156 MR. Cunningham’s remarks. 
bed. If a stream has constant fountains at its head, and 
numerous tributaries joining it in its course, and flows 
withal through a country of gradual descent, such a stream 
will never fail ; but if the supplies do not exceed the evapo- 
ration and absorption, to which every river is subject, if a 
river dependant on its head alone, falls rapidly into a level 
country, without receiving a single addition to its waters to 
assist the first impulse acquired in their descent, it must 
necessarily cease to flow at one point or other. Such is 
the case with the Lachlan, the Macquarie, the Castlereagh, 
and the Darling. Whence the latter originates, still re- 
mains to be ascertained ; but most undoubtedly its sources 
have been influenced by the same drought that has ex_ 
hausted the fountains of the three first mentioned streams. 
In supporting his opinion of the probable discharge of the 
interior waters of Australia upon its north-west coast, Mr. 
Cunningham thus remarks in the publication from which I 
have already made an extract. 
“ To those remarkable parts of the north-west coast above 
referred to in the parallel of 16" south, the Macquarie river, 
which rises in lat. 33", and under the meridian of 150" east, 
would have a course of 2045 statute miles throughout, 
while the elevation of its source, being 3500 feet above the 
level of the sea as shewn by the barometer, would give its 
waters an average descent of twenty inches to the mile, sup- 
posing the bed of the river to be an inclined plane. 
“ The Gwydir originating in elevated land, lying in 31" 
south, and long. 151“ east, at a mean height of 3000 feet. 
