Reflecting Circle
date: label: date made
content: late 1830s
name: label: maker
content: Troughton and Simms
notes: label: Description
content: Edward Troughton, a prominent instrument maker in London, introduced this type of reflecting circle in 1796. The telescope, mirror, and filters are on one side of the circle, while the silver scale is on the other. The scale is graduated to 20 minutes, and read by three verniers (one has a tangent screw) to 20 seconds. The circle is supported on a heavy brass stand with a counterweight. The inscription reads "Troughton & Simms 240 LONDON." This example belonged to Worcester Polytechnic Institute, and was probably made in the late 1830s. Troughton & Simms was still offering instruments of this sort in the 1850s–at a cost of £23.
label: Description
content: Ref: Abraham Rees, <i>The Cyclopaedia; or, Universal Dictionary of Arts, Sciences, and Literature</i> (London, 1819), vol. 8, art. "Circle," and Plate III of "Astronomical Instruments."
label: Description
content: "Directions for observing with Troughton’s Reflecting Circle," quoted in F. W. Simms, <i>A Treatise on the Principal Mathematical Instruments</i> (Baltimore, 1836), pp. 51-54.
label: Description
content: "Catalogue of Instruments Made By Troughton & Simms," appended to William Simms, <i>The Achromatic Telescope</i> (London, 1852).
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
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content: Navigation
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content: Measuring & Mapping
creditLine: label: Credit Line
content: Worcester Polytechnic Institute
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1987.0924.01
label: catalog number
content: 1987.0924.01
label: accession number
content: 1987.0924
objectType: label: Object Name
content: reflecting circle
physicalDescription: label: Measurements
content: reflecting circle: 10 in; 25.4 cm
label: Measurements
content: overall: 15 1/4 in x 12 in x 10 3/4 in; 38.735 cm x 30.48 cm x 27.305 cm