Corning milk glass USN watch mug

Handless watch mug, off-white but turns green under black light. Weighs 15 ounces, 3 1/2 inches tall and 3 1/2 inches in diameter. Marked with the hornblower, Corning, T. M. Reg., Made in U.S.A. In excellent condition, showing slight signs of use. Not sure of date but because of green, possibly from 1930's.