Smithsonian - National Museum of American History, Behring Center

Physical Sciences Collection - Surveying and Geodesy

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Altitude and Azimuth Instrument - click to enlarge

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Altitude and Azimuth Instrument

Catalogue number:

"Troughton & Simms, London"

height 21 inches; horizontal circle 11.5 inches diameter; vertical circle 9 inches diameter; telescope 20 inches long

This instrument was made by Troughton & Simms of 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.

Further Information:

Altitude & Azimuth Instrument
Troughton & Simms