To the lowlands belong almost the whole of Northern Asia to the north-west of the volcanic Celestial Mountains (Thian-schan); the steppes to the north of the Altai and the Sayanic chain; and the countries which extend from the mountains of Bolor, or Bulyt-tagh (Cloud Mountains in the Uigurian dialect), which run in a north and south direction, and from the upper Oxus, whose sources were discovered in the Pamershian Lake, Sir-i-kol (Lake Victoria), by the Buddhist pilgrims Hiuen-thsang and Song-yun in 518 and 629, by Marco Polo in 1277, and by Lieutenant Wood in 1838, towards the Caspian Sea; and from Lake Tenghiz or Balkasch, through the Kirghis Steppe, towards the Aral and the southern extremity of the Ural Mountains. In the vicinity of mountainous plains, whose elevation varies from 6000 to more than 10,000 feet above the sea’s level, we may assuredly be allowed to apply the term lowlands to districts which are only elevated from 200 to 1200 feet. The first of these heights correspond with that of the city of Mannheim, and the second with that of Geneva and Tübingen. If we extend the application of the word _plateau_, which has so frequently been misused by modern geographers, to elevations of the soil which scarcely present any sensible difference in the character of the vegetation and climate, physical geography, owing to the indefiniteness of the merely relatively important terms of _high_ and _low_ land, will be unable to distinguish the connexion between elevation above the sea’s level and climate, between the decrease of the temperature and the increase in elevation. When I was in Chinese Dzungarei, between the boundaries of Siberia and Lake Saysan (Dsaisang), at an equal distance from the Icy Sea and the mouth of the Ganges, I might assuredly consider myself to be in _Central Asia_. The barometer, however, soon showed me that the elevation of the plains watered by the Upper Irtysch between Ustkamenogorsk and the Chinese Dzungarian post of Chonimailachu (the sheep-bleating) was scarcely as much as from 850 to 1170 feet. Pansner’s earlier barometric determinations of height, which were first made known after my expedition, have been confirmed by my own observations. Both afford a refutation of the hypotheses of Chappe D’Auteroche (based on calculations of the fall of rivers) regarding the elevated position of the shores of the Irtysch, in Southern Siberia. Even further eastward, the Lake of Baikal is only 1420 feet above the level of the sea.