The sextant has an anodized brass triangle-pattern frame and a wooden handle. The tangent screw and clamping screw are 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 a capstan screw and a milled knob that is swivel-mounted.

Attached to the sextant is a magnifier on a 95mm 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 184mm in length with an inverted image and four cross wires. An extra drawtube is 81 mm long with an inverted image and two parallel cross wires. A second telescope is 83 mm long with an erect image. The sight-tube is 80 mm in length with a green shaded eyepiece and an adjusting pin. An unidentified part is missing.

The instrument has a polished brass limb with an inlaid silver scale from -5° to 135° by 10 arcminutes, measuring to 130°. The sextant has a silver vernier measuring to 10 arcseconds, with zero at the right.

The sextant is contained in a keystone box, lined with green textile and with a blank brass plate on the lid. The lid contains a certificate for the index error, issued by ‘Observatory’, Devonport and dated 10 November 1898, J. Coombes, Admiralty Agent, and [signed] ‘Capt. J. I. Graham RN’.

According to an advertisement in the 'Post Office Directory of Plymouth, Devonport and Stonehouse of 1906-1907', Messrs Coombes were optical and scientific instrument makers at ‘The Observatory’, Fore Street in Devonport (established 1806). They rated chronometers by transit observations and apparently also examined sextants. A similar certificate for a sextant, signed by Coombes and dated 1897, is preserved in the Peabody Essex Museum, Salem, Massachusetts, inv. no. M.11046.