Chap. IV.
ROMAN.
97
Siliceous stones , or what are called selce by the ancients, cannot be understood to meanthe same as those so designated by mineralogists of the present day : those have an ironcolour, are very hard, and are basaltic, and used only for street paving. Near the sepulchreof Cecilia Metella, on the Via Appia , and many other localities, it was abundantlyfound.
Pumice, brought from the vicinity of Vesuvius , was used in the vaults of the Coliseum,and in the palace of the Caesars, the dome of the Pantheon, &c.
The most ancient edifices of Rome were constructed of the Albano stone, put togetherwith metal cramps. Alba being the first important conquest made by the Romans, it wasmost likely they would employ the ex-cellent material found in that neighbour-hood, which had become a portion of theirdominions, in preference to seeking for itout of their territory. This stone wasused not only under their kings, but alsoafter the decline of their republic. TheMammertine prison, built under AncusMartius, and the Cloaca Maxima , underthe Tarquins ; the walls of Servius, re-maining near the Quirinal ; all that por-tion of the tombs of the Scipios not tufa,or which have not been restored ; oneof the three temples of S. Nicola in Car-cere ; the substruction of the Capitol;the aqueducts of Appius, Old Anio,and the Marcian , are all built of it.
After the conquest of Tivoli, in the yearof Rome 417, the travertine stone was introduced, and used in conjunction with that ofAlbano, and from its greater hardness was better suited to those portions of an edifice most
liable to injury, as arches, architraves, cornices, &c., as seen in the remains of the Vivarium.In the Tabularium we find it in the Doric capitals, the architraves, and imposts of the in-ternal arches : in the temple of Fortuna Virilis the isolated columns are formed of it, asare also the Doric and one of the Ionic temples of St. Nicola in Carcere, the arch ofDolabella on the Caelian Mount, the fayade of the Mammertine prison, which bears the nameof the consuls C. Vibio Ruffinus and M. C. Nerva, who restored it.
Under the kings, and during the republic, it appears from the remains, that thepublic buildings were usuallv of squared stone ( fig. 115.); but on the decline of the republic,
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