aqueduc

OBS: On applique d'ordinaire le nom d'«aqueduc» uniquement aux canaux construits en pierre ou en maçonnerie, pour conduire des eaux, avec pente réglée, à travers un sol inégal.
CONT: L'aqueduc peut être souterrain ou porté au-dessus du sol par une suite d'arcades.

CONT: In a nonpressure aqueduct, water moves downhill under the force of gravity. Ancient aqueducts were usually of the nonpressure type.
OBS: Closed conduits, such as aqueducts, pipelines, and tunnels, may also follow the hydraulic grade line, in which case they are called grade structures, or they may operate under pressure.
OBS: Aqueduct. ... In ordinary usage, ... the term is applied to large arched structures of masonry conveying water by gravitation, ... and the earliest aqueducts ... had therefore to be built on the hydraulic gradient, i.e. the slope at which the water would flow freely.