Old Captain Rocksalt informs us--and there is always wit, wisdom, and truth in the old man's stories--that he made voyages to Australia many times within the past thirty years, and having visited about all the sea-ports of the Continent, lived and almost died in Australia, his notes are worthy of attention. Capt. Cook discovered and named _Botany Bay_, the name originating from the fact that the land was covered with a luxurious growth of Botanical specimens. The Dutch discovered and named _Van Diemen's Land_. The English at once concluded to make Botany Bay a penal colony, and the first living freight of criminals and soldiers sent out, was some 700 in number, in 1788; but Capt. Phillip, the commander of the fleet, being dissatisfied with the looks of Botany Bay, hunted up a better place, and sailed to it. When Capt. Cook was cruising off there, one of his sailors, on the look out, cried, "Land ho!" Cook was over his wine and beef, in the cabin, and it took him some time to "tumble up" on deck. "Where the deuce is your land, eh?" bawls the old cruiser. "Larboard beam, sir!" responds the "lookout;" and, sure enough, a long, faint streak of land was visible from deck. The "lookout" announced a harbor, head-lands, &c.; but the rum old captain, not being able to see any such indication, with a chuckle, says he-- "You booby! harbor, eh? Ha, ha! well, we'll call it a port, you powder monkey--_Port Jackson!_" And faith, so the lookout, Jackson, became sponsor to the finest harbor in all Australia; for Capt. Phillip, upon rediscovering the harbor, took his fleet into it, and then and there began the now flourishing city of Sydney. Australia is an Island, lying opposite another--New Zealand. It is on the Indian Ocean, south side, while the east opens to the Pacific. Australia claims to contain a superficial area of over three million square miles, part desert, rather mountainous, and all being in one of the finest climates on the face of the earth. The air is dry, the soil light and sandy; the high winds stir up the dust and fine sand, and make ophthalmy the only positive ill peculiar to the country. Sheep-grazing, wool-growing, and boiling down sheep and cattle for tallow was the great business of the country from its earliest settlement up to 1851, when the _gold fever_ swept the land. Australia was inhabited by over 100,000 natives, black cannibals of the ugliest description; but at this day not a hundred of them remain. The natives were exceeding stupid and useless; the first settlers, who, as Capt. Rocksalt observes, were jail-birds and scape-gallows, were not very dainty in dealing with the obnoxious natives; so they determined to get rid of them as fast and easy as possible. For this purpose, they used to gather a horde of them together, and give them poisoned bread and rum, and so kill them off by hundreds. It was a sharp sort of _practice_, but the _ends_ seemed to justify the _means_.