There was again a considerable mirage or refraction this morning on the rising of the frost; and I hastened to a small hill near our camp that I might behold the transient vision of a distant horizon. The view was most interesting for the high lands on all sides appeared raised as if by magic; and I thus discovered that the hill, previously seen in the west, was connected with a chain which extended round to the north, and that there was higher land to the southward of Macculloch's range; the highest point being to the east, or east-north-east, beyond the hill discovered on the 21 instant. The horizon was lowest towards the west-south-west, for even in the south-west I could perceive a rise sufficient to confine the course of the river to the west-south-west. We proceeded nearly west by south over a soft bed of naked earth, across which, at one place, a well-beaten road of the natives led to the valley on the south and to some watercourse, if not to water itself. After 10 1/4 miles of weary travelling, we encamped on a bend of the Darling, in latitude 31 degrees 31 minutes 20 seconds South. The soil of the plains being extremely soft, uneven, and full of holes, the cattle were at length almost unable to get through their allotted journeys; I therefore determined to let them rest during the three following days while I proceeded to the hills beyond the Darling, in a west-north-west direction nearly, and distant from our camp 11 2/3 miles. VISIT A HILL BEYOND THE DARLING. June 26. I forded the Darling where the bottom was a hard clay; and I proceeded in a direction bearing 27 degrees north of west to the hill. There was much less of the soft soil on this bank, and at a mile from the ford we travelled on very firm clay, quite clear of vegetation, white, shining, and level as ice. At about seven miles from the river we reached the first rise of firm red earth. The vegetation upon it consisted of the two species of atriplex so very common on that soil, and more of the salsolae than I had before seen. This rise seemed to mark the extent of the bed of clay through which the Darling flows, at least as far as we had hitherto traced it. The country was open to about three miles from the summit where we passed through a scrub of stunted casuarinae, interspersed with a few of the acacia with spotted bark. Here we crossed some beds of conglomerate, consisting of grains and pebbles of quartz, cemented by a hard ferruginous matrix, probably decomposed felspar; and we saw soon after a few blocks of the same hard sandstone which occurs at Dunlop's range and other high points. VIEW FROM ITS SUMMIT.