1Thomas Cooper to Thomas Jefferson, 1 September 1820 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
2Thomas Jefferson to Robert Patterson, 10 November 1811 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
3Thomas Jefferson to John Quincy Adams, 1 November 1817 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
4Thomas Jefferson to Robert Patterson, 11 September 1811 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
5T. H. Pasley to Thomas Jefferson, 12 August 1816 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
6Robert Patterson to Thomas Jefferson, 10 January 1812 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]