To the lowlands belong almost the whole of Northern Asia to the north-west of the volcanic chain of the Thian-schan;--the Steppes to the north of the Altai and of the Sayan chain;--the countries which extend from the mountains of Bolor, or Bulyt-Tagh, (“cloud mountains” in the Uigurian dialect) which follow a north and south direction, and from the upper Oxus, (whose sources were found by the Buddhistic pilgrims Hiuen-thsang and Song-yun in 518 and 629, by Marco Polo in 1277, and by Lieutenant Wood in 1838, in the Pamer Lake, Sir-i-kol, Lake Victoria), towards the Caspian; and from Tenghir or the Balkhash Lake through the Kirghis Steppe, towards the sea of Aral and the southern extremity of the Ural mountains. As compared with high plains of 6,000 to 10,000 feet above the level of the sea, it may well be permitted to use the expression of “lowlands” for flats of little more than 200 to 1200 feet of elevation. The lowest of the last two numbers corresponds nearly to the altitude of the town of Mannheim, and the highest to that of Geneva and Tubingen. If the word plateau, so often misemployed in modern works on geography, is to have its use extended to elevations which hardly present any sensible difference in climate and vegetation, the indefiniteness of the expressions “highlands and lowlands,” which are only relative terms, will deprive physical geography of the means of expressing the idea of the connection between elevation and climate, between the profile or relief of the ground and the decrease of temperature. When I found myself in Chinese Dzungarei, between the boundary of Siberia and Lake Dsaisang, at an equal distance from the Icy Sea and from the mouth of the Ganges, I might well consider myself in Central Asia. The barometer, however, soon taught me that the plains through which the Upper Irtysh flows, between Ustkamenogorsk and the Chinese Dzungarian Post, Chonimailachu, (sheep-bleating,) are scarcely raised 850, or at the most 1170, feet above the level of the sea. Pansner’s older barometric measurements (which, however, were not published until after my expedition), are confirmed by mine. Both refute the hypothesis of Chappe, relative to the supposed high elevation of the banks of the Irtysh, in Southern Siberia; an hypothesis based on estimations of river declivities. Even further to the East, Lake Baikal is only 222 toises, or 1420 English feet, above the level of the sea. In order to connect the idea of the _relation_ of the terms _lowlands_ and _highlands_ and of the various gradations in the height of elevated plains or undulating grounds, with actual examples ascertained by measurement, I have subjoined a table, forming an ascending scale of such districts in different parts of the Globe. What I have said above respecting the mean height of those Asiatic plains, which I have termed lowlands, may be compared with the following numbers:--