The octant has an ebony frame and limb with a black-lacquered 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, which is a replacement, are located on the back of the index arm. The octant has three index shades, two red and one green. Index-glass adjustment is made by a screw and on the horizon glass by a lever, worm gear and a milled clamping screw. The sight vane has one pinhole. An ivory cap for a pencil is fitted in the crossbar. The octant has no box.

The instrument has an inlaid ivory scale from -8° to 106° by 20 arcminutes, measuring to 93°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.