But it seems equally extraordinary, that even the only two expeditions which within our time have added largely to our knowledge, alike should have neglected the most obvious and almost the only useful means of discovery. The especial object of exploration must be, to ascertain the existence of considerable rivers pouring into the sea, because it is only thus that the government can effectively form settlements. The especial difficulty of the explorers is, to find provisions, or carry the means of subsistence along with them. Both difficulties would be obviated by the steam-boat, and by nothing else. The natural process, therefore, would be, to embark the expedition in a well appointed and well provisioned steamer; to anchor it at the necessary distance from the coast, which in general has deep and sheltered water, within the great rocky ridge; and then send out the explorers for fifty or a hundred miles north and south, making the steamer the headquarters. Thus they might ascertain every feature of the coast, inch by inch, be secure of subsistence, and be free from native hostility. Yet all the expeditions have been overland, generally with the most imminent hazard of being starved, and occasionally losing some of their number by attacks from the natives. Thus also the present expedition of the surveyor succeeded but in part, though it had the merit of discovering that the reports of Australian barrenness belonged but to narrow tracts, while the general character of the country towards the north was of striking fertility. The purpose of Sir T. Mitchell's late expedition was, to ascertain the probability of a route from Sydney to the Gulf of Carpentaria. But as this route was to be made dependent on a presumed river flowing into the gulf, the actual object was to reach the head of that river--an object which could have been more effectually attained by tracing it upward from the gulf; and, in consequence of not so tracing it, the expedition ultimately failed. To establish an easy connexion between the colony of New South Wales and the traffic of the Indian Ocean had long been a matter of great interest. Torres Strait, the only channel to the north, is a remarkably dangerous navigation; while, by forming an overland communication directly with the Gulf of Carpentaria to the west of the strait, the commerce would find an open sea. A trade in horses had also commenced with India, which was impeded by the hazards of the strait. There had also been a steam communication with England by Singapore, and there was a hope that this line might be connected with a line from the gulf. The idea of tracing a river towards the north was a conjecture of several years' standing, in some degree founded on the natural probability that an immense indentation of the land could not but exhibit some outlet for the course of a considerable fall of waters, and also that there had been a report by a Bushman, of having followed its course to the sea.