overall: .3 cm x 22.3 cm x 3.7 cm; 1/8 in x 8 25/32 in x 1 15/32 in
Germany: Thuringia, Jena
This rectangular transparent glass ruler has a millimeter scale numbered by tens from 0 to 200. It is marked: Carl Zeiss, (/) Jena. The rule is cracked in the lower left corner. A tan envelope is made from folded paper.
In 1846 Carl Zeiss established a workshop in Jena, Germany, that became known for microscopes, telescopes, and photographic lenses. The firm sold this rule for making measurements on drawings and photographs for 5 marks at least as early as 1891. By 1902, it was numbered model 134 and described as a 20-cm rule instead of a 200-mm rule. The new price of 7 marks increased to 8 marks in 1906. The Department of Entomology at the National Museum of Natural History used this rule to study its collections.