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Roman Architecture - Aqueducts

( Originally Published 1921 )



The aqueducts, which served a strictly utilitarian purpose, were, by reason of their size and proportions, striking features of Roman landscape. Ruined aqueducts throughout the Empire show the importance attached by the Romans to an adequate water supply. Immense quantities of water were required for the great thermae and for public fountains, to say nothing of the domestic supply for the large population, and it has been computed that 350,000,000 gallons were daily poured into Rome through the eleven great aqueducts. In the days of Imperial Rome one of the most impressive sights in the Campagna must have been the long, level flights of majestic arches which bore the waters of the hills to the citizens of Rome. No more imposing triumphal procession ever entered Old Rome than that of the aqueducts bearing captive the waters of the distant hills, and no greater manifestation of the adoption of simple means to supply a need of every-day life is anywhere to be seen than in these water-carrying arches. The Romans were acquainted with the simple hydrostatic law that water rises to its own level in pipes, and the upper rooms of houses were supplied by " rising mains " in the same way as in modern buildings. As pipes could in those days only be made of costly lead or bronze, because cast iron was unknown, it was more economical to use slave labour to construct aqueducts of stone, or concrete faced with brick, with almost level water channels, either above or below ground. This system has been adopted even in modern times in the Croton Aqueduct which supplies New York City. The principle is the same in all cases. A smooth channel (" specus ") lined with hard cement is carried on arches, often in several tiers and sometimes of immense height (over zoo ft.), to convey the water from the high ground, across valleys, to the city reservoirs.

Many of them follow a circuitous course, to avoid making the slope of the channel too steep, when the source of the water was high above the level of distribution in Rome. Vitruvius (Bk. VIII, chap. vii) recommends a fall of 6 ins. to every zoo ft. in constructing aqueducts. In the time of Augustus Caesar there were nine of these aqueducts.

The Aqua Marcia, Rome (B.C. 144), forms part of a triple aqueduct which, by the Porta S. Lorenzo, carried the Aqua Marcia, the Aqua Tepula (B.C. 127), and the Aqua Julia (B.C. 33)—an economical arrangement by which several channels, one above the other, are carried by one series of arches.

The Aqua Claudia, Rome (A.D. 38) (p. 187 A), built by the Emperors Caligula and Claudius, brought water to Rome from Subiaco, 45 miles distant ; part of its length is on solid masonry, and for 9 1/2 miles it is borne on lofty arches, great lengths of which remain in the Campagna. It is probably the finest of all Roman aqueducts and some of the arches are over zoo ft. high ; three miles from Rome it is joined by the Anio Novus (A.D. 38), 62 miles in length.

The Pont du Gard, Nimes, France (B.C. 19) (pp. 172 E, 187 B), forms part of a magnificent aqueduct, 25 miles long, constructed by Agrippa to bring water to Nimes from the neighbourhood of Uzes. It is in good preservation, is about 900 ft. long, and is formed of three tiers of arches, crossing the valley 18o ft. above the river Gard. In the two lower tiers the central arch is the widest and the others vary in width, while in the uppermost tier there are thirty-five arches of 14 ft. span, supporting the " specus or water channel. The masonry is laid dry, without mortar, and some of the arch voussoirs of the intermediate tier were made to project to carry the temporary wooden framing or centering on which the arch was formed (p. 187 B).

Aqueducts at Tarragona, Segovia, Spalato, and elsewhere still testify to the importance which the old Romans attached to a good water supply, and the regulations connected with it throw a light on the detail of Roman administrative methods, both for the Imperial City and for the cities of the Roman Provinces.



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