Octant made by Spencer, Browning and Rust, London, about 1820. Ebony frame and limb with a brass index arm and fittings, inlaid ivory plates on the crossbar and on the back of the frame. Signed on the inlaid plate on the crossbar: . Spencer . Browning & Rust . London . Marked (stamped) on the scale (at 47°) SBR. Inlaid ivory scale from -2° to 99° every 20', measuring to 91°. Ivory vernier to 1', zero at the right. The tangent screw and clamping screw are on the back of the index arm. Three socket shades (two red, one green). Index-glass adjustment by a screw; adjustment of the horizon glass by a screw, and by a lever, worm gear and a milled clamping screw; adjustment of the back horizon glass by a lever, wing nut and a milled clamping screw. Threaded sight vane without adjustment and a swivelling shutter with one pinhole; the back sight vane has one pinhole. An ivory-capped pencil is fitted in the crossbar. Telescope (86 mm), erect image. In a stepped oak box.