The octant has an ebony frame and limb with a brass index arm and fittings. It also has inlaid ivory plates on the crossbar and on the back of the frame. The tangent screw and clamping screw are on the back of the index arm. The octant has three socket shades, one green, and two red, as well as two horizon shades in green and red. Index-glass adjustment is made by a screw, and on the horizon glass it is by a square-headed screw and detached key, a lever, worm gear and a milled clamping screw. Attached to the octant is a threaded telescope bracket without adjustment, and with a swivelling sight vane with one pinhole. The telescope is 86 mm in length, with an erect image, and a screw-on eyepiece. Accompanying the object is a milled adjusting key and an ivory-capped pencil fitted in the crossbar. The octant is contained in a mahogany keystone box, containing in the lid a trade label for Goy and Co, Outfitters, Leadenhall Street, London, and a certificate for the Halstead Science and Art Club Prize for an oil painting, awarded to Edgar Tarry Adams at the Members’ Work Competition 23 January 1907.

Inlaid ivory scale from -3° to 107° by 20 arcminutes, measuring to 92°. The octant has an ivory vernier measuring to 1 arcminute, with zero at the right.

As outfitters Goy and Co were only retailers, not makers of this instrument.