Mr. Gosse had been here from the Gill's Range of my former expedition, and must have crossed the extremity of Lake Amadeus. He named this Ayers' Rock. Its appearance and outline is most imposing, for it is simply a mammoth monolith that rises out of the sandy desert soil around, and stands with a perpendicular and totally inaccessible face at all points, except one slope near the north-west end, and that at least is but a precarious climbing ground to a height of more than 1100 feet. Down its furrowed and corrugated sides the trickling of water for untold ages has descended in times of rain, and for long periods after, until the drainage ceased, into sandy basins at its feet. The dimensions of this vast slab are over two miles long, over one mile through, and nearly a quarter of a mile high. The great difference between it and Mount Olga is in the rock formation, for this is one solid granite stone, and is part and parcel of the original rock, which, having been formed after its state of fusion in the beginning, has there remained, while the aged Mount Olga has been thrown up subsequently from below. Mount Olga is the more wonderful and grotesque; Mount Ayers the more ancient and sublime. There is permanent water here, but, unlike the Mount Olga springs, it lies all in standing pools. There is excellent grazing ground around this rock, though now the grass is very dry. It might almost be said of this, as of the Pyramids or the Sphinx, round the decay of that colossal rock, boundless and bare, the lone and level sands stretch far away. This certainly was a fine place for a camp. The water was icy cold; a plunge into its sunless deeps was a frigid tonic that, further west in the summer heats, would have been almost paradisiacal, while now it was almost a penalty. The hill or range further east seems farther away now than it did from Mount Olga. It is flat on the summit, and no doubt is the same high and flat-topped mount I saw from the Sentinel in August last. We are encamped in the roomy cave, for we find it much warmer than in the outer atmosphere, warmth being as great a consideration now, as shade had formerly been.