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 they were reladen. We again proceeded easterly, and for upwards of a mile we travelled up to our knees in water and mud: the horses were here stopped by running waters from the marshes, encircling a spot of comparatively dry ground; they were again unladen, and with the utmost difficulty we got every thing safe over. Both men and horses were so much exhausted by the constant labour they had undergone, that I determined to halt, in order to restore our baggage to some order. Our ardent hopes are fixed upon the high lands of Arbuthnot's Range, which I estimate to be about twenty miles off. The intermediate country, we fear, will be one continued morass.
August 4.—Proceeded on our journey. In the seven miles and a half which we accomplished to-day, the water and bog were pretty equally divided; and a plain covered with the former was a great relief both to men and horses, since an apparently dry brush, or forest, was found a certain forerunner of quicksands and bogs. The natives appear pretty numerous: one was very daring, maintaining his ground at a distance armed with a formidable jagged spear and club, which he kept beating against each other, making the most singular gestures and noises that can be imagined: he followed us upwards of a mile, when he left us, joining several companions to the right of us. Emus and kangaroos abound, and there is a great diversity of birds, some of which have the most delightful notes, particularly the thrush.
August 5.—At three o'clock we were obliged to give up all attempts to proceed farther this day; it was with the utmost difficulty we accomplished six miles: for the last half mile, the horses were not on their legs for twenty yards together. This, too, was in the middle of an apparently dry forest of iron bark and cypress trees: the surface gave way but little to the human tread, but the horses were scarcely on it before the water sprang at every step, and the ground sank with them to their girths. In this dilemma, it was agreed to rest for the night, and in the morning endeavour to proceed to the nearest hill, which appeared to be distant about two miles and a half, with very light loads upon the best track we could find, and then return for the remainder of the baggage and stores. A foreknowledge of the difficulties we should have to encounter would certainly have prevented me from attempting to reach these mountains; the nature of this country baffles all reasonable expectation and conjecture, and that which appears one thing at a distance, has a quite different form and aspect when more nearly approached. Neither rivers, brushes, nor marshes, seem to make the least difference in the vegetation of this singular tract: a dreary uniformity pervades alike its geology and its botany.
August 6.—At eight o'clock the horses set forward with half the baggage; with considerable difficulty they at length reached the hill, and were immediately sent back for the remainder of the stores. The hill was about three miles from our camp, and from it a view of Arbuthnot's Range was obtained, distant nine or ten miles: its elevated points were extremely lofty, and of a dark, barren, and gloomy appearance; the rocks were of a dark grey, approaching to black, and from their crevices, a few stunted trees protruded themselves. It was half past three o'clock before every thing was removed to the foot of the hill, when it was much too late to think of proceeding, anxious as we were to arrive at the main range itself. We killed this day one of the largest kangaroos we had seen in any part of New South Wales, being from one hundred and fifty to one hundred and eighty pounds weight. These animals live in flocks like sheep; and I do not exaggerate, when I say that some hundreds were seen in the vicinity of this hill; it was consequently named Kangaroo Hill: several beautiful little rills of water have their source in it, but are soon lost in the immeasurable morass at its base.
August 7.—About a mile from Kangaroo Hill, after crossing a marshy plain, we came to a limestone rock, spreading in smaller pieces over a low hill. It is somewhat remarkable, that this stone should again be found precisely under the same meridian as seen on the Lachlan and Macquarie Rivers: the same stratum appears to have run from south to north, upwards of two hundred miles. This hill is certainly its northern termination, since beyond it the low and marshy plains of the interior commence. At one o'clock we arrived under the hill which Mr. Evans had previously ascended: at this spot I intended to remain a couple of days, as well to refresh the horses, as for the purpose of ascending Mount Exmouth, from whence I promised myself an extensive view of the country over which our intended route lay. On ascending the hill before mentioned, I was surprised with the remarkable effect which the situation appeared to have on the compass. The station I had chosen was the highest part, and nearly the centre of the hill; placing the compass on the rock before me, the card flew round with extreme velocity, and then suddenly settled at opposite points, the north point becoming the south. Astonished at such a phenomenon, I made the following observations. The compass on the rock, Mount Exmouth, bore S. 60. W. (its true bearing being N. 75. E.), and on raising it gradually to the eye, the card was violently agitated, and the same point now bore N. 67. E. About one hundred yards farther south, the compass was again placed on the rock; the effect on the compass was very different, Mount Exmouth bore E. 48. S., and the tent in the valley beneath S. 74. W. The card on raising the compass was rather less agitated than before, and from the eye, Mount Exmouth bore N. 77. E., and the tent S. 15. W., the true bearing of the latter being S. 13 1/2. W. Thus the magnetic fluid seemed on this spot to have less influence on the needle, than on the spot where its power was first observed; and at a short distance from the base of the hill the needle regained its natural position. The rocks, when broken, were of a dark iron grey: they did not appear to contain any iron, for when tried at the tent, the magnet had no power over them. I could not discern any regular stratum of rock, the hill being covered with large detached stones, many of which formed figures of five and six sides: the evening was too far advanced to permit any farther observations to be made. [Note: The island of Cannay, one of the Hebrides, affects the needle in a nearly similar manner. A rock in it is named The Loadstone Rock.] Observed the variation of the needle by azimuth, to be 6. 22. E.
August 8.—We set off early this morning to ascend Mount Exmouth, distant four or five miles: at its base we crossed a pretty stream of water, having its source in the Mount; it took us nearly two hours of hard labour to ascend its rugged summits: we were however amply gratified for our trouble by the extensive prospect we had of the surrounding country. Directing our view to the west, Mount Harris and Mount Forster, whose elevations do not exceed from two to three hundred feet, were distinctly seen at a distance of eighty-nine miles. These two spots excepted, from the south to the north it was a vast level, resembling the ocean in extent and appearance. From east-north-east to south, the country was broken and irregular; lofty hills arising from the midst of lesser elevations, their summits crowned with perpendicular rocks, in every variety of shape and form that the wildest imagination could paint. To this grand and picturesque scenery, Mount Exmouth presented a perpendicular front of at least one thousand feet high, when its descent became more gradual to its base in the valley beneath, its total elevation being little less than three thousand feet. To the north-east commencing at N. 33. E., and extending to N. 51. E., a lofty and magnificent range of hills was seen lifting their blue heads above the horizon. This range was honoured with the name of the Earl of Hardwicke, and was distant on a medium from one hundred to one hundred and twenty miles: its highest elevations were named respectively Mount Apsley, and Mount Shirley. The country between Mount Exmouth and this bounding range was broken into rugged hills, and apparently deep valleys, and several minor ranges of hills also appeared. The high lands from the east and south-east gradually lessened to the north-west, when they were lost in the immense levels, which bound the interior abyss of this singular country; the gulf in which both water and mountain seem to be as nothing. Mount Exmouth seems principally composed of iron-stone; and some of the richest ore I had yet seen was found upon it. On its sides were many different stones; but its perpendicular cliffs were of a dark bluish grey colour, shining when broken, very heavy, and close grained. Mount Harris, and Mount Exmouth, are composed of distinct materials, and in their formation bear not the slightest resemblance to each other; the granite of the former being more allied to the hills to the south-south-east of it, from which however it is distant at least one hundred miles, a perfect level filling up the intermediate space. Many new, and otherwise interesting subjects of the indigenous botany were discovered on the hills: among which were a species of persoonia, not previously observed, some xanthorrhaeae or grass trees, and two or three coast plants. The heteromorphous sterculia of the interior, and some species of eucalyptus of very stunted growth covered its sides, which however for a considerable distance were not deficient in grass. Sandstone was found in large masses in the rivulet at its base, with pebbles of various colours, and of species none of which was found on the mount itself. It was near four o'clock before we returned to the tent, highly gratified with our excursion.
August 9.—In the course of the day, I again ascended Loadstone Hill, and repeated the experiments made on Friday, with the same results. Several different stations on the summit were tried, and the needle was variously affected; the spot where the phenomenon was first observed seemed to have the greatest effect on the needle. A common sewing needle was strongly rubbed with a magnet, and balanced on the point of the rock, when it was much agitated, and the point flew round from the north to the south. The needle of the circumferenter, taken out of the box, was affected in a similar manner, only that when balanced on the rock, the fluid did not possess sufficient power to turn the point more than one point of the circle instead of quite round, as when balanced in the compass box. A compound magnet was laid on the rock, and applied to it in different ways, but it did not seem in any manner affected by the power which had so surprised us with its effect on the compass. The weather within the last week has become perceptibly warmer: the thermometer being seldom under 70 degrees at noon. The fires of the natives were seen at no great distance from us; and they seem to attend upon our motions pretty closely. The observations made here placed us in lat. 31. 13. S., long. 148. 41. 30. E., and I estimate the mean variation to be about 7 1/2 easterly. We found that no reliance could be placed on bearings taken with the compass on heights in this vicinity, and I am fearful that the bearings taken from Mount Exmouth will require verification, a difference of 4 degrees being observed in some, when compared with other bearings, which could not be supposed to be affected by the magnetic fluid.