The quintant has an ebony frame and limb, with a black-lacquered brass index, fittings, and a wooden handle. It also has an inlaid ivory plate on the cross bar. The tangent screw and clamping screw are located on the back of the index arm. The instrument has three index shades, two red and one green. Index-glass adjustment is made by a screw and on the horizon glasses by a screw and capstan screws.

Attached to the quintant is a non-adjustable threaded telescope bracket. The telescope is 84 mm in length with an erect image. Accompanying the instrument is a green shaded eyepiece.

The instrument has an inlaid ivory scale from -2° to 140° (lower division) and from 40° to 180° (upper division) by 30 arcminutes, measuring to 120° and 160°. The quintant has a vernier measuring to 1 arcminutes, with zero at the right.

The quintant is contained in a wooden keystone box.

This is an experimental instrument allowing angles up to 140° to be measured with the upper horizon glass, and up to 180° with the lower horizon glass. The scale mark indicates that it was divided on Ramsden’s engine that was later used by Worthington.