THE WATERWORKS OF ANCIENT ROME.
Of all the cities of the Greek and Roman world, Rome was most abundantly provided with water, the importance of which element, in its domestic and sanitary aspects, it is now again, after centuries of neglect, beginning to be recognized as paramount among the physical conditions of urban life. We have, however, not yet quite learned to allow to water, as affecting the life, comfort, and decencies of life, the position which was accorded to it at Rome; but even to us it is inconceivable how many great cities of medieval and even of modern ages could have existed and been considered as elegant and refined abodes, with no artificial, or at most inadequate, arrangements for the introduction and distribution of water among the people. Even Paris, in some sort the arbiter elegantiarum of modern Europe, until recently derived its supply of drinking water from the Siene, the grand recipient of the sewerage of Paris, and from wells polluted by infiltration, and so late as 1836 Parent Duchatelet published a work in which the water of the Siene was proved to be altogether inoffensive to the taste and wholesome, because the foul matter contributed to its current by the superficial and subterranean drainage of the city was not sufficient in quantity to effect sensibly the taste, the limpidity, or the salubriiy of its waters !
The ancient Romans discriminated carefully between the waters of different springs. What tests they employed we in general know as little as we know their rules for judging of the quality of stone and other materials employed in architecture. After the great natural division of water into fresh and salt, the most obvious distinction between cold and hot Springs. The latter of these was everywhere sought, and in all the wide domain of imperial Rome, there is to be found scarcely a single spring above the ordinary temperature which is not surrounded by the ruins of old constructions obviously designed for ba’hing. They also considered specific gravity of drinking-wa’er a matter of much importance. A letter of Synesius to Hypatia describes and recommends an instrument for testing the weight of water. This was simply a graduated brazen tube, closed and weighted at one end. This, of course, by the height at which the tube stood in the fluid would answer for comparing the gravity of different waters. Chemistry had not yet taught natural philosophers that water, even in its simplest form, is not an elemental, but a compound substance ; they knew, however, that not only spring water, but even the purest rainwater, contains in suspension or in solution a variety of foreign ingredients.
Much of the water introduced into Rome by aqueducts was employed for feeding fountains—the younger Pliny speaks of a jet d’feau—as well as for domestic uses: but the principal object of these constructions was to supply water for bathing, for which an enormous quantity was required. Thus the aqueducts subserved the purposes’of luxury as well as the necessities of life. Cast iron being scarcely known to the Romans, the distribution of the water from the reservoirs was effected by pipes of baked clay, and, where those were not applicable, of lead ; and it is singular that, though skillful in casting bronze, the Roman founders were not yet able to cast lead pipe. The conduits of this material are made from cast sheets, or rather plates, of lead, wrapped around a mandel and riveted or clamped at the opposite edges. The plates being thick* r than modern rolled lead, the pipes were heavier, a* d accordingly the conmmplion ofthat metal was very great. From one single pr int of distribution of an aqueduct the Borgnese family took, in the sixteenth century, not less than 40,000 pounds of lead pipe. The citadel of Alatri was supplied with water carried across a deep ravine by an inverted siphon of earthen pipes, imbedded in concrete, to a height of more than 300 feet above the bottom of the ravine, and, of course, under a pressure of fully ten atmospheres.