The sextant has an ebony frame and limb with a brass index arm and fittings. It also has a wooden handle and an inlaid ivory plate on the crossbar. The tangent screw and clamping screw are positioned on the back of the index arm. The sextant has three shades, two red and one green, and two horizon shades in red and green. Index- and horizon-glass adjustment is made by square-headed screws and a detached key.

Attached to the sextant is a single lens magnifier on a 90mm hinged swivelling arm. There is also a threaded telescope bracket in two parts which has been fitted for correcting collimation error. It has perpendicular adjustment made by a rising-piece and a milled knob. The sight-tube is 81mm in length. The telescope, shaded eyepiece and the adjusting key are all missing. The sextant is contained in a wooden keystone box, with a trade label in the lid for Hubé, Méchanicien, Rue Basse Riche no. 6 (the road and number are handwritten), Brest. However, from records it has been found that Hubé Frères (rather than Hubé) are recorded as being established at this address in the nineteenth century.

The instrument has an inlaid ivory scale from -7° to 133° by 20 arcminutes, measuring to 117°. The sextant has an ivory vernier measuring to 1 arcminute, with zero at the right.