細節
A MID-19TH CENTURY 5IN. RADIUS VERNIER QUINTANT BY POTTER
with oxidised brass 'Y' frame, the polished brass arc with inset silvered scale divided 5°- 0°- 170° and signed Potter, Poultry, London, vernier with clamp, fine adjustment and swivel magnifier, sighting tube, two mirrors, one shade and ebony handle, in fitted mahogany case with button securing and lock -- 4 x 8 x 7¾in. (10 x 20.3 x 19.5cm.)
See illustration