In the days before electricity, light below a vessel's deck was limited to candles, oil and kerosene lamps. A clever solution for the light problem was the deck prism. Laid flush into the deck, the prism point drew light down below decks. This prism is a smaller reproduction of Mystic Seaport's last remaining original Charles W. Morgan deck prism. Size: 2.5 inches High, 2.5 inches Wide, 2.5 inches Length For decoration, gift and awards.