Assertion: roman aqueduct | /r/Desires | gravity
Facets:
value: for a constant flow of water
type: PURPOSE
Source sentences:
text: Lacking suitable pressurized piping, Roman aqueducts had to rely on gravity for a constant flow of water, and engineers such as Nonius Datus bridged ravines and tunneled through mountains to maintain the imperceptible downgrade—typically a few feet per mile