eight of a
few hundred feet above the surface of the Mediterranean; whereas in New
Grenada, at less than one hundred miles from the sea, the chain of the
Andes rises to elevations of from ten to fifteen thousand feet. Such an
ascent as that of a few hundred feet in hundreds of miles would be
wholly imperceptible to any ordinary mode of observation; and the great
rainless region, accordingly, of Africa and Asia is, as it appears to
the traveler, one vast plain, a thousand miles wide and five thousand
miles long, with only one considerable interruption to the dead monotony
which reigns, with that exception, every where over the immense expanse
of silence and solitude. The single interval of fruitfulness and life is
the valley of the Nile.

There are, however, in fact, three interruptions to the continuity of
this plain, though only one of them constitutes any considerable
interruption to its barrenness. They are all of them valleys, extending
from north to south, and lying side by side. The most easterly of these
valleys is so deep that the waters of the ocean flow into it from the
south, forming a long and narrow inlet called the Red Sea. As this inlet
communicates freely with the ocean, it is always nearly of the same
level, and as the evaporation from it is not sufficient to produce rain,
it does not even fertilize its own shores. Its presence varies the
dreary scenery of the landscape, it is true, by giving us surging waters
to look upon instead of driving sands; but this is all. With the
exception of the spectacle of an English steamer passing, at weary
intervals, over its dreary expanse, and some moldering remains of
ancient cities on its eastern shore, it affords scarcely any indications
of life. It does very little, therefore, to relieve the monotonous
aspect of solitude and desolation which reigns over the region into
which it has intruded.

The most westerly of the three valleys to which we have alluded is only
a slight depression of the surface of the land marked by a line of
_oases_. The depression is not sufficient to admit the waters of the
Mediterranean, nor are there any rains over any portion of the valley
which it forms sufficient to make it the bed of a stream. Springs issue,
however, here and there, in several places, from the ground, and,
percolating through the sands along the valley, give fertility to little
dells, long and narrow, which, by the contrast that they form with the
surrounding desolat