The sextant has an ebony frame and limb with a brass index arm,fittings, and a brass stop for the index arm. It also has a wooden handle and an inlaid ivory plate on the crossbar. The tangent screw is positioned on the front of the index arm and the clamping screw is on the back. The sextant has three shades, two red and one green, and three horizon shades, two red and one green. Index-glass adjustment is made by a screw and on the horizon glass by a milled knob, an extended brass lever, and a clamp operated from beneath the telescope bracket.

Attached to the sextant is a threaded telescope bracket with a swivelling sight vane and one pinhole. It has perpendicular adjustment made by a rising-piece and a milled knob. The telescopes for this instrument are missing. The sextant is contained in a shaped mahogany box with a stepped lid, which is probably not original to this instrument.

The instrument has an inlaid ivory scale from -2° to 136° by 20 arcminutes, measuring to 120°. The sextant has an ivory vernier measuring to 1 arcminute, with zero at the right.

Peter Dollond patented the horizon glass adjustment (no. 1017 of 1772).