WATER SUPPLY AND IRRIGATION. 181 
The great object to be attained is to provide a steady, certain 
supply that can be distributed by gravitation, and, to compass this, 
a sufficient body of water must be stored in the upper courses of 
our rivers being of a sound character, and no difficulties likely to 
arise from the flanking action of scour. Enormous bodies 0 water 
could be stored in such places without any lisproport t pense 
‘Ing incurred, and in some cases with a very small outlay. The 
tributaries to these rivers would have to be similarly dealt with, 
Means being provided in each case to allow the impounded waters 
to be discharged as required, so that any surplus over what would 
be needed for merely local wants could be passed down to supply 
the lower ponds where the water was being drawn off by the main 
Vague and ill-defined ; but we know enough of the conditions 
