To the south of the east corridor runs a vaulted ramp, a sloping passage from the great hall to the first floor. To the south of the ramp lie two groups of three vaulted chambers. In the inner group, Nos. 12, 13, and 14, the rooms are 7 metres long with an average width of 3·50 metres. They are separated from each other by walls 1 metre thick, and communicate with each other by doors covered by ovoid arches set back from the jambs. Each room possesses a door into the great hall, but since the position of these doors is determined by that of the recesses in the hall, which do not correspond with the rooms behind them, the doors are never in the centre of the rooms, and in one case, No. 13, the side wall is narrowed to allow space for the door. The wall which separates the rooms from the recesses of the great hall is 1·50 metres thick. A door at the east end of each room leads into the corresponding room of the second group. In this group the rooms 15, 16, and 17, while they have the same width as those of the first group, are considerably shorter, measuring only 4·80 metres. They communicate with each other and with the vaulted passage, 20. Room 17 has further a door in the north wall, which leads into the small vaulted room, No. 18, and this in turn is connected with a still smaller room, No. 19. Nos. 18 and 19 lie under the ramp, and No. 19 is in consequence extremely low. None of the chambers above described are provided with windows; what light they possess filters in through the doors. Nos. 12, 13, and 14 are therefore exceedingly dark, and must have been darker still when the south wall of the great hall was intact. Nos. 18 and 19 are totally unillumined, and for this reason, and on account of the inconvenience of their low vaults, it may be presumed that they were not used for dwelling purposes. [Illustration: FIG. 3. Arch construction. (From _Ocheïdir_, by kind permission of Dr. Reuther.)] The arches of the doorways in these rooms, and in all other small doorways in the palace, are constructed in a manner different from that which has been detailed above. Again I borrow the description from Dr. Reuther. A wooden centering has been placed upon the jambs; over this centering was laid a band of gypsum mortar and small stones, irregularly bedded, which, when it hardened, formed an inner arch of concrete (Fig. 3). When the span was narrow no other arch was considered necessary. When it was wider an outer arch of voussoirs laid horizontally encompassed the inner concrete arch. Not infrequently, besides the wooden centering, a permanent centering of mortar and reed was placed on either face of the concrete arch. When the wooden centering was removed the concrete arch remained, set back from the jambs, whereas in all the wide archways, such as those of room 4, the arch follows the principle of the vault and oversails the wall.