- This is a precision clock associated with Andrew Ellicott. Ellicott became Surveyor General of the United States in 1792 and completed critical national astronomical surveys—most notably the boundaries for the District of Columbia in 1791-92 and the border between the United States and Spanish Florida in 1800.
- The clock’s original case and seat board for the movement have not survived. The square iron dial is marked “Ellicott/Baltimore.” It was originally painted white, with added painted floral spandrels. It has Roman hour numerals, Arabic minute numerals and separate seconds in Arabic numerals under 12. Andrew Ellicott or his father Joseph Ellicott made the brass time-only, weight-driven movement sometime before about 1790. The younger Ellicott made and attached the gridiron temperature-compensating pendulum, which he described as the first ever made in the United States, in a letter to Thomas Jefferson on 6 March 1803.
- Astronomers and surveyors used precision clocks like this one to observe the time that specific "clock stars" passed overhead. With a transit, a special kind telescope for observing stars, they noted the instant the star passed the local line of longitude.
- Reference: Robert S. Edwards, “Andrew Ellicott’s Field Regulator,” NAWCC Bulletin (October 1990): 419-427.
- Currently not on view
- Object Name
- clock movement in wooden case
- date made
- ca 1790
- place made
- United States
- overall: 158.1404 cm x 45.4152 cm x 27.305 cm; 62 1/4 in x 17 7/8 in x 10 3/4 in
- overall - key: 3 in x 3 1/2 in x 1 1/2 in; 7.62 cm x 8.89 cm x 3.81 cm
- ID Number
- catalog number
- accession number
- Credit Line
- Henry Ellicott Magill
- Data Source
- National Museum of American History
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