The mystery of the Macquarie was now, to a certain extent, cleared up, but there still remained another riddle to solve in the course and outlet of the Darling. Sturt, the discoverer of this river, was destined to find the answer to this problem as well. We have now traced the gradual extension of exploration to the westward, and seen a river system growing up, as it were, piece by piece, as the result of these expeditions; it may, therefore, be as well to continue to follow up Captain Sturt's expeditions, and note how the Murray and its tributary streams were gradually elaborated, before touching upon events at this time occurring afar on the south-west coast of the continent. The desire to ascertain the course of the Darling naturally became a subject of great interest so soon as the result of Captain Sturt's expedition was known; and the Macquarie and Lachlan rivers having failed to afford a means of reaching the interior, it was determined to try the Morumbidgee. The fact that this river derived its supply from the highest known mountains, and was independent, to a large extent, of the periodical rainfall, was a great inducement to hope for success. Almost exactly a year after he had started on his journey down the Macquarie, Captain Sturt left Sydney, on his Morumbidgee expedition, on the 3rd of November, 1829. Hume, was not, on this occasion, able to accompany the party, his own affairs on his farm needing his attention; doubtless in spirit he was often with them, and it would have been but fitting had the discoverer of the Murray or Hume, been one of the party to first trace its downward course. In Hume's place went George M'Leay, the son of the then Colonial Secretary, Alexander M'Leay; with them also went Harris, Hopkinson, and Fraser, members of the Macquarie expedition, To our modern eyes the appearance of the troop that marched out of Sydney, early that summer morning, would have looked strange indeed.