The nature of the Mexican currency accords with the knowledge and experience of a people among whom metallurgic arts were of comparatively recent origin. The easily fused tin, and the attractive and accessible gold-dust, supplied ready materials for schooling the ingenious metallurgist in the use of the metals. Copper was probably first employed when found in a pure metallic state, as among the old miners of Lake Superior; while the art of fusing, taught by the Aztec Tubal-Cain, was tried only on the readily-yielding tin. By this means the arts of smelting and moulding the ores would be acquired, and applied to copper, silver, and gold, as well as to tin. Accident might suggest the next important stage, that of metallic alloys; but under the circumstances alike of Peruvian and Mexican civilisation, progressing in regions abounding with the most attractive and easily-wrought metals, it is not difficult to conceive of the independent discovery of the useful bronze alloy. Yet by the standard composition of their bronze, far more than by the ingenious intricacy of their personal ornaments, utensils, and architectural decorations, the actual progress of the Incas or of the Aztecs may fairly be tested. The delight of the savage in personal adornment precedes even the needful covering of his nakedness, and the same propensity long monopolises the whole inventive ingenuity of a semi-barbarous people; while the useful bronze tools embody the true germs of incipient civilisation. Tested by such a standard, the metallurgic arts of Peru furnish evidence of very partial development. The alloy of copper and tin, when destined for practical use in manufacture, is found to possess the most serviceable qualities when composed of about ninety per cent. of copper to ten of tin; and so near is the approximation to this theoretical standard among the bronze relics of the ancient world, that the archæologists of Europe have been divided in opinion as to whether they should assume a Phœnician or other common origin for the weapons, implements, and personal ornaments of that metal found over the whole continent; or that the mixed metal, derived from a common centre, was manufactured in various countries of Europe into the objects of diverse form and pattern abounding in their soil, or deposited among their sepulchral offerings.