A dictionary of Greek and Roman . ere pierced through by tunnels,and valleys crossed either by solid substructionsor arches of masonry, according to the height re-quired ; and of these arches there were often twotiers, and sometimes even three. The channelitself (specus, canalis) was a trough of brick orstone, lined with cement, and covered with acoping, which was almost always arched ; and thewater either ran directly through this trough, or itwas carried through pipes laid along the the channel was carried beneath the sur-face, if the hill through which it passed wa
A dictionary of Greek and Roman . ere pierced through by tunnels,and valleys crossed either by solid substructionsor arches of masonry, according to the height re-quired ; and of these arches there were often twotiers, and sometimes even three. The channelitself (specus, canalis) was a trough of brick orstone, lined with cement, and covered with acoping, which was almost always arched ; and thewater either ran directly through this trough, or itwas carried through pipes laid along the the channel was carried beneath the sur-face, if the hill through which it passed was ofrock, it was merely cut in the rock ; but if of earthor sand, it was constructed of blocks of stone. The following woodcut represents a portion ofa double-arched aqueduct, and shows a section ofthe specus (a) : b b are projecting blocks, whichare often seen in such positions, and which weredoubtless the supports for the centerings used inbuilding the arches. AQUAEDUCTUS. 113 aqueducts, will show how large a portion of themwas The object of covering the specus was to excludethe sun and rain, and other corruptions and ob-structions ; but it was necessary to provide a ventfor the air, which otherwise would have beencompressed to such a degree as to burst the wallsor roof of the specus. These vent-holes weremade at regular intervals in the roof of the specus,or, when another channel passed over it, in theside. They are represented in the sections, givenabove, of the J qua Claudia, Marcia, &c. Toventilate the subterranean channel of an aqueduct,a shaft (puteus) of masonry was carried to thesurface of the ground at intervals of an actus, or120 Roman feet (or two actus, according to Pliny,who calls them lumina), as shown in the followingwoodcut (after Hirt), which represents the plan,longitudinal section, and transverse section, ofpart of a rivus subterraneus, the ruins of whichstill exist at Palmyra. The rivus subterraneus possessed the advantageover the aquaeductu
Size: 1486px × 1681px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorsmithwilliam18131893, bookcentury1800, bookdecade1840
