As early as the year 1818 the Macquarie River had been explored as far as practicable by John Oxley, the Surveyor-General. This indefatigable traveller had traced its course into the far interior till it seemed lost and appeared to terminate in a series of swamps, overgrown with dense reeds. All his efforts to proceed further westward proved unavailing, and he turned aside to other work, being under the impression that he had seen all that was visible of the Macquarie. Like some others of his time, Oxley had taken up with the idea of a mediterranean sea which was supposed to cover the interior of Australia; and such being his opinion, it was natural to fancy he had reached its margin in those swamps of seemingly indefinite extent into which the Macquarie poured its flood. During the next ten years Cunningham had pushed as far north as the Darling Downs, while Hume and Hovell had been equally successful in forcing their way south to Port Phillip; but out west no progress was made beyond the goal of Oxley's explorations. But ignorance of the interior hung like a cloud over the settlement, a vague feeling of mystery kept curiosity awake, and a general desire began to be expressed for fresh explorations in that direction. The times, too, which in other respects happened to be signally disastrous, appeared to be just as favourable for such an enterprise. A drought of several years' standing was then devastating the colony; but this misfortune, which brought ruin to the doors of so many settlers, seemed, strangely enough, to be a strong recommendation to start an exploring expedition. It had been Oxley's misfortune to examine the country during an exceptionally wet season, and it was conjectured that floods had laid under water the low-lying country on the further reaches of the Macquarie, and thus interposed a temporary obstruction to the westward advance of exploration. But now, after a drought of long standing, it was hoped that the swamps, if not dried up, would at least be so much reduced as to render the much-desired object more likely to be accomplished. Governor Darling, accordingly, determined on sending out another expedition. In the all-important question of a leader, he was singularly fortunate in selecting Captain Sturt. The latter took as his associates Mr. Hamilton Hume, who had already gained his own laurels in exploration, Staff-Surgeon M'Leod, two soldiers, and eight convicts. The instructions received from headquarters were, generally, to follow up the discoveries of Oxley, to endeavour to ascertain the "fate" of the Macquarie, and to put forth the utmost effort to penetrate westward to the furthest possible limit.