The octant has an ebony frame and limb with a brass index arm and fittings. It also has inlaid ivory plates on the crossbar and on the back of the frame. The tangent screw and clamping screw are located on the back of the index arm. The octant has three socket shades, two red and one green. Index-glass adjustment is made by a screw and on both horizon glasses by levers, wing nuts and milled clamping screws. The sight vane, which is broken in two pieces, has two pinholes and a swivelling shutter, whereas the back sight vane has one pinhole. A pencil or screwdriver is missing from the crossbar. The octant is contained in a stepped oak box, with an oval handwritten label in the lid ‘[illegible] ... country Southampton 1908’.

The instrument has an inlaid ivory scale from -4° to 101° by 20 arcminutes, measuring to 90.5°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.