The sextant has a black-lacquered brass oval-pattern frame and a wooden handle. The tangent screw and clamping screw are located on the back of the index arm. The sextant 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.

Attached to the sextant is a magnifier on a 101mm swivelling arm. 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 171 mm in length, with an ocular section missing, and probably has an inverted image. A second telescope is 171 mm, with an ocular section missing, and probably has an inverted image. The sight-tube is 92 mm, and an incomplete second sight-tube is 76 mm in length, with an adjusting pin. A shaded eyepiece, magnifying glass and an unidentified part are missing.

The instrument has a polished brass limb with an inlaid silver scale from -5° to 145° by 10 arcminutes, measuring to 133°. The sextant has a silver vernier measuring to 10 arcseconds, with zero at the right.

The sextant is contained in a wooden keystone box, with a trade label in the lid for Henry Hughes and Son.

Edmund Swain, the original owner, is recorded in the ‘Navy List’ from 1847 to 1871 as rising from Assistant Master to Staff Commander. He died on active service on the China Station in HMS ‘Ocean’.