Alexis-Marie Rochon (Attributed)
Iceland crystal, brass, leather, pressed board, paper, and textile; L. closed 14 in. (35.6 cm), L. open 19 in. (48.3 cm), Diam. 2 1/6 in. (5.5 cm)
Monticello: The Home of Thomas Jefferson (Charlottesville, Va.), 1992-4-2a-c
This micrometer was given to Franklin by the pioneering astronomer Alexis Rochon, inherited by Francis Hopkinson, and given by him to Thomas Jefferson. It can still be seen at Monticello.