The octant has an ebony frame and limb with a brass index arm, fittings, and an ebony handle. It also has an inlaid ivory plate on the crossbar. The tangent screw and clamping screw are on the back of the index arm. The octant has three shades, two red and one green, and three horizon shades, two red and one green. Index-glass adjustment is made by a square-headed screw and a detached key and on the horizon glass by a square-headed key, a detached key, a lever, worm gear and a milled clamping screw. Attached to the octant is a threaded telescope bracket without adjustment. The telescope is 86 mm in length with a large objective lens, and erect image. The sight-tube is 96 mm in length with a red shaded eyepiece, a magnifying glass, and an adjusting key. The octant is contained in a polished mahogany keytone box, with a handwritten label in the lid ‘1910. E. Company 5th Batt.n Essex Reg.t Honorary Member 2nd Prize won by E. T. Adams’.

The instrument has an inlaid ivory scale from -2° to 104° by 20 arcminutes, measuring to 89°. The octant has an ivory vernier measuring to 30 arcseconds, with zero at the right.

This is an unusually large octant for this date. It appears unused and may have made been kept for display or demonstration purposes.