The publication in 1848 of the first volume of the _Smithsonian Contributions to Knowledge_, devoted to the history and explorations of the ancient monuments of the Mississippi valley, gave a wonderful stimulus to archæological research in the United States. For a time, indeed, much credulous zeal was devoted to the search for buried cities, inscribed records, and the fancied recovery, in more or less modified form, in northern areas, of the civilisation of the Aztecs; not unmingled with dreams of Phœnician, Hebrew, Scandinavian, and Welsh remains. The history of some of its spurious productions is not without interest; but its true fruits are seen in numerous works which have since issued from the American press, devoted to an accurate record of local antiquities. So thoroughly has this already been carried out, that it may now be affirmed that, to all appearance, the condition of the Indian tribes to the north of Mexico, as shown in the rude arts of a Stone age, scarcely at all affected in its character by their use of the native copper of Lake Superior, represents what prevailed throughout the whole northern continent in all the centuries—however prolonged,—since the hunters in the Delaware valley fashioned and employed their turtle-back celts. The condition of the nations of North America at the period of its discovery, at the close of the fifteenth century, may be described as one of unstable equilibrium; and nothing in its archæological records points to an older period of any prolonged duration of settled progress. The physical geography of the continent presents in many respects such a contrast to that of Europe, as is seen in the steppes of Northern Asia, though with great navigable rivers, which only needed the appliances of modern civilisation to make them for the New World what the Euphrates and the Tigris were to Southern Asia, and the Nile to Africa, in ancient centuries. Those vast tablelands, the great steppes of Mongolia and Independent Tartary, have ever been the haunts of predatory tribes by whom the civilisation of Southern Asia has been repeatedly overthrown; and from the same barbarian hive came the Huns who ravaged the Roman world in its decline. Europe, on the contrary, nursed its youthful civilisation among detached communities of its southern peninsulas on the Mediterranean Sea; and in later ages has repeatedly experienced the advantages of geographical isolation in the valleys of the Alps, in Norway and Denmark, in Portugal, the Netherlands, and the British Islands: where nations protected in their youth from predatory hordes, and sheltered during critical periods of change, have safely passed through their earlier stages of progress.