Above this the road followed the west bank of the river; the latter was a furious torrent, flowing through a gorge, fringed with a sombre vegetation, damp, and dripping with moisture, and covered with long _Usnea_ and pendulous mosses. The road was very rocky and difficult, sometimes leading along bluff faces of cliffs by wooden steps and single rotten planks. At 8000 feet I met with pines, whose trunks I had seen strewing the river for some miles lower down: the first that occurred was _Abies Brunoniana,_ a beautiful species, which forms a stately blunt pyramid, with branches spreading like the cedar, but not so stiff, and drooping gracefully on all sides. It is unknown on the outer ranges of Sikkim, and in the interior occupies a belt about 1000 feet lower than the silver fir (_A. Webbiana_). Many sub-alpine plants occur here, as _Lecesteria, Thalictrum,_ rose, thistles, alder, birch, ferns, bcrberry, holly, anemone, strawberry, raspberry, _Gnaphalium,_ the alpine bamboo, and oaks. The scenery is as grand as any pictured by Salvator Rosa; a river roaring in sheets of foam, sombre woods, crags of gneiss, and tier upon tier of lofty mountains flanked and crested with groves of black firs, terminating in snow-sprinkled rocky peaks. [Illustration: Tambur River at the lower limit of pines] I now found the temperature getting rapidly cooler, both that of the air, which here at 8,066 feet fell to 32° in the night, and that of the river, which was always below 40°. It was in these narrow valleys only, that I observed the return cold current rushing down the river-courses during the nights, which were usually brilliant and very cold, with copious dew: so powerful, indeed, was the radiation, that the upper blanket of my bed became coated with moisture, from the rapid abstraction of heat by the frozen tarpaulin of my tent. The rivers here are often fringed by flats of shingle, on which grow magnificent yews and pines; some of the latter were from 120 to 150 feet high, and had been blown down, owing to their scanty hold on the soil. I measured one, _Abies Brunoniana,_ twenty feet in girth. Many alpine rhododendrons occur at 9000 feet, with _Astragalis_ and creeping Tamarisk. Three miles below Wallanchoon the river forks, being met by the Yangma from the north-east; they are impetuous torrents of about equal volume; the Tambur especially (here called the Walloong) is often broken into cascades, and cuts a deep gorge-like channel.