“Now o’er their head the whizzing whirlwinds breathe,
And the live desert pants and heaves beneath;
Tinged by the crimson sun, vast columns rise
Of eddying sands, and war amid the skies,
In red arcades the billowy plain surround,
And stalking turrets dance upon the ground.”—DARWIN.
In the pathless desert, high mounds of sand, shifting with every change
of wind, surround the traveler on every side, and conceal from his view
all other objects. There the wind is of a surprising rapidity; and the
sand is so extremely fine, that it forms on the ground waves which
resemble those of the sea. These waves rise up so fast, that in a very
few hours a hill of from twenty to thirty feet high is transported from
one place to another. The shifting of these hills, however, does not
take place on a sudden, as is generally believed, and is not by any
means capable of surprising and burying a caravan while on the march.
The mode in which the transposition of the hills takes place is not
difficult of explanation. The wind sweeping the sand from the surface
continually, and that with an astonishing rapidity, the ground lowers
every moment: but the quantity of sand in the air increasing as quickly
by successive waves, can not support itself there, but falls in heaps,
and forms a new hill, leaving the place it before occupied level, and
with the appearance of having been swept.
It is necessary to guard the eyes and mouth against the quantity of sand
which is always flying about in the air; and the traveler has to seek
the right direction, to avoid being lost in the windings made in the
middle of the hills of sand which bound the sight, and which shift from
one spot to another so often, as not to leave anything to be seen
besides the sky and sand, without any mark by which the position can be
known. Even the deepest footstep in the sand of either man or horse
disappears the moment the foot is raised. The immensity, the swiftness,
and the everlasting motion of these waves when the wind is blowing,
disturb the sight both of men and beasts, so that they are almost
continually marching as if in the dark. The camel gives here a proof of
his great superiority; his long neck, perpendicularly erected, removes
his head from the ground, and from the thick part of the waves; his eyes
are well defended by thick eye-lids, largely provided with hair, and
which he keeps half shut; the construction of his feet, broad and
cushion-like, prevents his treading deep into the sand; his long legs
enable him to pass the same space with only half the number of steps of
any other animal, and therefore with less fatigue. These advantages give
him a solid and easy gait, on a ground where all other animals walk with
slow, short, and uncertain steps, and in a tottering manner. Hence the
camel, intended by nature for these journeys, affords a new motive of
praise to the Creator, who in his wisdom has given the camel to the
African, as he has bestowed the reindeer on the Laplander.
Lieutenant Pottinger, in his travels in Beloochistan, a province of
India, gives the following interesting account of those curious
phenomena. He had to pass over a desert of red sand, the particles of
which were so light, that when taken in the hand they were scarcely more
than palpable, the whole being thrown by the winds into an irregular
mass of waves, principally running east and west, and varying in hight
from ten to twenty feet. The greater part of them rose perpendicularly
on the opposite side to that from which the prevailing north-west wind
blew, and might readily have been fancied, at a distance, to resemble a
new brick wall. The side facing the wind sloped off with a gradual
declivity toward the base of the next windward wave, and then again
ascended in a straight line, in the same extraordinary manner as above
described, so as to form a hollow or path between them. Our traveler
kept as much in these paths as the direction he had to take would allow;
but it was not without great difficulty and fatigue that the camels were
urged over the waves, when it was requisite to do so, and more
particularly when they had to clamber up the leeward or perpendicular
face of them, in attempting which they were often defeated. On the
oblique or shelving side they ascended pretty well, their broad feet
saving them from sinking deeper than did the travelers themselves; and
the instant they found the top of the wave giving way from their weight,
they most expertly dropped on their knees, and in that posture gently
slid down with the sand, which was luckily so unconnected, that the
leading camel usually caused a sufficient breach for the others to
follow on foot. The night was spent under shelter of one of these sand
waves, the surrounding atmosphere being uncommonly hot and close.
On the following day, in crossing a desert of the same description, the
like impediments occurred; but these were trifling compared with the
distress suffered, not only by our traveler and his people, but also by
the camels, from the floating particles of sand; a phenomenon for which
he confesses himself at a loss to account. When he first observed it, in
the morning, the desert appeared to have, at the distance of half a mile
or less, an elevated and flat surface from six to twelve inches higher
than the summits of the sand waves. This vapor appeared to recede as he
advanced, and once or twice completely encircled his party, limiting the
horizon to a very confined space, and conveying a most gloomy and
unnatural sensation to the mind of the beholders, who were at the same
moment imperceptibly covered with innumerable atoms of small sand, which
getting into the eyes, mouth and nostrils, caused excessive irritation,
attended by an extreme thirst, which was increased in no small degree by
the intense heat of the sun. This annoyance is supposed by the natives
to originate in the solar beams causing the dust of the desert, as they
emphatically call it, to rise and float through the air; a notion which
appears to be in a great measure correct, this sandy ocean being only
visible during the hottest part of the day. The following simple theory
of these moving sands is submitted by the author. When the violent
whirlwinds which prevail in the desert, terminate in gusts of wind, they
usually expand over several square miles of surface, raging with
irresistible force, and bearing upward an immense body of sand, which
descends as the current of air that gave it action dies away, thus
creating the extraordinary appearance in question. If it should be asked
what prevents the sand from subsiding altogether, when it has so far
accomplished this as to rest apparently on the waves, the answer is,
that all the grosser particles do settle, but that the more minute ones
become rarefied to such a degree by the heat produced by the burning
sand on the red soil, that they remain as it were in an undecided and
undulating state, until the returning temperature restores their
specific gravity; when, by an undeviating law of nature, they sink to
the earth. This in some measure coincides with the opinion of the native
Brahoes; but, conformably to their notion, it is evident that the
floating sands would be apparent at all periods of excessive solar
influence; which not being the case, it becomes necessary to find a
primary cause for the phenomenon. To remove any suspicion of his having
been deceived in the reality of this floating vapor of sand, he adds
that he has seen this phenomenon, and the _shurab_, or watery illusion
so frequent in deserts, called by the French _mirage_, in opposite
quarters at the same moment, each of them being to his sight perfectly
distinct. While the former had a cloudy and dim aspect, the latter was
luminous, and could not be mistaken for water. To corroborate what he
has here advanced, he states that he was afterward joined by a faquir
from Kaboul, who informed him that he had witnessed the moving sands, in
passing through the desert from Seistan, to a much greater degree than
has been described; and, what is scarcely credible, he spoke of having
been forced to sit down, in consequence of the density of the cloud in
which he was enveloped.
Our traveler next proceeds to a curious description of the pillars or
columns of sand formed in the deserts. He experienced a violent tornado,
or gust of wind, which came on so suddenly, that, if he had not been
apprised of its strength by the guide, it might have been disastrous to
his party, in whom it would have been an act of temerity to have
endeavored to sit on the camels during its impetuous fury. Before it
began, the sky was clear, save a few small clouds in the north-west
quarter; and the only warnings it afforded, were the oppressive
sultriness of the air, and a vast number of whirlwinds springing up on
all sides. These whirlwinds, he observes, might perhaps be more
correctly expressed by some other name; but as the wind issued from them
he adopts the term. They are vast columns of sand, which begin by a
trifling agitation, with a revolving motion on the surface of the
desert, and gradually ascend and expand, until their tops are lost to
the view. In this manner they move about with every breath of wind, and
are observed, thirty or forty of them at the same time, of different
dimensions, apparently from one to twenty yards in diameter. Those who
have seen a waterspout at sea, may exactly conceive the same formed of
sand on shore. The moment the guide saw the whirlwinds disperse, which
they did as if by magic, and a cloud of dust approaching, he advised the
party to dismount, which they had hardly time to do, and lodge
themselves snugly behind the camels, when a storm burst upon them with a
furious blast of wind, the rain falling in huge drops, and the air being
so completely darkened, that they were unable to discern any object at
the distance of even five yards.
The following is Bruce’s account of this singular phenomenon, which he
represents as one of the most magnificent spectacles imaginable, and by
which he and his companions were at once surprised and terrified. Having
reached the vast expanse of desert which lies to the west and north-west
of Chendi, they saw a number of prodigious pillars of sand at different
distances, at times moving with great celerity, and at others stalking
on with a majestic slowness. At intervals the party thought they should
be overwhelmed by these sand-pillars; and small quantities of sand did
actually more than once reach them. Again, they would retreat so as to
be almost out of sight, their summits reaching the very clouds. There
the tops often separated from the bodies; and these once disjointed,
dispersed in the air, and did not appear more. They were sometimes
broken near the middle, as if struck by a large cannon-shot. About noon
they began to advance with considerable swiftness upon the party, the
wind being very strong at north. Eleven of them ranged alongside, at
about the distance of three miles from them; and at this interval the
greatest diameter of the largest of them appeared to Mr. Bruce to be
about ten feet. They retired with a wind at south-east, leaving an
impression on our traveler’s mind, to which he could give no name,
though assuredly one of its ingredients was fear, blended with a
considerable portion of wonder and surprise. It was in vain to think of
fleeing: the swiftest horse, or fastest sailing ship, would have been of
no use in rescuing him from his danger. The full persuasion of this
riveted him as it were to the spot where he stood, and he allowed the
camels to gain on him so much, that it was with difficulty he could
overtake them. On a subsequent occasion, an assemblage of these moving
pillars of sand, more numerous, but less in size than the former,
approached Mr. Bruce’s party soon after sunrise, and appeared like a
thick wood. They almost darkened the sun, the rays of which, shining
through them for nearly an hour, gave them an appearance of pillars of
fire. His people became desperate, some saying it was the day of
judgment, and others, that the world was on fire.
Dr. Clarke, in his travels in Egypt, thus describes this phenomenon.
“One of those immense columns of sand, mentioned by Bruce, came rapidly
toward us, turning upon its base as upon a pivot: it crossed the Nile so
near us, that the whirlwind by which it was carried, placed our vessel
upon its beam-ends, bearing its large sail quite into the water, and
nearly upsetting the boat. As we were engaged in righting the vessel,
the column disappeared. It is probable that those columns do not fall
suddenly upon any particular spot, so as to be capable of overwhelming
an army or a caravan; but that, as the sand, thus driven, is gradually
accumulated, it becomes gradually dispersed, and the column, diminishing
in its progress, at length disappears. A great quantity of sand is no
doubt precipitated, as the effect which gathers it becomes weaker; but,
from witnessing such phenomena upon a smaller scale, it does not seem
likely that the whole body of the sand is at once abandoned.”
-------------------------------------------