ride up the river to El ’Ashiḳ, but I was rewarded for my trouble by finding indubitable traces of a masonry bridge in the low ground almost exactly opposite a curious little building called Ṣlebîyeh. My attention was called to the bridge by seeing men digging out the brick piers and arches for building material. The peasants told me that when the river is low, piers can be seen in the bed of the stream and that the bridge ran in the direction of the Beit el Khalîfah. I give this information for what it is worth. Ya’ḳûbî mentions a bridge of boats (ed. de Goeje, p. 263); it is not impossible that pontoons may have been thrown across the deepest and swiftest part of the river and connected with the high ground on the west bank, which is at some distance from the stream, by a series of masonry arches of which I saw the remains. The piers and arches would therefore have stood on ground which was under water in time of high flood. This is exactly the arrangement of the modern bridge at Môṣul. The castle of the ’Ashiḳ consists of a great enclosure, 123 metres from north to south and 85 metres from east to west, surrounded by a wall with round bastions which are set upon a rectangular base (Fig. 146). All the buildings that may have stood within the wall have vanished, but adjoining the north wall there are remains of a gatehouse consisting of five parallel chambers opening on to a corridor or platform. The chambers and the corridor are built upon a substructure of vaults. Under the corridor the vaults run from east to west, except in the central part where the vault running from north to south is a continuation of the vault under the central chamber. Under the five chambers all the vaults run from north to south.[134] The vaults are built of flat tiles laid in slices against the head-wall without centering. They have the usual small set forward from the wall, but in one case, perhaps in more than one, there is a slight divergence from the customary arrangement. From the spring of the vault the tiles are laid horizontally for the first sixteen or seventeen courses, projecting forward so as to form a shallow curve; [Illustration: FIG. 148.--EL ’ASHIḲ, DETAIL OF NICHING ON NORTH FAÇADE.]