The octant has an ebony frame and limb with a brass index arm and fittings. The tangent screw is positioned on top of the index arm and the clamping screw is on the back. The octant has three socket shades, one red and two green and three horizon shades, which are all red. Index-glass adjustment is made by a square-headed screw and a detached key and on the horizon glass by a lever, worm gear, a square-headed screw and a detached key. The sight vane has two pinholes and a swivelling shade with a red or a green shade. Accompanying the instrument is a shaded eyepiece, which is missing, and a milled adjusting key. The octant is contained in a polished keystone box, with a trade label in the lid for Isidore Bianchetti, 1 Rue Beauvau, Marseille, France.

The instrument has an inlaid ivory scale from -5° to 112° by 20 arcminutes, measuring to 104°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.

Optician Isidore Bianchetti established his firm in 1827, and was later joined by two sons.