The sextant has a polished brass frame and limb with a wooden handle. The tangent screw with micrometer drum is located on the front of the index arm and the clamping screw is on the back. The lower part of the index glass is silvered and can be covered by the Maskelyne flap, whereas the upper part is not silvered. The sextant has three shades, two red and one green, and two horizon shades in red and green. Index-glass adjustment is made by a screw and on the horizon glass by a Dollond’s extended lever and clamp operated from beneath the telescope bracket. Attached to the sextant is a threaded telescope bracket in two parts, fitted for correcting collimation error. It has perpendicular adjustment by a rising-piece and a milled knob. The telescope is 127 mm in length and has an inverted image. The sextant is contained in a wooden keystone box.

The inatrument has a brass scale from -2° to 135° by 20 arcminutes, measuring to 120°. The sextant has a brass vernier measuring to 30 arcseconds, with zero at the right. It also has a brass micrometer drum measuring to 10 arcseconds.

The earliest recorded use of a serial number by Ramsden. Peter Dollond patented the horizon glass adjustment (no. 1017 of 1772). The micrometer is defective.