In searching back through the successive stages of human civilisation we arrive at a period when both written history and traditions fail. This prehistoric period, up to the commencement of the present century, was entirely lost in the thick veil of darkness which surrounded everything pertaining to the past history of the globe. As, however, the truths of geology became gradually formulated into a science, and men's minds got accustomed to apply the new methods of research to the elucidation of the origin and history of the human race, the sphere of prehistoric archæology became equally well defined. The group of phenomena with which it attempts to grapple occupies a sort of neutral territory or borderland between geology and history proper, from both of which, however, it receives large nutrient offshoots. The essential element which characterises the science of prehistoric archæology is an inductive process which depends on the clearness and precision with which the most primitive remains of human art and industries can be identified. But these remains, of whatever materials they may be composed, are liable to the destructive influences of time, and, sooner or later, they become obliterated by disintegration or decomposition. Few compound substances, even in the inorganic kingdom, resist this law, and as for the elaborate productions of the organic kingdom, such as plants and animals, they are hardly ushered into being when a counter process of decay begins, which ends in reducing them to their simple constituents, so that, in a short time, not a trace of their former existence remains. In the midst of these ever-changing activities of life and death which modern scientists have irrefutably shown to have been continuously and progressively at work for countless ages, it may be fairly asked--What is the nature of the evidence by which antiquaries have so largely extended their field of inquiry and propounded such startling opinions regarding the origin and antiquity of our race? In their case the evidence is due to exceptional circumstances which tend to counteract or retard the gnawing tooth of time, and cheat, as it were, Dame Nature out of her ordinary results. Thus, if the handicraft products of reasoning man, or perishable organisms, such as the bodies of animals, be accidentally deposited in the mud of a sea, lake, or river, or suddenly buried in the ruins of a city, or sunk in a bed of growing peat, or become frozen up in a field of perpetual ice, these exceptional results are apt to follow. Hence, an object may be preserved for centuries after its congeners, in ordinary circumstances, have crumbled into dust; or, if ultimately it should become decomposed, a cast or mould may have been previously formed by means of which, ages afterwards, an intelligent observer will be enabled to determine its distinguishing characteristics. In arctic regions the carcasses of animals known to have been extinct for