Troughton & Simms Altitude and Azimuth Instrument

Description
The altitude and azimuth instruments made by Edward Troughton in London from the 1790s were remarkably stable and accurate, and Troughton & Simms continued this tradition. Indeed, Frederick W. Simms described the portable Troughton & Simms instruments as being "the most generally useful of all instruments for measuring angles, being applicable to geodesical as well as astronomical purposes."
This example, made in 1837 for Columbia College (now University), is of this sort. It has a large and powerful achromatic telescope. The horizontal and vertical circles are silvered, graduated to 5 minutes, and read by microscopes with micrometers to 5 seconds. The graduated vertical circle is counterbalanced by a second circle on the other side of the telescope. The telescope assembly and horizontal axis rest on two conical pillars, supported by wyes and friction rollers. A long level is mounted between the microscopes reading the vertical circle. The inscriptions read "Troughton & Simms, London, 1837" and "Property of Columbia College."
Ref: Frederick W. Simms, A Treatise on the Principal Mathematical Instruments (Baltimore, 1836), pp. 81–98.
Location
Currently not on view
Object Name
altitude and azimuth instrument
Date made
1837
maker
Troughton and Simms
Measurements
telescope aperture: 2 in; 5.08 cm
telescope: 24 in; 60.96 cm
horizontal circle: 16 in; 40.64 cm
vertical circle: 16 in; 40.64 cm
level: 11 in; 27.94 cm
place made
United Kingdom: England, London
ID Number
PH*319190
catalog number
319190
accession number
236206
subject
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
cited
Simms, Frederick W.. Treatise on the Principal Mathematical Instruments Employed in Surveying, Levelling, & Astronomy; 2nd Edition

Visitor Comments

Add a comment about this object

**Please read before submitting the form**

Have a comment or question about this object to share with the community? Please use the form below. Selected comments will appear on this page and may receive a museum response (but we can't promise). Please note that we generally cannot answer questions about the history, rarity, or value of your personal artifacts.

Have a question about anything else, or would you prefer a personal response? Please visit our FAQ or contact page.

Personal information will not be shared or result in unsolicited e-mail. See our privacy policy.

Image CAPTCHA
Enter the characters shown in the image.