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CLIMATE. 89
snow. On the southern slopes of the Himalayas the snows drifting before the
winds descend much lower than on the Tibetan side, and the passes over these
mountains are closed earlier in the season than the more elevated routes across the
various plateau ranges farther north. Even in the depth of winter the road is
practicable between Kashmir and Yarkand, thanks to the slight snowfall. So
great is the dryness of the air in some parts of Tibet that the doors and wooden
pillars of the houses have to be wrapped in cloths to prevent them from warping,
and to keep the skin from chapping many travellers are accustomed to smear their
faces with a black grease. The animals dying on the routes across the plateaux
soon shrivel up, and some of the more difficult roads are lined with the mummified
yaks, horses, and sheep. AVhen a beast of burden falls the caravan people generally
cut away the choice parts, and spit them on the thorny scrub for the benefit
of passing wayfarers.
But if the snow is relatively slight, the climate of Tibet is none the less severe.
Here Prjevalsky, Drew, and others speak of the terrible cold, combined with a defi-
ciency of oxygen, which they had to endure. On the higher passes and crests the
rarefaction of the air renders all exertion very distressing, and men and animals
alike suffer from the so-called " mountain sickness," often causing the camels to fall as
it struck with lightning, or, as the Chinese writers say, "poisoned by the deadly
exhalations from the ground." In 1870 a caravan of three hundred human beings,
which left Lassa in February, lost all its thousand camels and fifty men before
reaching the end of its journey. In winter all the streams and lakes are everywhere
frozen down to within 8,000 or even 7,000 feet of sea-level. Even in
July and August the caravans often find the water ice-bound on the passes. The
long-haired yaks are at times burdened with a heavy coating of icicles, and Hue
tells us that when crossing the frozen surface of the Lower Muru-ussu he perceived
some fifty dark and shapeless objects, which, on a nearer view, proved to be a long
line of these animals suddenly frozen to death while attempting to cross the stream.
The attitude of the bodies in the act of swimming was perfectly visible through the
clear ice, above which protruded their fine horned heads, from which the eagles
and ravens had plucked the eyes.
The radiation of heat into the clear, cloudless upper regions contributes greatly
to reduce the temperature of the plateaux, and here travellers suffer all the more
that there is almost a complete dearth of fuel. Little can be found beyond some
scanty brushwood, except on the more favoured camping grounds. Fortunately
the nights are nearly always calm ; but during the day, when the tablelands are
exposed to the solar rays, while the depressions remain buried in a chilly gloom,
the surface is swept by fierce sand-storms, the terror of all travellers. In some of
the
low-lying tracts the tillers of the land usually flood their fields at the beginning
of winter in order to protect the vegetable soil from the erosive action of the
winds, and this method appears also to increase its fertility.
Altogether the Tibetan plateau, enclosed as it is by lofty border ranges, is
characterized by great dryness and the extremes of heat and cold. But little
moisture reaches it from the Indian Ocean ; the force of the southern monsoons is