1To Thomas Jefferson from Alexander Macomb, 4 December 1824 (Jefferson Papers)
M r Thomas Levins, Professor of Natural and Experimental Philosophy in the College of Georgetown...
2To James Madison from Alexander Macomb, 18 June 1827 (Madison Papers)
Mr Thos. C. Levins, now of the city of new york, but formerly professor of mathematics & natural...
3James Madison to Alexander Macomb, 22 July 1834 (Madison Papers)
Professor Bonnycastle is desirous of obtaining your opinion on an improvement he has thought of...