Repeating Circle
name: label: maker
content: Troughton and Simms
notes: label: Description
content: This is one of two double repeating circles that Ferdinand Rudolph Hassler, the first superintendent of the U. S. Coast Survey, ordered from Edward Troughton in London in 1812, and that was shipped in 1815. The large circle may be angled from vertical to horizontal to the opposite vertical position. It is graduated to 10 minutes, and read by four verniers and two magnifiers to single minutes.
label: Description
content: A repeating circle is a geodetic instrument with two telescopes that is designed to reduce errors by repeated observations taken on all parts of the circumference of a circle. The form was developed by the Chevalier de Borda, first executed by Etienne Lenoir in Paris around 1789, and popular for about 50 years.
label: Description
content: Ref: F. R. Hassler, "Papers on Various Subjects Connected with the Survey of the Coast of the United States," <i>Transactions of the American Philosophical Society</i> 2 (1825): 232-420, on 315-320 and pl. VII.
label: Description
content: "The Repeating Circle Without Reflection, as made by Troughton," in <i>The Cyclopaedia: or, Universal Dictionary of Arts, Sciences, and Literature</i>, edited by Abraham Rees (London, 1819), Vol. VII, Art "Circle."
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: American Philosophical Society. Transactions of the American Philosophical Society
label: Related Publication
content: Cyclopedia; or, Universal Dictionary of Arts, Sciences, and Literature
creditLine: label: Credit Line
content: United States Coast & Geodetic Survey
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.314640
label: catalog number
content: 314640
label: accession number
content: 208213
objectType: label: Object Name
content: repeating circle
physicalDescription: label: Measurements
content: overall: 32 1/8 in x 26 3/4 in x 17 in; 81.6356 cm x 67.945 cm x 43.18 cm
label: Measurements
content: upper circle: 17 1/2 in; 44.45 cm
label: Measurements
content: circle at base: 13 1/2 in; 34.29 cm
label: Measurements
content: telescope: 24 in; 60.96 cm
label: Measurements
content: overall; base: 16 3/4 in x 15 1/4 in x 16 in; 42.545 cm x 38.735 cm x 40.64 cm
label: Measurements
content: overall; horizontal circle: 13 in x 23 in x 20 in; 33.02 cm x 58.42 cm x 50.8 cm