chain of the Himalaya is broken through, than toward the southern declivities facing Hindostan, and he there estimates the line of perpetual snow at 15,000 feet. The most striking differences are presented between the vegetation on the Thibetian plateau and that characteristic of the southern slopes of the Himalaya. On the latter the cultivation of grain is arrested at 9974 feet and even there the corn has often to be cut when the blades are still green. The extreme limit of forests of tall oaks and deodars is 11,960 feet; that of dwarf birches, 12,983 feet. On the plains, Captain Gerard found pastures up to the height of 17,000 feet; the cereals will grow at 14,100 feet, or even at 18,540 feet; birches with tall stems at 14,100 feet, and copse or brush wood applicable for fuel is found at an elevation of upward of 17,000 feet, that is to say, 1280 feet and above the lower limits of the snow-line at the equator, in the province of Quito. It is very desirable that the 'mean' elevation of the Thibetian plateau, which I have estimated at only about 8200 feet between the Himalaya and the Kuen-lun, and the difference in the height of the line of perpetual snow on the southern and on the northern slopes of the Himalaya, should be again investigated by travelers who are accustomed to judge of the general conformation of the land. Hitherto simple calculations have too often been confounded with actual measurements, and the elevations of isolated summits with that of the surrounding plateau. (Compare Carl Zimmerman's excellent Hypsometrical Remarks in his 'Geographischen Analyse der Karte von Inner Asien', 1841, s. 98.) Lord draws attention to the difference presented by the two faces of the Himalaya and those of the Alpine chain of Hindoo-Coosh, with respect to the limits of the snow-line. "The latter chain," he says, "has the table-land to the south, in consequence of which the snow-line is higher on the southern side, contrary to what we find to be the case with respect to the Himalaya, which is bounded on the south by sheltered plains, as Hindoo-Coosh is on the north." It must, however, be admitted that the hypsometrical data on which these statements are based require a critical revision with regard to several of their details; but still they suffice to establish the main fact, that the remarkable configuration of the land in Central Asia affords man all that is essential to the maintenance of life, as habitation, food, and fuel, at an elevation above the level of the sea which in almost all other parts of the globe is covered with perpetual ice. We must except the very dry districts of Bolivia, where snow is so rarely met with, and where Pentland (in 1838) fixed the snow-line at 15,667 feet, between 16 degrees and 17 3/4 degrees south latitude. The opinion that I had advanced regarding the difference in the snow-line on the two faces of the Himalaya has been most fully confirmed by the barometrical observations