Contact goniometer with detachable arms

A. Picart, 20 rue Mayet, Paris
Contact goniometer with detachable arms (brass and steel, outside diameter 9.4 cm) in red plush-lined ray-skin-covered case (11.4 cm wide).
Signed on the instrument "A. PICART | 20 RUE MAYET | PARIS" and on the case "A. PICART | OPTICIEN | RUE MAYET 20 | PARIS", 2nd half 19th century.

private collection