These simple observations in the hands of the Scandinavian scientists supplied the essential elements of a new system of classification, which has since become so familiar all over the world as the three ages of Stone, Bronze and Iron. Its adoption by Dr. Thomsen, in 1830, as the basis of arranging the prehistoric materials in the Museum of Northern Antiquities at Copenhagen, and, a few years later, in the Museums of Lund and Stockholm, marks the commencement of a new era in the history of prehistoric archæology. Other nations were not slow in following in the footsteps of the northern savants, and to such an extent was this new departure carried that for a time at least, all antiquarian objects were classified as belonging to one or other of the so-called ages, on the mere knowledge of their composition. So fascinating was the spell of this new doctrine, that it was some time before even experienced archæologists could see the fallacy of adhering rigidly to such a method of arranging objects; as if, the instant a bronze or an iron implement became known, the manufacture of its analogues in the inferior materials there and then ceased for ever. While, therefore, conceding that the chronological sequence of the three ages, as determined in Scandinavia, is generally correct, and holds good also for European countries, I consider it radically wrong to suppose that the respective epochs indicated by these successive stages of civilisation, especially in districts widely separated, are identical in point of time. Many local circumstances in a country, such as the poverty of the people, their isolation and distance from commercial highways, etc., have often so contributed to the persistency of customs and usages, elsewhere become obsolete and entirely superseded, that a chronological comparison of its progress in civilisation, as defined by the three ages, becomes perplexing, if not misleading, when applied to other countries. The question resolves itself, therefore, into this: that each well-defined archæological or geographical area must ascertain the chronological sequence and duration of these ages for itself.