WATER SUPPLY IN THE INTERIOR OF NEW SOUTH WALES. 99 
watersheds sometimes carry off as much as 90 per cent. of the 
amount of rain which falls within their drainage area. 
The following tables of outflow of various rivers in different 
parts of the world by different observers will perhaps give a 
tolerably fair average or normal ratio of outflow to rainfall :— 
Ratio of drainage or outflow to rainfall. 
0°24 
Ohio River 
Missouri 0°15 
Upper ississippi 0°24 
Small tributaries 2.......s.<cesseesers 0°30 Messrs. Humphreys and 
Arkansas and White Rivers ...... 0°15 | Abbott, Engineers to the 
i 0-20 { United States Government, 
River ocd decrees ces ica. 
fib PERIGIS “IVOR 55s, fis sapucnie «> 0°90 
The Thames, in England, carries off a little less than one- 
third of the rainfall (Beardmore’s Hydrology, p. 201). e 
Elbe carries off one-quarter of the rainfall (Verhandl Geol. 
Reichsanstalt, p. 173). The Seine, at Paris, carries off a t i 
of the rainfall (A. Geikie). The Upper Nepean and Cataract 
Wales, carry off about 39 per cent. of the rainfall, as shown by 
hi 
(H. C. Russell: Journal of the Royal Society of New South 
Wales, 1883). The Murray is a western river, and in area of 
drainage is only second to the Darling of all our Australian 
vers. 
Mr. Russell’s calculations as to average evaporation in the 
pted as 
proves—that in a dry year in the interior of New South Wales, 
from a water surface the evaporation cannot be more than 5, orat 
most, 6 feet per year, and is probably less than either of these 
% 
