Altitude and Azimuth Instrument
date: label: Date made
content: 1837
name: label: maker
content: Troughton and Simms
notes: label: Description
content: 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."
label: Description
content: This example, made in 1837 for Columbia College (now University), 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."
label: Description
content: Ref: Frederick W. Simms, <i>A Treatise on the Principal Mathematical Instruments</i> (Baltimore, 1836), pp. 81–98.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: England, London
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Surveying and Geodesy
label: See more items in
content: Measuring & Mapping
publisher: label: Related Publication
content: Simms, Frederick W.. Treatise on the Principal Mathematical Instruments Employed in Surveying, Levelling, & Astronomy; 2nd Edition
creditLine: label: Credit Line
content: Columbia University. Deparment of Astronomy
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.319190
label: catalog number
content: 319190
label: accession number
content: 236206
objectType: label: Object Name
content: altitude and azimuth instrument
label: Object Name
content: transit, geodetic
physicalDescription: label: Measurements
content: telescope aperture: 2 in; 5.08 cm
label: Measurements
content: telescope: 24 in; 60.96 cm
label: Measurements
content: horizontal circle: 16 in; 40.64 cm
label: Measurements
content: vertical circle: 16 in; 40.64 cm
label: Measurements
content: level: 11 in; 27.94 cm