The octant has an ebony frame 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. The tangent screw and clamping screw are located on the back of the frame. 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 detached key, a lever, worm gear and a milled clamping screw. The sight vane has two pinholes and a red swivelling shade. The adjusting key and an ivory cap for a pencil fitted in the crossbar are missing The octant has no box.

The instrument has an inlaid ivory scale from -2° to 100° by 20 arcminutes, measuring to 91°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.