Mahogany and brass octant.

Octant by an unknown English maker, about 1750. Mahogany frame, limb, and index arm, brass fittings, and a brass stop for the index arm; an inlaid (ivory) plate missing from the crossbar. Inlaid boxwood transversal scale from 0° - 90° and vice versa every 20' (for zenith distance), measuring to 90°. The scale reads to 2' by use of the ivory-lined fiducial edge at the end of the index arm. There is no tangent screw, the clamping screw (missing) is on the back of the index arm. Three socket shades (two red, one green). Index-glass adjustment by a screw; adjustment of both horizon glasses is by levers, wing nuts and milled clamping screws. The sight vane has two pinholes and a swivelling shutter; the back sight vane is missing. No box.