The octant has an ebony frame and limb with a brass index arm and fittings.The brass stop for the index arm is missing and the hole has been filled in. The octant also has inlaid ivory plates on the crossbar and on the back of the frame. A tangent screw is positioned on top of the index arm, and the clamping screw is on the back. The socket shades for the octant are missing. Index-glass adjustment is made by a screw. On the horizon glass it is made by a lever and worm gear 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, whereas the back sight vane has one pinhole. A pencil or screwdriver is missing from the crossbar. There is an extension on the back of the index arm, which slides through a groove let into the bottom of the limb. The crossbar is cracked. The octant is contained in a damaged stepped oak box, containing in the lid the remains of a trade label for a London instrument maker, probably Thomas Lorkin.

The instrument has an inlaid ivory scale from -2° to 99° by 20 arcminutes, measuring to 90°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.