|Ivory Inlaid Rosewood & Boxwood Mariner's Davis Type Quadrant (Backstaff). A rare and desirable mariner's quadrant, with rosewood frame, boxwood scales and sights, whale ivory inlays and brass and copper pins and fittings; inscribed on an ivory plaque; Made for M: Joseph White (thought to be a Maine sea captian); probably made in Newburyport. One of the earliest types of celestial navigation instruments made and used in Colonial America. Length 23", Width 13". Circa 1755.