The practical value of linguistic frontiers as national boundaries is due to their geographical growth. They are natural because they are the result of human intercourse based largely on economic needs. Having developed naturally, they correspond to national aspirations. Such being the case, the task of frontier delimitation can be made to assume a scientific form. Only in the case of uninhabited or sparsely populated regions will an artificial boundary--say, of the straight line type--prove adequate. But in tenanted portions of the earth’s surface where human wills and desires come into play the problem cannot be dismissed so lightly. The ordinary laws of science must then be applied. This, after all, merely implies drawing on the stock of common sense accumulated by the human race in the course of its development. The clear duty of statesmen engaged in a revision of boundaries is to put the varied interests at stake into harmony with the facts of nature as they are revealed by geography. This is possible because the science deals with the surface of the earth considered as the field of man’s activity. Its data can be drawn upon just as successfully as the engineer draws upon the energy of a waterfall or a ton of coal. Soundness and permanency of the labor of delimitation can thus be insured. The preceding remarks should not be considered as implying that a mountain, or a river, or even the sea are to be arbitrarily regarded as frontiers. Lines of water-parting deserve particular mention as having provided satisfactory national borders in history. But in boundaries each case should be treated upon its own merits. There was a time when, in Cowper’s words: Mountains interposed Make enemies of nations who had else Like kindred drops been mingled into one. And yet the passes of the Alps refute the poet’s statement. Their uniting function eventually overcame their estranging power. The easterly spread of French language over the Vosges concurs in the same trend of testimony. The imposing mass of the Urals is no more of a parting than are the Appalachians. To be pertinent, it will be necessary, in each instance, to consider the complex operations of natural laws and the process of fusing and building up of nationality brought about by their agency.