The octant has an 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. A tangent screw, with the knob missing, is positioned on the front of the index arm and the clamping screw is on the back. The octant has three socket shades, two red, and one green. Index-glass adjustment is made by a screw. On the horizon glass it is made by a lever, worm gear and a milled clamping screw, and on the back horizon glass by a lever, wing nut, and a milled clamping screw. The sight vane has two pinholes and a swivelling shutter, which is missing, along with the back sight vane. One foot is missing from the frame and a pencil or screwdriver is missing from the crossbar. The octant is contained in a damaged wooden stepped keystone box.

The instrument has an inlaid ivory scale from -3° to 100° by 20 arcminutes, measuring to 92°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.