In Asia, the later hypsometrical observations have shown that the lowlands are by no means so extensive as they were formerly supposed. The highland extends, according to von Middendorf, much farther northeast of the Yenisei, toward the northern limit of Siberia and Tschatschi, than was formerly supposed; and the Siberian plain extending westward to the Ural Mountains is narrowed down from 4,079,970 to 2,233,800 square miles. Yet this lowland comprises, including central Bokhara or Toorkistan, 1,051,200 square miles, and other low Asiatic plains 1,314,000, the enormous area of 4,599,000, or more than twice the extent of Europe, leaving 9,636,000 square miles for the highlands. In Africa there are almost no lowlands to speak of, excepting the districts around the mouths of the great rivers indicated a few pages back. To all equatorial Africa this physical feature is entirely wanting. In the north, where the whole Sahara was formerly thought to be one vast low plain, there are now known to be the moderate plateaus already indicated. The area of true lowland is, therefore, sensibly diminished. Vogel’s barometrical observations have already shown us that the country around Lake Tchad is about 1200 feet above the sea; the surface of Lake Tchad is 850 feet above the ocean level, and the lower limit of that region does not, therefore, come within the range already set as the point where lowlands become highlands. In Australia the lowland seems to be the prevailing physical form, although here and there exceptions to it occur. In Europe there are three great lowland plains to be specially mentioned. The greatest, that of middle Europe, embraces the shores of the North Sea and the Baltic far inland, and extend the farthest to the southeast. A second, hardly of less extensive proportions, comprises all northern Russia as far as the White Sea and the Arctic. It embraces but one-third of the great polar plain, and is really one with the region beyond the Ural chain. The third is the region around the Black and Caspian Seas. The Middle European Lowlands. The Germanic-Sarmatia-Russian plain extends, without a break, from the mouths of the Rhine, through all central Europe, to the middle Volga and the Ural. It is pre-eminently a region of lowlands, without any elevations of importance, and having no change of level, except very gently undulating swells, and on the north and south margin plateaus which very seldom rise over 500 feet. It begins with the deltas of the Rhine and the Scheldt, in Holland, passes through Lower Westphalia, Lower Saxony, the Marks, Lower Silesia, Lower Gallicia, and Poland, as far as the upper Dnieper and the middle Volga. It extends up the Rhine as far as Strasbourg, 474 feet above the sea, up the Weser as far as Cassel, 486 feet, and up the Elbe as far as Dresden, 280 feet.