIGATION. 167 



CHAPTEE VI. 

 FARM IMPLEMENTS OF IRRIGATION. 



THE level of land surface in Egypt represents the maximum 

 height at which flood Niles have deposited silt, and it 

 follows that after the flood has passed and the river grad- 

 ually sinks below the level of the land, the water must be 

 lifted, if irrigation is to be accomplished. This necessity 

 produced the Shadoof which figures on some of the ancient 

 temples of Egypt, and more than 2000 years ago Archi- 

 medes invented his screw for irrigation in this country. 



In Upper Egypt the difference between high and low 

 Nile is 7 to 8 metres, in northern Lower Egypt it is not 

 more than 1 metre. The varied conditions of height of 

 lift, and quantity of water required, have given rise to 

 many types of water-lifting machines, ranging from the 

 humble shadoof lifting its 100 cubic metres per day to 

 huge steam-driven pump lifting 350 cubic metres per 

 minute. All these machines have their special uses, and 

 in adopting any particular type careful consideration of 

 the local conditions is necessary. 



All water lifts, of whatever nature, must be reduced to 

 one common standard of Water Horse Power, W.H.P., 

 i.e., the actual quantity of water lifted a certain height. 



French "Horse Power" is 4,500 kilogrametres per 

 minute. 



