(1) One might suppose that for what has taken place during the historical period, the documentary records would be all sufficient. But as it is only recently that the subject has been determined to be worthy of the historian's serious attention, we cannot look for much light to be thrown upon it in the pages of the ordinary histories. Still less need we expect to meet with any full measure of information regarding it in the original documents from which such histories have been mostly compiled. In truth, the facts of which we are in search must be gleaned from brief allusions and implications rather than from actual descriptions. It was no part of the duty of an old chronicler purposely to record any natural fact, short of some terrific earthquake or storm that destroyed human life and damaged human property. But in describing historical events he could hardly avoid reference to woods, lakes, marshes, and other natural features which served as boundaries to the theatre of these events. By comparing, therefore, his local topography with the present aspect of the same localities, we may glean some interesting particulars as to changes of landscape in the course of centuries. Such a comparison, however, to be effective and trustworthy, involves two special qualifications. The inquirer must be master of the language and style of the author he is studying, and he must be completely familiar with the present condition of the ground to which allusion is made. The want of this combination of knowledge has led to some curious blunders on the part of able scholars.