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
evaporation 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
remains to be ascertained; but most undoubtedly its sources have been
influenced by the same drought that has exhausted 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 degrees south, the Macquarie river, which rises in
lat. 33 degrees, and under the meridian of 150 degrees 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 shown by the
barometer, would give its waters an average descent of twenty inches to
the mile, supposing the bed of the river to be an inclined plane.

"The Gwydir originating in elevated land, lying in 31 degrees south,
and long. 151 degrees east, at a mean height of 3000 feet, would have
to flow 2020 miles, its elevated sources giving to each a mean fall of
seventeen inches.

"Dumaresq's river falling 2970 feet from granite mountains, in 28 1/4
degrees under the meridian of 152 degrees, would have to pursue its
course for 2969 miles, its average fall being eighteen inches to a
mile."

As I have never been upon the banks either of the Gwydir or the
Dumaresq, I cannot speak of those two rivers; but in estimating the
sources of the Macquarie at 3500 feet above the level of the sea, Mr.
Cunningham has lost sight of, or overlooked the fact, that the fall of
its bed in the first two hundred miles, is more than 2800 feet, since
the cataract, which is midway between Wellington Valley and the
marshes, was ascertained by barometrical admeasurement, to be 680 feet
only above the ocean. Th