Green’s Dictionary of Slang

(US) a black servant: a porter, a waiter.

1917

R. Lardner Gullible’s Travels 119: They was about two dozen uniformed Ephs on the job to meet us. And when I seen ’em all grab for our baggage with one hand and hold the other out, face up, I knowed why they called it Palm Beach. [Ibid.] 135: ‘How about a little bronix before the feed?’ I says. ‘It would taste good,’ says the Missus. So I called Eph and give him the order. In somethin’ less than half an hour he come back empty-handed.