d more than one half of the visible horizon, that is to say, from
10 degrees east of north, westward round to south. As to the eastward, so
here the ridges we had just crossed abutted upon it, and as many of them
were lower than the line of the horizon, they looked like sea dunes,
backed by storm clouds, from the dusky colour of the plain.

After surveying this gloomy expanse of stoneclad desert we looked for
some object on the N.W. horizon upon which to move across it, but none
presented itself, excepting a very distant sand hill bearing 308 degrees,
towards which I determined to proceed. We accordingly descended to the
plain, and soon found ourselves on its uneven surface. There was a narrow
space destitute of stones at the base of the sand hill, stamped all over
with the impressions of natives' feet. From eighty to one hundred men,
women, and children must have passed along there; and it appeared to me
that this had been a migration of some tribe or other during the wet
weather, but it was very clear those poor people never ventured on the
plain itself.

Descended from our high position, we could no longer see the sand hill
just noticed, but held on our course by compass like a ship at sea, being
two hours and forty minutes in again sighting it; and reaching it in
somewhat less than an hour afterwards, calculated the distance at
thirteen miles. As we approached, it looked like an island in the midst
of the ocean; but we found a large though shallow sheet of water amongst
the stones under it, for which we were exceedingly thankful. From this
point we crossed to another sand hill that continued northerly further
than we could see, having the Desert on either hand. Our horses beginning
to flag, I halted at five on the side of the ridge, near a small puddle
that had only water enough for them to drink off at once.

The morning of the 20th was bitterly cold, with the wind at S.S.E., and I
cannot help thinking that there are extensive waters in some parts of the
in terior, over which it came: the thermometer stood at 42 degrees. We
started on a course of 335 degrees for a distant sandy peak rising above
the general line of the horizon. At a mile, one of the horses fortunately
got bogged in a little narrow channel just like that in the grassy plain;
I say fortunately, for we might otherwise have passed the water it
contained without knowing it, so completely was it shaded. In looking
along the channel more closely, we disc