The sextant consists of circular polished brass plates with a lid that when screwed on the back of the instrument serves as the handle. The index arm is moved by a milled knob on the upper plate. The instrument has two index shades in red and green, which are moved by levers. Index-glass adjustment is made by a screw and on the horizon-glass by a square-headed screw and a milled key shipped in the upper plate.

Attached to the sextant is a single lens magnifier on a 50mm swivelling arm. The telescope is 63 mm in length with an erect image and a sliding pinhole shutter. It also has a green shaded eyepiece and an angled bracket for attaching it to the instrument. The case contains an adjusting key, which is probably from another instrument.

The instrument has an inlaid silver scale from -5° to 165° by 30 arcminutes, measuring to 136° (the digits are read from the pivot). The sextant has a silver vernier measuring to 1 arcminute, with zero at the left.

The sextant is contained in a fitted velvet-lined leather carrying case, with its strap missing, The case is marked in handwriting, ‘E. T. Adams R. Terrence’.