AQUEDUCT, or AQUEDUCT, (from Latin aqua, water, and deco, to lead,) a construction upon or through uneven ground, for the purpose of forming a level canal for conduct ing water from one place to another. Aqueducts were formed either by erecting one or several rows of arcades across a valley, and making these arcades support one or more level canals, upon one or each of the ranges, or by piercing through mountains which would have interrupted the watercourse. They were built of stone or brick, and covered with a vaulted roof, or with flat stones, to shelter the water from the sun and rain. Some aqueducts were paved • but others conveyed the water through a natural channel of clay, to reservoirs or castella of lead or stone, whence it was brought to the houses by leaden pipes.
Aqueducts had also ponds disposed at certain distances, where the sediment of the water might be deposited. When the water was conveyed under ground, there were openings at about every 240 feet. Some of the Roman aqueducts
brought water from the distance of sixty miles, through rocks and mountains, and over valleys, in places more than 109 feet high. The inclination of the aqueduct, according to Pliny, was one inch, and, according to Vitruvius, half a foot in the hundred. The proportions adopted by the moderns is nearly the same as that mentioned by Pliny. The prin cipal aqueducts now remaining are—Aqute Virginia, repaired by Pope Paul IV.; Aquw Felice, constructed by Pope Sextus V. ; the Apar Paulina, repaired by Pope Paul V. in the year 1611 ; and that built by Louis XIV. near Maintenon, to convey water from the river Bure to Versailles. This latter is perhaps the largest aqueduct in the world, it being 7,000 fiithonis long, is elevated 2,560 fathoms, and contains 242 arcades.