Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/832

808 ROME [TOPOGRAPHY AND And under the present Government an even more extensive plan, called the "piano regolatore," is being (1886) gradually carried out, with the object of reducing hills and valleys to one uniform level, on which wide boulevards are being constructed on the chess- board plan of an American city. The constant fires which have devastated Rome have been a great agent in obliterating the natural contour of the ground. The accumulated rubbish from these and other causes has in some places covered the ground to the depth of 40 feet, especially in the valleys. imate The climate of Rome in ancient times appears to have been id colder than it is at present. Malarious fever in and around the lalth. city existed to some extent, but to a much less degree than it does now. The magnificent villa of Hadrian and other country houses near Rome are built on sites which are now very unhealthy. The sanitary superiority of the Campagna in ancient times was mainly due to its more complete drainage and thicker population. That fever did exist is, however, proved in many ways. Altars to the goddess Febris were erected on the Palatine and other hills, and on the Esquiline was a grove dedicated to Mephitis. The popula- tion of Rome 1 increased with great rapidity, till, during its most populous period in the 4th century, it was probably not less than 2 millions. 8 ANCIENT ROME. Architecture and Construction. lilding The chief building materials used in ancient Rome were those aterials. enumerated below. (1) Tufa, the "ruber et niger tophus" of Vitruvius (ii. 7), the formation of which has been described above, is usually a warm brown or yellow colour. The Aventine, Palatine, and Capitoline Hills contained quarries of the tufa, much worked at an early period (see Liv., xxvi. 27, xxxix. 44, and Varro, L.L. , iv. 151). It is a very ba.d "weather-stone," but stands well if pro- tected with stucco (Plin., H.N., xxxvi. 48). (2) Lapis Albanus, from Alba Longa, is also of volcanic origin, a conglomerate of ashes, gravel, and fragments of stone ; its quarries are still worked at Albano and Marino. (3) Lapis Gabinus, from Gabii, is very similar to the last, but harder and a better weather -stone ; it contains large lumps of broken lava, products of an earlier eruption, and small pieces of limestone. According to Tacitus (Ann., xv. 43), it is fire-proof, and this is also the case with the Alban stone. Both are now called peperino, from the black scoriae, like pepper- corns, with which the brown conglomerate mass is studded. (4) Silex (mod. selce), a lava from the now extinct volcanoes in the Alban Hills, was used for paving roads, and when broken into small pieces and mixed with lime and pozzolana formed an im- mensely durable concrete. It is dark grey, very hard, and breaks with a slightly conchoidal fracture (Plin., ff.N., xxxvi. 29 ; Vitr., ii. 7), but does not resemble what is now called silex or flint. (5) Lapis Tiburtinus (travertine), the chief quarries of which are at Tibur (Tivoli) and other places along the river Anio, is a hard pure carbonate of lime, of a creamy white colour, deposited from run- ning or dripping water in a highly stratified form, with frequent cavities and fissures lined with crystals. As Vitruvius (ii. 5) says, it is a good weather-stone, but is soon calcined by fire. If laid horizontally it is very strong, but if set on end its crystalline struc- ture is a great source of weakness, and it splits from end to end. Neglect on the part of Roman builders of this important precau- tion in many cases caused a complete failure in the structure. This was notably the case in the rostra (see below). (6) Pulvis Puteo- lanus (pozzolana), so called from extensive beds of it at Puteoli, is a volcanic product, which looks like red sandy earth, and lies in enormous beds under and round the city of Rome. When mixed with lime it forms a very strong hydraulic cement, of equal use in concrete, mortar, or undercoats of stucco. It is to this material that the concrete walls of Rome owe their enormous strength and durability, in many cases far exceeding those of the most massive stone masonry. Vitruvius devotes a chapter (bk. ii. ch. (?) to this very important material. Bricks were either sun-dried or kiln-baked (latercs crudi aut cocti). The remarks of Vitruvius (ii. 3) seem to refer wholly to sun-dried bricks, of which no examples now exist in Rome. It is very important to recognize the fact that among the existing ancient buildings of Rome there is no such thing as a brick wall or a brick arch in the true sense of the word ; bricks were merely used as a fac- ing to concrete walls and arches and have no constructional import- ance. Concrete (fartura, cxmentum, or opus structure ctementitise, Vitr., ii. 4, 6, 8), the most important of all the materials used, is made of rough pieces of stone or of fragments of brick, averaging from about the size of a man's fist and embedded in cement made of lime and pozzolana, forming one solid mass of enormous 1 Sec a good article on this subject in the Monografia di Roma, vol. ii., 1878. 2 Work* to be consulted. GEOLOGY. Brocchi, Suolo di Kama, 1820, and its supplement by Ponzi, Storia fisica di Roma, 1867 ; Mantovani, Descriziont gechgica delta Campagna di Roma, 1875 ; Giordano and Mantovani, Monografia di Roma, 1878, vol. i. pp. i.-cxxiii., and pp. 51-79 ; Mauro, Analisi chimica delle aque potabUi di Roma, 1884 ; Pinto, Aque potaUli mil' Agro Romano, 1883. BOTANY AND ZOOLOGY. Bonaparte, Fauna Italica, 1835; Sanguinetti, Pro- dromus Florx Romans ; Deakin, Flora of the Colosseum, 1855 : Terrigi, "Flora, Ac., del Quirinale," in Acad. Pont. d. Lincei, May 1882. strength and coherence. Stucco, cement, and mortar (tectorium, opus albarium, structura testacea, and other names) are of many kinds ; the ancient Romans especially excelled in their manufac- ture. The cement used for lining the channels of aqueducts (opus signinum) was made of lime mixed with pounded brick or potsherds and pozzolaua ; the same mixture was used for floors under the "nucleus " or finer cement on which the mosaic or marble paving- slabs were bedded, and was called csementum ex tcslis tunsis. For walls, three or four coats of stucco were used, often as much as 5 inches thick altogether ; the lower coats were of lime and pozzolann, the finishing coats of powdered white marble (opus albarium) suit- able to receive painting. Even marble buildings were usually coated with a thin layer of this fine white stucco, nearly as hard and durable as the marble itself a practice also employed in the finest buildings of the Greeks probably because it formed a more absorbent ground for coloured decoration ; stone columns coated in this way were called "columnse dealbatse " (Cic., In Verr., ii. 1, 52 sq.). For the kinds of sand used in mortar and stucco Vitruvius (ii. 4) mentions sea, pit, and river sand, saying that pit sand is to be preferred. Marble appears to have come into use about the beginning of the Deco 1st century B.C. Its introduction was at first viewed with great tive jealousy, as savouring of Greek luxury. The orator Crassus was mate the first to use it in his house on the Palatine, built about 92 B.C. ; and, though he had only six small columns of Hymettian marble, he was for this luxury nicknamed the "Palatine Venus" by the stern republican M. Brutus (Plin., H.N., xxxvi. 3). The tem- porary wooden theatre of the sedile M. jEmilius Scaurus, built in 58 B.C., appears to have been the first building in which marble was more largely used ; its 360 columns and the lower order of its sceua were of Greek marble (see Plin., H.N., xxxvi. 3, 24). In a very few years, under the rule of Augustus, marble became very common. 3 Of Avhite statuary marble four principal varieties were used. (1) Marmor Lunense. from Luna, near the modern Carrara (Strabo, v.), is of many qualities, from the purest creamy white and the finest grain to the coarser sorts disfigured with bluish grey streaks. (Ex., the eleven Corinthian columns in the Dogana di Terra.) (2) Mar- mor Hymettium, from Mount Hymettus, near Athens, is coarser in grain than the best Luna marble and is usually marked with grey or blue striations (Strabo, x. ). (Ex. , the forty-two columns in the nave of S Maria Maggiore and the columns in S. Pietro in Vincoli.) (3) Marmor Pentelicum, from Mount Pentelicus, also near Athens, is very fine in grain and of a pure white ; it was more used for architectural purposes than for statues, though some sculptors pre- ferred it above all others, especially Scopas and Praxiteles (Paus., Arcad., viii.). (Ex., the bust of the young Augustus in the Vatican.) (4) Marmor Parium, from the Isle of Paros, is very beautiful, though coarse in texture, having a very crystalline structure. Nine chief varieties of coloured marbles were used in Rome. (1) Colo Marmor Numidicum (mod. giallo antico; Plin., H.N., . 3), from marl Numidia and Libya, hence also called Libycum, is of a rich yellow, deepening to orange and even pink. Enormous quantities of it were used, especially for columns, wall-linings, and pavements. (Ex., six large columns in the Pantheon and seven on the arch of Con- stantine, taken from the arch of Trajan ; the eighth column is in the Lateran basilica.) (2) Marmor Carystium (mod. cipollino), from Carystus in Eubcea (Strabo, x. ), has alternate wavy strata of white and pale green the "undosa Carystos " of Statius (Silv., i. 5, 36). From its well-defined layers like an onion (cipolla) is derived its modern name. (Ex. , columns of temple of Faustina. ) (3) Marmor Phrygium or Synnadicum (mod. pavonazctto), from Synnada in Phrygia (Strabo, xii. ; Juv., xiv. 307 ; Tibull, iii. 3, 13), is a slightly translucent marble, with rich purple markings, violet verging on red. It was fabled to be stained with the blood of Atys (Stat., Silv., i. 5, 36). (Ex., twelve fluted columns in S. Lorenzo fuori le Mura, and large columns in the apse of S. Paolo fuori, saved from the ancient nave of the basilica, burnt in 1823.) (4) Marmor lasium (probably the modern porta santa), from lasus, is mottled with large patches of dull red, olive green, and white. The " holy door" of St Peter's is framed with it, hence its modern name. (Ex., the slabs in front of the Graecostasis and four columns in S. Agnese fuori le Mura. ) (5) Marmor Chium (probably the modern Africano), from Chios, is similar in colour and marking to the porta santa, but more brilliant in tint. (Ex., a great part of the paving of the Basilica Julia and two large columns in the centre of the facade of St Peter's.) (6) Rosso antico (the ancient name is un- known) is a very close-grained marble of a rich deep red, like blood. As a rule it does not occur in large pieces, but was much used for 3 The oft-quoted boast of Augustus (Suet., Aug., 29) that he " found Rome of brick and left it of marble" has probably much truth in it, if for "brick" we read "peperino and tufa." In the time of Augustus burnt brick was very little used, the usual wall-facings being opus quadratum of tufa or peperino, and opus reticulatum of tufa only. The confessiones or crypts in front of the higli altars of St Peter's, S. Maria Maggiore, S. Pietro in Vincoli, and other churches in Rome are museums of the rarer and more splendid marbles used by the ancient Romans, as their walls and pavements are covered with the richest specimens found during excavations. All the fine marbles in Roman churches have been taken from ancient buildings ; an excellent account of these is given by Corsi, Pietre antiche, 1845.