1From Thomas Jefferson to Thomas Freeman, 16 November 1805 (Jefferson Papers)
Th: Jefferson asks the favor of mr Freeman, as he will be in the Mathematical shops in Philadelphia to endeavor to procure for him an accurate compass for surveying, with 2. pair of sights moving concentrically, an outer graduated circle with a Nonius to take angles accurately without regard to the needle, with it’s ball & socket & staff. he believes they are called Circumferentors but is not...