running in a specified direction or for a certain distance, or as the arc of a circle, or as the tangent to a circle, are very familiar features in African treaties, where use has to be made of visible features or landmarks. But they are a fruitful source of error or misunderstanding, both in terminology and topography. For instance, the Alaskan dispute between Canada and the United States turned upon the meaning of the ambiguous words 'a line parallel to the windings of the coast which shall never exceed the distance of ten marine leagues therefrom'. What was the coast referred to, and what was the practicability or meaning of a line that scaled inaccessible peaks and was lost amid ice and eternal snow?
I have now passed in review the various forms of Frontiers either furnished by nature or created by man, and have endeavoured to indicate their degrees of strength or weakness. In practice the tendency of mankind has been to ignore or override nature, and in the case of older States to adopt racial or linguistic or purely political lines of division, in the case of the partition of new countries to adopt the temporary or conditional expedients which have been described. In North America few of the internal boundaries correspond to any natural feature. In South America where, owing to the configuration and history of the country, natural boundaries are commoner, there is scarcely an undisputed Frontier. In Europe, apart from certain ranges of mountains, (but few rivers), which being genuine barriers have exercised a permanent influence upon the formation of States and the distribution of men, the boundaries of the majority of States are purely political, and find their origin in the events of history; although geographical conditions,
