The reflecting circle consists of a circular polished brass frame, with a wooden handle. A detached U-shaped bracket holds a second handle, which is cracked, with a brass-lined threaded hole for a third handle, which can also be screwed in 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 in red, orange, and green, and three horizon shades in red, orange, and green. Index-glass adjustment is made by a screw and on the horizon glass by a screw and a capstan screw.

Attached to the instrument is a magnifier on a 150 mm swivelling arm serving all three verniers. An accompanying detached magnifier, with its lenses missing, is on a 65mm swivelling arm for use on each of the verniers separately. There is a threaded telescope bracket with perpendicular adjustment made by a rising-piece and a milled collar. The telescope is 180 mm in length with an inverted image and two parallel cross wires. Two extra drawtubes are 80 mm and 87mm long, both with two parallel cross wires. Accompanying the circle is a sight-tube, which is 134 mm in length with a red shaded eyepiece, an adjusting pin, two shaded eyes pieces, one red and the other is missing, and a magnifying glass, which is missing.

The instrument has a polished limb with an inlaid silver scale indicated from 150° to 0° to 150°, although the entire scale is graduated by 20 arcminutes. The reflecting circle has three silver verniers to 20 arcseconds, with zeros at the left.

The circle is contained in a square fitted box of which the lid is missing.

This is an example of Troughton’s largest reflecting circle, which he designed in 1796. The U-shaped bracket was recommended by Mendoza Rios, and according to him first applied by Troughton.