While he was at Cairo, intelligence was received of the landing of Buonaparte in that country, when the just indignation of the natives vented itself upon all Europeans, and, amongst others, on Horneman, who was arrested and confined in the castle.

He was relieved upon the victorious entry of the French commander, who immediately set him at liberty, and very liberally offered him money, and every other supply which might contribute to the success of his mission.
It was not before the 5th September 1798, that Horneman could meet with a caravan proceeding to the westward, when he joined the one destined for Fezzan.

The travellers soon passed the cultivated lands of Egypt, and entered on an expanse of sandy waste, such as the bottom of the ocean might exhibit, if the waters were to retire.

This desert was covered with the fragments, as it were, of a petrified forest; large trunks, branches, twigs, and even pieces of bark, being scattered over it.

Sometimes these stony remains were brought in as mistake for fuel.