July 28.—­The river during the night had risen upwards of eight feet; and still continued rising with surprising rapidity, running at the rate of from five to six miles per hour, bringing down with it great quantities of driftwood and other wreck.  The islands were all deeply covered, and the whole scene was peculiarly grand and interesting.  The sudden rise probably was caused by the heavy rains of the preceding days; but great must be the sources from whence so stupendous a body of water is supplied, and equally grand must be that reservoir, which is capable of containing such an accumulation of water as is derived from this and the Macquarie Rivers; not to mention the supplies from the occasional streams which had their sources in the marshes which we have crossed.  The water was so extremely thick and turbid, that we could not use it; but were forced to send back to the marshes for what we wanted.  At night, the river seemed at its greatest height.

July 29.—­The waters this day subsided rapidly.  It is evident that there has been no flood in the river for a very considerable period prior to the present one, there being no marks of wreck or rubbish on the trees or banks.  Now the quantity of matter is astonishing, and, such as must take some years to remove.  The rapid rise and fall in the water would seem to indicate that neither its source nor its embouchure can be at any great distance.  The former is probably not far east of Arbuthnot’s Range.

August 2.—­It was not until this morning that the river had fallen sufficiently to allow us to ford it.  Though the morning was unpromising with slight rain, it was not deemed prudent to lose a moment in passing it, while in our power; and by one o’clock every thing was safely over, to our great satisfaction.  Before this, it had begun to rain hard, and it continued to do so throughout the day, and great part of the night.  Our observations place this part of Castlereagh River in lat. 31. 14. 14.  S., long. 148. 18.  E., variation 8. 14.  E.

August 3.—­A dark cloudy morning.  At nine o’clock proceeded on our eastern course towards Arbuthnot’s Range.  The river had risen in the night so considerably, that had we delayed until this morning, we should have been unable to pass it.  The rain had rendered the ground so extremely soft and boggy, that we found it impossible to proceed above three-quarters of a mile on our eastern course.  We therefore returned, resolving to keep close to the river’s edge, until we should be enabled to sound the vein of quagmire, with which we appeared to be hemmed in.  In this attempt we were equally unfortunate, the horses falling repeatedly:  one rolled into the river, and it was with difficulty we saved him:  my baggage was on him, and was entirely spoiled; the chart case and charts were materially damaged, and our spare thermometer broken:  we therefore unladed the horses where they stood, and the men carried the provisions to a firmer spot, where