Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/833

Rh ARCHEOLOGY.] ROME 809 small cornices and other mouldings in interiors of buildings. Its quarries in Greece are still worked. (The largest pieces known are the fourteen steps to the high altar of S. Prassede and two columns nearly 12 feet high in the Rospigliosi Casino dell' Aurora.) (7) Nero antico is probably the ancient marmor Tsenarium, from Cape Ttenarus in Sparta. It is mentioned by Tibullus (iii. 3, 14) in con- junction with Phrygian and Carystian marbles; see also Prop., iii. 2, and Plin., H.N., xxxvi. 43. (Ex., two columns in the choir of the church of Ara Cceli.) (8) Lapis Atracius (verde antico), found at Atrax in Thessaly (Liv., xxxii. 15), was one of the favourite materials for decorative architecture; it is not strictly a marble (i.e., a calcareous stone) but a variety of "precious serpentine," with patches of white and brown on a brilliant green ground. It seldom occurs in large masses. (The finest known specimens arc the twenty -four columns beside the niches in the nave of the Lateran basilica.) (9) The hard Oriental alabaster, the "onyx" or " alabastrites " of Pliny (H. N., xxxvi. 12, xxxvii. 32); its chief quarries were on the Nile near Thebes, 1 in Arabia, and near Damascus. In Pliny's age it was a great rarity; but in later times it was introduced in large quantities, and fragments of a great many columns have been found on the Palatine, in the baths of Caracalla, and elsewhere. It is semi-transparent, and beautifully marked with concentric nodules and wavy strata. An immense number of other less common marbles have been found, including many varieties of breccia, but their ancient names are unknown. Qlrites From the latter part of the 1st century B.C. hard stones granites aa and basalts were introduced in great quantities. The basalts Mlts. " basanites " of Pliny (xxxvi. 11) are very refractory, and can only be worked by the help of emery or diamond dust. The former was obtained largely at Naxos; diamond-dust drills are mentioned by Pliny (H.N., xxxvii. 76). The basalts are black, green, and brown, and are usually free from spots or markings; examples of all three exist, but are comparatively rare. The red variety called "por- phyry " was used in enormous quantities. It is the " porphyrites " of Pliny (H.N., xxxvi. 11), and was brought from Egypt. It has a rich red ground, covered with small specks of white felspar; hence it was also called "leptopsephos." A large number of columns of it exist, and it was much used for pavements of opus Alexandrinum. A rich green porphyry or basalt was also largely used, but not in such great masses as the red porphyry. It has a brilliant green ground covered with rectangular light green crystals of felspar. This is the lapis Laced&monius (wrongly called by the modern Romans " serpentino "), so named from its quarries in Mount Taygetus in Lacedsemonia (Paus., Lac., iii. and viii.; Plin., H.N., xxxvi. 11; Juv., xi. 173). It appears to have been mostly used for pavements and panels of wall linings. The granites used in Rome came mostly from near Philae on the Nile (Plin., H.N., xxxvi. 13). The red sort was called lapis pyrrhopcecilus and the grey lapis psaronius. The columns in the Basilica Ulpia are a fine example of the latter; both sorts are used for the columns of the Pantheon and those of the temple of Saturn in the Fomm. Gigantic ships were specially made to carry the obelisks and other great monoliths (Plin., H.N., xxxvi. 1, 14). Ahi- The style of architecture employed in ancient Rome may be said Kural to have passed through three stages, the Etruscan, the Greek, and stes- the Roman. During the first few centuries of the existence of the city, both the methods of construction and the designs employed appear to have been purely Etruscan. The earliest temples were either simple cellse without columns, as we see on the Palatine by the Scalre Caci, or else, in the case of the grander temples, such as that of Capitoline Jupiter, the columns were very widely spaced (arseostyle), and consequently had entablatures of wooden beams. The architectural decorations were more generally in gilt bronze or painted terra-cotta than in stone, and the paintings or statues which decorated the buildings were usually the work of Etruscan artists. 2 The Greek influence is more obvious; almost all the temples of the earlier imperial age are Greek, with certain modifi- cations, not only in general design but in details and ornaments. Greek architects were largely employed; and Roman architects such as Vitruvius and C. Mutius in the 1st century B.C., Severus and Celer under Nero, and Rabirius under Domitian were Greek by education, and probably studied at Athens (see Vitr., vii., Prsef.; Hirt, Gesch. d. Baukunst, ii. p. 257; Burn, Rome, p. 76). 3 The Romans, however, though quite devoid of artistic originality, were 1 These Nile quarries have been worked during the present century, and many blocks were imported into Rome for the rebuilding of S. Paolo fuori le Mura. 2 Pliny (H.N., xxxv. 45), quoting Varro, says that the decorations in paint- ing and sculpture of the temple of Ceres near the Circus Maximus (now 8. Maria in Cosmedin) were the work of the first Greek artists employed in Rome, and that before that (c. 493 B.C.) "all things in temples were Etruscan." Vitruvius (iii. 3) says, " Oruantque signis flctilibus aut sereis inauratis earum fastigia Tuscanico more, uti est ad Circum Maximum Cereris, et Herculis Pompeiani, item Capitolii " (comp. iv. 7, vi. 3). 3 The frequent use of engaged columns is a peculiarity of Roman architec- ture, but it is not without precedent in Greek buildings of the best period, e.g., in the lion-tomb at Cnidus and the temple of Zeus at Agrigentum. Sur- face enrichments over the mouldings were used far more largely by the Romans than by the Greeks. very able engineers, and this led to the development of a new and more purely Roman style, in which the restrictions imposed by the use of the stone lintel were put aside and large spaces were covered with vaults and domes cast in semifluid concrete, a method which had the enormous advantage of giving the arched form without the constant thrust at the springing which makes true arches or vaults of wide span so difficult to deal with. The enormous vaults of the great thermse, the basilica of Constantine, and the like cover their spaces with one solid mass like a metal lid, giving the form but not the principle of the arch, and thus allowing the vault to be set on walls which would at -once have been thrust apart had they been subjected to the immense leverage which a true arched vault con- stantly exerts on its imposts. 4 This is a very important point, and one which is usually overlooked, mainly owing to the Roman prac- tice of facing their concrete with bricks, which (from an examina- tion of the surface only) appear to be a principal item in the con- struction. The walls of the Pantheon, for example, are covered with tiers of brick arches, and many theories have been invented as to their use in distributing the weight of the walls. But a re- cognition of the fact that these walls are of concrete about 20 feet thick, while the brick facing averages scarcely 6 inches in thickness, clearly shows that these ' ' relieving arches " have no more con- structional use as far as concerns the pressure than if they were painted on the surface of the walls. Exactly the same reasons apply to the superficial use of brick in all arches and vaults. At first tufa only was used in opus quadrature, as we see in the Opus so-called wall of Romulus. Next the harder peperino began to be quad- worked : it is used, though sparingly, in the great Servian wall, ratum. and during the later republic appears to have been largely employed for exterior walls or points where there was heavy pressure, while other parts were built of tufa. Thirdly, travertine appears to have been introduced about the 2d century B.C., but was used at first for merely ornamental purposes, very much as marble was under the ' empire; after about the middle of the 1st century A.D. travertine began to be largely used for tl of Vespasian and the Colosseum. The tufa or peperino blocks were roughly 2 (Ro- man) feet thick in regular courses, iso- domum, by 2 feet across the end, and under the republic often exactly 4 feet long, so that two blocks set endways ranged with one set lengthways. They were then arranged in alternate courses of headers and stretchers, so as to make a good bond; this is the "em- plecton" of Vitruvius (ii. 8). The so-called Tabularium of the Capitol is a good example of this (see fig. 1). The harder and more valuable travertine was not cut in this regular TRAVERTINE way, but pieces of all i7p<s WPTP ii<;prl iii<st sizes were used, just as they happened to come from the rmnTTv in mvW tn quarry, 11 oroer TO avoid waste : blocks ass of walls, as in the temple TUFA ROCK J.ATER LEVEL FIG. 1. Example of opus quadratum, 78 B.C. Arch at foot of the stairs of the Tabularium (see Plate VI.). The flat arch C is of travertine, the rest of peperino. A. Footing-course of rough stones. B. Concrete foundation, exposed by the lowering of the paving when the temple of Vespasian was built. as much as 15 by 8 feet were used, and the courses varied in thickness the " pseudisodomum " of Vitruvius. When tufa or peperino was mixed with' the travertine, it was cut so as to range with the irregular courses of the latter. It is an interesting point to note the manner in which the Roman builders mixed their different materials according to the weight they had to carry. While tufa was frequently used for the main walls, peperino (e.g., in the Servian wall on the Aventine) or travertine (e.g., in the forum of Augustus and the temple of For- tuna Virilis, so called) was inserted at points of special pressure, such as piers or arches (see fig. 21 below). The Colosseum is a particularly elaborate example of this mixed construction with three degrees of pressure supported by three different materials (see fig. 2). _ __ 1873) the structural importance of the brick used in vaults and arches is very much exaggerated. XX. 102
 * In the beautiful drawings of Choisy (L'Art de Ititir chez les Remains, Paris,