dark the clouds suddenly cleared away, and the effect was quite
magical. The great mountains, bright with the full moon, seemed
impending over us on all sides, as over a deep crevice: one morning,
very early, I witnessed the same striking effect. As soon as the
clouds were dispersed it froze severely; but as there was no wind, we
slept very comfortably.
The increased brilliancy of the moon and stars at this elevation, owing
to the perfect transparency of the atmosphere, was very remarkable.
Travelers having observed the difficulty of judging heights and
distances amidst lofty mountains, have generally attributed it to the
absence of objects of comparison. It appears to me, that it is fully
as much owing to the transparency of the air confounding objects at
different distances, and likewise partly to the novelty of an unusual
degree of fatigue arising from a little exertion,--habit being thus
opposed to the evidence of the senses. I am sure that this extreme
clearness of the air gives a peculiar character to the landscape, all
objects appearing to be brought nearly into one plane, as in a drawing
or panorama. The transparency is, I presume, owing to the equable and
high state of atmospheric dryness. This dryness was shown by the
manner in which woodwork shrank (as I soon found by the trouble my
geological hammer gave me); by articles of food, such as bread and
sugar, becoming extremely hard; and by the preservation of the skin and
parts of the flesh of the beasts, which had perished on the road. To
the same cause we must attribute the singular facility with which
electricity is excited. My flannel waistcoat, when rubbed in the dark,
appeared as if it had been washed with phosphorus,--every hair on a
dog's back crackled;--even the linen sheets, and leathern straps of the
saddle, when handled, emitted sparks.
March 23rd.--The descent on the eastern side of the Cordillera is much
shorter or steeper than on the Pacific side; in other words, the
mountains rise more abruptly from the plains than from the alpine
country of Chile. A level and brilliantly white sea of clouds was
stretched out beneath our feet, shutting out the view of the equally
level Pampas. We soon entered the band of clouds, and did not again
emerge from it that day. About noon, finding pasture for the animals
and bushes for firewood at Los Arenales, we stopped for the night. This
was near the uppermost limit of bushes, and the elevation, I suppose,
was between seven and eight thousand feet.
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