The octant has an ebony frame and limb with a brass index arm, fittings, and a brass stop for the index arm. It also has decorative diamond-shaped inlaid ivory pieces in both struts, as well as inlaid ivory plates on the crossbar and on the back of the frame. A double-ended tangent screw is positioned on the front of the index arm and the clamping screw is on the back. The octant has three socket shades, one green and two red. 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, whereas the back sight vane has one pinhole. A pencil or screwdriver is missing from the crossbar. Decorative engravings, including flags and a drum, are found on the lower half of the index arm.

The octant is contained in an oak keystone box with a stepped lid, painted dark blue on the outside and containing a trade label for ‘Henry Edgeworth, Opposite the Dial, on the Quay, Bristol’, including an inventory of instruments sold by him in 1779. Another trade label is for Antoine Roux in Marseilles, selling charts and navigational instruments, sails, and flags of all colours.

Inlaid ivory scale from -5° to 95° by 20 arcminutes, measuring to 90°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the centre.