WATER SUPPLY AND IRRIGATION. I 
conditions under which the rainfall occurs must also have an 
important influence ; the heaviness of the fall, that is, the quantity 
enormous bodies of water brought down by the rivers that are 
intereepted and diverted in filling lagoons, warrambools, swamps 
| lakes ; and that in heavy floods, are thrown back over the 
level country for scores of miles, and largely retained there when 
the floods in the rivers recede ; retainedin shallow-creek beds am 
swamps, when the evaporation is enormous. : 
These catises—over-estimated rainfall—under-estimated dis- 
charge—enormous evaporation on the levels which form the largest 
proportion of the area of the basin—the loss in filling secondary 
els, &e.—and the surface soakage—all taken together, may 
probably materially modify the results arrived at by Mr. Russell. 
_ That there may be places where large quantities of water find 
tts way underground, to supply the lower drift beds, cannot be 
Positively denied ; but that such wholesale percolation takes place 
Senerally is very improbable ; and if the cond 
body of water ig disposed of: and how far our knowledge of the 
te, posed of; an i : 4 
Conditions under which water-bearing drifts are discovered in that 
twat MI sustains or disproves the assumption that they are 80 
ishiy supplied from the surface. . 
ae doe ical ings of the case I leave for those more con- 
absorbed on the Darling watershed above Bourke, if Mr. 
