The sextant has a blackened brass oval-pattern frame and a wooden handle. The tangent screw and clamping screw are positioned on the back of the index arm. The instrument has four shades, three 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 capstan screws.

Attached to the sextant is a magnifier on an 82mm 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 telescope is 185 mm in length with an inverted image and four cross wires. A second telescope is 84 mm long with an erect image. The sight-tube is 82 mm in length with a red shaded eyepiece and an adjusting pin, which is missing. The sextant is contained in a wooden keystone box lined with green textile. A brass disc on the lid is marked ‘T.M. Hardy. R.N. 1793’.

The instrument has a polished brass limb with an inlaid silver scale from -5° to 160° by 10 arcminutes, measuring to 134°. The sextant has a silver vernier measuring to 10 arcseconds, with zero at the right.

The inscription on the brass disc suggests that this instrument belonged to Vice-Admiral Sir Thomas Masterman Hardy (1769-1839) who was in ‘Amphitrite’ in 1793, was later Nelson’s flag-captain including at Trafalgar, and was Governor of Greenwich Hospital from 1834 until his death. The sextant is, however, of much later date.