6TH OCTOBER.--Thermometer, at 6 A. M., 48 deg.. Height above the sea, 696 feet. This day we hoped to rejoin the party at the camp of the Pyramids; but the journey was long, and it included an ascent of Mount Pluto, from which I had still to observe some important angles. I marked this bivouac, with 70 cut on a tree, the two last being, respectively marked, 71 and 72, as already stated; these numbers continuing the series from LXIX, my lowest camp on the Belyando. The scrub is thick about these volcanic ranges, but on the downs and plains of Central Australia, that impediment disappears. My men and myself were in rags from passing through these scrubs, and we rejoiced at the prospect of rejoining, this day, our countrymen at the Pyramids. I found a fine open forest between the ponds where we had formerly passed the night, and Mount Pluto; and we crossed several water-courses, the grass on their banks being green and young, because the old grass had been burnt off by the natives. These water-courses form the highest sources of the Salvator. We were at no very considerable elevation above the sea where we had slept (696 feet), yet we found the air on the mountains much cooler than that of the interior plains. There was much Callitris in the woods passed through this day; and the soil, although well covered with grass, was sandy. I ascended Mount Pluto by the N. W. side, where the loose fragments of trap, on a very steep slope, obstruct the growth of a thorny scrub, covering other parts of the mountain sides. The view from the summit was very favourable for my purpose, and I passed an hour and a half in taking angles on all distant points. Mount Owen and Mount Kilsyth were both visible; Buckland's Table-land in the East, and some of the recently discovered ranges in the west, were just visible across the trap-rock range, which connected Mount Playfair with Mount Hutton; which range almost shut out the view to the westward. In the S. W., some very remarkable features appeared to terminate westward, in abrupt cliffs over a low country, into which the Maran (as far as known), the Warrego, and the Nive, seem to carry their waters. What that country is, was a most interesting point, which I was very reluctant to leave still a mystery. No volcanic hills appeared to the westward of this trio, which thus seem to mark the place where the upheaving forces have most affected the interior structure of Australia. The temperature on Mount Pluto, at noon, was 90 deg.; and the elevation above the sea, 2420 feet.