Chap. IV.
HOMAN.
93
called into use were brought from distant parts of Italy or the provinces, as the marbles,granites, and porphyries.
Vitruvius treats of bricks, but confines himself to the description of those which areunburnt. Scainmozzi imagined that the houses in Rome were originally built of unburntbrick, and that none are found, he observes, is in consequence of the frequent fires that citywas subject to, which had the effect of thoroughly burning them. Pliny (lib. vii. cap. 56.)mentions unburnt bricks as having been in use. Gellio Doxius, son of Ccelus, was theinventor of clay houses, taking the example from the nests of swallows. Burnt brickscame into very general use for public buildings about the time of Augustus , continuedtill the fall of the empire, and were considered as durable and solid as stone.
Bricks have undergone various changes, not only in form and colour, but also in the man-ner in which they were employed. In the time of Augustus , they were made of a red earth,less than an inch in thickness, of atriangular shape ; they were not equi-lateral, as the base was the longest side.
Such bricks may be seen in the gardensof Sallust, the house of Augustus , andother buildings erected in the time ofTiberius . In the praetorian camp atPreneste they were rather thicker, andof a deeper red colour, or mixed withyellow. In the time of Nero , thesecolours were generally united, as maybe seen in the aqueduct constructedin his time, near the Porta Maggiore ,where the bricks are somewhat thinnerthan those used in the time of Au-gustus or Tiberius ; they were alsothicker at the base, that the face mightallow the edges almost to touch, andnot show any joint or mortar. Thewalls, built of brick, by Augustus andTiberius , show a joint of mortar almostequal to the thickness of the brick.
Palatine, and on the Palatine itself, though of the time of Nero , have large joints, andare not so regularly laid.
Of the time of Vespasian and his successors, we have brick constructions, as in the Coli-seum, the baths of Titus, and the villa of Domitian at Albano, all of which have more ofthe Augustan workmanship than that of the time of Nero . The remains belonging to thetime of Trajan, on the Quirinal , and called the baths of Paulus Emilius, and the villaof Adrian, prove that the same style was adopted. In the buildings constructedat the latter period of these reigns, bricks are mixed with the opus reticulatum;although there is an evident decline in the taste and execution of the ornaments in the timeof Caracalla , the construction was excellent. One of the best examples is the wall at theback of the great central hall of that emperor’s baths. After this period, the constructiondeclined in excellence, bricks were made of various thicknesses, and the quantity of mortarwas increased. There are scarcely any remains of brick construction between the times ofCaracalla and Diocletian ; the walls of Rome, usually attributed to Aurelian , probablybelong to Honorius , as we learn from the inscription remaining over the gate of St. Lo-renzo, as well as from a passage in Claudian , which affirms such to have been the case.Hie baths of Diocletian show a falling off, not only in style, but in construction, whichrapidly deteriorated ; in the basilica of Constantine, erected on the Via Sacra , in the time ofMaxentius, and the baths of Constantine, on the Quirinal , we see still greater negligencein the selection of materials, with an inferiority of workmanship.
After this period, from economy, or desire to save bricks, a mixed construction ofbricks and tufa was introduced, as in the restoration of the tomb of the Scipios, in the circuscalled Caracalla ’s, though of a date much posterior to that emperor ; the ruins adjoining tothat circus ; and the hippodrome of Constantine on the Via Nomentana . 'Hie basilica? andchurches founded in the fourth, fifth, and sixth centuries, as those of S. Croce in Gerusa-leme, S. Giovanni e Paolo, &c. &c., show the same poverty of construction, irregular bricksbeing used with quantities of mortar of an inferior quality. With the decline of Romaninstitutions, the art of construction lost its excellence; no care was taken in the selection ofthe materials, but those purloined from other edifices were indiscriminately employed. Forbricks, they used stone of a similar shape, tufa, pepperino, and a variety of other ma-terials ; which practice was adopted at Rome in all the constructions till the end of thefourteenth century, and which has been denominated Saracenic work.
The bricks which Vitruvius describes as unburnt were formed of white earth or chalk,