1T. H. Pasley to Thomas Jefferson, 12 August 1816 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
2Robert Patterson to Thomas Jefferson, 10 January 1812 (Jefferson Papers)
pendulum; as basis for system of weights and measures [index entry]
3Thomas Jefferson to Robert Patterson, 10 November 1811 (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]