The octant has an ebony frame and limb with a dark, brown-lacquered, brass index arm and fittings, a wooden handle, and 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 index shades, two red and one green. Index-glass adjustment is made by a screw; however, one side of the mount is missing. The horizon glass is adjusted by a milled screw, a lever, worm gear and a milled clamping screw. Attached to the octant is a threaded telescope bracket without adjustment. The telescope is 78 mm in length and has an erect image. The sight-tube is 83 mm in length. A shaded eyepiece and adjusting pin are missing. The octant is contained in a keystone polished mahogany box, with a trade label in the lid for F. Smith, 18 Southside Street, Plymouth.

The instrument has an inlaid ivory scale from -2° to 105° by 20 arcminutes, measuring to 88°. The octant has an ivory vernier measuring to 30 arcseconds, with zero at the right.

The record on the object mentions that it came from the possession of the Griffin family, one of whose members sailed with James Cook in the ‘Resolution’. The reference to William Griffin (Griffith), who sailed as a cooper in the ‘Resolution’ (1776-80), suggests that it came from him. However, because of the date of the instrument this is impossible.