Bk. XI. Ch. II. CHURCHES WITH STONE ROOFS. 429 basilicas and the temples of the classical age. The Romans, however, had built temples with aisles and vaulted them as early as the age of Augustus, as at Nnues, for instance (Woodcut No. 189), and they had roofed their largest basilicas and batlis with intersecting vaults. We should not therefore feel surprised if the Christians sometimes attempted the same thing in their rectangular churches, more espe- cially as the dome was always a favorite mode of roofing circular buildings ; and the problem which the Byzantine arcliitects of the day set themselves to solve was — as we shall j^resently see — how to fit a circular dome of masonry to a rectangular building. One of the earliest examples of a stone-roofed church is that at Tafkha in the Hauran. It is probably of the age of Constantine, WA « 860. Section A B, Tafkha. (From De Vogue.) Scale 50 ft. to 1 iii. 861. Plan, Tafkha. Scale 100 ft. to 1 in. 862. Section on C D, Tafkha. 863. Halt Front Elevation, Tafkha. Scale 50 ft. to 1 in. though as likely to be before his time as after it. Its date, however, is not of very great importance, as its existence does not prove that the form was adopted from choice by the Christians : the truth being that, in the country where it is found, wood was never used as a l)uilding material. All the buildings, botli domestic and public, are composed wholly of stone — the only available material for the purpose which the country afforded. In consequence of tliis, when that tide of commercial prosperity which rose under the Roman rule flowed across the country from the Euphrates valley to the Mediterranean, the inhabitants had recourse to a new mode of construction, which was practically a new style of architecture. This consisted in the employment of arches instead of beams. These were placed so near one another that flat stones could be laid side by side from arch to arch. Over these a layer of concrete was spread, and a roof was thus
