Cad APE BLE OV is 
CERTAIN IMPORTANT QUESTIONS RELATING 
TO IRRIGABLE LANDS. 
THE UNIT OF WATER USED IN IRRIGATION. 
The unit of water employed in mining as well as manufacturing enter- 
prises in the west is usually the inch, meaning thereby the amount of water 
which will flow through an orifice one inch square. But in practice this 
quantity is very indefinite, due to the “head” or amount of pressure from 
above. In some districts this latter is taken at six inches. Another source 
of uncertainty exists in the fact that increase in the size of the orifice and 
increase in the amount of flow do not progress in the same ratio. An ori- 
fice of one square inch will not admit of a discharge one-tenth as great as 
an orifice of ten square inches. An inch of water, therefore, is variable 
with the size of the stream as well as with the head or pressure. For these 
reasons it seemed better to take a more definite quantity of water, and for 
this purpose the second-foot has been adopted. By its use the volume of a 
stream will be given by stating the number of cubic feet which the stream 
will deliver per second. 
THE QUANTITATIVE VALUE OF WATER IN IRRIGATION. 
In general, throughout the Arid Region the extent of the irrigable 
land is limited by the water supply; the arable lands are much greater 
than the irrigable. Hence it becomes necessary, in determining the amount 
of irrigable lands with reasonably approximate accuracy, to determine the 
8h 
LAR 
