than the day, and the melting of snow being less, the volume of
waters must be somewhat, though not conspicuously, diminished.
The interference of sound by heated currents of different density is
the most obvious cause of the diminished reverberation during the
day, to which Humboldt adds the increased tension of vapour, and
possibly an echo from its particles.] of the boulders rolling along
its bed, was my lullaby for many nights. Its temperature at Zemu
Samdong was 45 degrees to 46 degrees in June. At its junction with
the Thlonok, it comes down a steep gulley from the north,
foreshortened into a cataract 1000 feet high, and appearing the
smaller stream of the two; whilst the Thlonok winds down from the
snowy face of Kinchinjunga, which is seen up the valley, bearing
W.S.W., about twenty miles distant. All around are lofty and rocky
mountains, sparingly wooded with pines and larch, chiefly on their
south flanks, which receive the warm, moist, up-valley winds; the
faces exposed to the north being colder and more barren: exactly the
reverse of what is the case at Choongtam, where the rocky and sunny
south-exposed flanks are the driest.

My tent was pitched on a broad terrace, opposite the junction of the
Zemu and Thlonok, and 10,850 feet above the sea. It was sheltered by
some enormous transported blocks of gneiss, fifteen feet high, and
surrounded by a luxuriant vegetation of most beautiful rhododendrons
in full flower, willow, white rose, white flowered cherry, thorn,
maple and birch. Some great tuberous-rooted _Arums_* [Two species of
_Arisaema,_ called "Tong" by the Tibetans, and "Sinkree" by the
Lepchas.] were very abundant; and the ground was covered with small
pits, in which were large wooden pestles: these are used in the
preparation of food from the arums, to which the miserable
inhabitants of the valley have recourse in spring, when their yaks