This acquisition was made in the year 1803, and within four years of this period, three exploratory expeditions were sent out by the United States. The principal object of the first, which was under the direction of Major Pike, was to trace the Mississippi to its source, and to ascertain the direction of the Arkansa and Red Rivers, further to the west. In the course of this journey, an immense chain of mountains, called the Rocky Mountains, was approached, which appeared to be a continuation of the Andes. The ulterior grand object, however, of this expedition was not obtained, in consequence of the Spaniards compelling Major Pike to desist and return. A second attempt was made, by another party, but the Spaniards stopped them likewise. In the years 1804, 5, and 6, Captains Lewis and Clarke explored the Missouri to its source, crossed the Rocky Mountains, and proceeding towards the North Pacific Ocean, ascertained, the origin and course of the River Columbia.
In the years 1819 and 1820, several persons, well qualified for the undertaking by their science, spirit, and enterprize, accompanied by riflemen, hunters, and assistants, were sent out by the government of the United States, for the purpose of gaining a more full and accurate knowledge of the chain of the Rocky Mountains, and of the rivers, winch, rising there, flowed into the Mississippi. After passing through a great extent and variety of country, and gaining some curious information respecting various Indian tribes, especially of those who inhabit the upper course of the Missouri, they reached the Mountains: these and the adjacent districts they carefully examined. They next separated, one party going towards the Red River, and the other descending the Arkansa. The former party were misled and misinformed by the Indians, so that they mistook and followed the Canadian River, instead of the Red River, till it joined the Arkansa. They were, however, too exhausted to remedy their error. The latter party were more successful.
The great outline of the coast, as well as of the greater portion of the vast continent of America, is now filled up. In the northernmost parts of North America, the efforts of the British government to find a north-west passage, the spreading of the population of Canada, and the increasing importance of the fur trade, bid fair to add the details of this portion; the spread of the population of the United States towards the west, will as necessarily give the details of the middle portion; while, with respect to the most southern portions of North America, and the whole of South America, with the exception of the cold, bleak, and barren territory of Patagonia, the changes which have taken place, and are still in operation, in the political state of the Spanish and Portuguese provinces, must soon fill up the little that has been left unaccomplished by Humboldt, &c.
What portions, then, of Asia, America, and Africa, are still unknown?--and what comparison, in point of extent and importance, do they bear to what was known to the ancients? In Asia, the interior of the vast kingdom of China is very imperfectly known, as well as Daouria and other districts on the confines of the Chinese and Russian empires; central Asia in general, and all that extensive, populous, and fertile region which extends from the southern part of Malaya, nearly under the equator, in a northerly direction, to the fortieth degree of latitude, are still not explored, or but very partially so, by European travellers. This region comprehends Aracan, Ava, Pegu, Siam, Tsiompa, and Cambodia. The south and east coasts of Arabia still require to be more minutely and accurately surveyed. In the eastern archipelago, Borneo, Celebes, and Papua, are scarcely known. Though all these bear but a small proportion to the vast extent of Asia, yet some of them, especially the country to the north of the Malay peninsula, and the islands in the eastern archipelago, may justly be regarded as not inferior, in that importance which natural riches bestows, to any part of this quarter of the globe.
Still, however, we possess some general notice, and some vague reports of all these countries; but it is otherwise with respect to the unknown portions of Africa. The whole of this quarter of the world, from the Niger to the confines of the British settlement at the Cape of Good Hope, may, with little limitation, be considered as unknown. Travellers have indeed penetrated a short distance from the western coast into the interior, in some parts between the latitude of the Niger and the latitude of the extreme northern boundary of the Cape settlement: and a very little is known respecting some small portions of the districts closely adjoining to the eastern coast; but the whole of central Africa is still unexplored, and presents difficulties and dangers which it is apprehended will not be speedily or easily overcome. To the north of the Niger lies the Sahara, or Great Desert; of this, probably, sufficient is known to convince us that its extent is such, that no country that would repay a traveller for his fatigue and risk, is situated to the north of it. To the east of the Niger, however, or rather along its course, and to the north of its course, as it flows to the east, much remains to be explored; many geographical details have been indeed gathered from the Mahomedan merchants of this part of Africa, but these cannot entirely be trusted. The course and termination of the Niger itself is still an unsolved problem.
Captain Scoresby, a most intelligent and active captain in the whale fishery trade, has very lately succeeded in reaching the eastern coasts of Greenland, and is disposed to think that the descendants of the Danish colonists, of whose existence nothing is known since this coast was blocked, up by ice at the beginning of the fifteenth century, still inhabit it. The northern shores of Greenland, and its extent in this direction are still unknown.
Notwithstanding the zeal and success with which the government of the United States prosecute their discoveries to the west of the Mississippi, there is still much unexplored country between that river and the Pacific Ocean. It is possible that lands may lie within the antartic circle, of which we have hitherto as little notion as we had of South Shetland ten years ago; but if there are such, they must be most barren and inhospitable. It is possible also, that, notwithstanding the care and attention with which the great Pacific has been so repeatedly swept, there may yet be islands in it undiscovered; but these, however fertile from soil and climate, must be mere specks in the ocean.
But though comparatively little of the surface of the globe is now utterly unknown, yet even of those countries with which we are best acquainted, much remains to be ascertained, before the geography of them can justly be regarded as complete. Perhaps we are much less deficient and inaccurate in our knowledge of the natural history of the globe, than in its geography, strictly so called; that is, in the extent, direction, latitudes and longitudes, direction and elevation of mountains, rise, course, and termination of rivers, &c. How grossly erroneous geography was till very lately, in some even of its most elementary parts, and those, too, in relation to what ought to have been the most accurately known portion of Europe, may be judged from these two facts,--that till near the close of the last century, the distance from the South Foreland, in Kent, to the Land's End, was laid down in all the maps of England nearly half a degree greater than it actually is; and that, as we have formerly noticed, "the length of the Mediterranean was estimated by the longitudes of Ptolemy till the eighteenth century, and that it was curtailed of nearly twenty-five degrees by observation, no farther back than the reign of Louis XIV."
To speak in a loose and general manner, the Romans, at the height of their conquests, power, and geographical knowledge, were probably acquainted with a part of the globe about equal in extent to that of which we are still ignorant; but their empire embraced a fairer and more valuable portion than we can expect to find in those countries which remain to reward the enterprise of European travellers. The fertile regions and the beautiful climate of the south of Europe, of the north of Africa, and above all of Asia Minor, present a picture which we can hardly expect will be approached, certainly will not be surpassed, under the burning heats of central Africa, or even the more mitigated heats of the farther peninsula of India. The short and easy access of all portions of the Roman Empire to the ocean, gave them advantages which must be denied to the hitherto unexplored districts in the interior of Asia and Africa. The farther peninsula of India is infinitely better situated in this respect.
At that very remote period, when sacred and profane history first displays the situation, and narrates the transactions of the human race, the countries, few in number, and comparatively of small extent, that were washed by the waters of the Mediterranean, comprised the whole of the earth which was then known. Asia Minor, which possessed the advantage of lying not only on this sea, but also on the Euxine, and which is moreover level in its surface, and fertile in its soil, seems to have been the first additional portion of the earth that became thoroughly known. The commercial enterprize of the Phoenicians, and their colonists the Carthaginians,--the conquests of Alexander the Great, and of the Romans, gradually extended the knowledge of the earth in all directions, but principally in the middle regions of Europe, in the north of Africa, and in Asia towards the Indus. At the period when the Roman empire was destroyed, little more was known; and during the middle ages, geography was feebly assisted and extended by a desire to possess the luxuries of the East, (which seems to have been as powerful and general with the conquerors of the Romans as with the Romans themselves,) by the religious zeal of a few priests, and by the zeal for knowledge which actuated a still smaller number of travellers.