ClIAF. IV.
ROMAN.
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It was 14,105 paces In length, 12,865 underground, 1240 above, and TOO on arches, someof which were of great beauty.
The plan, elevation, and section, is from the work of Alexander Donatus, as it existed inhis time.
This aqueduct had its commencement on the Via Collatina, about eight miles from the city.
The covered piscina, situated near the Pincian Hill , has two stories, and is a curiousand perfect example of a part of the aqueduct; these cisterns in all probability were sonamed from having become recep-tacles for small fish. The con-ceptacula was the vaulted cistern,covered in a manner to protectthe water from the sun’s influence,which was preferable to the openreservoir or limaria. The waterhere entered at the top of one alleyand descended by the other to thelower compartments, where it de-posited the earthy matter it held.
The contents of this piscina wereaccurately known, and the w’atercould always be let out in any givenquantity.
The plan and elevation of thestairs which conduct above arewell contrived for the access ofthe superintendents to the passagesabove.
The arches which decorate someportion of this aqueduct are notonly well proportioned, but receivefurther embellishment from a re-gular order of Corinthian columns:where the passage is preservedthrough the line, the elevation isincreased by an additional height.
Hie section at the side showsthe channel for the stream, whichflowed in the attic, built above the order, covered in by a vault carefully worked andwell tied together : here every precaution seems to have been taken to guard againstleakage, which, if it ever happened, would be immediately discovered, by the pouring outof the water at the defective place ; and along the whole line of aqueduct, materials weredeposited, that there might be no delay in the work; there would be also less to performthan to take up a whole length of mains laid under a solid and hard pavement, renderedimpassable during the progress. Such an inconvenience in crowded streets, the Romanswisely avoided, and continued to prefer the system of raised aqueducts to those buried invaults under ground.
CONCEPTACULA, AQUA VIRGINS.
i
Fig. 194.
SECTION OF STAIRS.
W
Fig. 195.
AQUA V1UG1NE.