The sextant has an anodized brass diamond-pattern frame with a wooden handle. The tangent screw and clamping screw are positioned 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 square-headed screw, a detached key, and two capstan screws.

Attached to the sextant is a magnifier on an 80mm 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 83 mm in length with an erect image. A second telescope is 162 mm with an inverted image and two parallel cross wires. The sight-tube is 75 mm and has a red shaded eyepiece; a second grey shaded eyepiece is from another instrument.

Accompanying the sextant is a screwdriver, an adjusting pin, and a milled adjusting key; two unidentified parts are missing. The sextant is contained in a wooden keystone box, with a trade label in the lid for John Lilley and Son, London. Inside the lid is a handwritten inscription, ‘E.T. Adams 1906’ and a small handwritten label, ‘40 TAL’.

The instrument has a polished brass limb with an inlaid silver scale from -3° to 155° by 15 arcminutes, measuring to 130°. The sextant has a silver vernier measuring to 15 arcseconds, with zero at the right.