With the growing wants of men as they gathered into communities, novel arts were developed; and the demands of each new-felt want called into being means for its supply. Artificers in brass and iron multiplied, and the sites of the first cities of the earth were adorned with temples, palaces, sculptured marbles, and cunningly-wrought shrines. But whenever communities were broken up and scattered, the elements of an acquired civilisation were inevitably left behind. All but the most indispensable arts disappear during the process of migration; and although the wanderers might at length find a home in “a land whose stones are iron, and out of whose hills thou mayest dig brass,” no arts are so speedily lost among migratory tribes as those of metallurgy. The hold of the accumulated wisdom and experience of successive generations must be partial and uncertain among an unlettered people, dependent on tradition for all knowledge excepting such as is practically transmitted in the operations of daily experience. Few indeed of all the wanderers from the old centres of European civilisation to the wilds of the New World bring with them the slightest knowledge either of the science or the practice of metallurgy. Every chemical analyst knows what it is to receive pyrites for silver, and ochres for iron or gold. Even now the skill of the American miner has to be imported, and the copper-miners of Lake Superior are chiefly derived from Cornwall, Norway, or the mining districts of Germany. With all our many artificial wants so promptly supplied, even in the remotest colony, we are slow to perceive how much we owe to the wondrous appliances of modern civilisation, and its division of labour. The Dutchman exported his very bricks across the Atlantic, wherewith to found his New Amsterdam on the banks of the Hudson; and the English colonist, with enterprise enough to mine the copper and iron of Lake Superior, still seeks a market for the ores in England, and imports from thence both the engineers and the iron wherewith to bridge his St. Lawrence. With such facts before us in relation even to the systematic colonisation of a highly civilised and enterprising commercial nation, it is easy to understand what must have been the condition of the earth’s primeval wanderers. Their industrial arts were all to begin anew; and thus we see that the non-metallurgic condition of primitive social life which is designated its Stone Period, is not necessarily the earliest human period, but only the rudimentary state to which man had returned, and may return again, in the inevitable deterioration of a migratory era.