4TH APRIL.--We were now to proceed along the right bank of the Culgoa upwards to the United Balonne, and thence to continue ascending along the right bank of that river also, as far as the direction was favourable to our progress northward. This remained to be ascertained in exploring that river upwards. In gaining the right bank of the Culgoa, we had crossed the vast basin of clay extending from the Bogan on the south, to this river on the north, and westward to New Year's Range and Fort Bourke. That country was liable to be rendered quite impassable, had the rains set in. But even in such seasons we could still travel over the dry, firm ground bounding this basin of clay on the northward, as the left bank of the Bogan was also passable, however rainy the season, indeed more conveniently then than during a dry one. Rain, if it had fallen at this time, had greatly facilitated our exploration of the northern interior; but these rivers we had reached would supply us with water for some degrees to the northward, as I had been informed by the Commissioner of the district, and in our progress so far, I hoped we should arrive at a better watered country. Taking a northerly course, we traversed fine grassy land, on which grew luxuriantly the ACACIA PENDULA and other shrubs, that reminded us of the banks of the Bogan, to which country we found here the exact counterpart, only that this was better watered. The course of the Culgoa was more easterly than I had calculated on, for, after going six miles northward, I had to travel at least as many eastward before I again found the river. We encamped on the acute north-western angle of an anabranch biting into the firm soil, and it was evident that we had reached the Balonne Major, or that part above the separation of the Culgoa from the Minor Balonne, both of which we had already crossed, and which ran thus, as from our camp the lines of trees along each of the minor channels were distinctly visible. The character of these rivers had been described to me by Commissioner Mitchell, the discoverer thereof. It was late before the drays came in, and Mr. Kennedy was led into the camp quite blind, having been suddenly attacked with purulent ophthalmia, when engaged in the survey of our route, about four miles from the camp. The heat had somewhat abated, but still this complaint, which we had attributed to it, had lately affected many of the party suddenly, as in the case of Mr. Kennedy. Latitude, 28 deg. 27' 11" S. Thermometer at sunrise, 33 deg.; at noon, 83 deg.; at 4 P.M., 88 deg.; at 9, 53 deg.; with wet bulb, 47 deg..