I had a long conversation with the Arabs I met with at Aira, and from them I learned pretty nearly the situation of the different clans or tribes in Atbara. These were all in their way northward to the respective countries in the sands to the eastward of Mendera and Barbar. These sands, so barren and desolate the rest of the year, were beginning now to be crowded with multitudes of cattle and inhabitants. The fly, in the flat and fertile mold which composes all the soil to the southward of Sennaar, had forced this number of people to migrate, which they very well knew was to cost them at least one half of their substance; of such consequence is the weakest instrument in the hand of Providence. The troops of Sennaar, few in number, but well provided with every thing, stood ready to cut these people off from their access to the sands, till every chief of a tribe had given in a well-verified inventory of his whole stock, and made a composition, at passing, with Shekh Adelan. All subterfuge was in vain. The fly, in possession of the fertile country, inexorably pursued every single camel till he took refuge in the sands, and there he was to stay till the rains ceased; and if, in the interim, it was discovered that any concealment of number or quality had been made, they were again to return in the beginning of September to their old pastures; and in this second passage, any fraud, whether real or alledged, was punished with great severity. Resistance had been often tried, and as often found ineffectual. However great their numbers, encumbered with families and baggage as they were, they had always fallen a sacrifice to those troops, well mounted and armed, that awaited them in their way within sight of their own homes. Arrived once in the sands, they were quiet during the rains, having paid their passage northward, and so they were afterwards, for the same reason, when they came again to their own station, southward, when those rains had ceased. It may be asked reasonably, What does the government of Sennaar do with that immense number of camels which they receive from all those tribes of Arabs in their passage by Sennaar? To this I answer, That all this tribute is not paid in kind. The different tribes possessing so many camels, or so many other cattle, have a quantum laid upon them at an average value. This is paid in gold, or in slaves, the rest in kind; so many for the maintenance of the king and government; for there is no flesh commonly used at Sennaar in the markets but that of camels. The residue is bought by the merchants of Dongola, and sent into Egypt, where they supply that great consumption of these animals made every year by the caravans going to Mecca.