Pistor & Martins Astronomical Transit Instrument

This graduated circle is the only surviving part of a large instrument that was designed for determining the positions of stars, produced by Pistor & Martins in Berlin, and installed at the U.S. Naval Observatory in Washington, D.C., in 1865.
The circle measures 45.30 inches in diameter overall. The diameter of graduation is 43.40 inches. It is graduated to 2 minutes of arc, and would have been read by 4 microscope micrometers to 0.5 seconds of arc.
Ref: Instruments & Publications of the United States Naval Observatory (1876), pp. 21-22.
Elias Loomis, An Introduction to Practical Astronomy (1855), pp. 494-495, provides prices of meridian circles and transit instruments made by Pistor & Martins.
Currently not on view
Object Name
transit, astronomical
astronomical transit instrument
date made
ca 1865
Pistor & Martins
overall: 115 cm x 4.5 cm; 45 9/32 in x 1 25/32 in
place made
Deutschland: Berlin, Berlin
ID Number
accession number
catalog number
Science & Mathematics
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
U.S. Naval Observatory

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