The arrangement of the west wing of the three-storied block is dissimilar from that of the east wing. Three chambers, 8, 9, and 10, lie to the west of the great hall. They have an average width of 3·70 metres, but in length they are only 5·75 metres. They are lighted by small windows high up in the west wall. They communicate with one another by doors covered with ovoid arches set back from the jambs, and with the great hall by small doors in the recesses. The vaults are pointed and oversail the walls. South of No. 10, a stair leads up from the southernmost doorway in the great hall to the first floor. The vault over this stair, of which I give a photograph (Plate 16, Fig. 2), will serve to illustrate the construction of all vaults at Ukhaiḍir over an inclined plane. They are built in horizontal sections, which form inverted steps; an unbroken rising vault is not to be found in the palace. To the east of this group of rooms with its stair is the cloistered court which I suggested, after my first visit, might be a mosque.[21] The suggestion has been borne out by the discovery of an arched niche in the south wall, which I believe to be the miḥrâb.[22] The mosque (since I may now give it this title without hesitation) is approached by two doorways from the west corridor, 5. These doorways lead into an open rectangular court, the ṣaḥn, 10·30 metres from north to south by 16 metres from east to west. To east, south, and west of the court ran porticoes, or riwâqs, to use their Arabic name, which have now fallen (Plate 18, Fig. 1). The engaged columns on the north side and the south-east angle pier are, however, standing, and they determine the width of the riwâqs. The southern riwâq was the widest (4·05 metres), and this is the portion of the mosque which is known as the ḥaram. The east and west riwâqs are alike 3 metres wide. The arcades, which separate the riwâqs from the ṣaḥn, occupy a space 1 metre thick. On the west side the arcade is entirely ruined, but on the east side part of the arches at either end are still to be seen (Plate 19, Figs. 1 and 2). From these fragments it is apparent that there must have been three arches on the east and west sides, while approximately similar proportions would allow five arches on the south side. (The span of the south arches must have been about ·30 metre less than the span of the east and west arches.) The north end of the east and west vaults rested against the north wall, the south end against a transverse arch, in order to avoid intersection with the vault of the ḥaram. The east vault, which is best preserved, is a slightly pointed ovoid and oversails the east wall. Below the spring of the vault can be seen the windows of rooms 8 and 9; the window of room 10 opens into the ḥaram. Immediately above the springing of the vault there are three holes for cross beams, the decay of which has entailed the ruin of the vault. The fallen masses