Hi Andrew,

Thank you for contacting Mearto with your appraisal inquiry.

Johann Martin (also spelled Johan Martin and often signing his work "Johann Martin in Augspurg") was one of the finest German makers of portable scientific instruments during the late 17th and early 18th centuries.

Martin was born in Frankfurt am Main in 1642. By 1669 he had settled in Augsburg, one of Europe's leading centers for precision metalwork and scientific instrument making. He married into the family of Augsburg watchmaker Elias Weckherlin, eventually taking over his workshop and establishing himself as one of the city's foremost instrument makers. He remained active until his death in 1721.

During Martin's lifetime, Augsburg rivaled London, Paris, and Nuremberg as a center for luxury scientific instruments. Wealthy merchants, scholars, military officers, and travelers purchased finely made pocket compasses,
sundials, proportional compasses, surveying instruments, astronomical devices, and mathematical tools. Martin worked at the highest level of this tradition.

Martin is best known for refining—or, according to some authorities, inventing—the octagonal equinoctial "Augsburg dial"...you have one of these.

These ingenious portable instruments combine several functions: a magnetic compass, an adjustable equinoctial sundial, a folding gnomon, and engraved latitude tables listing dozens of European cities. Once aligned with magnetic north and set for the correct latitude, they provided remarkably accurate solar time almost anywhere in Europe. Antiquorum notes that Martin is often credited with creating the crescent-shaped equinoctial sundial, and regards him as one of Augsburg's finest makers.

Interestingly, the "48" inscribed does not refer to a year but rather to the approximate latitude of Augsburg

In 2003, a virtually identical equinoctial "Augsburg" dial with compass sold in Zurich for about $4,000. Based on more recent auctions of his works, the market has not cooled, and an early one with noteworthy provenance sold for €12,500 in 2019.

His works seem to fly under the radar in US auctions so if you're looking to sell this, I would suggest approaching auction houses in Europe, such as Dorotheum or Antiquorum, where this would probably sell in the range of €3,000-6,000

Please let us know if you have additional items to appraise, or questions/concerns, and thank you again for using Mearto.
~ Delia