W. & S. Jones Reflecting Circle

This reflecting circle belonged to Georgetown University in Washington, D.C. and may have been purchased when Georgetown built an astronomical observatory in the early 1840s. It is of the "English" form designed by Edward Troughton in 1796. Here the telescope, mirror, and filters are on one side of the circle, while the silver scale is on the other side. This scale is graduated to 20 minutes, and read by three verniers (one has a micrometer screw) to 20 seconds. The circle is supported on a heavy brass stand with a counterweight. The inscription reads "W. & S. Jones, 30 Holborn, London."
Ref: Abraham Rees, The Cyclopaedia; or, Universal Dictionary of Arts, Sciences, and Literature (London, 1819), vol. 8, art. "Circle," and Plate III of "Astronomical Instruments."
Currently not on view
Object Name
reflecting circle
date made
ca 1845
W. & S. Jones
overall: 10 1/2 in; 26.67 cm
place made
United Kingdom: England, London
ID Number
catalog number
accession number
Measuring & Mapping
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Georgetown University
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