The octant has a mahogany frame and limb with a brass index arm, fittings, and a stop for the index arm. There is an inlaid ivory plate on the crossbar. There is no tangent screw, and the clamping screw is on the back of the index arm. The socket shades are missing, though the mount is present. Index-glass adjustment is made by a screw and both horizon glasses by levers, wing nuts, and milled clamping screws. The sight vane has two pinholes and a swivelling shutter, and the back sight vane has one pinhole. Both vanes may be later replacements. The octagon has no box.

The instrument has an inlaid boxwood scale from -5° to 95° by 20 arcminutes, measuring to 93°. The octant has a brass vernier measuring to 1 arcminute, with zero at the centre.