Scientist and politician.

Professor of mathematics at the College of Philadelphia (1761-64). Enthusiastically supported proprietary government; published several anti-Franklin pamphlets, including the scurrilous What is Sauce for a Goose Is Also Sauce for a Gander, in the election campaign of 1764. Practiced medicine in Philadelphia (c. 1767-73). Elected to American Philosophical Society (1768). Visited England (1773-76), where he warned the Privy Council that British policy might drive the colonies to revolt. He did not secure the Hutchinson correspondence for Franklin, as is often alleged, but he may have helped obtain copies of additional Hutchinson letters. Settled as a merchant in Edenton, North Carolina (1777). Surgeon-general of North Carolina troops; advocated smallpox inoculation and better sanitation at military camps. Served in North Carolina legislature, Continental Congress (1782-85, 1787-89), Constitutional Convention (1787), and U.S. Congress (1789-93). Moved to New York and devoted himself to scholarship, publishing numerous books and essays on history, natural history, medicine, and commerce; his work on climate and disease brought him international acclaim.

Son of John W. and Mary (Davison) Williamson of Chester County, Pennsylvania. Educated at the College of Philadelphia (B.A. 1757), Edinburgh, London, and Utrecht (M.D. 1766). Also licensed as a preacher. Married Maria Apthorpe (1789); two sons.