Ebony frame and limb with a brass index arm and fittings. It has inlaid ivory plates on the crossbar and on the back of the frame. The tangent screw and clamping screw are positioned on the back of the index arm. The octant has three index shades, two red and one green, which is cracked. Index-glass adjustment is made by a screw and on the horizon glass by a square-headed screw, a lever, worm gear and a milled clamping screw. The sight vane has two pinholes and a swivelling shutter. A pencil or screwdriver is missing from the crossbar. The octant has no box.

The instrument has an inlaid ivory scale from -3° to 104° by 20 arcminutes, measuring to 90°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.