The sextant has a polished brass frame and limb, brass stop for the index arm. There is no tangent screw and the clamping screw is located on the back of the index arm. The sextant has two red index shades and no horizon shades. Index-glass adjustment is made by a screw and on the horizon glass, whose glass is missing, by a lever wing nut and a milled clamping screw. The sight vane has two pinholes and a swivelling red shade. The sextant is contained in a mahogany keystone box, which is possibly of later date.

The instrument has a polished brass scale from -5° to 135° by 30 arcminutes, measuring to 120°. The sextant has a brass vernier measuring to 1 arcminute, with zero at the right. A second vernier measuring to 1 arcminute, with zero at the right, is fitted to the left of the index arm (the difference between is two zeros is 24°30 arcminutes).