III
Afewremarks must be made on the technique of Roman bridges and aqueducts. Vitruvius mentions a method known asopus quadratumin which stones were put in regular courses of headers[74]and stretchers[75]; they were big stones, about two feet by four feet and two feet high, as in the Marcian Aqueduct dating fromB.C.145.[76]Each stone was bordered with a draft cut one and a half inches wide, and the middle surface was roughed with a pick. This technique may be studied in the aqueducts at Segovia and Tarragona. The arches were set back at their springing behind the imposts, leaving ledges upon which the scaffolds rested.
Not all the Roman aqueducts were of stone. The one named after Nero was in brickwork of the finest kind; andanother, the Alexandrine, that brought water to the Thermæ of Alexander Severus, was faced with bricks over concrete. At Minturnæ, a town of the Volci, a decorative effect was given to the wall surfaces by means of coloured tufa arranged in geometrical patterns. This is enough to show that the virile conservatism of Rome did not stereotype building methods.
Many persons believe that the Romans built aqueducts because they were unacquainted with the hydraulic principle that water in a closed pipe finds its own level. Yet Vitruvius gives an account of the leaden pipes that distributed water in Roman towns; and Pliny says that this piping was used very often for rising mains to carry water to the upper floors of houses. But lead pipes might burst, and they were costly; it was cheaper to build aqueducts, for their materials belonged to the State and slave labour was invogue.[77]
Finally, we should pay attention to the Roman aqueducts because they were an apprenticeship in the building of lofty and daring arches. In the Anio Vetus, for example, which dates from about the yearB.C.272, some of the arches rise to a height that exceeds ninety feet. And any architect who conceived and brought to completion a fine aqueduct, such as the Pont du Gard, or the wonderful structure at Segóvia, deserved to take rank with Caius Julius Lacer. No problem of bridge construction would have baffled his matured knowledge.
It is said that the earliest vaulted bridge of the Romanswas erected under the elder Tarquin, about six hundred years before the Birth of Christ. Emiland Gauthey says, for example, “Pont Salaro, à Rome, sur le Teverone. Cet ouvrage, composé de trois arches en plein cintre, de 16,6 à 21 mètres, et de deux arches plus petites, de 6,8 mètres, fut élevé sous Tarquin l’ancien, six cents ans avant J. C.” Yet there is no evidence to justify this dogmatism. The bridge may have been a timber one, like the Pons Sublicius. It carried the Via Salaria over the Anio (Teverone) about two and a half miles from Rome, and was called usually the Pons Salarus. Livy speaks of it under another name, Pons Anienis, and makes it the theatre of an immortal fight, the one between Manlius and a gigantic Gaul,B.C.361. In single combat Manlius killed the barbarian, and took a chain (torques) from the dead body, and put it around his own neck, as a proof of his victory, winning by this act the surname of Torquatus.
The Pons Salarus does not appear again in early history. By the yearB.C.361 it may have been made into an arched bridge of stone, though it was not tillB.C.313 that the first aqueduct to Rome was constructed. In any case, however, we learn from an inscription, which Sir William Smith accepted as authentic, that the Pons Salarus was rebuilt in the sixth centuryA.D., by Narses, general and statesman, in the reign of Justinian. If in this reconstruction any earlier work was preserved, we must look for it in the smallest arches described by Gauthey, for we find narrow spans in the earliest Roman aqueducts. Those of the Marcian areonly eight metres. The Ponte Salaro existed till 1867, when it was blown up during a panic caused by Garibaldi’s march to Rome. A fortified castle stood above one side of the central arch, rising from the footway, whose width was more than eight metres. The bridge was about a hundred metres long, and its vaults were built with exceedingly heavy stones remarkable for their bossage work. A woodcut of this late Roman bridge is given by Professor Fleeming Jenkin, but it differs from the illustration in Emiland Gauthey’s “Traité de la Construction des Ponts,” Paris, 1809-16,Vol. I.
PONTE ROTTOPONTE ROTTO AT ROME, ANCIENTLY THE PONS PALATINUS OR SENATORIUS
PONTE ROTTO AT ROME, ANCIENTLY THE PONS PALATINUS OR SENATORIUS
There has been so much controversy over the antique bridges at Rome that the steadiest head becomes giddy while reading Palladio, Becker, Bunsen, Piranesi, Sir William Smith, and other experts. Perhaps we may be on safe ground when we step delicately on tiptoe into the historic environment of the Pons Palatinus, a bridge which seems to have been erected in the yearB.C.179.[78]A good part of this bridge was rebuilt in the time of Pope GregoryXIII(1572-85), but in 1598 it was wrecked by a terrible flood, and people began to speak of it as the Ponte Rotto, or broken bridge. From Palladio’s book on architecture, printed at Venice in 1570, we learn that the Pons Palatinus, or Senatorius, was known also as the Ponte Santa-Maria, so Rome must have been horrified when a classic bridge recently dedicated to the Virgin was overthrown by a spate, which spared the Pons Cestius and the Pons Fabricius.
The arches of this bridge were rather more than twenty-four metres in span, and their large archivolts were boldly prominent. The piers, about eight metres thick, were protected by angular cutwaters, and above each cutwater was a tall niche flanked by pilasters whose capitals touched the broad cornice that framed the spandrils in a vigorous manner. Each spandril was ornamented with a sea-horsecarved in relief; and this decoration was foiled by the plain, deep parapets whose horizontal lines were diversified here and there by a projection. Brangwyn’s drawing of the Ponte Rotto gives all the architectural character, and we see that this bridge was a great Roman citizen, manly and brave and noble. Further, when we speak of any bridge as virile as this one arch, we have a right to use masculine pronouns, “he” and “his” and “him.” The trivial word “it” is a feeble neutrality that belongs to a great many bridges, both ancient and modern; but a Cæsarian achievement like the Pons Palatinus, or the Pont du Gard, or the Puente Trajan at Alcántara, takes rank among the rare deeds that do honour to a splendid manhood; and this we should recognise in our pronouns.
Palladio says that in his time, from 1518 to 1580, three other bridges over the Tiber, at Rome, were in good preservation. Let us take a glance atthem:—
1. The Pons Ælius, called then, as now, the Ponte Sant’ Angelo, built by Ælius Hadrianus, who reigned fromA.D.117 to 138, and who erected his bridge as a passage over the Tiber to his own mausoleum, which forms the groundwork of the present castle ofSt.Angelo. An earlier bridge connected the Vatican and its neighbourhood with that part of the city which Caligula and Nero had beautified with gardens; and remains of it still exist near S. Spirito. The date of its disappearance I do not know, but in the days of Procopius, the sixth century of the Christian era, the Pons Ælius was the only communication between the city and theVatican district. Either legend or truth says that the Ælius had a bronze cover upheld by forty-two pillars. If this gleaming roof ever existed (and writers should be afraid of pretty details in ancient history), it must have been damaged very much when the parapets were broken down in the fifteenth century. This accident was caused by a great crowd that lost control of itself on the bridge, when thronging toSt.Peter’s to receive the Pope’s benediction. At last the parapets gave way, and ninety-two persons were either drowned or crushed to death. Long afterwards, as we know, Giovanni L. Bernini (1598-1680) designed balustrades of iron and stone, but dwarfed them with ten huge statues commissioned by Pope ClementIX(p.324). The figures ofSt.Peter andSt.Paul at the city entrance were put up by ClementVII. The bridge itself—or himself, shall we say?—has a technical inspiration akin to that of the Pons Palatinus; but there is less ornament, and above the cutwaters, instead of tall niches, we find rectangular pillars with plain capitals, upon which Bernini erected pedestals for his “breezy angels.”
2. The Pons Fabricius, connecting Rome on the city side with the Insula Tiberina. In very early times this island in the Tiber was united to each bankside by a bridge, and hence it was calledInter Duos Pontes. The present Pons Fabricius was either founded or restored by L. Fabricius, curator viarum inB.C.62, as appears from the inscription on it, and from Dion Cassius. It is mentioned by Horace as a bridge very attractive tosuicides:—
... jussit sapientem pascere barbamAtque a Fabricio non tristem ponte reverti.
... jussit sapientem pascere barbamAtque a Fabricio non tristem ponte reverti.
... jussit sapientem pascere barbam
Atque a Fabricio non tristem ponte reverti.
Since Palladio’s time, if not from a much earlier date, the Pons Fabricius has been known as the Ponte Quattro Capi, because its entrance from the left bank has a protective emblem, a quadrupled head of Janus, the guardian deity of gates, and a divinity with many other occupations, all very alert and troublesome. So we must add this pagan emblem to the other symbols of religious faith with which bridges have been sanctified. In 1680 the Pons Fabricius was repaired by Pope InnocentXI. There are two arches, each with a span of 25, 34 metres; and there used to be two other arches, only 3, 50 metres wide, pierced through the abutments, but they have disappeared among the houses on each bankside. The bridge in its greatest width measures a little more than 15 metres. It has a bold cornice ornamented with mutules, and its relief bay for spate water is flanked by pilasters. M. Degrand says of the Pons Fabricius:“C’est le premier pont dans lequel les têtes des voûtes ne forment pas des demi-circonférences: l’intrados est un arc de cercle de 25 m. de rayon et de 20 m. de flèche.”Here we find a starting-point for the lovely arch invented at Avignon by Saint Bénézet (p.81).
3. The Pons Cestius, on the other side of the island, known to-day, and in Palladio’s time, as Ponte S. Bartolommeo. Yet its inscription, which is mentioned by Canina and by Sir William Smith, speaks of it as Pons Gratianus, and commemorates its repair by Valentinian, Valens, andGratian. It has but one arch, nearly a metre less in span than those of the Pons Fabricius. These two bridges, according to Piranesi, were founded in a very remarkable manner, on reversed arches built under water. Gauthey gives two drawings of this construction, but he does not guarantee the truth of Piranesi’s details.
Five other antique bridges crossed the Tiber at or near Rome, but Palladio found nothing more of them than a few remnants. Already I have spoken of two, the Pons Sublicius and its understudy (p.140). On the left bank, facing the church of S. Spirito, Palladio saw remains of the Pons Triumphalis; but Piranesi and Bunsen do not agree with Palladio. They place the Pons Triumphalis beyond the Pons Ælius, and Sir William Smith thinks it probable that the remains near S. Spirito belong to a bridge which theMirabilianames Pons Neronianus, and which ancient topographers describe as Pons Vaticanus. Then there was the Janiculine bridge upon the foundations of which, between 1471 and 1484, Pope SixtusIVhad erected the Ponte Sisto. As the Janiculine bridge went from the Janiculum to the Porta Aurelia, it was known also as Pons Aurelius; and in the Middle Ages it seems to have been called Pons Antoninus. As for the Ponte Molle, anciently the Pons Milvius, it belonged to the Flaminian Way, crossing the Tiber beyond the walls of Rome, a mile and a half outside the city. Its founder was said to be the earlier Æmilius Scaurus, who died about eighty-five years before the Birth of Christ. Yet it certainly existed inB.C.207, for Livy relates how the people poured out of Rome as far as the Milvian bridge in order to meet the messengers who brought tidings of the defeat of Hasdrubal. This may have been a timber bridge, and Æmilius Scaurus may have displaced it for a stone bridge during his consulship,B.C.110.
Only a few fragments of the Pons Milvius existed in Palladio’s time; and so the Ponte Molle now extant has a false reputation of being Roman. In fact, it is a very poor structure, badly designed and very uncouth.