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

Attached to the sextant is an incomplete magnifier on a 95mm swivelling arm; this is not original to the instrument. 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 telescope is 175 mm in length and is incomplete. A second telescope is 84 mm long, and is incomplete. The sight-tube is 76 mm in length. Two further telescopes and shaded eyepieces are missing. The sextant is contained in a wooden keystone box with a brass plate on the lid marked, ‘Lord John Hay R.N’. The lid contains a trade label for J. C. Dennis, 122 Bishopsgate Street, London (1850-62).

The instrument has a polished brass limb with an inlaid silver scale from -5° to 145° by 10 arcminutes, measuring to 130°. The sextant has a silver vernier measuring to 10 arcseconds, with zero at the right.

There are two Lord John Hays that could have owned this instrument. The elder (1793-1851) rejoined the Royal Navy in 1832 and his nephew (1827-1916) joined in 1839.