The octant has an ebony frame and limb with a brass index arm, fittings, and an inlaid ivory plate on the crossbar. The tangent screw is positioned on top of the index arm and the clamping screw is on the back; both screws are broken. The octant has three shades, two red and one green, and one green horizon shade, which is probably not original to this instrument. Index-glass adjustment is made by a screw and on the horizon glass, with its glass missing, by a lever worm gear and a milled clamping screw. Attached to the octant is a threaded telescope bracket without adjustment, and a swivelling sight vane with one pinhole. The telescope, adjusting pin and shaded eyepiece are missing, and the milled screws vary in type, implying some must be replacements. The octant is contained in a shaped mahogany box, with a badly damaged trade label in the lid for William Langford, Bristol (1828-73).

The instrument has an inlaid ivory scale from -2° to 108° by 20 arcminutes, measuring to 93°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.