Troughton & Simms Altitude and Azimuth Instrument

This instrument marked "Troughton & Simms, London" belonged to Columbia College (now University), and dates from around 1837. The horizontal and vertical circles are silvered, graduated to 10 minutes, and read by verniers to 10 seconds. There is a trough for a magnetic needle.
Ref: Frederick W. Simms, A Treatise on the Principal Mathematical Instruments Employed in Surveying, Levelling, & Astronomy (Baltimore, 1844), pp. 89–109, describes a similar instrument, but with two vertical circles.
Currently not on view
Object Name
altitude and azimuth instrument
date made
ca 1837
Troughton and Simms
overall: 21 in; 53.34 cm
horizontal circle: 11 1/2 in; 29.21 cm
vertical circle: 9 in; 22.86 cm
telescope: 20 in; 50.8 cm
place made
United Kingdom: England, London
ID Number
catalog number
accession number
Measuring & Mapping
Surveying and Geodesy
See more items in
Medicine and Science: Physical Sciences
Surveying and Geodesy
Data Source
National Museum of American History, Kenneth E. Behring Center
similar type referenced
Simms, Frederick W.. Treatise on the Principal Mathematical Instruments Employed in Surveying, Levelling, & Astronomy; 5th Edition

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