ClipArt ETC
"An artificial channel formed to carry off any stagnany body of water, like the sluices in modern use. Some works of this kind are among the most remarkable efforts of Roman ingenuity. That through which the waters of the lake Fucinus discharged themselves into the Liris, is represented in the preceding woodcut." — Smith, 1873.

Emissarium

"An artificial channel formed to carry off any stagnany body of water, like the sluices in modern use.…