The sextant has an anodized brass oval-curve pattern frame and a wooden handle. The tangent screw and clamping screw are on the back of the index arm. The instrument has three shades, one green and two red, 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 moved on a brass-covered screw by milled knobs at either end. There is also a threaded telescope bracket with perpendicular adjustment by a rising-piece and a milled knob. The telescope is 150 mm in length with an inverted image and four cross wires. A second telescope is 89 mm with an erect image. An extra drawtube is 40 mm long with inverted image and four cross wires. The sight-tube is 82 mm in length and has an adjusting pin.

The instrument has a polished brass limb with inlaid gold scale from -2° to 139° by 10 arcminutes, measuring to 122°. The sextant has a gold vernier measuring to 10 arcseconds, with zero at the right.

The sextant is contained in a mahogany keystone box, with trade labels in the lid for Dollond and Co, London, and for William Gerrard, Liverpool (1862-90), and an oval handwritten label, ‘A. Bulmermill 1907’.