The octant has an ebony frame and limb with a brass index arm and fittings. It has inlaid ivory plates on the crossbar and on the back of the frame. Tangent screw and clamping screw are on the back of the index arm. The octant has three socket shades, two red, and one green, as well as three horizon shades, two red, and one green. Index-glass adjustment is made by a screw, whereas on the horizon glass it is made by a lever, a milled screw and worm gear. Attached to the octant is a threaded telescope bracket without adjustment. The telescope is 182 mm in length, with an inverted image, and four cross wires. A pencil or screwdriver is missing from the crossbar. The octant is contained in a stepped keystone oak box marked on the inside in ink ‘S. Hayman 3-‘ [and] ‘M. Sulivan’, and on the top of the lid ‘Hayman 3’ [and] ‘T Ager 10’ and various illegible names.

The instrument has an inlaid ivory scale from -2° to 100° by 20 arcminutes, measuring to 92°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.