The products of cultivation which are here noticed lead to the belief that over extensive districts the elevation of the soil is very slight. At so great a distance from the sea side, and in the easterly situation which so much increases the degree of winter cold, a plateau, as high as Madrid or Munich, might indeed have a very hot summer, but would hardly have, in 43° and 44° latitude, an extremely mild and almost snowless winter. I have seen a high summer heat favour the cultivation of the vine, as at the Caspian Sea, 83 feet below the level of the Black Sea (at Astrakhan, latitude 46° 21′); but the winter cold is there from –4° to –13°. Moreover, the vine is sunk to a greater depth in the ground after the month of November. We can understand that cultivated plants, which, as it were, live only in the summer, as the vine, the cotton plant, rice, and melons, may be cultivated with success between the latitudes of 40° and 44°, on plateaux at an elevation of more than 3000[BL] feet, and may be favoured by the action of radiant heat; but how could the pomegranate trees of Aksu, and the orange trees of Hami, whose fruit Father Grosier extolled as excellent, endure a long and severe winter (the necessary consequence of a great elevation[BM])? Carl Zimmerman[BN] has shown it to be extremely probable that the Tarim depression, or the desert between the mountain chain of Thian-schan and Kuen-lün, where the steppe river Tarim-gol discharges itself into the Lake of Lop, formerly described as an alpine lake, is hardly 1280 feet above the level of the sea, or only twice the elevation of Prague. Sir Alexander Burnes also ascribes to Bokhara only an elevation of 1188 feet. It is most earnestly to be desired that all doubt regarding the elevation of the plateaux of Central Asia, south of 45° north latitude, should finally be removed by direct barometrical measurements, or by determinations of the boiling point of water, conducted with greater care than is usual in these cases. All our calculations of the difference between the limits of perpetual snow and the maximum elevation of vine cultivation in different climates, rest at present on too complex and uncertain elements.