A Text-Book of the History of Architecture Part 7

[Ill.u.s.tration: FIG. 47.--GROINED VAULT.

_g, g_, _Groins._]

The groined vault is formed by the intersection of two barrel-vaults (Fig. 47). When several compartments of groined vaulting are placed together over an oblong plan, a double advantage is secured. Lateral windows can be carried up to the full height of the vaulting instead of being stopped below its springing; and the weight and thrust of the vaulting are concentrated upon a number of isolated points instead of being exerted along the whole extent of the side walls, as with the barrel-vault. The Romans saw that it was sufficient to dispose the masonry at these points in ma.s.ses at right angles to the length of the hall, to best resist the lateral thrust of the vault. This appears clearly in the plan of the Basilica of Constantine (Fig. 58).

The dome was in almost all Roman examples supported on a circular wall built up from the ground, as in the Pantheon (Fig. 54). The pendentive dome, sustained by four or eight arches over a square or octagonal plan, is not found in true Roman buildings.

The Romans made of the vault something more than a mere constructive device. It became in their hands an element of interior effect at least equally important with the arch and column. No style of architecture has ever evolved n.o.bler forms of ceiling than the groined vault and the dome. Moreover, the use of vaulting made possible effects of unenc.u.mbered s.p.a.ciousness and amplitude which could never be compa.s.sed by any combination of piers and columns. It also a.s.sured to the Roman monuments a duration and a freedom from danger of destruction by fire impossible with any wooden-roofed architecture, however n.o.ble its form or careful its execution.

+CONSTRUCTION.+ The constructive methods of the Romans varied with the conditions and resources of different provinces, but were everywhere dominated by the same practical spirit. Their vaulted architecture demanded for the support of its enormous weights and for resistance to its disruptive thrusts, piers and b.u.t.tresses of great ma.s.s. To construct these wholly of cut stone appeared preposterous and wasteful to the Roman. Italy abounds in clay, lime, and a volcanic product, _pozzolana_ (from Puteoli or Pozzuoli, where it has always been obtained in large quant.i.ties), which makes an admirable hydraulic cement. With these materials it was possible to employ unskilled labor for the great bulk of this ma.s.sive masonry, and to erect with the greatest rapidity and in the most economical manner those stupendous piles which, even in their ruin, excite the admiration of every beholder.

[Ill.u.s.tration: FIG. 48.--ROMAN WALL MASONRY.

a, _Brickwork_; b, _Tufa ashlar_; r, _Opus reticulatum_; i, _Opus incertum_.]

+STONE, CONCRETE, AND BRICK MASONRY.+ For buildings of an externally decorative character such as temples, arches of triumph, and amphitheatres, as well as in all places where brick and concrete were not easily obtained, stone was employed. The walls were built by laying up the inner and outer faces in _ashlar_ or cut stone, and filling in the intermediate s.p.a.ce with rubble (random masonry of uncut stone) laid up in cement, or with concrete of broken stone and cement dumped into the s.p.a.ce in successive layers. The cement converted the whole into a conglomerate closely united with the face-masonry. In Syria and Egypt the local preference for stones of enormous size was gratified, and even surpa.s.sed, as in Herod's terrace-walls for the temple at Jerusalem (p. 41), and in the splendid structures of Palmyra and Baalbec. In Italy, however, stones of moderate size were preferred, and when blocks of unusual dimensions occur, they are in many cases marked with false joints, dividing them into apparently smaller blocks, lest they should dwarf the building by their large scale. The general use in the Augustan period of marble for a decorative lining or wainscot in interiors led in time to the objectionable practice of coating buildings of concrete with an apparel of sham marble masonry, by carving false joints upon an external veneer of thin slabs of that material. Ordinary concrete walls were frequently faced with small blocks of tufa, called, according to the manner of its application, _opus reticulatum_, _opus incertum_, _opus spicatum_, etc. (Fig. 48). In most cases, however, the facing was of carefully executed brickwork, covered sometimes by a coating of stucco. The bricks were large, measuring from one to two feet square where used for quoins or arches, but triangular where they served only as facings. Bricks were also used in the construction of skeleton ribs for concrete vaults of large span.

+VAULTING.+ Here, as in the wall-masonry, economy and common sense devised methods extremely simple for accomplis.h.i.+ng vast designs. While the smaller vaults were, so to speak, cast in concrete upon moulds made of rough boards, the enormous weight of the larger vaults precluded their being supported, while drying or "setting," upon timber centrings built up from the ground. Accordingly, a skeleton of light ribs was first built on wooden centrings, and these ribs, when firmly "set,"

became themselves supports for intermediate centrings on which to cast the concrete fillings between the ribs. The whole vault, once hardened, formed really a monolithic curved lintel, exerting no thrust whatever, so that the extraordinary precautions against lateral disruption practised by the Romans were, in fact, in many cases quite superfluous.

+DECORATION.+ The temple of Castor and Pollux in the Forum (long miscalled the temple of Jupiter Stator), is a typical example of Roman architectural decoration, in which richness was preferred to the subtler refinements of design (see Fig. 44). The splendid figure-sculpture which adorned the Greek monuments would have been inappropriate on the theatres and thermae of Rome or the provinces, even had there been the taste or the skill to produce it. Conventional carved ornament was subst.i.tuted in its place, and developed into a splendid system of highly decorative forms. Two princ.i.p.al elements appear in this decoration--the acanthus-leaf, as the basis of a whole series of wonderfully varied motives; and symbolism, represented princ.i.p.ally by what are technically termed _grotesques_--incongruous combinations of natural forms, as when an infant's body terminates in a bunch of foliage (Fig. 49). Only to a limited extent do we find true sculpture employed as decoration, and that mainly for triumphal arches or memorial columns.

[Ill.u.s.tration: FIG. 49--ROMAN CARVED ORNAMENT.

(Lateran Museum.)]

The architectural mouldings were nearly always carved, the Greek water-leaf and egg-and-dart forming the basis of most of the enrichments; but these were greatly elaborated and treated with more minute detail than the Greek prototypes. Friezes and bands were commonly ornamented with the foliated scroll or _rinceau_ (a convenient French term for which we have no equivalent). This motive was as characteristic of Roman art as the anthemion was of the Greek. It consists of a continuous stem throwing out alternately on either side branches which curl into spirals and are richly adorned with rosettes, acanthus-leaves, scrolls, tendrils, and blossoms. In the best examples the detail was modelled with great care and minuteness, and the motive itself was treated with extraordinary variety and fertility of invention. A derived and enriched form of the anthemion was sometimes used for bands and friezes; and grotesques, dolphins, griffins, infant genii, wreaths, festoons, ribbons, eagles, and masks are also common features in Roman relief carving.

[Ill.u.s.tration: FIG. 50.--ROMAN CEILING PANELS.

(a, From Palmyra; b, Basilica of Constantine.)]

The Romans made great use of panelling and of moulded plaster in their interior decoration, especially for ceilings. The panelling of domes and vaults was usually roughly shaped in their first construction and finished afterward in stucco with rich moulding and rosettes. The panels were not always square or rectangular, as in Greek ceilings, but of various geometric forms in pleasing combinations (Fig. 50). In works of a small scale the panels and decorations were wrought in relief in a heavy coating of plaster applied to the finished structure, and these stucco reliefs are among the most refined and charming products of Roman art. (Baths of t.i.tus; Baths at Pompeii; Palace of the Caesars and tombs at Rome.)

+COLOR DECORATION.+ Plaster was also used as a ground for painting, executed in distemper or by the encaustic process, wax liquefied by a hot iron being the medium for applying the color in the latter case.

Pompeii and Herculaneum furnish countless examples of brilliant wall-painting in which strong primary colors form the ground, and a semi-naturalistic, semi-fantastic representation of figures, architecture and landscape is mingled with festoons, vines, and purely conventional ornament. Mosaic was also employed to decorate floors and wall-s.p.a.ces, and sometimes for ceilings.[13] The later imperial baths and palaces were especially rich in mosaic of the kind called opus Grecanic.u.m, executed with numberless minute cubes of stone or gla.s.s, as in the Baths of Caracalla and the Villa of Hadrian at Tivoli.

[Footnote 13: See Van d.y.k.e's _History of Paintings_, p. 33.]

To the walls of monumental interiors, such as temples, basilicas, and thermae, splendor of color was given by veneering them with thin slabs of rare and richly colored marble. No limit seems to have been placed upon the costliness or amount of these precious materials. Byzantine architecture borrowed from this practice its system of interior color decoration.

CHAPTER IX.

ROMAN ARCHITECTURE--_Continued_.

BOOKS RECOMMENDED: Same as for Chapter VIII. Also, Guhl and Kohner, _Life of the Ancient Greeks and Romans_. Adams, _Ruins of the Palace of Spalato_. Burn, _Rome and the Campagna_. Cameron, _Roman Baths_. Mau, tr. by Kelcey, _Pompeii, its Life and Art_.

Mazois, _Ruines de Pompeii_. Von Presuhn, _Die neueste Ausgrabungen zu Pompeii_. Wood, _Ruins of Palmyra and Baalbec_.

+THE ETRUSCAN STYLE.+ Although the first Greek architects were employed in Rome as early as 493 B.C., the architecture of the Republic was practically Etruscan until nearly 100 B.C. Its monuments, consisting mainly of city walls, tombs, and temples, are all marked by a general uncouthness of detail, denoting a lack of artistic refinement, but they display considerable constructive skill. In the Etruscan walls we meet with both polygonal and regularly coursed masonry; in both kinds the true arch appears as the almost universal form for gates and openings.

A famous example is the Augustan Gate at Perugia, a late work rebuilt about 40 B.C., but thoroughly Etruscan in style. At Volaterrae (Volterra) is another arched gate, and in Perugia fragments of still another appear built into the modern walls.

The Etruscans built both structural and excavated tombs; they consisted in general of a single chamber with a slightly arched or gabled roof, supported in the larger tombs on heavy square piers. The interiors were covered with pictures; externally there was little ornament except about the gable and doorway. The latter had a stepped or moulded frame with curious _crossettes_ or ears projecting laterally at the top. The gable recalled the wooden roofs of Etruscan temples, but was coa.r.s.e in detail, especially in its mouldings. Sepulchral monuments of other types are also met with, such as _cippi_ or memorial pillars, sometimes in groups of five on a single pedestal (tomb at Albano).

Among the temples of Etruscan style that of +Jupiter Capitolinus+ on the Capitol at Rome, destroyed by fire in 80 B.C., was the chief. Three narrow chambers side by side formed a cella nearly square in plan, preceded by a hexastyle porch of huge Doric, or rather Tuscan, columns arranged in three aisles, widely s.p.a.ced and carrying ponderous wooden architraves. The roof was of wood; the cymatium and ornaments, as well as the statues in the pediment, were of terra-cotta, painted and gilded.

The details in general showed acquaintance with Greek models, which appeared in debased and awkward imitations of triglyphs, cornices, antefixae, etc.

[Ill.u.s.tration: FIG. 51.--TEMPLE FORTUNA VIRILIS. PLAN.]

+GREEK STYLE.+ The victories of Marcellus at Syracuse, 212 B.C., Fabius Maximus at Tarentum (209 B.C.), Flaminius (196 B.C.), Mummius (146 B.C.), Sulla (86 B.C.), and others in the various Greek provinces, steadily increased the vogue of Greek architecture and the number of Greek artists in Rome. The temples of the last two centuries B.C., and some of earlier date, though still Etruscan in plan, were in many cases strongly Greek in the character of their details. A few have remained to our time in tolerable preservation. The temple of +Fortuna Virilis+ (really of Fors Fortuna), of the second century (?) B.C., is a tetrastyle prostyle pseudoperipteral temple with a high _podium_ or base, a typical Etruscan cella, and a deep porch, now walled up, but thoroughly Greek in the elegant details of its Ionic order (Fig. 51).

Two circular temples, both called erroneously +Temples of Vesta+, one at Rome near the Cloaca Maxima, the other at Tivoli, belong among the monuments of Greek style. The first was probably dedicated to Hercules, the second probably to the Sibyls; the latter being much the better preserved of the two. Both were surrounded by peristyles of eighteen Corinthian columns, and probably covered by domical roofs with gilded bronze tiles. The Corinthian order appears here complete with its modillion cornice, but the crispness of the detail and the fineness of the execution are Greek and not Roman. These temples date from about 72 B.C., though the one at Rome was probably rebuilt in the first century A.D. (Fig. 52).

[Ill.u.s.tration: FIG. 52.--CIRCULAR TEMPLE. TIVOLI.]

+IMPERIAL ARCHITECTURE; AUGUSTAN AGE.+ Even in the temples of Greek style Roman conceptions of plan and composition are dominant. The Greek architect was not free to reproduce textually Greek designs or details, however strongly he might impress with the Greek character whatever he touched. The demands of imperial splendor and the building of great edifices of varied form and complex structure, like the thermae and amphitheatres, called for new adaptations and combinations of planning and engineering. The reign of Augustus (27 B.C.-14 A.D.) inaugurated the imperial epoch, but many works erected before and after his reign properly belong to the Augustan age by right of style. In general, we find in the works of this period the happiest combination of Greek refinement with Roman splendor. It was in this period that Rome first a.s.sumed the aspect of an opulent and splendid metropolis, though the way had been prepared for this by the regularization and adornment of the Roman Forum and the erection of many temples, basilicas, fora, arches, and theatres during the generation preceding the accession of Augustus.

His reign saw the inception or completion of the portico of Octavia, the Augustan forum, the Septa Julia, the first Pantheon, the adjoining Thermae of Agrippa, the theatre of Marcellus, the first of the imperial palaces on the Palatine, and a long list of temples, including those of the Dioscuri (Castor and Pollux), of Mars Ultor, of Jupiter Tonans on the Capitol, and others in the provinces; besides colonnades, statues, arches, and other embellishments almost without number.

+LATER IMPERIAL WORKS.+ With the successors of Augustus splendor increased to almost fabulous limits, as, for instance, in the vast extent and the prodigality of ivory and gold in the famous Golden House of Nero. After the great fire in Rome, presumably kindled by the agents of this emperor, a more regular and monumental system of street-planning and building was introduced, and the first munic.i.p.al building-law was decreed by him. To the reign of Vespasian (68-79 A.D.) we owe the rebuilding in Roman style and with the Corinthian order of the temple of Jupiter Capitolinus, the Baths of t.i.tus, and the beginning of the Flavian amphitheatre or Colosseum. The two last-named edifices both stood on the site of Nero's Golden House, of which the greater part was demolished to make way for them. During the last years of the first century the arch of t.i.tus was erected, the Colosseum finished, amphitheatres built at Verona, Pola, Reggio, Tusculum, Nimes (France), Constantine (Algiers), Pompeii and Herculanum (these last two cities and Stabiae rebuilt after the earthquake of 63 A.D.), and arches, bridges, and temples erected all over the Roman world.

The first part of the second century was distinguished by the splendid architectural achievements of the reign of Hadrian (117-138 A.D.) in Rome and the provinces, especially Athens. Nearly all his works were marked by great dignity of conception as well as beauty of detail.

During the latter part of the century a very interesting series of buildings were erected in the Hauran (Syria), in which Greek and Arab workmen under Roman direction produced examples of vigorous stone architecture of a mingled Roman and Syrian character.

The most-remarkable thermae of Rome belong to the third century--those of Caracalla (211-217 A.D.) and of Diocletian (284-305 A.D.)--their ruins to-day ranking among the most imposing remains of antiquity. In Syria the temples of the Sun at Baalbec and Palmyra (273 A.D., under Aurelian), and the great palace of Diocletian at Spalato, in Dalmatia (300 A.D.), are still the wonder of the few travellers who reach those distant spots.

While during the third and fourth centuries there was a marked decline in purity and refinement of detail, many of the later works of the period display a remarkable freedom and originality in conception. But these works are really not Roman, they are foreign, that is, provincial products; and the transfer of the capital to Byzantium revealed the increasing degree in which Rome was coming to look to the East for her strength and her art.

[Ill.u.s.tration: FIG. 53.--TEMPLE OF VENUS AND ROME. PLAN.]

+TEMPLES.+ The Romans built both rectangular and circular temples, and there was much variety in their treatment. In the rectangular temples a high _podium_, or bas.e.m.e.nt, was subst.i.tuted for the Greek stepped stylobate, and the prostyle plan was more common than the peripteral.

The cella was relatively short and wide, the front porch inordinately deep, and frequently divided by longitudinal rows of columns into three aisles. In most cases the exterior of the cella in prostyle temples was decorated by engaged columns. A barrel vault gave the interior an aspect of s.p.a.ciousness impossible with the Greek system of a wooden ceiling supported on double ranges of columns. In the place of these, free or engaged columns along the side-walls received the ribs of the vaulting.

Between these ribs the ceiling was richly panelled, or coffered and sumptuously gilded. The temples of +Fortuna Virilis+ and of +Faustina+ at Rome (the latter built 141 A.D., and its ruins incorporated into the modern church of S. Lorenzo in Miranda), and the beautiful and admirably preserved +Maison Carree+, at Nimes (France) (4 A.D.) are examples of this type. The temple of +Concord+, of which only the podium remains, and the small temple of Julius (both of these in the Forum) ill.u.s.trate another form of prostyle temple in which the porch was on a long side of the cella. Some of the larger temples were peripteral. The temple of the +Dioscuri+ (Castor and Pollux) in the Forum, was one of the most magnificent of these, certainly the richest in detail (Fig. 44). Very remarkable was the double temple of +Venus and Rome+, east of the Forum, designed by the Emperor Hadrian about 130 A.D. (Fig. 53). It was a vast pseudodipteral edifice containing two cellas in one structure, their statue-niches or apses meeting back to back in the centre. The temple stood in the midst of an imposing columnar peribolus entered by magnificent gateways. Other important temples have already been mentioned on p. 91.

Besides the two circular temples already described, the temple of Vesta, adjoining the House of the Vestals, at the east end of the Forum should be mentioned. At Baalbec is a circular temple whose entablature curves inward between the widely-s.p.a.ced columns until it touches the cella in the middle of each intercolumniation. It ill.u.s.trates the caprices of design which sometimes resulted from the disregard of tradition and the striving after originality (273 A.D.).

[Ill.u.s.tration: FIG. 54.--PLAN OF THE PANTHEON.]

+THE PANTHEON.+ The n.o.blest of all circular temples of Rome and of the world was the +Pantheon+. It was built by Hadrian, 117-138 A.D., on the site of the earlier rectangular temple of the same name erected by Agrippa. It measures 142 feet in diameter internally; the wall is 20 feet thick and supports a hemispherical dome rising to a height of 140 feet (Figs. 54, 55). Light is admitted solely through a round opening 28 feet in diameter at the top of the dome, the simplest and most impressive method of illumination conceivable. The rain and snow that enter produce no appreciable effect upon the temperature of the vast hall. There is a single entrance, with n.o.ble bronze doors, admitting directly to the interior, around which seven niches, alternately rectangular and semicircular in plan and fronted by Corinthian columns, lighten, without weakening, the ma.s.s of the encircling wall. This wall was originally incrusted with rich marbles, and the great dome, adorned with deep coffering in rectangular panels, was decorated with rosettes and mouldings in gilt stucco. The dome appears to have been composed of numerous arches and ribs, filled in and finally coated with concrete.

A recent examination of a denuded portion of its inner surface has convinced the writer that the interior panelling was executed after, and not during, its construction, by hewing the panels out of the ma.s.s of brick and concrete, without regard to the form and position of the origin skeleton of ribs.