The lowlands, which make up far the larger part of the country, are covered with soil which furnishes rich farming areas, though in many places this soil is a heavy and impervious clay, expensive to drain and cultivate. The hard ridges are covered with thin soil only. Many of them therefore remained for a long time covered with forest, and they are devoted even yet to grazing or to occasional cultivation only. The abundance of harbors and rivers, navigable at least to the small vessels of the Middle Ages, has made a seafaring life natural to a large number of the people, and commercial intercourse comparatively easy with all parts of the country bordering on the coast or on these rivers. Thus, to sum up these geographical characteristics, the insular situation of England, her location on the earth's surface, and the variety of her material endowments gave her a tolerably well-balanced if somewhat backward economic position during the Middle Ages, and have enabled her since the fifteenth century to pass through a continuous and rapid development, until she has obtained within the nineteenth century, for the time at least, a distinct economic precedency among the nations of the world. *2. Prehistoric Britain.*--The materials from which to construct a knowledge of the history of mankind before the time of written records are few and unsatisfactory. They consist for the most part of the remains of dwelling-places, fortifications, and roadways; of weapons, implements, and ornaments lost or abandoned at the time; of burial places and their contents; and of such physical characteristics of later populations as have survived from an early period. Centuries of human habitation of Britain passed away, leaving only such scanty remains and the obscure and doubtful knowledge that can be drawn from them. Through this period, however, successive races seem to have invaded and settled the country, combining with their predecessors, or living alongside of them, or in some cases, perhaps, exterminating them.