NEW SOUTH WALKS. 455 
its mouth in South Australia. But notwithstanding the large extent 
of surface drained by these water-courses,—not less than 250,000 
square miles,—the main branches, as the Darling for example, are 
often reduced to mere streamlets, or pools of standing water. Some 
of the rivers become subterranean in the limestone region west of the 
Dividing range. This is the case with the Macquarie west of 
Bathurst, which was visited by Mr. Hale. ‘Though a large stream, 
it entirely disappears in ordinary seasons by sinking into the caverns 
of the country. 
It is a remarkable fact that many of the pools to which the rivers 
become reduced in dry weather, consist of brackish or saline water. 
The interior of Australia is still ‘terra incognita.’ The early sup- 
position that the whole was a vast internal sea, had been seemingly 
confirmed by the explorations of Mr. Eyre over the northern parts of 
South Australia.* But the later journeys of Captain Frome (1843), 
and Mr. Poole (1845), have made deserts of the fancied lakes. Some 
small pools were all the water found. It appears to be the most proba- 
ble conclusion, therefore, that the interior is mostly an arid waste. 
The peculiar dryness of the climate and soil of a large part of 
Australia,—a fact which cannot be doubted, as it is abundantly 
proved by observations,—admits of ready explanation on established 
principles in meteorology. [For this semi-continent hes to a great 
extent within the desert latitudes of the globe. In Africa, and on the 
west coast of the Americas, both north and south, the latitudes 18° to 
30° or 35° are remarkably dry, and are occupied by complete or par- 
tial deserts. ‘The desert of Atacama, between Chili and Peru, the 
semi-desert of California, and the far-famed Sahara are the regions 
referred to. Sahara stretches across Africa, and the arid territory is 
continued on over Arabia. 
In Australia, the same condition as regards surface exists as in 
Africa, though varied by the more insular character of the land. Mr. 
W.C. Redfield has satisfactorily explained the existence of deserts on 
the western side of continents in the latitudes referred to, on the prin- 
ciple that the winds reaching these coasts blow from a colder region, 
and are passing to a warmer, and, consequently, with the increase of 
heat, their capacity for moisture is increasing. ‘They are therefore 
* Mr. Eyre first stated the existence of the so-called Lake Torrens in South Australia, 
near latitude 30° and longitude 139° or 140°. Captain Frome found that the appearance 
of water was due to mirage. 
