May 12.--The fine weather still continues to favour us. The river rose in the course of the night upwards of a foot. It is a probable supposition that the natives, warned by experience of these dangerous flats, rather choose to seek a more precarious, but more safe subsistence in the mountainous and rocky ridges which are occasionally to be met with. The river and lagoons abound with fish and fowl, and it is scarcely reasonable to suppose that the natives would not avail themselves of such store of food, if the danger of procuring it did not counterbalance the advantages they might otherwise derive from such abundance. About three quarters of a mile farther westward we had to cross another small arm of the river, running to the northward, which although now full, is, I should think, dry when the river is at its usual level. It is probable that this and the one which we first crossed join each other a few miles farther to the westward, and then both united fall into the stream which gave them existence. We had scarcely proceeded a mile from the last branch, before it became evident that it would be impossible to advance farther in the direction in which we were travelling. The stream here overflowed both banks, and its course was lost among marshes: its channel not being distinguishable from the surrounding waters. Observing an eminence about half a mile from the south side, we crossed over the horses and baggage at a Place where the water was level with the banks, and which when within its usual channel did not exceed thirty or forty feet in width, its depth even now being only twelve feet. We ascended the hill, and had the mortification to perceive the termination of our research, at least down this branch of the river: the whole country from the west north-west round to north was either a complete marsh or lay under water, and this for a distance of twenty-five or thirty miles, in those directions; to the south and south-west the country appeared more elevated, but low marshy grounds lay between us and it, which rendered it impossible for us to proceed thither from our present situation. I therefore determined to return back to the place where the two branches of the principal river separated, and follow the south-west branch as far as it should be navigable; our fears were however stronger than our hopes, lest it would end in a similar manner to the one we had already traced, until it became no longer navigable for boats.