The whole ground upon which the town is built (being the edge of a table-land, which coincides with the transition from granite to sandstone[193]), seems to be greatly impregnated with salt at a certain depth, of which not only the ponds, but even the wells bear evidence,—two of the three wells still in use having saltish water, and only that of Shedwánka being, as to taste, free from salt, though it is still regarded as unwholesome, and all the water used for drinking is brought from the wells outside the walls. Formerly, it is said, there were nine wells inside the town. From what I have said above, it may be concluded that the commerce of Ágades is now inconsiderable. Its characteristic feature is, that no kind of money whatever is current in the market, neither gold, nor silver, nor kurdí nor shells; while strips of cotton or gábagá (the Kanúri, and not the Háusa term being employed in this case, because the small quantity of this stuff which is current is imported from the north-western province of Bórnu) are very rare, and indeed form almost as merely nominal a standard as the mithkál. Nevertheless the value of the mithkál is divided into ten rijáls or érjel, which measure means eight drʿa or cubits of gábagá. The real standard of the market, I must repeat, is millet or dukhn (“géro” in Háusa, “éneli” in Temáshight, _Pennisetum typhoïdeum_), durra or _Holcus sorghum_ being scarcely ever brought to market. And it is very remarkable, that with this article a man may buy everything at a much cheaper rate than with merchandise, which in general fetches a low price in the place; at least it did so during my stay, when the market had been well-stocked with everything in demand, by the people who had come along with us. English calico of very good quality was sold by me at twenty per cent. less than it had been bought for at Múrzuk. Senna in former times formed an article of export of some importance; but the price which it fetches on the coast has so decreased that it scarcely pays the carriage, the distance from the coast being so very great; and it scarcely formed at all an article in request here, nor did we meet on our whole journey a single camel laden with it, though it grows in considerable quantities in the valleys hereabouts.