August 12.--Steering to the N. W. to a low range (the highest summit of which I named Mount North-west,) we just kept far enough in the plains to intercept the watercourses from the hills where they spread into the level country, and by this means we got excellent feed for our horses; generally the same rich succulent herbage I have mentioned before, occasionally mixed with wild oats. It was only in places of this description that we could expect to find anything for our horses. In the plains or on the hills there was not a blade of of anything green; at night we encamped upon a small dry channel with tolerable feed, but no water, and we again gave each horse three gallons from our kegs. The country we were traversing as yet under-went no alteration, the only difference being, that the hills were getting lower and the watercourses less numerous, and both apparently without water; the sand ridges came more in among the hills, and the dry beds of small salt lakes were often met with; the salsolae were more abundant, but the traces of natives were now less frequent; whilst those we fell in with seemed for the most part to have been left during the wet season. The rock formation still continued the same, quartz, ironstone, slate, and grey limestone, with saline crusts peeping above the ground in many places in the lower levels; the sky was cloudy and threatened rain, but none fell: our stage was 18 miles. August 13.--Continuing our course to the N. W. I took on the cart for 13 miles to a large dry channel, coming from the hills, upon which we halted for an hour or two to rest and feed the horses, as there were some sprinklings of grass around. We had now a change in the appearance of the country; the ironstone ranges seemed to decrease rapidly in elevation to the north, and the region around appeared more level, with many very singular looking table-topped elevations from 50 to 300 feet in height and with steep precipitous sides which were red, with the ironstone above, and white, with a substance like chalk, below. The country was covered with salsolae, and we passed the beds of many dried up salt lakes. Ascending the highest ridge near us, I found Lake Torrens was no longer visible, being shut out by the sandy ridges to the westward, whilst the low ironstone hills impeded our view to the north, and to the east. Having given our horses water, we buried twelve gallons against our return, and sending back the man with the cart, and extra horses, the native boy and I still pushed on to the N. W., taking a pack-horse to carry our provisions and a few quarts of water for ourselves.