Ballast, alidade, bail, and ring. Mariner's astrolabe is cast wheel type with base ballast. Surface is pitted. Throne cast with body; ring and bail are pivoted. Date 1616 is punched on triangular spoke at bottom. This was one of five found on Spanish ship Nuestra Señora de Atocha, sunk off Marquesa Keys in September 1622. Cast brass wheel. Alidade with two pinhole sights.
Inscription/Sig.
Unsigned. Marked on the ballast on the front: "1616"
