The reflecting circle consists of a circular polished brass frame, with a wooden handle. A detached U-shaped bracket holds a second handle with a brass-lined threaded hole for a third handle, now missing, which can also be screwed on the front of the frame. The instrument has three rigidly connected index arms on the back of the frame, and a double-ended tangent screw and a clamping screw on the back of one of the arms. It has three index shades, two red and one green, and three horizon shades, two red and one green. Index-glass adjustment is made by a screw and on the horizon glass by a screw and a capstan screw.

Accompanying the circle is a detached magnifier on a 102mm swivelling arm serving all three verniers. There is also a threaded telescope bracket in two parts, fitted for correcting collimation error. It has perpendicular adjustment made by a rising-piece and a milled collar. The telescope is 185 mm in length with an inverted image and two parallel cross wires. An extra drawtube is 84 mm long with two parallel cross wires. A second telescope is 74 mm with an erect image. Accompanying the reflecting circle is a sight-tube, which is 130 mm in length, an adjusting pin, and two shaded eyepieces, which are missing.

The instrument has a polished brass limb with an inlaid silver scale indicated from 160° to 0° to 160°, although the entire scale is divided by 20 arcminutes. The reflecting circle has three silver verniers measuring to 20 arcseconds, with zeros at the left.

The instrument is contained in a square fitted wooden box marked on the lid ‘C.23’.

The U-shaped bracket was recommended by Mendoza Rios, and according to him first applied by Troughton. ‘C.23’ was the Hydrographic Office serial numbering adopted in February 1828, whereby C was the letter given to altitude and azimuth instruments and circles.