Aqueducts are conveyances for carrying water from one place to another; made on uneven ground, to preserve the level. Aqueducts of every kind were long ago the wonders of Rome; the vast quantity of them which they had; the prodigious expense employed in conducting waters over arcades from one place to another, at the distance of thirty, forty, sixty, and even one hundred miles, which were either continued or supplied by other labours, as by cutting mountains and piercing rocks: all this may well surprise us, as nothing like it is undertaken in our times; we dare not purchase conveniency at so dear a rate. Appius Claudius, the censor, devised and constructed the first aqueduct. His example gave the public luxury a hint to cultivate these objects; and the force of prodigious and indefatigable labour diverted the course of rivers and floods to Rome. Agrippa, in that year when he was edile, put the last hand to the magnificence of these works.

The aqueduct of the Aqua Martia, had an arch of sixteen feet in diameter. The whole was composed of three different kinds of stone; one of them reddish, another brown, and a third of an earth colour. Above, there appeared two canals, of which the highest was fed by the new waters of the Tiverone, and the lower by what they called the Claudian river. The entire edifice is seventy Roman feet high. Near this aqueduct, we have, in Father Montfaucon, the plan of another, with three canals; the highest supplied by the Aqua Julia, that in the middle from Tepula, and the lowest from the Aqua Martia. The arch of the aqueduct of the Aqua Claudia is of hewn stone, very beautiful; that of the aqueduct of the Aqua Neronia is of bricks, they are each of them seventy-two Roman feet in height. The canal of the aqueduct which was called Aqua Appia, deserves to be mentioned for a singularity which is observed in it; for it is not, like the others, plain, nor gradual in its descent, but much narrower at the lower than the higher end. The consul Frontinus, who superintended the aqueducts under the emperor Nerva, mentions nine of them which had each 13,594 pipes of an inch in diameter. Vigerus observes, that, in the space of twenty-four hours, Rome received 500,000 hogsheads of water. Not to mention the aqueducts of Dru-sus and Rhiminius, that which gives the most striking idea of Roman magnificence, is the aqueduct of Metz, of which a great number of arcades still remain. These arcades crossed the Moselle, a river which is of vast breadth at that place. The copious sources of Gorze furnished water for the representation of a sea-fight. This water was collected in a re-servoir; whence it was conducted by subterraneous canals formed of hewn-stone, and so spacious, that a man could walk erect in them: it traversed the Moselle upon its superb and lofty arcades, which may still be seen at the distance of two leagues from Metz; so nicely wrought, and so finely cemented, that except those parts in the middle which have been carried away by the ice, they have resisted, and will still resist, the severest shocks of the most violent seasons. From these arcades, other aqueducts conveyed the waters to the baths, and to the place where the naval engagement was exhibited.

If we may trust Colmenarus, the aqueduct of Segovia may be compared with the most admired labours of antiquity. There still remain one hundred and fifty-nine arcades, wholly consisting of stones enormously large, and joined without mortar. These arcades, with what remains of the edifice, are one hundred and two feet high; they are formed in two ranges, one above another. The aqueduct flows through the city, and runs beneath the greatest number of houses, which are at the lower end. After these enormous structures, we may be believed when we speak of the aqueduct which Louis XIV. caused to be built near Maintenon, for carrying water from the river Bucq to Versailles: it is perhaps the greatest aqueduct now in the world, being 7000 fathoms in length, above 2560 in height, and containing no fewer than two hundred and forty-two arcades.