An open quadrant 5.75" (14.6cm) radius, mounted vertically apex at top with one side vertical. An index bar 8.4" (21.3cm) long is pivoted 5.9" (15cm) from its lower end, at the apex. A vernier scale is atached to the lower end of bar. Two lenses are mounted on bar, one at upper end, the other 1.5" (3.5cm) from lower end. A third lens is attached to an arm 2.5" (6.4cm) long which rotates about pivot. A spirit level in a brass casing 4.9" (12.5cm) long is mounted on upper edge of quadrant. The base of the instrument forms a bar 8.75" (22.2cm) long, a levelling screw is fitted at one end and a folding brass pointer at the other. A slot is cut in the underside of the base 1.2" (3cm) in from the pointer and to accommodate a brass plate 5.1" (13cm) long with a levelling screw at either end, set at right angles to the instrument.
Graduations-one edge of quadrant is graduated -10-100, by 30' with a hole at 90 degs. A silver vernier scale at end of index bar is graduated 15-30-15, 45-60-45. "Trinia Minuta".
In fitted wooden box, lined with blue paper; containing 2 spare eyepieces and 2 plumb bobs. Under tray there is a sheet of manuscript instructions for use of micrometer.