He further noticed that on the floors of the chambers, in various parts of the palace, there had been discovered stone rollers closely resembling those still in use at Mosul and Baghdad, for keeping close-pressed and hard the earthen surface of such roofs; which rollers had, in all probability, been applied to the same use by the Assyrians, and, being kept on the roofs, had fallen through during the conflagration.
The first difficulty which presented itself here was one of those regarded as most fatal to the vaulting theory, namely, the width of the chambers.

Where flat timber roofs prevail in the East, their span seems never to exceed twenty-five feet.

The ordinary chambers in the Assyrian palaces might, undoubtedly, therefore, have been roofed in this way, by a series of horizontal beans laid across them from side to side, with the ends resting upon the tops of the side walls.

But the great halls seemed too wide to have borne such a roofing without supports.
Accordingly, M.Botts suggested that in the greater apartments a single or a double row of pillars ran down the middle, reaching to the roof and sustaining it.

His theory was afterwards warmly embraced by Mr.
Fergusson, who endeavored to point out the exact position of the pillars in the three great halls of Sargon at Khorsabad.