The octant has a dark-brown lacquered brass frame and wooden handle. Double-ended tangent screws, which are missing, are positioned on top of the index arms and the clamping screws are on the backs. The octant has three socket shades, two red and one green, and two horizon shades, one red, and one green. Index-glass adjustment is made by a screw and on the horizon glass by a screw and a capstan screw. Attached to the octant is a magnifier on a 63mm swivelling arm serving both verniers. There is also a threaded telescope bracket with perpendicular adjustment by a rising piece and a milled knob. A second telescope bracket is non-adjustable. The telescopes and unidentified parts are missing. The instrument is in poor condition. The octant originally had a box or case which is now missing.

The artificial horizon consists of a glass tube, which is missing, containing spirits or mercury fitted in a groove on the inside of the limb, and ending in a finger operated airtight valve. For an observation the air valve is kept open allowing the fluid to flow freely. At the instant the sight is taken, the valve is closed and the fluid is held in position. The altitude of the sight is taken as the average height of the two columns of fluid read against the two scales. Averaging eliminates any error due to expansion or contraction of the fluid by temperature.

Captain Donald Beatson patented the altimeter (no. 12,949 of 1850). The provenance of this instrument, and a signed and complete example (including its leather carrying case) preserved in the Nederlands Scheepvaartmuseum in Amsterdam, inv. no. B.0191(07), suggest that Hughes is the manufacturer.