LXXIV. REVIEW OF WATER CONSERVATION IN N.S.W. 
the quantities of water ultimately available, as there are 
no rain-gauges on the highest peaks of the dividing range, 
where the heaviest rains and snows occur. 
I should like to make a remark here on the vexed question 
of the unit to be adopted in measurements of flowing water. 
The natural and scientific unit derived from British meas- 
ures is obviously the cubic foot per second of time. This 
unit represents a large quantity of water when converted 
into gallons per day, and since British water engineering 
has been chiefly concerned with town supplies, the smaller 
unit of a cubic foot per minute has crept into use. In 
irrigation work, however, it is convenient to have a unit 
which bears some simple relation to the area of ground 
irrigated. In America, the term “‘acre-foot’’ has been 
introduced as a unit of volume, it means, of course, the 
quantity of water which would flood an acre of ground one 
foot deep, or 43,560 cubic feet. A flow ofa cubic foot per 
second, called a ‘‘cusec,’’ will deliver an acre-foot in 12°1 
hours, roughly, a cusec will give 4 acres of grounda 3 inch 
watering in a working day. 
After having obtained a proper survey of the water 
resources of the State by long continued gauging, it will 
be necessary to utilize them in the most economical manner. 
This must be so, because the supplies will be used as a 
factor in the pastoral industry, and the margin of profit in 
that industry has descended to a low level. For many 
years to come, the most obvious use of irrigated ground 
wili be for growing fodder on which to feed sheep. Along 
with this might proceed the cultivation of small gardens 
for vegetables, and in this way the arid areas might be 
insured against bad seasons. It is quite clear that any 
schemes must be rigourously economical to ensure adoption. 
It may be remarked that the occupation of the State by 
the pastoral industry has produced important changes in 
