well of Esalan, &c. &c.  These matters being at length settled, we proceeded for Aisou, and journeyed a long day of twelve hours and a-half.  I was looking out every moment, expecting to clear the rocks, and enter upon the immeasurable stretch of plain reported to us.  But all was a rocky granite expanse, with conical-shaped rocks, exactly as before described.  We begin to tire of this kind of country, which seemed so picturesque when we first entered upon it.

To-day the weather was misty, and we felt as if entering into the circle of a new climate.  Few or no animals were seen.  All is dismal and dreary.

15th.—­We rose at daybreak, and proceeded steadily on, making a day’s journey of thirteen long weary hours.  The stony plain opened rather more than yesterday, but there were always rocks on either hand.

To-day we had the first drops of Soudan rain, and a complete Soudan atmosphere.  We also observed the vermilion tinge on the clouds, peculiar to Central Africa; and the air was hot and clammy.  Every sort of desert phenomenon is seen in these parts in perfection.  The mirage often fills up the interstices left between the rocks, and inundates the plain ahead with its fantastic waters.

16th.—­We were early in motion this day; and started, cheered by the hope held out to us, that at the termination of two long marches we should at length reach, at the Seven Wells of Aisou, the frontiers of Aheer.  It is true that we were promised no town, no village, not even visible landmarks; above all, no custom-house officers to suggest the blessings of civilisation.  There was, in truth, some idea that very indefinite dues might be exacted of us during our progress through the northern districts of the Asben territory.  Still it was a comfort to get at last within the limits of the influence of a form of polity, however rude.

Whilst we were indulging in these reflections, there came on a regular desert-storm.  A vault of clouds, like huge irregular rocks, was soon heaped up overhead.  The thunder roared from side to side of the horizon.  The lightning flashed, sometimes above, sometimes between, the isolated hills, showing them like long black tents pitched here and there on the plain.  Our beasts moved eagerly on; and their drivers, though accustomed to such phenomena, were hushed into awe.  The tempest did not last many minutes; but it was accompanied by wind so violent that we could scarcely preserve our seats in the saddles, and finished off with so violent a shower of rain that we got quite wet through almost in an instant.  This is a fair warning that we are really within the tropics.