Full-circle contact goniometer with detachable arms

unsigned
Full-circle contact goniometer (brass with silvered scale, outside diameter 9 cm) with detachable steel arms in a leather-covered case lined with dark blue velvet.
Unsigned, but certainly by Lingke in Freiberg, mid 19th century.
The upper part of the case has a label "J.D. Dana".
James Dwight Dana (1813 – 1895) was an American geologist, mineralogist and zoologist, and Silliman Professor of, first Natural History, later of Mineralogy and Geology in Yale College, from 1850 till 1892.

collection of the Division of Mineralogy and Meteoritics, Yale Peabody Museum

YPM MINAR.000076. Courtesy of the Division of Mineralogy and Meteoritics; Yale Peabody Museum; peabody.yale.edu. Photography by Harold Moritz

YPM MINAR.000137. Courtesy of the Division of Mineralogy and Meteoritics; Yale Peabody Museum; peabody.yale.edu. Photography by Stefan Nicolescu