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JULY, 1915)
THE DOME IN PERSIA
135
largest in the world, Roman dome construction reached its zenith and then almost died out. Few are the domes in Roman architecture, and as Fergusson remarks "So far as I know all the domed buildings erected by the Romans up to the time of Constantine, and indeed long afterwards, were circular in the interior, though, like the temple built by Diocletian at Spalatro, they were sometimes octagonal externally." One thing, a satisfactory pendentive, was warted, before domed construction could come to its own.
In the case of the domes on the bas-relief found by Layard, which I have already mentioned, the setting at the angles was no doubt as unsatisfactory as in the Egyptian examples referred to by Prof. Petrie, and quite impossible on a large scale.
Now it seems to me that the Persians, who were the first people to solve this problem, and devise a satisfactory pendentive, played for this reason a very important, in fact vital, part in the evolution of domical construction.
We will now consider the two earliest domed buildings in Persia, namely the palaces of Firûzâbâd and Sarvistån. I put Firůzâbâd first, contrary to the usual order, for reasons which I shall give later. At Firůzâbâd we see the dome applied on a large scale for the first time, this dome being 45 feet in diameter, and we see also the means by which this setting of a really large dome over a square space became possible, viz: by means of a squinch, a device wholly Persian. By the squinch, which here consists of a series of concentric arches, thrown across the angle, and advancing one over the other, the square is reduced to an octagon, upon which it is easy to set a dome (Fig. 3). It is impossible to overrate the importance of this discovery, which did for the East what the Byzantine pendentive did for the Wesů. By it Persia, so to speak, ennobled the dome, raising it to the very front
Fig. 3. rank as a method of roofing, a position it has kept in Persia ever since. In fact I think I may make this generalization, that Persia is the land of the dome, whereas Mesopotamia is the land of the vault. Thus while in Persia we have these two palaces in which the dome plays a conspicuous part, in Mesopotamia we have the palaces of Al Hadra (or Hatra) and Tak Kisra where the vault alone is found. Later in the palace of Mashita, in the 8th century palace of Ukhaidir and at Kasr Kharâneh this is also the case and even in the 9th century Bait-ul-Khalifah at Rakka. In all these buildings the vault is employed to the complete exclusion of the dome. These two palaces Firûzâbâd and Sarvistân, are attributed to the Sasanian period by all authorities on the subject with the single exception of Dieulafoy, who, in his work, “L'Art antique de la Perse", attributes them to the Achaemenian age.
* Ferguson (James), Handbook of Architecture, London, 1859, p. 346.
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