Undeterred by the difficulties incurred on the Lachlan, Oxley, during the following year (1818), engaged in a similar expedition for the exploration of the lower course of the Macquarie. Tracing the unknown stream to the westward, he found himself led out of the region of hills into a country presenting a dead and monotonous level. Here the river began to lose its well-defined course and to spread its waters over the dreary expanse. With great difficulty, he succeeded in distinguishing the river from the lake for a short distance onward, after which further effort in a wide waste of water was to no purpose. Now, at last, he lost sight of land and trees altogether, though again able to discern the current of the Macquarie in a stream three feet deep winding in and out among thickets of reeds, which here grew to a gigantic height. Oxley conjectured he had now reached the commencement of an inland sea--a phantom which long played fast and loose with those who loved to speculate on the mysterious regions of Central Australia. In this pet fancy the explorer, like many other theorists, was quite mistaken, for this delusive expanse of water was not even the termination of the Macquarie River. Ten years later Captain Sturt succeeded in tracing it for 66 miles further, and found it ending its dubious career in the River Darling. Two courses were now open to the expedition--either to return home disappointed, or strike out in a new direction and make fresh discoveries. The latter alternative was adopted. During an earlier part of the journey their attention had been drawn to a lofty range of dark mountains lying athwart the northern horizon. The march was now towards this prominent landmark of the unknown domain of nature. Before it was reached, and after the expedition had been out for about two months, progress was arrested by the discovery of a river running in high flood. This was named the Castlereagh, and a safe passage was obtained after a short delay. There remained a weary journey to the range which had so long loomed in the distance, and was reached after much difficulty, owing to the boggy character of the ground. One of the principal elevations was ascended, from which a magnificent prospect was obtained, and the height ascertained to be about 3,000 feet. Oxley gave to this chain the name of the Arbuthnot Range, but it is still most generally known as the Warrambungle Mountains. The course of the expedition was now directed toward the east, in the hope of ultimately reaching the coast somewhere northward of Sydney. This purpose was rewarded by the discovery of the Liverpool Plains, the most valuable find that had hitherto fallen to the lot of any explorer. This is a splendid area of first-class land, consisting of level country embracing about 17,000 square miles, supposed to have formed in past ages the bed of a small inland sea. The next discovery was the Namoi River, called after Sir