as we advanced ; and offered a prospect the most tempting and de-
lightful, but at the same time the most tantalizing, to a thirsty
traveller; and, to complete the illusion, its surface seemed to play
in a lively rippling motion. The day was warm and cloudless. The
cause of this phenomenon is, very probably, the vapor and heat
of the sun’s rays, reflected from a great extent of level surface.
A similar effect, on a small scale, may be observed even in England,
on very hot days : not asserting that it ever produces the appearance
of water; but meaning only that the operation of the same cause
may often be witnessed, by looking obliquely along any heated and
extensive surface. In the present example of this phenomenon, and
in all others which I have seen in Africa, the optical lake is only,
visible when backed by very distant mountains, whose angle of altitude
is not greater than ten or fifteen minutes of a degree ; that is,
just appearing above the horizon : for, as the traveller advances,
and these mountains appear higher, the lake always vanishes. Consequently,
it divides itself into separate lakes or ponds, as soon as the
spectator’s nearer approach occasions the higher mountains of the
range, or the loftier peaks, to rise above that angle; a fact which I
have invariably noticed in such circumstances.
As if in compensation for this tantalizing illusion, we soon
afterwards came to a large pool of real water, and had cause for rejoicing
when we found it perfectly fresh. The newly-discovered
river, which we had hitherto wronged by the name of the “ Brackish,
river,” seemed as if kindly resolved to keep us company and lend us
its friendly assistance during this journey ; for it held the same
general course, which, according to my calculation, we ought to
take towards the Colony; although in its meanderings it often
quitted us, and as often crossed our track. From this spot, which is
marked on the map with the name of Freshwater Halt, the river in
every part upwards affords abundance of wholesome water; and its
pools, which occur at very short intervals, are in many places nearly
confluent.
Feeds, exactly resembling the common reeds of the 'English
rivers, almost every where mark its course. These are a sure
indication of fresh water, and, if attended to, will often be of service
in pointing out a spring at a distance, which might otherwise be
passed unnoticed. In cases where a traveller may be in want of
water while traversing the arid regions in the interior of Southern
Africa, he may sometimes be relieved from his distress by ascending
the nearest eminence, and thence carefully examining the country
with his telescope; when he may chance fortunately to discover
some clump of reeds, to which he may direct his steps, with the
greatest probability of finding sufficient for quenching his thirst.
Some species of trees, easily distinguishable from afar, are also peculiar
to moist situations *, and are therefore equally useful as guides
to a spring or rivulet. These facts are well worth an African
traveller’s attention.; and a little observation will bring to his knowledge
many others of the same kind.
We immediately unpacked the oxen, and turned them loose to
graze in some meadows of excellent grass. After making our breakfast
from the ostrich-eggs, my men found employment enough in
drying our clothes and baggage, which were thoroughly soaked with
yesterday’s rain. Philip entered upon his new office of “ washerwoman,”
nor was Speelman, or Uncle Hans, or Old Cobus, at all
surpassed by him in versatility of talents: and I believe that, had
there been amongst them a missionary of a certain class, it would not
have hurt his conscience to assert that we carried on “ eighteen different
trades.”
We were visited by two natives, whose kraal, they said, was at
some distance eastward; and who being out in search of wild roots,
happened to observe our track, and had discovered us by following
it. One of them wore on the side of his head, as an ornament, and
tied close to the hair, a circular plate of shining brass three inches
indiam eter. The other carried, what my Hottentots called a graaf-
stok (a digging-stick), to which there was affixed a heavy stone to
increase its force in pecking up bulbous roots. The stone, which was
* Such as the Karree-wood (Rhus viminoHe), the Buffido-thom (Zizt/phiis Imbalintis),
the Willow (Stdix Gariepina) and the Karro-thom (Acacia Capensis).