Beginning of Essay
An example of the Roman ability to turn necessity into practical reality was the development of the aqueduct (from the Latin ducere, meaning, "to lead," and aqua, meaning "water"). Aqueducts were designed to bring fresh water from springs into the city for public ....

Middle of Essay
.... weigh up to 6 tons each. They were precisely cut to standard measurements, dressed (shaped and smoothed), and then fitted into place with no mortar or clamps. The vault system of construction was well suited to a massive engineering project such as the Pont du Gard bridge and aqueduct. With the tunnel vaults in a continuous series side by side, the lateral thrust of each vault is counteracted by its neighbor, so that only the end vaults need to be buttressed. The placement of larger vaults below and smaller ones above serves a structural purpose-support-as well as an esthetic one. The repeated arches not only carry water, but also formally lead ....