westward or Pacific side. As the observations have been chiefly made
in summer, this wind must be an upper and return current. The Peak of
Teneriffe, with a less elevation, and situated in lat. 28 degs., in
like manner falls within an upper return stream. At first it appears
rather surprising, that the trade-wind along the northern parts of
Chile and on the coast of Peru, should blow in so very southerly a
direction as it does; but when we reflect that the Cordillera, running
in a north and south line, intercepts, like a great wall, the entire
depth of the lower atmospheric current, we can easily see that the
trade-wind must be drawn northward, following the line of mountains,
towards the equatorial regions, and thus lose part of that easterly
movement which it otherwise would have gained from the earth's
rotation. At Mendoza, on the eastern foot of the Andes, the climate is
said to be subject to long calms, and to frequent though false
appearances of gathering rain-storms: we may imagine that the wind,
which coming from the eastward is thus banked up by the line of
mountains, would become stagnant and irregular in its movements.
Having crossed the Peuquenes, we descended into a mountainous country,
intermediate between the two main ranges, and then took up our quarters
for the night. We were now in the republic of Mendoza. The elevation
was probably not under 11,000 feet, and the vegetation in consequence
exceedingly scanty. The root of a small scrubby plant served as fuel,
but it made a miserable fire, and the wind was piercingly cold. Being
quite tired with my days work, I made up my bed as quickly as I could,
and went to sleep. About midnight I observed the sky became suddenly
clouded: I awakened the arriero to know if there was any danger of bad
weather; but he said that without thunder and lightning there was no
risk of a heavy snow-storm. The peril is imminent, and the difficulty
of subsequent escape great, to any one overtaken by bad weather between
the two ranges. A certain cave offers the only place of refuge: Mr.
Caldcleugh, who crossed on this same day of the month, was detained
there for some time by a heavy fall of snow. Casuchas, or houses of
refuge, have not been built in this pass as in that of Uspallata, and,
therefore, during the autumn, the Portillo is little frequented. I may
here remark that within the main Cordillera rain never falls, for
during the summer the sky is cloudless, and in winter snow-storms alone
occur.
At the place where we slept water necessarily boiled, from the
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