The octant has a mahogany frame and limb with a brass index arm, fittings, and a brass stop for the index arm. It also has inlaid ivory plates on the crossbar and on the back of the frame. There is no tangent screw and the clamping screw is located on the back of the index arm. The octant has three socket shades, one in red, one in orange and one now missing,. Index-glass adjustment is made by a screw and on both horizon glasses by levers, wing nuts, and milled clamping screws. The sight vane has two pinholes and a swivelling shutter, whereas the back sight vane has one pinhole. An ivory-capped pencil is fitted in the crossbar. The octant is contained in an oak keystone box with a stepped lid.

The instrument has an inlaid ivory scale from -5° to 95° by 20 arcminutes, measuring to 89.5°.The octant has a damaged ivory vernier measuring to 1 arcminute, with zero at the centre.