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This is a compound monocular designed for petrographic work. It has coarse and fine focus, analyzer in the tube, square stage with circular top graduated to degrees, sub-stage polarizer, sub-stage mirror, heavy horseshoe base, and wooden box. The inscription on the tube reads “Dr. E. Hartnack / Potsdam.” The serial number “19544” appears on a smaller wooden box that holds seven lenses. A brass plate on the box reads “C. Whitman Cross.”
Edmund Hartnack (1826-1891) was an accomplished microscope maker in Paris who received an honorary doctorate from the University of Bonn in 1868, moved to Potsdam in 1870, at the start of the Franco-Prussian War, and adopted the "Dr. E. Hartnack" signature in 1879.
Charles Whitman Cross (1854-1959) was an American geologist who graduated from Amherst College, studied in Göttingen, and received a PhD from the University of Leipzig. His dissertation was supervised by Ferdinand Zirkel, an early proponent of microscopical petrography, the practice of using a polarizing microscope to observe thin sections of rocks. Joining the U.S. Geological Survey, Cross specialized in the classification of igneous rocks. He became an active member of the National Academy of Sciences, and an Associate in Petrology at the Smithsonian Institution.
Currently not on view
Object Name
date made
ca 1880
Hartnack, Edmund
place made
Germany: Brandenburg, Potsdam
Physical Description
glass (overall material)
brass (overall material)
nickel (overall material)
overall: 11 1/4 in x 3 1/2 in x 4 3/4 in; 28.575 cm x 8.89 cm x 12.065 cm
overall in case: 4 5/8 in x 12 1/4 in x 7 1/4 in; 11.7475 cm x 31.115 cm x 18.415 cm
ID Number
catalog number
accession number
Credit Line
Whitman Cross II
Science & Scientific Instruments
See more items in
Medicine and Science: Physical Sciences
Science & Mathematics
Data Source
National Museum of American History
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The serial number can also be found stamped into the wood on the top edge of the box to the right of the lock.

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