that I was afraid to take him, for I was told that even if
he saw an ostrich at a distance, he would mistake it for an Indian,
and would fly like the wind away. The distance to Buenos Ayres is
about four hundred miles, and nearly the whole way through an
uninhabited country. We started early in the morning; ascending a
few hundred feet from the basin of green turf on which Bahia Blanca
stands, we entered on a wide desolate plain. It consists of a
crumbling argillaceo-calcareous rock, which, from the dry nature of
the climate, supports only scattered tufts of withered grass,
without a single bush or tree to break the monotonous uniformity.
The weather was fine, but the atmosphere remarkably hazy; I thought
the appearance foreboded a gale, but the Gauchos said it was owing
to the plain, at some great distance in the interior, being on
fire. After a long gallop, having changed horses twice, we reached
the Rio Sauce: it is a deep, rapid, little stream, not above
twenty-five feet wide. The second posta on the road to Buenos Ayres
stands on its banks, a little above there is a ford for horses,
where the water does not reach to the horses' belly; but from that
point, in its course to the sea, it is quite impassable, and hence
makes a most useful barrier against the Indians.

Insignificant as this stream is, the Jesuit Falconer, whose
information is generally so very correct, figures it as a
considerable river, rising at the foot of the Cordillera. With
respect to its source, I do not doubt that this is the case; for
the Gauchos assured me, that in the middle of the dry summer this
stream, at the same time with the Colorado, has periodical floods,
which can only originate in the snow melting on the Andes. It is
extremely improbable that a stream so small as the Sauce then was
should traverse the entire width of the continent; and indeed, if
it were the residue of a large river, its waters, as in other
ascertained cases, would be saline. During the winter we must look
to the springs round the Sierra Ventana as the source of its pure
and limpid stream. I suspect the plains of Patagonia, like those of
Australia, are traversed by many watercourses, which only perform
their proper parts at certain periods. Probably this is the case
with the water which flows into the head of Port Desire, and
likewise with the Rio Chupat, on the banks of which masses of
highly cellular scoriae were found by the officers employed in the
survey.