The sextant has an anodized brass straight-bar pattern pillar frame, with twenty pillars, and a wooden handle. The tangent screw and clamping screw are positioned on the back of the index arm, both of which are defect and incomplete. The sextant has four shades, one green and three red, and three horizon shades, two red and one green. Index-glass adjustment is made by a screw and on the horizon-glass by a square-headed screw and a detached key.

Attached to the sextant is a magnifier on an 89mm swivelling arm with a frosted glass shade. There is also a threaded telescope bracket in two parts, fitted for correcting collimation error. It has perpendicular adjustment made by a rising-piece and a milled knob. The sight-tube is 130 mm in length. The adjusting key and one foot from the frame are missing. The sextant has no box.

The instrument has a polished brass limb with inlaid silver scale from -5° to 157° by 10 arcminutes, measuring to 131°. The octant has a silver vernier measuring to 10 arcseconds, with zero at the right.

Edward Troughton patented the pillar and plate frame (no. 1644 of 1788).