Beyond Sir John Cox's plantations extends the unbroken "open forest," as the English call it, which can be crossed on horseback, and consists chiefly of the eucalyptus, acacias of various kinds, and the dark-leaved casuarinas. The next day, an excursion was made up the river Nepean, a tributary of the Hawkesbury, on which trip many valuable facts of natural history were obtained, Bougainville enriching his collection with canaries, waterfowl, and a very pretty species of kingfisher and cockatoos. In the neighbouring woods was heard the unpleasant cry of the lyre-pheasant and of two other birds, which feebly imitate the tinkling of a hand-bell and the jarring noise of the saw. These are not, however, the only feathered fowl remarkable for the peculiarity of their notes; we must also mention the "whistling-bird," the "knife-grinder," the "mocking-bird," the "coachman," which mimics the crack of the whip, and the "laughing jackass," with its continual bursts of laughter, which have a strange effect upon the nerves. Sir John Cox presented the commander with two specimens of the water-mole, also called the ornithorhynchus, a curious amphibious creature, the habits of which are still little known to European naturalists, many museums not possessing a single specimen. Another excursion was made in the Blue Mountains, where the famous "King's Table-land" was visited, from which a magnificent view was obtained. The explorers gained with great difficulty the top of an eminence, and an abyss of 1600 feet at once opened beneath them; a vast green carpet stretching away to a distance of some twenty miles, whilst on the right and left were the distorted sides of the mountain, which had been rudely rent asunder by some earthquake, the irregularities corresponding exactly with each other. Close at hand foams a roaring, rushing torrent, flinging itself in a series of cascades into the valley beneath, the whole passing under the name of "Apsley's Waterfall." This trip was succeeded by a kangaroo hunt in the cow-pastures with Mr. Macarthur, one of the chief promoters of the prosperity of New South Wales. Bougainville also turned his stay at Sydney to account by laying the foundation-stone of a monument to the memory of La Perouse. This cenotaph was erected in Botany Bay, upon the spot where the navigator had pitched his camp. [Illustration: "Apsley's Waterfall."] On September 21st the _Thetis_ and the _Esperance_ at last set sail; passing off Pitcairn Island, Easter Island, and Juan Fernandez, now a convict settlement for criminals from Chili, after having been occupied for a half-century by Spanish vine-growers.