All Bones Considered: Laurel Hill Stories #043: Henry & Thomas Voigt, Isaiah Lukens & Henry Seybert – Tick Tock, Clocks and Watches, part 1, section 2

Henry Voigt built a special clock for Thomas Jefferson that he used for his astronomical experiments until the day he died.  You can see clocks made by Voigt both at Monticello and in the US Senate.