1Thomas Jefferson to Robert Patterson, 11 September 1811 (Jefferson Papers)
scientific instruments; pendulums [index entry]
2Thomas Jefferson to Robert Patterson, 10 November 1811 (Jefferson Papers)
scientific instruments; pendulums [index entry]
3Robert Patterson to Thomas Jefferson, 10 January 1812 (Jefferson Papers)
scientific instruments; pendulums [index entry]
4Robert Patterson to Thomas Jefferson, 24 April 1813 (Jefferson Papers)
scientific instruments; pendulums [index entry]
5Thomas Jefferson to Charles Willson Peale, 21 March 1815 (Jefferson Papers)
scientific instruments; pendulums [index entry]
6Charles Willson Peale to Thomas Jefferson, 2 May 1815 (Jefferson Papers)
scientific instruments; pendulums [index entry]
7Robert Patterson to Thomas Jefferson, 24 October 1815 (Jefferson Papers)
scientific instruments; pendulums [index entry]
8Robert Patterson to Thomas Jefferson, 28 November 1815 (Jefferson Papers)
scientific instruments; pendulums [index entry]