Equinoctial ring-dial signed "A.C. Toblhanhb Mockba" (i.e. A.S. Trinidin, Moscow) undated, 18th century.

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Equinoctial ring-dial signed "A.C. Toblhanhb Mockba" (i.e. A.S. Trinidin, Moscow) undated, 18th century. Wellcome Collection. Source: Wellcome Collection.