The other tumuli examined by this indefatigable explorer either contained objects generally of the same class or nothing that was of interest as marking their age. If his other works, or those of others, were abstracted in the same way, numerous examples of the same sort might be adduced. The above, however, are probably sufficient to show how little reliance can be placed on the hard and fast distinction between the flint, bronze, and iron ages which have hitherto been supposed to govern every determination of age in this science. If in a hundred short pages of one man's work so many instances of overlapping, and, indeed, of reversal of the usual order of things, can be found, it is easy to understand how many might be added if other works were also examined. All, however, that is wanted here is to show that the Danish system is neither perfect nor final, and that we must look for some other means of ascertaining the age of these monuments if we are to come to a satisfactory conclusion regarding them. The fact is that, though a tomb containing only stone and bone implements may be 10,000 or 20,000 years old, unless it can also be shown that stone and bone were no longer used after the Christian era, it may also be as modern, or more so, than that epoch. Unless, also, it can be proved that stone implements were never used after iron was introduced, or that bronze was never employed down to a late period, this system is of no avail; and after the examples just quoted from the Bateman diggings, it seems the merest empiricism to assume that the use of each class of implements ceased on the introduction of another; and till it can be shown at what date their use did really cease, any argument based on their presence is of very little value. This, however, is a task to which no antiquary has yet applied himself; all have been content to fix the age of the monuments from the assumed age of their contents, empirically determined. It is a far more difficult task, however, to ascertain the age of the contents from that of the monument in which they are found; it is a task that requires an investigation into the history and circumstances of each particular example. With the scant materials that exist, this is by no means easy; but as it seems the only mode by which truth can be arrived at, it is the task to which we propose to devote the following pages; should it prove impossible, we may indeed despair.