Page:Popular Science Monthly Volume 11.djvu/36

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HE remains of the lofty arcades upon which the aqueducts of ancient Rome were carried to the city have been justly classed among the finest and most picturesque ruins of the Roman Empire. Stretching across the plain eastward of the city, and towering high above the landscape, they are the first objects to fix the gaze and command the admiration of the stranger approaching the home of the Cæsars, and to fill his mind with visions of the strength and grandeur of the nation which mastered the world two thousand years ago. But these ruins speak not only of the mechanical skill and physical greatness of that vanished people, but also of their refinement and their acquaintance with the deeply-hidden laws of hygiene; for they well knew what has become known to us only after a lapse of twenty centuries, after the measurement of the heavens, and the discovery of the steam-engine, that for every large city an abundant supply of pure, fresh water is indispensable to the preservation of health. At the zenith of her grandeur, Rome had eleven distinct aqueducts, whose aggregate discharge was equivalent to a stream twenty feet wide by six deep, with a fall six times as rapid as that of the river Thames, The daily supply was in the proportion of 332 gallons to each inhabitant, and it was distributed to the palaces and humbler dwellings in every part of the city, as well as to innumerable fountains, many public wells and large reservoirs, to the numerous baths, and to several artificial lakes, where the emperors held their naumachiæ, or sham naval battles. These eleven constituted the most extensive and perfect system of aqueducts that has been possessed by any city even up to the present time. Their combined length was over 300 miles, 50 of which were above-ground either upon low substructures or more imposing arcades. The loftiest arcade was that belonging to the Aqua Claudia and the Anio Novus; it was in one place 109 feet high. In respect to height of arcades, however, the aqueducts of Rome were less remarkable than several built by the emperors, about the same time, for certain provincial cities of the empire, and others of more recent times. Thus the Emperor Agrippa built an aqueduct for the city of Nemausus (Nimes) in France, and carried it across the river Gard upon an arcade 180 feet high, and about 900 feet long. This splendid structure, still perfect, is now called the Pont du Gard, and is an object of attraction and astonishment to modern travelers. It consists of a triple row of arches, which in the two lower tiers are of wide span, and in the upper one narrow. This arcade "has no rival for lightness and boldness of