“CELEUSTES, in the ships of the ancients, was the boatswain, or other officer appointed to give the fignal to the rowers, when to pull, and when to stop their hands. –– The strokes of the oar were directed by a fong or Formula, called Celeufma. The Celeuftes was also called Epopeus, and by the Romans, Portifculus, or fimply Hortator.–– Ovid. Met. L. 3. v. 618, &c.”
[An Archæological Dictionary: Or, Classical Antiquities of the Jews, Greeks, and Romans, Wilson, 1781]