Besides the violent or organic changes produced in a population by the invasion or colonisation of a foreign people which history marks, and the effects of which we can trace in the events recorded in the annals of the country, there is another silent and inorganic spread of one race over the territory of another, the eventual results of which are apparent enough, and the causes which led to it may be divined, but the steps of its progress are less easily marked. In the one, whole nations or tribes take possession of part or the whole of new districts; in the other, they spread not collectively but in families or groups. In the one, the inroad is effected by force or by direct convention. In the other, it is the result of natural causes arising from the contact of two races possessing different qualities and states of civilisation, and from the influence which the force of character of one people may exercise over another. Their influence, too, upon the spoken language and the place-names of the people presents itself in different aspects. In the one, the language of the invading people is established as the language of the country when the subject population has been exterminated or driven out, and the older place-names are either adopted into the language or changed at once. In the other, the silent and gradual inorganic colonisation changes by degrees the spoken language, but not the bulk of the place-names. The great natural features of the country usually retain the names imposed upon them by its original inhabitants, but those of the homesteads occupied by the colonising race assume the forms of their language, and those applicable to the dwellings of man only remain unchanged when the original people have lingered longer, or when the name is expressive of some common natural feature, which has been readily adopted as such by the intruders. Topography thus affords us some help in indicating the presence of the stranger, and marking the extent to which the race to which he belongs has spread over the country.