Bidspirit auction | 18th Century Ebony/Brass/Ivory Navigation Octant

18th Century Ebony/Brass/Ivory Navigation Octant - This mariner octant, also known as a Hadley?s Quadrant, is a navigational instrument from the late 18th century. The frame is constructed of ebony with brass fittings and features white inlaid scales and plates. A bone or ivory nameplate inset into the cross-brace is engraved with the maker's name and location reading JEACOCK: LONDON. The instrument features a polished brass index arm with a secondary vernier scale graduated from 0 to 20. This arm includes a brass tangent screw mechanism for fine adjustments. The main arc scale is inlaid into the ebony frame and is graduated from 0 to 95 degrees, with markings every 20 minutes. The optical and sighting components consist of a brass sight vane with both a pinhole and larger aperture, a horizon mirror, and an index mirror located at the pivot point. Three colored glass sun shades are mounted on a brass swivel to protect the user's eyes during solar observations. The brass components show a natural aged patina throughout.