{"product_id":"swiss-spherometer-by-jauge-patent-no-28680-precision-optical-watchmaking-instrument-steel-early-20th-century","title":"Swiss Spherometer - “Jauge Patent” No. 28680, Precision Optical \u0026 Watchmaking Instrument, Steel, Early 20th Century","description":"\u003cp data-start=\"702\" data-end=\"1159\"\u003eA 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.\u003c\/p\u003e\n\u003cp data-start=\"1161\" data-end=\"1709\"\u003eThe 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.\u003c\/p\u003e\n\u003cp data-start=\"1711\" data-end=\"1802\"\u003e\u003cstrong data-start=\"1711\" data-end=\"1721\"\u003eCirca:\u003c\/strong\u003e Early 20th century (c. 1900–1920)\u003cbr\u003e\u003cbr data-start=\"1755\" data-end=\"1758\"\u003e\u003cstrong data-start=\"1758\" data-end=\"1773\"\u003eProvenance:\u003c\/strong\u003e Thomas Guenther Collection\u003c\/p\u003e\n\u003cp data-start=\"1804\" data-end=\"1860\"\u003e\u003cstrong data-start=\"1804\" data-end=\"1821\"\u003eMeasurements:\u003c\/strong\u003e\u003cbr data-start=\"1821\" data-end=\"1824\"\u003eHeight: 12.0 cm\u003cbr data-start=\"1839\" data-end=\"1842\"\u003eDiameter: 6.6 cm\u003cbr\u003e\u003cstrong data-start=\"1862\" data-end=\"1873\"\u003eWeight:\u003c\/strong\u003e 510 g\u003c\/p\u003e","brand":"Esteemed Antiques","offers":[{"title":"Default Title","offer_id":53518411432277,"sku":"TG HE 011","price":380.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1008\/2353\/1861\/files\/1_34121f8e-b501-47d0-9f9c-52d5e8824ad6.png?v=1774092582","url":"https:\/\/esteemedantiques.com\/products\/swiss-spherometer-by-jauge-patent-no-28680-precision-optical-watchmaking-instrument-steel-early-20th-century","provider":"Esteemed Antiques","version":"1.0","type":"link"}