The true Rhine delta may be defined as lying between Amsterdam, on the sea, and Dusseldorf, 107 feet above the sea level. Then passing by the broken and romantic tract lying between Dusseldorf or Cologne and Mayence, we come to the true Rhenish lowland, 240 feet above the sea. Munster is 400 feet above the ocean level. East of the Weser is the Lüneburg Heath, which advances in elevation, as we go toward the Elbe and the Havel, to 300 or 400 feet. Brunswick lies at an altitude of 200 feet; Magdeburg, of 128 feet. The height gradually increases; at Wittenburg it reaches 204 feet; at Dresden 280 feet, where the Elbe issues from the highlands; and in Lower Silesia we find Breslau, 375 feet above the sea, and its observatory, standing on the hills around the city, at a height of 453 feet, which seems to be the highest point in the whole vast tract. Between the Rhine delta and the now dry basin of Paderborn, from the Ems to the Weser, Aller, and middle Elbe, is the mountain tract of the Hartz, (with the Brocken at the north, 3500 feet high,) running up as far as 52½° N. lat. By this natural feature the breadth of the great plain is considerably curtailed. As it is also more to the east of the Leipsic basin, from which the Mulde, Elbe, and Elster flow, by the hill country of Lausatia and North Silesia, with the Riesengeberge, (Giant Mountains,) 5000 feet high, which extends northward as far as 51° N. lat. A third basin is in the Silesian, from which the Oder flows toward the northwest, and enters the southern limits of the great plain near Oppeln and Brieg. A third tract of hill country lies on the east bank of the Oder, and extends to the middle Vistula, the Tarnowitz Heights, in Upper Silesia, about 1000 feet in altitude. The plateau north of the Carpathian range, on which Cracow lies, is 669 feet above the sea; and the most northern hill group of Kielce, between the Pilica and the Vistula, rises in the Kreutzberg to a height of 1920 feet, and in St. Catherine to 2000 feet. The great lowland advances eastward, with always diminishing breadth from north to south, over the extensive plains of the middle Vistula, at Warsaw, 330 feet above the sea; over the Lithuanian morasses of the Bug; over the Sarmatian district of Minsk and Pinsk as far as Kiev, on the middle Dnieper, at the southeast, and as far as Orsha and Smolensk, at the northeast. Pinsk, in the middle of this tract, lies about 400 feet above the sea. The north side of the plain is bounded by the very moderate plateau south of the Valdai hills, at Smolensk, 792 feet high; at Osmana, southeast of Minsk, 882 feet. On the south side it is bounded by the equally moderate plateau of Wolhynia and Podolia, whose absolute altitude is yet undetermined, but which, at the source of the Bug, is about 1000 feet.