The celebrated Raban Maur, of Mayence, composed in the ninth century a treatise, entitled _De Universo_, divided into twenty-two books. It is a kind of encyclopaedia, in which he gives an abridged view of all the sciences. According to his cosmographic system the earth is in the form of a wheel, and is placed in the middle of the universe, being surrounded by the ocean; on the north it is bounded by the Caucasus, which he supposes to be mountains of gold, which no one can reach because of dragons, and griffins, and men of monstrous shape that dwell there. He also places Jerusalem in the centre of the earth. The treatise of Honorus, entitled _Imago Mundi_, and many other authors of the same kind, represent, 1st, the terrestrial paradise in the most easterly portion of the world, in a locality inaccessible to man; 2nd, the four rivers which had their sources in Paradise; 3rd, the torrid zone, uninhabited; 4th, fantastic islands, transformed from the Atlantis into _Antillia_. [Illustration: FIG 44.--EIGHTH CENTURY MAP OF THE WORLD.] In a manuscript commentary on the Apocalypse, which is in the library of Turin, is a very curious chart, referred to the tenth, but belonging possibly to the eighth century. It represents the earth as a circular planisphere. The four sides of the earth are each accompanied by a figure of a wind, as a horse on a bellows, from which air is poured out, as well as from a shell in his mouth. Above, or to the east, are Adam, and Eve with the serpent. To their right is Asia with two very elevated mountains--Cappadocia and Caucasus. From thence comes the river _Eusis_, and the sea into which it falls forms an arm of the ocean which surrounds the earth. This arm joins the Mediterranean, and separates Europe from Asia. Towards the middle is Jerusalem, with two curious arms of the sea running past it; while to the south there is a long and straight sea in an east and west direction. The various islands of the Mediterranean are put in a square patch, and Rome, France, and Germany are indicated, while Thula, Britannia, and Scotia are marked as islands in the north-west of the ocean that surrounds the whole world. [Illustration: FIG. 45.--TENTH CENTURY MAPS.] We figure below two very curious maps of the world of the tenth century--one of which is round, the other square. The first is divided into three triangles; that of the east, or Asia, is marked with the name of _Shem_; that of the north, or Europe, with that of _Japhet_; that of the south, or Africa, with that of _Cham_. The second is also divided between the three sons of Noah; the ocean surrounds it, the Mediterranean forms the upright portion of a cross of water which divides the Adamic world.