Swiss Spherometer - “Jauge Patent” No. 28680, Precision Optical & Watchmaking Instrument, Steel, Early 20th Century

A Swiss-made spherometer, marked “Jauge Patent” with Swiss cross and patent numbers, designed for measuring the radius of curvature of surfaces. Instruments of this type are traditionally used in optical workshops to determine the curvature of lenses, but were also employed in precision horological environments where control of curvature and surface geometry was critical, particularly in balance staff components, jewel settings, and domed watch glasses.

The instrument operates via a finely threaded central spindle descending onto a surface, with measurement taken relative to a fixed base plane. The calibrated arc scale allows controlled, repeatable readings. Constructed in cast and machined steel with a weighted base, the piece reflects early 20th century precision engineering. The engraved markings remain legible, and the mechanism appears complete, with wear consistent with workshop use. Instruments of this type are increasingly valued by collectors of scientific and horological apparatus.

Circa: Early 20th century (c. 1900–1920)

Provenance: Thomas Guenther Collection

Measurements:
Height: 12.0 cm
Diameter: 6.6 cm
Weight: 510 g