island from the other; it was impossible, indeed, to traverse them as I
had done, and not feel convinced that they had at one period or the other
been covered by the waters of the sea. It naturally struck me, that if I
was correct in this conjecture, the difficulty or facility with which the
interior might be penetrated, would entirely depend on the breadth and
extent of these once submarine plains, which in such case would now
separate the available parts of the continent from each another, as when
covered with water they formerly separated the islands. This hypothesis,
if I may so call it, was based on observations which, however erroneous
they may appear to be, were made with an earnest desire on my part to
throw some light on the apparently anomalous structure of the Australian
interior. No one could have watched the changes of the country through
which he passed, with more attention than did I--not only from a natural
curiosity, but from an anxious desire to acquit myself to the
satisfaction of the Government by which I was employed.

When Mr. Oxley, the first Surveyor-General of New South Wales, a man of
acknowledged ability and merit, pushed his investigations into the
interior of that country, by tracing down the rivers Lachlan and
Macquarie, he was checked in his progress westward by marshes of great
extent, beyond which he could not see any land. He was therefore led to
infer that the interior, to a certain extent, was occupied by a shoal
sea, of which the marshes were the borders, and into which the rivers he
had been tracing discharged themselves.

My friend, Mr. Allan Cunningham, who was for several years resident in
New South Wales, and who made frequent journeys into the interior of the
continent as botanist to his late Majesty King George IV. and who also
accompanied Captain P. P. King, during his survey of its intertropical
regions, if he did not accompany Mr. Oxley also on one of his