Assertion: sluice | /r/HasProperty | placed with hollow side
Facets:
Source sentences:
text: At the Blue Spur Consolidated Gold Company’s plant, Gabriel’s Gully, New Zealand, where the sluice is necessarily very short, most of the stones are first separated from the gravel, and the finer material is then passed over a sluice paved with transverse angle-iron riffles, placed with the hollow side facing down stream (Fig 19, in which the arrow shows the direction of the stream); these iron riffles are placed 2 or 3 inches apart.