It is little to be wondered at if all this rashness of speculation and carelessness in quotation should have produced a belief that the solution of the problem was impossible from any literary or historical data, or if consequently our modern antiquaries should have grasped with avidity at a scheme, first proposed by the Danes, which seemed at all events to place the question on a scientific basis. No country could well be more favourably situated for an enquiry of this sort than Denmark. It is rich in megalithic remains of all sorts. Its tumuli and tombs seem generally to have been undisturbed; and it was exceptionally fortunate in having a government with sufficient common sense to enact a law of treasure-trove, so just and, at the same time, so liberal as to prevent all metal articles from finding their way to the melting pot, and governors so intelligent as fully to appreciate the scientific value of these early remains. In consequence of all this, the museums at Copenhagen were soon filled with one of the richest collections of antiquities of this sort that was ever collected, and when brought together it was not difficult to perceive the leading features that connected them in one continuous sequence. First it appeared that there was an age extending into far prehistoric times, when men used only implements of stone and bone, and were ignorant of the use of any of the metals; then that an age had succeeded to this when the use of bronze was known, and also probably that of gold; and, lastly, that there was a third age, when iron had been introduced and had superseded the use of all other metals for weapons of war and utilitarian purposes. The Danish antiquaries were somewhat divided in opinion as to the exact period when bronze was first introduced, some carrying it back as far as 2000 B.C., others doubting whether it was known in Denmark more than 1000 or 1200 years B.C.; but all agreed that iron was introduced about the Christian era. Having satisfied themselves on these points, the Danish antiquaries proceeded at once to apply this system to the monuments of their country. Any tomb or tumulus which was devoid of any trace of metal was dated at once at least 1000, probably 2000, years before Christ, and might be 10,000, or 20,000 years old, or even still older. Any tomb containing bronze was at once set down as dating between the war of Troy and the Christian era; and if a trace of iron was detected, it was treated as subsequent to the last-named epoch, but still as anterior to the introduction of Christianity, which in Denmark dates about the year 1000 A.D.