ANCIENT AND MEDLEVAL BRIDGES.
It is thought that probably the Chinese first employed the masonry arch for bridging streams. All that is known, however. is that bridges and other public works were executed in China B.C. 2000.and that arch bridges of evidently very great age are found in different parts of the Empire, some of which are excellent examples of masonry arch construction. As no bridges have survived from ancient Egypt, which had little use for them, or from Babylonia or Assyria, where they were never attempted on a large or permanent scale, the earliest remaining examples, apart from China, appear to belong to that interesting group of 'Hittite' and 'Pelasgie' tribes that peo pled the shores and islands of the Mediterranean in prehistoric times. The Cretans. many' of whose cities are known to be of earlier founda tion than Troy, Tiryns„ or Myceme. in their pos sessions in Asia Minor. Syria, Greece. Italy, and the adjoining islands, connected theireit ies with a network of maeadamized roads requiring bridges. and their work shows that they were skillful engineers. The earliest examples are built with immense abutments and piers of polygonal ma sonry, connected by wooden planks, like the later one across the Euripus in Eubcea. Then the blocks of the piers were overhung so as finally to meet in an almost triangular false pointed arch. like the gallery at Tiryns and the gate at Arpi num. This was the case at Metaxidi, and across the Pamisus. in Messenia, as well as in a bridge near Sparta. Other early bridges, all of stone, exist near Mycence and Plilius. Finally, for nar row rivers, the end piers were connected by true voussoired round arches. This stage was not reached until the Seventh or Sixth Century B.C. in Italy, as is shown by the bridges at Bieda, Cora, and Vulei, and was probably never known in Greece. where the arch was not developed. even for engineering purposes. What the usual Greek method was in historic times is probably shown by the bridge at ASSOS, where the stone piers are connected by parallel stone lintels, dow eled together.
First the Etruseans, and then the Romans. in herited and developed the engineering ability of the 'Pelasgie' tribes. As soon as the building of the Via Appia had initiated, in the Fourth Cen tury B.C., the policy of binding the possessions of Rome together by great macadamized roads, the Romans entered upon an unrivaled career of bridge and viaduct construction, which has fur nished models for all succeeding ages until the modern invention of the metal bridge. As in all their public structures, the Romans made their bridges far more monumental and artistic than necessity required. Some of the Republican period remain. The Ponte Lupo and other mag nificent bridges and viaducts for the Anio Vetus aqueduct (n.e. 144-140) are great stone arches of tufa and travertine; so is the viaduct near Gabii (Porte di Nona), probably built in n.c.
124-121, with seven arches, and 285 feet long, still in use. In Rome itself the --Emilian Bridge, in n.c. 179-142, is said to have been the first stone bridge to span the Tiber, all previous bridges having been of wood; and until quite a late date wooden bridges continued in use, especially for wide rivers. Then came the Fabrieian Bridge, in uses 62, with two round arches, built. like the rest in Rome, of peperino and tufa, faced with mas sive blocks of travertine, and the only one of these ancient bridges that has remained intact. the _El inn Bridge, or 'Ponte Sant' Angelo,' built by Hadrian in A.D. 136, with eight arches, was the most superb of all. and remains in great part. It was almost rivaled by the later Sisto' of Valentinian. These bridges had a considerable upward grade toward the centre, which added to their architectural effectiveness.
The great roads radiating from Rome like the spokes of a wheel, such as the Via Solaria ( Porte Salaro), Appia, Aurelia. Flaminia, Valeria. La tina, Cassia, _Emilia, required a number of bridges. The Flaminia, commencing at the great Mul•ian Bridge, built in n.e. 109, was construct ed by Augustus with all its bridges; that at. the further end of the road, at Ariminium (Rimini). is the best preserved, with its five great arches and length of 23G feet. Other Augustan bridges, in ruins, are near Borghetto and Narni; and, in the north, near Aosta. Calzi, etc. The great one at Verona is rebuilt, as is that of Vicenza. The spread of Roman dominion to Spain, Gaul, Af rica, Greece, Asia Minor, Syria. the Danubian lands, Germany, Britain, meant everywhere the building of great military roads with permanent bridges by the Roman legions, under the direction of their military engineers. The most colossal was the bridge over the Danube. built in Am. 102 and 103 by Apollodorus, the greatest architect and engineer of his time, for Trajan, to enable the Emperor to conquer Dacia. The stone piers still stand; its superstructure was of wood. Previous bridges of such enormous length had been temporary and on boats. Throughout the countries that had been included in the western provinces of the Empire so little care of time bridges was taken in the Dark Ages that few have survived. In France are those near Chateau neuf, Vaison, and Saint-Chamas, and the founda tions of many more. The Spanish Peninsula is the great exception. Its bridges were among the most superb pieces of Roman engineering, and the high culture of the Moors insured their pres ervation. The best examples are at Martorell, Cuenca, Evora, Aheonetar, Cordova, Merida, Al enntara, Chaves, Orense. 011oniego, Ona, Alma zan, and especially the superb example at Sala manca. built, like so many of the others, by Tra j a n.