The repeating circle consists of a circular blackened brass frame with bright fittings and a detached wooden handle. The index arm carries the index glass and the telescope arm carries the horizon glass. The tangent screw and clamping screw are positioned on the back of the index arm. A second tangent screw, without a clamp, is at the ocular end of the telescope arm; the vernier is at the other end. The instrument has two detached grey index shades and no horizon shades. Index-glass adjustment is made by a thumbscrew and square-headed screws and on the horizon-glass by screws, a square-headed-screw and a detached key. The telescope is 125 mm in length with an inverted image and two parallel cross wires.

Attached to the repeating circle are two threaded telescope brackets with perpendicular adjustment made by a rising-piece and milled knobs. Accompanying the instrument is a red shaded eyepiece, an adjusting key with a wooden handle, and a magnifying glass.

The instrument has a polished brass scale from 0° to 720° by 30 arcminutes. The repeating circle has two brass verniers measuring to 1 arcminute, with the zeros at the right.

The repeating circle is contained in a square fitted mahogany box, with a handwritten label in the lid, ‘Constant Angle 201° 10'’. Another handwritten label in the lid reads ‘A/. Old Bike is ABRW.j.ea. 1911’.

The inscription, which translates as ‘Jean Hyacinthe de Magellan invented and caused [this instrument] to be commissioned in London’ is also found on several clocks with his name. As with these it is not possible to determine what Magellan’s contribution to the Borda circle was. In his related article Betts recorded Ramsden as the probable manufacturer of this instrument.